Records of the Museums and Art Galleries
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Volume 16

December 2000

The Beagle, Records of the Museums and Art Galleries of the Northern Territory

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Front cover: Leptothecate hydroid colonies, Lytocarpia angulosa (left) and Nemertesia cylindrica (right), from Darwin Harbour
(From J. E. Watson, pages 1-82)

The Beagle

Records of the Museums and Art Galleries
OF THE Northern Territory

Volume 16, December 2000
CONTENTS

WATSON, J.E. - Hydroids (Hydrozoa: Leptothecatae) from the Beagle Gulf and Darwin Harbour,

northern Australia.1

BRUCE, A. J. - The rediscovery of Leandrites stenopus Holthuis, 1950 (Crustacea: Palaemoninae),

from Lucinda, Queensland.83

BRUCE, A. J. - Onycocaridella prima Bruce, 1981, a rare pontoniine shrimp from Darwin Harbour

(Crustacea: Decapoda: Pontoniinae).89

BRUCE, A. J. - Biological observations on the commensal shrimp Paranchistus armatus (H. Milne

Edwards) (Crustacea: Decapoda: Pontoniinae).91

VON HAGEN, H.-O.- Vibration signals in Australian fiddler crabs - a first inventory.97

BROWN, G. R. - Caetmthynnus, Nitidothynnus and Procerothynnus, new genera of Thynninae

(Hymenoptera: Tiphiidae) from northern Australia.107

MACHIDA, Y. - A new bythitid genus and species, Acarobythites larsonae, from shallow rocky reefs

off northern Australia (Pisces, Ophidiiformes, Bythitidae).123

KAILOLA, P. J. - Six new species of fork-tailed catfishes (Pisces, Teleostei, Ariidae) from Australia

and New Guinea.127

MURRAY, P. and MEGIRIAN, D. Two new genera and three new species of Thylacinidae

(Marsupialia) from the Miocene of the Northern Territory, Australia.145

CHATTO, R. and WARNEKE, R. M. - Records of cetacean strandings in the Northern Territory

of Australia. 163

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The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 2000 16 : 1-82

Hydroids (Hydrozoa: Leptothecatae) from the Beagle Gulf and Darwin Harbour,

northern Australia

JEANETTE E. WATSON

Honorary Associate, Invertebrate Zoology, Museum of Victoria,
GPO Box 666E, Melbourne, VIC 3001, AUSTRALIA,
jewatson @bigpond. com

ABSTRACT

Sixty-three species of leptothecate hydroids including 12 new species and six new records for Australia are reported
from three collections (one dredging and two SCUBA diving) made in the Beagle Gulf and Darwin Harbour in the
Northern Territory of Australia. Large, visually dominant hydroid colonies from reef and soft bottom include known
species with distributional ranges throughout the Indo-Pacific, Indonesia and the Timor Sea. The systematic status of
several poorly known species is reviewed and ecological observations used to unravel past confusion of several species.
The preferred and possibly obligatory habitat for many species is the tubiculous polychaete worm Eunice tubifex.

Keywords: Hydroids, Leptothecatae, Beagle Gulf, Darwin Harbour, northern Australia.

INTRODUCTION

This is the second report on hydroids collected from
the Beagle Gulf and environs of Darwin Harbour in the
Northern Territory of Australia. The first paper (Watson
1999) described the anthoathecate hydroids; this paper
describes the leptothecate hydroids. The Beagle Gulf is
a large, open embayment of the northern Australian
mainland facing the Timor Sea between Melville and
Bathurst Islands; Darwin Harbour lies on an inlet of the
Beagle Gulf (Fig. 1). A description of the physical regime
of the Beagle Gulf and environs of Darwin Harbour is
given in Watson (1999).

Leptothecate species reported in this paper are derived
from three separate collections: a major dredging survey
of the invertebrate fauna of the Beagle Gulf undertaken
in 1993 by the Parks and Wildlife Commission of the
Northern Territory (formerly Northern Territory
Conservation Commission) and two collections made in
the environs of Darwin Harbour in August-September
1998 and in September 1999, the latter two collections
being made by the author and others using SCUBA.
Underwater collections in the environs of Darwin were
made on reefs I km off East Point (EP), Plater Rock, I
km offshore from Talc Head (PR), from the breakwater
and channel bed off the East Arm Port (EA) and on wharf
piles and port structures in the Port of Darwin (PD).
These collections from hard substrate augment the
Beagle Gulf collection which was dredged from
predominantly soft bed. While the collections upon
which this report and Watson (1999) are based have

considerably increased knowledge of the hydroid fauna
in the Beagle Gulf, future collecting will certainly add
more species to the faunal list.

Materials and methods of collection are given in
Watson (1999). Station number, locality, depth and date
of sampling in the Beagle Gulf Survey from which
hydroids were recovered are listed in Table 1. Species
and sites of collection are listed in Table 2. A taxonomic
index is provided as Appendix 1. Type and voucher
specimens are lodged in the Museums and Art Galleries
of the Northern Territory, Darwin (NTM C) and the
Museum of Victoria, Melbourne (MV F).

Eighty-three of the 162 stations occupied in the
Beagle Gulf Survey yielded leptothecate hydroids. Of
the 63 leptothecate species recorded in this study, 12 are
described as new, five of these being collected by
SCUBA diving in the environs of Darwin Harbour and
six species are new records for Australia. Twenty-two,
20 and 19 species were recorded from three Beagle Gulf
stations (Stns 136, 154, 87 respectively). These stations
were among those sampled furthest from land, but apart
from this geographical relationship they appear to share
no common environmental features, the bed ranging from
coarse sand at -6 m (Stn 87), rocky bottom at -30 m,
(Stn 154) and a sponge bed at -18 m (Stn 136). Species
recorded at these stations include Macrorhynchia
Phoenicia, Idiellana pristis, Thyroscyphus torresii,
Plumularia scabra, Plumularia badia, Nemertesia
cylindrica, Lytocarpia angulosa, and Gymnangium
longicorne. These species were also the most visually
dominant seen in the two extensive SCUBA surveys in
the environs of Darwin Harbour. Underwater

1

J.E. Watson

Fig. 1. Map of mainland Australia showing location of Beagle Gulf
and Darwin.

observations in the environs of Darwin Harbour found
that some other species (e.g. Sertularella diaphana, S.
quadhdens, Gymnangium hians, Agkwphenia delicatula,
Macrorhynchia philippina and Thyroscypbiisfruticosus)
as well as several new species, were much more abundant
than indicated by the dredged material. The only well
represented species in the Beagle Gulf Survey collection
not seen in Darwin Harbour was Salacia simiosa.

Most of the previously known species range
throughout the Indo-Pacific, Indonesia and the Timor
Sea; many have circumtropical affinities extending to
the Suez area, the Mediterranean Sea and the West Indies.
Two ( Thyroscyphus macrocytharus, Salacia sinuosa), are
endemic to tropical and subtropical Australia. Kir-
chenpaueria irregularis and Monotheca flexuosa are
known only from Australia and South Africa while
Filellum serratum, Antennella secundaria and Plu-

Table 1. Beagle Gulf stations from which leptothecate hydroids were recovered.

Stn

No.

Locality

Depth

m

Substrate

Date

sampled

7

N of Cape Ford, Anson Bay, 13° 25.08’S, 129° 53.94’S

13

Sand, shale, coral rubble

1/10/1993

9

NE of Cape Ford, Anson Bay 13° 25.02’S, 129° 55.98’E

16

Sine sandy mud

1/10/1993

13

NNE of Cape Ford, Anson Bay 13° 22.14’S, 129° 53.40’E

24

Sandy mud

2/10/1993

17

Anson Bay, I3°21.96’S, I30°4.98’E

12

Mud

2/10/1993

20

N of Cape Ford, Anson Bay. 13° 19.14’S, 129° 56.28’E

29

Coarse sand and shale

2/10/1993

21

W of Daly River mouth, Anson Bay, 12° 19.14’S, 129°.59.16’E

31

Mud

2/10/1993

26

S of Bateman Shoal, Anson Bay, 13° 16.08’S, 129°55.82’E

23

Coarse sand, shale and gravel

3/10/1993

27

SE of Bateman Shoal, Anson Bay 13° 15.90’S, 129° 58.86’E

19

Coarse sand

3/10/1993

32

E of Batemen Shoal. Anson Bay, 13° 12.96’S, 129° 59.10’E

13

Rocky bottom

3/10/1993

33

S of North Peron Island. Anson Bay, 13° 13.26’S, 130°1.92’E

9

Coarse sand and shale

3/10/1993

35

E of South Peron Island. 13° 12.84’S, I30°7.98’E

6

Coiase sandy mud and shale

2/10/1993

36

W of North Peron Island, Anson Bay, 13° 10.26’S, 129° 55.62’E

15

Coarse sand and shale

.3/10/1993

38

Channel Point to North Peron Island. 13° 9.24’S, 130° 5.52’E

20

Gravel

.3/10/1993

40

W of North Peron Island, 12° 6.96’S, 129° 58.86’E

8

Mud and rock

3/10/1993

48

NNE of North Peron Island, I3°0.96'S, I30°4.98’E

13

Mud, shale and sand

4/10/1993

49

N of North Peron Island, 12° 57.90’S, 130° 1.92’E

16

Mud

4/10/1993

50

NNE of Point Peron, I2°57.96’S, I30°4.98’E

10

Sandy mud

4/10/1993

52

E of Point Blaze, Fog Bay, I2°54.96’S, 130° 7.98’E

7

Mud and shale

4/10/1993

53

Eof Point Jenny, Fog Bay, 12°54.78’S, 130° 14.16’E

4

Sandy mud

4/10/1993

54

E of Point Jenny, Fog Bay. 12° 54.96’S, 130° 15.60’E

4

Sandy mud

4/10/1993

56

NW of Blaze Reef, Fog Bay. 12° 52.02’S. 130° 11.10’E

6

Coarse sand and shale

4/10/1993

57

E of Blaze Reef. Fog Bay, 12° 51.96’S, 130° 14.10’E

7

Mud and shale

4/10/1993

58

W of Finniss River, Fog Bay, 12° 7.02’S, 130° 56.10’E

7

Fine mud

4/10/1993

61

W of Five Mile Beach. Fog Bay, 12°49.92’S, 130° 19.38’E

7

Fine mud

5/10/1993

66

Bynoe Harbour. 12°41.88’S, 130°36.30’E

8

Sponge bed

7/10/1993

67

Bynoe Harbour, 12°70.92’S, I30°33.12’E

9

Coarse sand and shale

7/10/1993

69

SW of Dun In Mirrie Island, Fog Bay. 12°40.02’S, 130° 19.92’E

6

Mud

5/10/1993

74

Bynoe Harbour. I2°36.96’S. 130 32.04'E

26

Coarse sand and shale

7/10/1993

77

W of Unjin Point, Port Patterson. 12° 33.60’S, 130° 27.90’E

16

Sandy mud and gravel

6/10/1993

78

Eof Unjin Point. Bynoe Harbour, 12° 34.02’S, 130° 32.04’E

28

Coarse sand, shale and gravel

7/10/1993

80

NW of Roche Reef, Grose Islands. 12° 31.02’S, 130° 17.22’E

17

Coarse sand, shale and gravel

5/10/1993

81

N of Bass Reef. Grose Islands. 12° 31.02’S, 130° 20.04’E

15

Gravel and sponges

5/10/1993

82

W of Quail Island. Grose Islands, 12° 30.96’S, 130° 22.92’E.

9

Coarse sand and gravel

6/10/1993

84

E of Moira Reef, Bynoe Harbour 12° 31.20’S, 130° 31.74’E,

11

Coarse sand and gravel

6/10/1993

85

N of Bass Reef, Bynoe Harbour, 12° 27.96’S, 130° 20.16’E

19

Coarse sand, shale and mud

6/10/1993

87

S of Fish Reef. Grose Islands, 12° 27.90’S. 130° 26.70’E

6

Coarse sand

6/10/1993

88

W of Middle Reef, Bynoe Harbour, 12°28.02’S, 130° 28.98’E

38

Mud. gravel and rock

6/10/1993

89

Middle Reef, Bynoe Harbour, 12° 28.80’S, 130° 32.10’E

14

Mud and gravel

7/10/1993

91

NW of Fish Reef, Grose Islands, 12° 25.44’S, 130° 25.92’E

19

Mud and gravel

6/10/1993

2

Beagle Gulf and Darwin Harbour hydroids

miliaria setacea are temperate and tropical cosmopolitan
species. Seven, mostly small and inconspicuous species
{Hebella llaterocaudata, Anthohebella parasitica,
Sertularella decipiens, Halopteris plagiocampa,
Plumularia bedoti, Clytia Iwarreni, Clytia linearis) are
new to the tropical Australian region.

Abundant material and diving observations of
previously unknown habitat preferences, habit and colour
of colonies served to differentiate between several
species which in the past have been confused or con¬
sidered to be variants of known species. Ample material
from the diving surveys has also provided a basis for

review of the systematic status of several poorly known
species.

Many of the species reported in this paper were found
on the tubes of the polychaete worm Eunice tubifex
Crossland, 1904. The tough mucilaginous tubes which
stand erect to a height of c. 30 cm, occur abundantly on
reef and man-made structures throughout Beagle Gulf
and Darwin Harbour. The tubes provide a more or less
sediment-free substrate for a diverse invertebrate com¬
munity of small compound ascidians, bryozoans, sponges
and hydroids. Eunice tubifex is a preferred and possibly
obligatory habitat for several hydroid species.

Table 1 (cent.). Beagle Gulf stations from which leptothecate hydroids were recovered.

Stn

No.

Locality

Depth

m

Substrate

Date

sampled

92

E of Fish Reef, Bynoe Harbour, 12° 24.84’S, 130° 28.92’E

17

Coarse sand and gravel

6/10/1993

93

Thrings Channel, Bynoe Harbour, 12° 24.96'S, 130°31.98’E

29

Shale

7/10/1993

95

Charles Point, 12° 21.90’S, I30°3I.92’E

15

Gravel and sponges

7/10/1993

97

NE of Charles Point, 12°21.84’S, 130°37.86’E

14

Coarse sand and shale

7/10/1993

100

N of Nightcliff. Darwin Harbour, 12° 21.18’S, 130° 50.40’E

5

Muddy sand and seagrass

12/10/1993

101

WNW of Charles Point, 12° 19.02’S, 130° 34.02’E

19

Sand, gravel and mud

7/10/1993

104

Darwin Harbour, 12° 19.08’S, 130°43.92’E

15

Fine sandy mud

13/10/1993

105

Outer Darwin Harbour, 12° 19.02’S, 130° 47.10’E

15

Mud, sand, shale and seagrass

12/10/1993

106

Outer Darwin Harbour, 12° 18.08’S, 130° 50.40’E

12

Mud, gavel and shale

12/10/1993

110

Outer Charles Point, 12° 15.84’S, 130°37.86’E

27

Sandy mud

13/10/1993

111

Outer Charles Point. 12° 16.08’S. 130°40.98’E

28

Sandy mud

13/10/1993

113

Outer Darwin Harbour. 12° 15.84’S, I30°47.22’E

20

Sandy mud and shale

12/10/1993

114

Outer Darwin Harbour, 12° 16.08’S, 130°50.04’E

18

Mud, gravel and shale

12/10/1993

115

N of Lee Point, Shoal Bay. 12° 16.02’S, 130° 53.04’E

16

Mud and shale

11/10/1993

116

Shoal Bay, 12° 15.96’S, 130° 55.86’E

13

Sandy mud and seagrass

12/10/1993

118

Fenton Patches, Darwin Harbour, 12° 13.08’S, 130°44.04’E

20

Coarse sand and shale

12/10/1993

119

Outer Darwin Harbour, 12° 12.90’S, 130°47.04’E

23

Mud

12/10/1993

120

Outer Darwin Harbour, 12° 13.02’S, 130°50.04’E

22

Coarse sand, shale and mud

12/10/1993

121

Shoal Bay, 12° 13.02’S, 130° 52.92’E

19

Mud

12/10/1993

122

Shoal Bay, 12° 13.08’S, 130° 55.98’E

17

Sandy mud and seagrass

12/10/1993

126

Outer Darwin Harbour, 12° 10.08’S, 130°46.92’E

30

Mud and gravel

12/10/1993

127

Outer Darwin Harbour, 12° 10.02’S, 130°49.86’E

27

Muddy sand, shale, sponges

12/10/1993

129

W of Gunn Point. Shoal Bay, 12° 09.96’S, 130° 59.76’E

15

Gravel

131

Mouth of Leaders Creek, Shoal Bay, 12° 9.36’S, 131° 8.32’E

4

Sandy mud

10/10/1993

132

NE of Stephens Point, Adam Bay. 12° 10.02’S, 131° 11.40’E

4

Sandy mud, shale and gravel

10/10/1993

136

Outer Shoal Bay, 12° 6.90’S, 130°49.92’E

18

Sponge bed

12/10/1993

137

SW of Marsh Shoals, outer Shoal Bay, 12° 7.02’S, 130° 52.92’E

20

Sponge bed

12/10/1993

138

S of Marsh Shoal, Vernon Islands. 12° 7.02’S. 130°56.10’E

16

Gravel

11/10/1993

139

SSE of Lyne Reef, Vernon Islands. 12° 7.08’S, 130° 59.04’E

30

Shale and rock

11/10/1993

140

Wof .South West Vernon Island. 12° 6.90’S, 13I°4.80’E

13

Coral rubble

10/10/1993

144

WofRuby Island, Chambers Bay, 12°7.08’S, 13I°20.04’E

22

Shale and coral rubble

146

N of Marsh Shoal, Vernon Islands. 12°4.02’S, 131° 55.86’E

39

Rocky bottom

10/10/1993

147

SW of North West Vernon Islands. 12° 4.02’S, 131° 58.86’E

16

Shale and gravel

10/10/1993

148

Sof North West Vernon Island, 12°3.96’S, 131° 1.92’E

25

Rock

10/10/1993

149

EofEast Vernon Island. 12°4.98’S, 131°8.40’E

26

Gravel, shale and sand

10/10/1993

150

Rooper Reef. Vernon Islands, 12° 3.96’S, 131° 11.IO’E

22

Gravel

10/10/1993

152

Wof Elizabeth Reef, Cape Hotham, 12° 4.02’S. I3I°20.04’E

21

Shale

9/10/1993

153

E of Dryston Reef, Cape Hotham, 12°4.08’S, I31°22.80’E

6

Sponge bed

9/10/1993

154

N of Oliver Reef. Vernon Islands. 12° 1.02’S, 130° 58.86’E

30

Rocky bottom

11/10/1993

155

Nof Nonh West Vernon Island. 12° 1.02’S, 131° 1.86’E

38

Shale and gravel

11/10/1993

156

W of Knight Reef, Vernon Islands. I2°I.20’S, 131° 3.96’E

22

Coarse sand, shale and rocks

11/10/1993

157

NW of Knight Reef, Vernon Islands, 12° 1.44’S, 13I°8.04’E

14

Gravel

10/10/1993

159

NW of Cape Hotham. 12° 1.32’S, 131° 13.92’E

34,

Coarse sand and shale

9/10/1993

160

North of Cape Hotham, I2°0.96’S, 131° 16.92’E

29

Sand, shale, gavel, sponges

9/10/1993

161

SE of Cape Hotham, 12°0.96’S, 131° 19.86’E

22

Coarse sand and shale

9/10/1993

162

Nof Dayton Reef, Cape Hotham, 12° 0.12’S, 13I°22.74’E

12

Mud and shale

9/10/1993

3

J.E. Watson

Table 2. List of species and sampling sites. Numerals represent Beagle Gulf Survey station numbers. SCUBA sampling sites in Darwin
Harbour are: EA = East Arm Port breakwater and channel, PD = Port of Darwin wharves, EP = East Point reefs, PR = Plater Rock, off Talc
Head.

Species

Sampling Sites

Lafoeimi amiranlensis (Millard and Bouillon, 1973)
Filellum Iserratum (Clarke, 1879)

Hebettopsis costata (Bale. 1884)

Hebellopsis scandens (Bale, 1888)

Hebella Itaterocaudata Billard, 1942

Anthohebella parasitica (Ciamician, 1880)
Anihohebella danvinensis sp. nov.

Halecium dyssymetrum Billard, 1929

Halecium spatulum sp. nov.

Hydrodendron dichotomum (Allman, 1888)

Diphasia nmtulata (Busk, 1852)

Dipha.ria digitalis (Busk, 1852)

Dynamena quadridentata Ellis & Solander, 1786
Dynamena bilamellata sp. nov.

Dynamena mertoni (Stechow and Muller, 1923)
Tridentata sp.

Idiellana pristis (Lamouroux, 1816)

38, 146

121, PR

7, 8, 13, 38, 40, 53, 57, 80, 85,136 137, 140, 146, 159, PD, EA, PR

20, PD, EA, PR

139

7, 13,33,38,40, 53, 137, 146, 159, PR

EA

40, EP

40, 48, PD.

138, PD, PR

77, 111, 127, 129, 137, 140, 146, PR

136

87

87

147, 52,156,40, 160, PD, PR

156

7, 13, 20, 26, 27, 35, 36, 40,48, 50, 53,57,58, 74, 78, 80, 81, 82, 84, 85, 88, 97, 121, 122,

Idiellana lepida .sp. nov.

Salacia he.xodon (Bu.sk, 1852)

Salacia sinuosa (Bale, 1884)

Salacia tetracythara (Lamouroux, 1816)

Salacia flavidula sp, nov.

Salacia alata sp. nov.

Salacia bidentata sp. nov.

Sertularella decipiens Billard, 1919

Sertularella quadridens (Bale. 1884)

Sertularella diaphana (Allman, 1885)

Sertularia trigonostoma Busk, 1852

Thuiaria opercidata sp. nov.

Thuiaria plumularioides sp. nov.

Thyroscyphus macrocytharus (Lamouroux, 1824)
Thyroscyphus torresii (Busk, 1852)

Thyroscyphus fruticosus (Esper, 1793)

Synthecium campylocarpum Allman, 1888
Synthecium orthogonium (Busk, 1852)

Antennella secundaria (Gmelin, 1791)

Halopteris polymorpha (Billard, 1913)

Halopleris plagiocampa (Pictet, 1893)
Monothecaflexuosa (Bale. 1894)

Nemertesia cylindrica (Kirchenpauer, 1876)
Plumularia badia Kirchenpauer, 1876

Plumularia scabra Lamarck, 1816

Plumularia setacea (Linnaeus, 1758)

Plumularia bedoti (Billard, 1911)

Plumularia tuhacarpa sp. nov.

Polyplumaria cornuta (Bale, 1884)

Kirchenpaueria irregn/ara Millard, 1958
Aglaophenia delicatiila (Busk, 1852)

Gymnangium Mans (Busk, 1852)

Gymnangium longicorne (Busk, 1852)

127, 129, 132, 136, 137, 140, 146, 147, 148, 150, 154, 159, 161, PD, PR, EP

PR

7, 20,42,54, 89, PR

48, 100, 137, 139, 147, 154, 155, 156

81, 126, 152, 155

PR

40

132

40, 147, 153, 154

97, 138 EP, PR

40, 87, 110, 113, 131, 146, 154, 156, EP, PR

7, 82, 84, 138, 154

146, EA
no, 153, 154

154

13, 48, 67, 78, 87, 110, 127, 136, 137, 138, 155, EA, PD, PR

PD, PR

13, 20,21,26,81, 110, 111,26, EA, PR

7.20.40, 87, 126, 136, PR

7, 37,82, 84, 95, 110, III, 127, 136

129, 146, I38,EP

121

87

121, 136, 139, 146, 147, 91, 137, EA, PR

52,58, 67,95, 101 EA, EP, PR

80, 136, 137, 147, PR

40, 137

136

87

66, 67, 92, 87, EA

PD

40,81, 127, 153, 154, 156, PR

154, EP, PR

7.40, 32,38,77, 78,81,87,91,97, 104, 110 127, 129, 136, 137, 144, 147, 149, 150, 152,

Gymnangium undulatum sp. nov.

Gymnangium unjinense sp. nov.

Lytocarpia angulosa (Lamarck, 1816)

156, 157, 159, 160, EA, PR

PR

77 104, 110,

17, 27, 67, 77, 82, 87, 89, 93, 100, 104, 105, 110, 111, 113, 114, 115, 116, 119, 120, 126,

Lytocarpia phyteuma (Kirchenpauer, 1872)
Macrorhynchia philippina (Kirchenpauer, 1872)
Macrorhynchia Phoenicia (Busk, 1852)
Macrorhynchia amhigua sp. nov.

Macrorhynchia quadriarmata sp. nov.

Clytia Iwarreni Stechow, 1919

C/yt/a/mean's (Thornely, 1900)

Clytia sp. 1

Clytia sp. 2

127, 132, 136, 161, EA

154, EP

49,61, no, 127, PD, EP

7, 127, 137, 136, 138, 154, 156, EA, PR

PD, PR

137

87

56

61

38

4

Beagle Gulf and Darwin Harbour hydroids

SYSTEMATIC REPORT

Order Conica Broch, 1910
Family Campanulinidae Hincks, 1868
Genus Lafoeina G.O. Sars, 1874
Lafoeina amirantensis (Millard and Bouillon, 1973)
(Fig. 2A, B)

Egmundella amirantensis Millard and Bouillon,
1973: 40. - Millard 1975: 133. - Gibbons and Ryland
1989: 389. - Ramil and Vervoort 1992: 22.

Lafoeina amirantensis - Calder 1991: 10. - Watson
1994: 147. - Calder and Vervoort 1998: 15.

Records and material. NTM C12947, alcohol
preserved material; NTM Cl2607, microslide, from
infertile colony, Stn 38. NTM Cl2608, microslide, from
infertile colony from Stn 146. Both colonies on
calcareous bryozoan.

Description. Colonies stolonal, hydrothecae minute,
arising at intervals from a creeping tubular hydrorhiza.
Hydrothecae tubular, perisarc thin, sometimes asym¬
metrically curved, base expanding from a very short
pedicel, body of hydrotheca increasing slightly in
diameter just below margin. Operculum of many fine
segments loosely overlapping at apex; no line of
demarcation between opercular segments and hydro-
thecal body. Nematotheca clavate, very small, borne on
stolon between hydrothecae.

Colour. Colourless to white.

Measurements (pm).

Hydrotheca

length including operculum

120 -

200

maximum width

52 -

72

Nematotheca

length

32 -

36

Remarks. The specimen and the single nematotheca
in the sample conform to previous descriptions and
dimensions of L. amirantensis (Watson 1994).

Distribution. Indian Ocean (Millard and Bouillon
1973), Mediterranean Sea, east Atlantic (Ramil and
Vervoort 1992), Bermuda (Calder 1991), Fiji (Gibbons
and Ryland 1989), and mid-Atlantic Ridge (Calder and
Vervoort 1998). This is the second Australian record of
L. amirantensis, the first being from Bass Strait, southern
Australia (Watson 1994).

Family Lafoeidae A. Agassiz, 1865
Genus Filellum Hincks, 1868
Filellum Iserratum (Clarke, 1879)

(Fig. 2C)

Lafoea serrata Clarke, 1879: 242. - Hartlaub 1905:
595.

Reticularia serrata - Ralph 1958: 312.

Filellum serratum - Millard 1975: 178. - Gravier-
Bonnet 1979: 22. - Ramil and Vervoort 1992: 54.
- Hirohito 1995: 110. - Pena Cantero et al. 1998: 304.

Fig. 2. A, B. Lafoeina amirantensis: A, hydrothecae. B,
nematotheca. C, Filellum ? serratum on tdiellana prist is. Scale bars:
A, B, 200 (im; C, 500 |im.

Records and material. NTM Cl2609, microslide,
sparse infertile colony creeping on Idiellana pristis, Stn
121. Other record. Plater Rock, infertile colony on
aglaopheniid stem, coll: J. E. Watson, depth 10 m, 21/9/
1999.

Description. Hydrolhecae erect, long, tubiform,
narrowing proximally to Junction with hydrorhiza;
marginal rim slightly but distinctly everted, marginal
replications common. Anterior adnate surface closely
transversely striated in some hydrothecae, smooth in
others.

Colour. Colourless.

Measurements (pm).

Hydrotheca

length of free part 320 - 560

diameter at margin 96 - 128

Remarks. In the absence of a coppinia it is difficult
to distinguish between Filellum antarcticum and
Filellum serratum, especially when proximal striations
are variable among hydrothecae as in the present
material. Striations typical of F. serratum are also
reported to occur on some hydrothecae of F. antarcticum
(Millard 1975). The present material is therefore

5

J.E. Watson

doubtfully assigned to F. serratum on the basis of the
longer erect part of the hydrothecae and shorter adnate
part, more typical of F. serratum than F. antarcticum.

Distribution. Cosmopolitan (Pena Cantero et al.,
1998). Previously recorded from Western Australia
(Stechow 1925, Watson 1996).

Genus Hebellopsis Hadzi, 1913
Hebellopsis costata (Bale, 1884)

(Fig. 3A)

Campaniilaria costata Bale, 1884: 56. - Stechow and
MUller 1923: 463.

Scandia corrugata Millard and Bouillon, 1973: 60.

Hebella muscensis Millard and Bouillon, 1975:
10. - BoQToetal. 1997: 22.

Records and material. NTM C1294I, alcohol
preserved material; NTM C12610, MV F86888, microslides,
colony on Idiellana pristis from Stn 57. NTM C12943,
alcohol preserved material from Stn 13. NTM Cl2942,
alcohol preserved material from Stn 85. Other records.
Many infertile colonies on Thyroscyphus torresi,
Synthecium campylocarpum and aglaopheniid hydroids,
Stns 7, 8, 13, 38, 40, 53, 80, 136, 137, 140, 146, 159.
Wharf pilings. Port of Darwin, infertile colonies on other
hydroids, coll: J. E. Watson, depth 1 - 10 m, 16/9/1998.
Plater Rock, infertile colonies on aglaopheniids and
Idiellana pristis, coll: J. E. Watson, depth 4 - 10 m, 19/
9/1999. East Point, infertile colonies on Thyroscyphus
torresii, coll: J. E. Watson, depth 1 m, 19/9/1999.

Description. Hydrorhiza tubular, creeping on stems
and branches of host. Hydrothecal pedicel short, tubular,
perisarc smooth, widening a little distally and merging
into base of hydrotheca. Hydrotheca long, tubular,
perisarc thick, inclined to one side in distal third so that
one wall convex and other concave, body with 8-11
deep entire annulations these becoming indistinct proxi-
mally, in some hydrothecae annulations reduced to
undulations. Margin circular, with up to four replications,
inclined to hydrothecal axis, rim distinctly everted,
perisarc fairly thin. Diaphragm saucer-shaped, thin,
indistinct, without thickening along hydrothecal wall, in
empty hydrothecae line of attachment of hydranth
marked by a row of internal upward-facing, thorn-like
desmocytes. Hydranths too poorly preserved for tentacle
count.

Colour. White to colourless.

Measurements (pm).
Pedicel

length

136

- 160

diameter below hydrotheca

96

- 136

Hydrotheca

length, diaphragm to margin.

convex wall

1,000

-1,120

diameter of margin.

including everted rim

440

- 500

width of marginal rim

48

- 56

Remarks. The specimens conform exactly with
Bale’s (1884) description and figures of Hebellopsis
costata epizootic on Idiellana pristis from the type
locality of Port Darwin. Dimensions of the hydrothecae
are, however, a little greater than those extracted from
Bale’s figure. No gonothecae were found among the
abundant material in the collection.

Millard and Bouillon (1975) were unable to distin¬
guish between sterile colonies of Scandia corrugata and
Hebella costata, and regarded both as nomina oblita,
replacing the name H. costata with H. muscensis and 5.
corrugata with 5. lubitheca. Their opinion, adopted by
Boero et al. (1997) is untenable since both H. costata
and H. corrugata are valid names used in the literature
during the past 50 years (Billard 1941, Pennycuik 1959,
Mammen 1965 and see Calder 1991).

Distribution. Indian Ocean, (Millard and Bouillon
1975) Papua New Guinea (Boero et al. 1997), Australia
(Bale 1884).

Hebellopsis scandens (Bale, 1888)

(Fig. 3B, C)

Lafoea scandens Bale, 1888: 758. - Jaderholm 1903:
274; - Billard 1904: 481; - Billard 1906: 174; - Warren
1908: 272, 341, 349.

Hebella scandens - Marktanner-Turneretscher 1890:
214. - Millard 1975: 182. - Gili and Ballesteros 1991:
247. - Genzano 1992: 144. - Migotto 1996: 26. - Watson
1996: 78.- Migotto 1997: 35. - Boero eta/. 1997: 8.

Hebellopsis scandens - Vannucci 1949: 237.
- Vannucci 1950: 85. - Calder 1991: 43, 45, 95.

Records and material. NTM Cl 3082, MV F86890,
microslides, infertile colonies on Synthecium campylo¬
carpum from Stn 20. Other records. Port of Darwin on
wharf pilings, fertile colonies on Idiellana pristis and
Thyroscyphus torresi, coll: J. E. Watson, depth 1-10 m,
18/9/1998. Plater Rock, infertile colony on aglaopheniid
stem, coll: J. E. Watson, depth 10 m, 21/9/1999.

Description. Hydrorhiza reptant on host; hydrothecae
long, tubular, directed upwards for first third or half of
length then bending sharply outwards and often
downwards, lower wall with a deep inflexure but without
internal thickening of perisarc; perisarc moderately thick,
thinning to margin. Margin transverse, circular, even,
with a short outrolled rim; some margins replicated two
or three times

Colour. Transparent white.
Measurements (pm).

Hydrorhiza, diameter

64

Hydrotheca

length abcauline wall,
base to bend

224 -

296

length abcauline wall,
bend to margin

200 -

304

diameter at margin

144 -

192

6

Beagle Gulf and Darwin Harbour hydroids

Fig. 3. A. Hehellopsis costata: two hydrothecae from colony on
Idiellana pristis. B, C, Hehellopsis scandens: B, colony on
Synthecium campylocarpum, hydrothecae inserted between those
of host. C. strongly flexed hydrotheca with everted margin. D,
Hebella? lateracaudata, infertile colony on Idiellana pristis. Scale
bars; A, B, 1,000 (im; C, D, 500 gm.

Remarks. Boero et al. (1997) reported colonies of
Hebella scandens from Papua New Guinea the
hydrothecae of which ranged in shape from almost
straight to a right-angle bend. Hydrothecae from Beagle
Gulf also show this morphological range, although it
does not occur along the same colony as described by
Boero et al. Colonies on Thyroscyphus torresii from
Plater Rock show even more extreme torsion, all
hydrothecae having two sharp right-angled bends.
Neither singly nor doubly bent hydrothecae on any of
the colonies I have examined seem to result from being
forced to accommodate to the morphology of the host
hydrothecae as described by Boero et al., most,
especially those on T. torresii being freely reptant. Either
H. scandens shows extreme morphological variation
according to the host species or there may be a different,
although clo.sely related species involved. The question
must remain unresolved until fertile material of the
doubly bent form is found.

Distribution. Cosmopolitan. Type locality, south¬
eastern Australia (Bale 1888).

Genus Hebella Allman, 1888
Hebella Haterocaiidata Billard, 1942
(Fig. 3D)

Hebella lateracaudata Billard, 1942: 69. - Van Praet
1979: 883. - Van Soest 1976: 81. - Boero 1980:
134.-Calder 1991: 39. - Boero era/. 1997: 18.

Record and material. NTM Cl2612, small infertile
colony on stem of Idiellana pristis from Stn 139.

Description. Hydrorhiza very thin, tubular, reptant
on branches of host, following imbrications of adnate
hydrothecal walls of host. Hydrothecae emergent
between Idiellana hydrothecae, proximal wall of
Hehellopsis resting on adcauline wall of host; hydrotheca
tubiform, asymmetrical, usually inclined downwards,
sometimes projecting directly away from host, wall in
contact with host convex, free wall sinuous, swollen
proximally, floor rounded, hydropore inserted on
abcauline side of floor. Marginal rim circular, transverse,
very thin, neither everted nor replicated.

Colour. White to colourless.

Measurements (pm).

Diameter of hydrorhiza 52

Hydrotheca

length 280 - 320

diameter at margin 120 - 128

Remarks. The hydrorhiza appears to be too weak to
support the hydrothecae, so that most rest on the
adcauline hydrothecal walls of the host. The short, stubby
hydrotheca with eccentrically placed hydropore is closest
to Hebella lateracaudata', the hydrotheca is, however,
shorter than the length of 560 pm given by Van Praet for
that species, the hydrotheca narrows, rather than expands
distally and the pedicel is smooth rather than slightly
undulated as in Billard’s (1942) figure. As the material
consists of only one small, infertile colony, it is assigned
with some reservation to H. lateracaudata.

Distribution. Indonesia (Billard 1942). This is the
first record of the species from the Australian region.

Genus Antliohebella Boero, Bouillon
and Kubota, 1997

Boero et al. (1997) proposed the genus Anthohebella
to accommodate hebellid species showing general
characters of the subfamily Hebellinae but liberating
swimming gonophores rather than a medusa. A hebellid
species collected in Darwin Harbour, which generally
conforms with these authors’ concept of Anthohebella,
but which liberates a partially formed medusa ne¬
cessitates amendment of the generic diagnosis of
Anthohebella.

Amended diagnosis of Anthohebella. Colony
stolonal, hydrotheca borne on a short pedicel, campan-
ulate or cylindrical, usually with annular thickening and
thin membranous diaphragm. Hydranth with conical
hypostome. Gonotheca solitary, originating from
hydrorhiza, with or without opercular flaps. Swimming

7

J.E. Watson

gonophore with or without a velum, four radial canals,
four marginal reduced tentacles or atentaculate bulbs,
and gametes on the spadix.

Anthohebella parasitica (Ciamician, 1880)

(Fig. 4A, B)

Lafoea parasitica Ciamician, 1880: 673.

Hebella parasitica - Marktanner-Turneretscher 1890:
213. - Hadzi 1913: 105. - Leloup 1937: 4, 28. - Leloup
1938: 8. -Da Cunha 1950:124. - Rossi 1950:
25. - Dawydoff 1952: 55. - Picard 1952: 347. - Yamada
1958: 51, 55. - Yamada 1959: 45. - Riedl 1970: 150.

- Vervoort and Vasseur 1977: 12. - Mergner and Wedler
1977: 16. - Boero 1980: 142. - Garci'a et al. 1979: 16.

- Gili 1982: 71. - Boero and Fresi 1985: 143. - Gili and
Gastello 1985: 13. - Boero and Bouillon 1989: 37.

- Gibbons and Ryland 1989: 380, 394. - Ryland and
Gibbons 1991: 527, 559. - Hirohito 1995: 122. - Watson
1996: 78.

Anthohebella parasitica - Boero et al. 1997: 24.
Records and material. NTM Cl2613, MV F86891
microslides from Stn 7. NTM Cl2614, microslide, from
Other records. Stns 13,38,40,53, 137, 146, 159,
many infertile colonies on stems of Gymnangium
longicorne. Plater Rock, infertile colonies on stems of
aglaopheniid hydroid, coll: J. E. Watson, depth 10 m, 22/
9/1999.

Description. Hydrorhiza tubular, creeping on stem
of Gymnangium longicorne, stolons running parallel
along fascicular tubes of host. Hydrothecal pedicels long,
deeply and roughly corrugated, perisarc very thick,
merging into body of hydrotheca.

Hydrotheca large, deeply campanulate, asymmetrical,
lower third of one wall convex, body then becoming
almost tubiform, walls smooth to slightly undulated,
perisarc moderately thick, thinning towards margin.
Diaphragm shallow dish-shaped, indistinct, marked by
a granular thickening at base of hydrotheca. Margin
oblique with a large, strongly outrolled rim, perisarc of
rim thin, some margins with a single replication.
Hydranths large, not well preserved, with c. 25 tentacles.

Measurements (pm).

Pedicel

length to diaphragm

400

- 720

diameter at junction with hydrorhiza

104

- 144

Hydrotheca

length, diaphragm to margin

1,000

-1,160

diameter at diaphragm

220

- 300

diameter at margin

66

- 800

width of marginal flange

96

- 112

Remarks. Anthohebella parasitica was abundant on
stems of many of the larger aglaopheniid hydroids from
many localities.

Distribution. Widely distributed in tropical and
subtropical Pacific and Atlantic Oceans (Vervoort and
Vasseur 1977), Mediterranean Sea (Boero 1980),

Fig. 4. A. B. Anthohebella parasitica from stem of Gymnangium
longicorne: A, hydrotheca with replicated margin and undulated
pedicel. B, hydrotheca with smooth pedicel. C, D, Hebellopsis
hartmeyeri Stechow and Muller, 1923 drawn from type specimen
on Lytoscyphus fniticosus: C, part of colony. D, hydrotheca showing
diaphragm and strongly outrolled marginal rim. Scale bars: A, B, C,
1,000 pm; D, 500 pm.

doubtfully recorded from Japan (Hirohito 1995).
Recorded from Western Australia (Watson 1996).

Anthohebella darwinensis sp. nov.

(Fig. 5A-D)

Record and material. Holotype, NTM Cl2958,
alcohol preserved material; NTM C12615, NTM
Cl2616, MV F86889, microslides from holotype, fertile
colony on Thyroscyphus torresi, from bed of channel.
East Arm port site, Darwin Harbour depth 6 m, coll: J.
E. Watson 17/8/1998.

Description. Colony stolonal, hydrorhiza tubular,
reptant on stem and branches of host. Hydrotheca arising
from stolon at regular intervals, usually beside a
hydrotheca of host. Hydrotheca long, narrow, tubiform,
bending outwards from hydrorhiza and away from host;
pedicel short, asymmetrically placed at base of
hydrotheca, sometimes with a single twist. Diaphragm
thin, concave, adjoined to wall by a ring of perisarc,
better developed as a triangular shelf on adcauline wall.
Margin circular, not everted, sometimes with a single
replication; perisarc of hydrotheca moderately thick.
Hydranth with conical hypostome surrounded by 20 -
24 tentacles.

Gonotheca large, elongate conical, borne without
pedicel on hydrorhiza, orifice distal, circular, operculum
a single flap, perisarc of gonotheca thin. Nearly mature
gonophore a single large eumedusoid; umbrella a small
disk with four vestigial radial canals; four long
rudimentary tentacles contracted into a wavy pattern; no
velum or manubrium.

8

Beagle Gulf and Darwin Harbour hydroids

Fig. 5. Anthofiehella darwinensis sp. nov. A, part of fertile holotype
colony on Thyroscyphiis torresii. B, hydrotheca, showing replicated
margin. C, base of hydrolheca showing thin diaphragm and perisarcal
ring. D, gonotheca with nearly mature cumedusoid. Scale bars: A,
1,000 pm;B-D, 500 pm.

Colour. In life, hydrotheca white, gonotheca
transparent to bluish-white, tentacles of gonophore white
to pink, radial canals pink.

Measurements (pm).

Hydrotheca

length of pedicel (to diaphragm)

160

- 200

narrowest width of pedicel

300

- 360

length, margin to diaphragm

960

-1,360

diameter at margin

368

- 424

Gonotheca

length

1,600

-1,760

maximum width

700

- 740

Remarks. The decidedly asymmetrical position of the
hydrothecal pedicel permits bending of the hydrotheca
alongside the hydrotheca of the host but depending on
aspect of view, the pedicel may appear to be centrally
placed. The large, solitary eumedusoids in the sample
are almost mature. The umbrella is quite small in
comparison with the length of the rudimentary tentacles.
Neither manubrium, velum nor gametes were found.

Since the hydrotheca of Anthohebella darwinensis
resembled figures of Hehellopsis hartmeyeri Stechow
and Muller, 1923 from the Aru Sea (see Stechow and
Muller, 1923, fig. 4), I examined type material of H.
hartmeyeri loaned by the Zoologische Staatssammlung,
Munich, Germany. The type series comprises two

Fig. 6. Halecium dyssymetrum from stem of Gymnangium
longicorne: A, stem. B, primary and secondary hydrophores. Scale
bars: A, 2,000 pm; B, 300 pm.

microslide preparations containing several hydrothecae
but no gonothecae. Both microslides are labelled
“Hehellopsis hartmeyeri, sp. nov., auf Lytoscyphus
fruticosus, Aru Inseln, Merton”. Stechow and Muller’s
figure of H. hartmeyeri is somewhat misleading as it
does not show the everted and outrolled marginal rim
distinctly visible in the few undamaged hydrothecae in
the microslides. Although considerably larger, the
hydrotheca of H. hartmeyeri closely resembles Hebella
scandens Bale. For comparison with A. darwinensis,
Hehellopsis hartmeyeri is drawn from the type microslide
(Fig. 4C-D).

Etymology. Named for the type locality of Darwin
Harbour.

Family Haleciidae Hincks, 1868
Genus Halecium Oken, 1815
Halecium dyssymetrum Billard, 1929
(Fig. 6A-B)

Halecium dyssymetrum Billard, 1929: 307. - Leloup
1935:1. - Millard 1975: 150. - Watson 1996: 78.
- Migotto 1996: 32. - Watson 1997: 514.

Endothecium dyssymetrum - Cix\der 1991: 15.

Records and material. NTM Cl2921, alcohol
preserved material; NTM Cl2617, microslide, infertile
colony on Gymnangium longicorne Irom Stn 40. Other
records. East Point, many infertile colonies on coral
rubble, coll: J. E. Watson, depth 1 m, 26/9/1999.

Description. Hydrorhiza tubular, reptant on host;
stems to 5 mm high, simple, monosiphonic, internodes
geniculate, nodes oblique, indi.stinct to absent. Primary
hydrophore distal on stem internode, long, expanding to
diaphragm; diaphragm marked by an internal flexure of
perisarc, secondary hydrophores when present, arising
from diaphragm of primary hydrotheca. Hydrotheca deep

9

J.E. Watson

bowl-shaped, expanding to a circular margin; margin not
everted. Hydranths large.

Colour. White.

Measurements (pm).

Stem

length of internode

400 -

600

diameter at node

112 -

152

Hydrotheca

length of primary hydrophore

to diaphragm

60 -

360

depth of hydrotheca.

diaphragm to margin

100 -

180

diameter at diaphragm

120 -

160

diameter of margin

200 -

236

Remarks. The species conforms to the description
and dimensions of Haleciuin dyssymetrum reported from
Western Australia (Watson 1997). Abundant infertile
colonies were found on coral rubble in shallow water at
East Point (author’s observation. Sept. 1999).

Distribution. Halecium dyssymetrum is known from
the Indian Ocean, Indo-Pacific and West Indies (Millard
1975). Australian distribution: Houtman Abrolhos
Islands, Western Australia (Watson 1997).

Halecium spatulum sp. nov.

(Fig. 7A-E)

Halecium beanii (Johnston, 1838). - Stechow and
Muller 1923: 460.

Records and material. Holotype, NTM Cl3049,
alcohol preserved material, NTM C12618, NTM
Cl2619, microslides from holotype, female colony on
Eunice tubifex. Port of Darwin, on wharf pilings, coll:
J. E. Watson, depth 8 m, 18/9/1998. Paratypes, NTM
Cl2620, microslide, colony detached from substrate, Stn
40. NTM Cl2623, microslide, sparingly fertile colony
creeping on aglaopheniid stem, Stn 48. Other records.
Plater Rock, infertile colonies on other invertebrates,
coll: J. E. Watson, depth 5-10 m, 22/9/1999.

Description. Hydrorhiza reptant on substrate, stems
to 10 mm high, lower stems lightly to heavily fascicled,
irregularly branched in one to several orders of branching
more or less in the same plane; branches given off
opposite stem node, stem and branch internodes long,
straight, smooth, expanding distally to hydrophore, nodes
oblique, facing in opposite directions, a tumescence
above and below node. Primary hydrophores alternate,
short, usually a minute saddle-shaped notch between
hydrophore and stem, secondary hydrophores common,
tertiary hydrophores rare; secondary hydrophores
variable in length, base tumid on adcauline side, walls
expanding evenly to margin. Hydrotheca shallow dish¬
shaped, expanding a little to a circular margin with thin,
not everted rim; some hydrothecal margins replicated one
or twice, diaphragm distinct, a few very small ellipsoidal
desmocytes above diaphragm.

Hydranths extensible, with c. 16 tentacles.

Gonotheca elongated, spatulate, widening from base
to distal margin, arising without distinct pedicel from
below a primary hydrophore, distal end truncate, slightly
domed, no operculum, perisarc thin and smooth.

Colour. Fascicled stems pale brown, becoming white
in monosiphonic parts, female gonophore pale blue.

Mea.surements (pm).

Stem and branches

length of internode

400 -

504

width at node

64 -

80

Hydrotheca

primary hydrophore,
depth margin to diaphragm

24 -

28

diameter at margin

88 -

120

secondary hydrophore, depth,
base to margin

120 -

208

Gonotheca

maximum length

440 -

460

distal width

136 -

200

Remarks. Material of Halecium spatulum from
Beagle Gulf is meagre in comparison to the abundant
colonies collected in the environs of Darwin. The fragile,
lacy, white colonies are easily recognised in situ. The
few gonothecae present in the Beagle Gulf collection
were empty; those from Darwin Harbour were mature
female, each gonophore containing many small ova.

In size and shape of colony Halecium spatulum
resembles H. lankesteri (Bourne, 1890); however, the
marginal rim of the hydrotheca is more flaring in that
species (see Cornelius 1995). Halecium spatulum is also
closely related to H. sibogae Billard, 1929 (see Gibbons
and Ryland 1989, Ramil and Vervoort 1992), but lacks
the comma-shaped notch at the base of the adcauline
hydrothecal wall found in that species. Furthermore, the
marginal rim is much less everted than shown by Ramil
and Vervoort (1992), for H. sibogae marconanum
Billard, 1934. An infertile specimen referred to H. beanii
(Johnston, 1838) by Stechow and Muller (1923) from
Aru Island is undoubtedly H. spatulum.

Etymology. Named for the spatulate gonotheca.

Genus Hydrodendron Hincks, 1874
Hydrodendron dichotomiim (Allman, 1888)

(Fig. 8A-B)

Diplocyathus dichotomus Allman, 1888: 17.

- Kirkpatrick 1890: 604. - Billard 1929: 71. - Leloup
1939: 5. - Yamada 1959: 35.

Ophiodes dichotomus - Billard 1910: 4. - Jaderholm
1916: 4.

Hydrodendron dichotomus - Pennycuik 1959:155.

- Hirohito 1983: 13.

Hydrodendron dichotomum - Rees and Vervoort
1987:14.-Watson 1996: 78.

Records and material. NTM C12922, alcohol
preserved material; NTM Cl2621, NTM Cl2622, MV
F86894, microslides, large infertile colony intergrown

10

Beagle Gulf and Darwin Harbour hydroids

Fig. 7. Halecium spatulum sp. nov. A, stem from holotype colony. B, stem internodes from holotype. C, D, primary and secondary hydrophores
from holotype. E, female gonotheea from paratype NTM Cl2623. Scale bars: A, 2,000 pm; B - D, 300 pm; E, 500 pm.

Fig. 8. Hydrodendron dichotomum: A, stem. B, hydrothecae with strongly outrolled marginal rim and short and long dactylothecae. Scale
bars: A, 2,000 pm; B, 500 pm.

11

J.E. Watson

with bryozoan, from Stn 138. NTM C12923, MV
F86947, alcohol preserved material; NTM Cl3078,
microslide, infertile colony from wharf pilings. Port of
Darwin, coll: J. E. Watson, depth 12 m, 16/8/1998. Other
records. Plater Rock, infertile colony on sponge, coll: J.
E. Watson, depth 10 m, 21/9/1999.

Description. Colonies to 70 x 70 mm, hydrocaulus
unfascicled, a tangled and anastomosing mass of
dichotomous branches without main stem. Branches and
hydrorhiza of same diameter; cauline perisarc very thick
proximally, thinning a little toward distal end of
branches. Branches usually given off from distal part of
internode below an oblique to transverse node; in
younger branches sometimes an extra node or a series
of imperfect intemodal annulations, a hydrophore in each
branch dichotomy. Hydrophores alternate on younger
branches, borne distally on internode on short, thickened
apophyses, pedicel crumpled, walls of hydrophore above
pedicel swollen, more tumid on adcauline side, walls
thereafter smooth, expanding evenly to hydrothecal
margin; diaphragm deep bowl-shaped, no desmocytes
observed; margin circular, rim everted and somewhat
outrolled.

Nematothecae borne on a small platform below
apophysis, vase-shaped to almost tubiform, narrowest
at base and slightly constricted just below margin, rim
circular, sometimes weakly everted, perisarc thin.

Hydranths extensible, with c. 30 tentacles.

Colour. Live colony pale yellow-brown, hydrothecae
white.

Measurements (pm).

Stem

length of internode

400 - 440

diameter of internode

above apophysis

152- 184

Hydrotheca

length

256- 352

diameter at base

40- 56

diameter at margin

136- 160

Nematotheca

length

80- 120

diarrieter at margin

40- 60

Remarks. The colonies are so intimately intergrown
with their invertebrate substrates that it is difficult to
disentangle them. Few hydrothecae and axillary
nematothecae remain on older branches. No secondary
hydrothecae or desmocytes were seen in the samples.

The material corresponds to the description and
figures of Hydrodendron dichotomum from Cape York,
northern Australia (Allman 1888) and Indo-Pacific
localities given by other authors. The hydrothecae and
nematothecae are somewhat larger than dimensions given
by Rees and Vervoort (1987) for material from the Gulf
of Aden. Hydrodendron dichotomum is an epizooite of
invertebrates in Darwin Harbour; it has also been

reported on sponge and antipatharians by Rees and
Vervoort (1987).

Distribution. Indo-West Pacific, Gulf of Aden (Rees
and Vervoort 1987). Type locality, Torres Strait (Allman
1888); also recorded from tropical eastern and western
Australia (Pennycuik, 1959, Watson 1996) and Timor
Sea.

Family Sertulariidae Lamouroux, 1812
Genus Diphasia L. Agassiz, 1862
Diphasia miitiilata (Busk, 1852)

(Fig. 9A-G)

Sertularia mutulata Busk, 1852: 391.

Diphasia mutulata - Bale 1884: 101. - Ritchie 1910:
12. - Thornely 1904: 118. - Thornely 1908: 83. - Billard
1933: 16. - Mergnerand Wedler 1977: 18.-Watson 1996:
78.

Diphasia pinaster Billard, 1907: 357.

Diphasia heurteli BiWixrd, 1924:67.-Millard 1975:258.

Diphasia heurteli \av. 5 /nip/ejc Billard, 1933: 19.

Nigellastrum mutulatum - Stechow and Muller 1923:
468.

Records and material. NTM Cl2907, alcohol
preserved material; NTM Cl2624, NTM Cl2626, MV
F86908, microslides, colonies on .stems of agloapheniids,
bryozoans and Idiellana pristis from Stn 77. NTM
C12906, alcohol preserved material; NTM C12625,
microslides from Stn 146. MV F86907, microslide,
colony on Idiellana pristis from Stn 111. MV F86937,
alcohol preserved material, from Stn 137. Other records.
Stns 127, 129. Plater Rock, fertile colonies on stems of
agalopheniid hydroids, coll: J. E. Watson, depth 9 m,
22/9/1999.

Description. Colonies of simple stems to 10 mm high
arising at intervals from tubular hydrorhizae creeping
on host; stems unbranched, proximal stem region
variable in length, tubular, athecate, perisarc smooth,
ending in a strong hinge Joint. Hydrothecae biseriate,
paired, sometimes in contact, one pair on internode,
nodes transverse, indistinct or absent.

Two distinct kinds of stems, each with differently
shaped hydrothecae morphologically similar to Diphasia
mutulata and D. heurteli occur in the colony.

Diphasia mutulata morph: tubular, adcauline wall
sinuous, often a distinct hump in mid-region, free
adcauline wall one quarter to one third length of adnate
wall; abcauline wall concave to sinuous, deflected
outwards, sometimes an internal shelf of perisarc well
below margin; margin large, shovel-shaped, facing
upwards, operculum dome-shaped, perisarc very
delicate, often collapsed into hydrotheca.

Diphasia heurteli morph: tubular, long, narrow at
base, expanding a little to margin, adnate adcauline wall
convex, free part concave, c. half adcauline wall free;
abcauline wall concave, a long upwardly pointed internal

12

Beagle Gulf and Darwin Harbour hydroids

Fig. 9. Diphasia mutulata: A, stem from colony on Idiellana pristis. B, C, stem internodes from same colony. B, Diphasia mutulata
morph. C, Diphasia heurteli morph. D, lateral view of hydrotheca of Diphasia mutulata morph. E, lateral view of hydrotheca of Diphasia
mutulata morph showing operculum. F, gonotheca. G, orifice of gonotheca with operculum. Scale bars: A, 2,000 pm; B, C, 500 pm; D, E,
G, 200 pm; F, 500 pm.

shelf about two-thirds distance up wall; margin facing
upwards almost perpendicular to cauline axis with a pair
of low lateral lobes, operculum usually collapsed
inwards, perisarc delicate.

Gonothecae monoseriate and closely adpressed to
hydrocaulus, one between each hydrothecal pair on a
short, wide, pedicel; gonotheca ovoid, body covered in
irregular rows of short, thick, distally-facing spines,
distal orifice a small tube surrounded by spines.

Colour. Pale shining brown.

Measurements (pm).

Stem

length of athecate part

60

-1,900

diameter of athecate part

88

- 128

Internode

length of D. mutulata morph

400

- 440

length of D. heurteli morph

408

- 448

width at node, D. mutulata morph

240

- 264

width at node, D. heurteli morph

208

- 240

Hydrotheca

depth, abcauline margin to base,

D. mutulata morph

496

- 520

length adnate adcauline wall.

D. mutulata morph

336 -

392

length free adcauline wall,

D. mutulata morph

80 -

160

width across pair, margin to margin,
D. mutulata morph

720 -

808

width of margin,

D. mutulata morph

256 -

280

depth, abcauline margin to base,

D. heurteli morph

480 -

504

length adnate adcauline wall,

D. heurteli morph

400 -

408

length free adcauline wall,

D. heurteli morph

80 -

160

width across pair, margin to margin
D. heurteli morph

768 -

808

width of margin D. heurteli morph

176 -

240

Gonotheca

overall length

584 -

632

width (lateral view)

256 -

272

Remarks. The two morphologically distinct hydro¬
thecae occur on several of the colonies, the most

13

J.E. Watson

abundant morph corresponding to Diphasia mutulata
Busk (1852) and the less abundant to D. heurteli. Busk
(1852) drew attention to morphological differences
between hydrothecae of the stems and branches of D.
mutulata while Bale (1884) figured three different shapes
of hydrothecae for that species. Billard (1907), recorded
material from Mo 9 ambique as Diphasia pinaster (Ellis
and Solander 1786) but in 1924 synonymised the name
with D. heurteli. Millard (1975) remarked upon the
similarity of S. heurteli and D. mutulata, but nevertheless
considered the two species separate. In the present
material depth of the hydrotheca is similar in both
morphs, the main difference between them being the
slenderer hydrotheca with a stronger outward bend and
much more pronounced internal shelf in the heurteli
morph (Fig. 9B). The mutulata morph is wider across
the margins and the margin is broader and more bracket¬
like (Fig. 9C). There is no discernible intergradation in
hydrothecal size or shape between the two morphological
extremes in the present colonies and while there is no
intermingling, the morphs arise in groups from a common
hydrorhiza. The gonotheca of D. heurteli figured by
Millard (1975) is immature; in the present material
gonothecae of both morphs are identical.

Distribution. Torres Strait (Busk 1852), Queensland
(Bale 1884) Gulf of Manaar (Thornely 1904), Andaman

Islands (Ritchie 1910), Suez area (Thornely 1908, Billard
1933), Red Sea (Mergner and Wedler 1977).

Diphasia digitalis (Busk, 1852)

(Fig. lOA-B)

Sertularia digitalis Busk, 1852: 387, 393.
Desmoscyphus longitheca Allman, 1877: 26.
Desmoscyphus acanthocarpus Allman, 1888:73.
Nigellastrum digitale - Stechow 1923: 12, 161.

- Mammen 1965: 57.

Diphasia digitalis - von Lendenfeld 1885a: 415, 633.

- Nutting 1900: 110. Nutting 1904: 110. - Ritchie 1910:
821. - Bale 1884: 101. - Bale 1915: 265. - Jaderholm
1916: 5, 16. - Jaderholm 1916: 16. - Jaderholm 1919:
16. - Jaderholm 1920: 4. - Jarvis 1922; 332, 343. - Hargitt
1924: 501. - Billard 1925: 209. - Gravely 1927: 14.

- Nutting 1927: 218. - Billard 1931: 249. - Leloup 1932:
161. - Vervoort 1946: 307. - Vervoort 1959: 254.

- Vervoort 1968: 37. - Vervoort 1972: 99. - Deevey 1954:
270. - Pennycuik 1959: 191. - Yamada 1959: 54. - Rees
and Thursfield 1965: 120.-Millard and Bouillon 1973:
67.-Millard and Bouillon 1974: 31.-Millard 1975:257.

- Mergner and Wedler 1977: 16. - Mayal 1983: 7.
-Watson 1996: 78.

Record and material. NTM C12627, colony of four
small infertile stems on Idiellana pristis from Stn 136.

Fig. 10. A, B, Diphasia digitalis: A, proximal part of stem. B, proximal stem internode with hinge joint and hydrothecate internode. C - E,
Dynamena quadridentata: C, stem from colony on aglaopheniid hydroid. D, stem internode. E, hydrotheca showing cuspate margin. Scale
bars: A, C, 2,000 pm; B, D, E, 200 pm.

14

Beagle Gulf and Darwin Harbour hydroids

Description. Stems arising from a creeping tubular
hydrorhiza; stems short, unbranched, each bearing three
to seven pairs of hydrothecae; proximal stem region
athecate, long, tubular, perisarc smooth, ending in a
strong hinge joint. Hydrothecae biseriate, paired, one pair
on internode, node transverse, often indistinct.
Hydrothecae long, tubular, expanding from a narrow base
at summit of long infrathecal part of internode, adnate
adcauline wall twice to three limes length of free wall;
free wall convex. Abcauline wall concave, sometimes
with a slight proximal bulge. Margin quadrangular,
perisarc delicate, a low cusp at summit of a longitudinal
frontal pleat extending from base of hydrotheca to
margin.

Colour. Colourless to pale brown.

Measurements (pm).

Stem

length athecate

1,280

-1,700

diameter athecate part

160

- 184

length thecate internode

744

- 832

diameter at node

168

- 192

Hydrotheca

width of pair across base

280

- 296

length adnate adcauline wall

552

- 632

length free adcauline wall

176

- 360

length abcauline wall

640

- 760

width across margin

216

- 240

Remarks. Although the sample

is small

and the

hydrothecal margins are extensively damaged; there is
no doubt that the specimen should be referred to D.
digitalis.

Distribution. Circumglobal in tropical and sub¬
tropical seas. Australian distribution, Torres Strait (Busk
1852); Queensland (Pennycuik 1959), north-western
Australia (Watson 1996).

Genus Dynainena Lamouroux, 1812
Dynamena quadridentata (Ellis and Solander, 1786)
(Fig.lOC-E)

Sertularia quadridentata Ellis and Solander, 1786: 57.

Pasya elongata Stechow and Muller, 1923: 469.

Dynamena quadridentata van elongata Billard, 1925:
195. - Yamada 1959: 57. - Pennycuik 1959: 193.

Dynamena quadridentata - Watson 1996: 520.

Record and material. NTM C12911, alcohol
preserved material; NTM Cl 2628, MV F86912,
microslides, infertile colony on stem of aglaopheniid
hydroid, from Stn 87.

Description. Stems simple, straight, to 10 mm high,
arising from a tubular, replant hydrorhiza. Proximal stem
region tubular, athecate, perisarc thick, ending in a strong
hinge Joint; stem thereafter thecate, internodes with three
or four pairs of opposite hydrolhecae, nodes transverse,
collar-shaped, a short infrathecal part below hydrothecal
groups. Hydrolhecae frontal on stem, laterally separated
or sometimes in contact; hydrotheca almost tubiform.

maximum width in distal third, bases and adcauline walls
in contact in each internodal group, adnate adcauline wall
convex, free part short, concave to convex, abcauline
wall concave to margin, a submarginal knob of perisarc
below margin; base of hydrotheca flat to slightly concave,
a small knot of perisarc at base of adcauline wall. Margin
facing outwards, oval, with two almost triangular lateral
lobes and a minute adcauline cusp, perisarc thin, an
abcauline opercular flap attached to submarginal knob.

Colour. Colourless.

Measurements (pm).

Stem

length of internode

1,200

-1,500

width at node

136

- 152

diameter of athecate stem

152

- 168

Hydrotheca

length adnate adcauline wall

324

- 336

length free adcauline wall

56

- 68

length abcauline wall

212

- 256

maximum width hydrotheca

112

- 128

depth of margin (lateral view)

88

- 96

width across marginal lobes
(ventral view)

180

- 192

Remarks. Although the hydranth shows no evidence
of a caecum, the species is referred to Dynamena rather
than Amphisbetia, a difficulty in interpretation also
remarked upon by Billard (1925). The minute adcauline
cusp noted by Billard (1925) is visible only in lateral
view of the hydrotheca in the present material. Dynamena
quadridentata is a highly variable species, many varieties
having been reported in the past; the present material
closely resembles the var. elongata previously recorded
from Australian waters.

Distribution. Dynamena quadridentata is known
from the Indonesian region (Billard 1925) the Aru Sea
(Stechow and Miiller 1923) and Japan (Yamada 1959).
In Australia it has been recorded from Western
Australia (Stechow 1925, Watson 1996) and Queens¬
land (Pennycuik 1959).

Dynamena bilamellata sp. nov.

(Fig. 1 lA-E)

Record and material. Holotype, NTM C12957,
alcohol preserved material; NTM C12629, NTM
Cl2630, MV F86920, microslides from holotype,
infertile colony on red alga, from Stn 87.

Description. Stems simple, monosiphonic, to 10 mm
high, arising from a flat, strap-like hydrorhiza; inflexures
in perisarc not reaching coenosarc canal. Proximal stem
region short, ending in a strong hinge joint, stem
internodes thereafter thecate, nodes slender, a transverse
collar-like constriction but sometimes with additional
hinge joint; infrathecal part widening from node to base
of hydrolhecae, suprathecal part short.

Hydrolhecae biseriate, in contact on front of stem,
separated behind, facing slightly forward and outward;

15

J.E. Watson

base of hydrotheca flat, body tubular, narrowing to
margin, adnate adcauline wall parallel to cauline axis,
free wall at an angle of 60“ to cauline axis, a little shorter
than adnate wall, straight to slightly convex, two small
spurs pointing downward into infrathecal part at base of
adcauline wall; abcauline wall gently concave, slightly
tumid near the base with a small submarginal thickening
below hydrothecal margin; in older hydrothecae two
prominent submarginal shelves project inwards into the
hydrotheca from adcauline and abcauline walls. Perisarc
of hydrotheca moderately thick.

Margin almost elliptical to subquadrate with two
broad lobate cusps midway between adcauline and
abcauline walls and a rounded, low adcauline cusp.
Operculum pyramidal, low, moderately thick, abcauline
valve the larger, adcauline flap divided into two; some
margins untidily renovated by regenerated opercular
valves. Hydranth stout, with c. 10 tentacles; no abcauline
caecum.

Colour. Colourless.

Measurements (pm).

Stem

distance between hydrothecal pairs

336 -

440

diameter at node

56 -

64

depth of infrathecal chamber

160 -

192

Hydrotheca

length adnate adcauline wall

92 -

136

length free adcauline wall

80 -

96

length abcauline wall

144 -

160

width across hydrothecal pair at floor

128 -

140

maximum width

84 -

108

width margin (lateral view)

60 -

64

Remarks. The hydrothecal margin is more delicate
than the opercular valves so it is often obscured; it is
better seen in ventral view. The adcauline marginal cusp
is more a change in angle of the rim rather than a true
cusp. While the abcauline submarginal shelf is always
present in younger hydrothecae, sometimes as a mere
thickening of the wall, it is more pronounced in older
hydrothecae, where it is produced into a distinct shelf
opposite an identical shelf projecting inwards from the
adcauline wall. Several stems end in long, trailing,
tendrils.

Dynamena bilamellata is related to several species:
1) to D. cornicina McCrady (1859) in its strongly
opposed cauline nodes, simple, unbranched stems, a
tendency towards apical stolonisation and the presence
of a submarginal abcauline shelf; there is, however, no
mention in the literature of paired abcauline and
adcauline shelves in that species, 2) to D. heterodonia
(Jarvis, 1922) in the presence of opposed shelves and
regeneration of the opercular valves but that species is
typified by overlapping sets of hydrothecae along the
internode and 3) to D. dalmasi (Versluys, 1899) (see
Calder 1991) in general morphology and in the presence

of opposed submarginal shelves. While fitting some of
the above criteria, the hydrocauli of D. bilamellata are
considerably smaller in all critical dimensions than any
of the above species.

Etymology. Named for the two internal submarginal
shelves.

Dynamena mertoni (Stechow and Miiller, 1923)
(Fig. 12A-G)

Sertularia mertoni Stechow and Muller, 1923: 472.

Records and material. NTM Cl2910, alcohol
preserved material; NTM C12631, MV F86927,
microslides, infertile colonies on Eunice tubifex from Stn
40. NTM Cl2909, MV F86934, alcohol preserved
material; MV F86926, microslide, colony from Stn 156.
NTM Cl2632, microslide, colony from Stn 52. NTM
Cl2633, microslide, colony from Stn 147. NTM Cl2634,
microslide, colony from wharf piles, Darwin Harbour,
coll: J. E. Watson 8/9/1998, depth 6 m, fertile colonies
on Eunice tubifex. Other records. Stn 160. Plater Rock,
on compound ascidian and sponge, coll: J. E. Watson,
depth 6 m, 22/9/1999.

Description. Hydrorhiza tubular, replant, and
strongly adherent to substrate. Stems to 20 mm high,
monosiphonic, pinnate, arising at irregular intervals from
hydrorhiza, pinnate, monosiphonic, rather lax, straight
or slightly flexuose, lower part of stem athecate,
moderately long, perisarc thick, ending in a strong hinge
joint. Stem internodes thereafter short, nodes transverse,
distinct, internodes becoming narrower distally. First two
hydrocladia above hinge joint usually opposite,
hydrocladia thereafter alternate, inserted above node at
an angle of 70 - 80° to stem axis on short apophyses
with transverse distal node varying from a mere
constriction to a deep collar; node followed by a short
athecate internode with one, sometimes two, deep, distal
hinge joints; hydrocladium thecate, inflated beneath
hydrothecae, nodes narrow, internodes bearing up to four
pairs of hydrothecae.

Hydrothecae biseriate, opposite, seated on front of
internode, long, tubular, adnate adcauline walls
conjoined, free adcauline wall c. one third length of
adnate wall, curved outwards, abcauline wall partly
adnate, straight proximally, concave distally, floor of
hydrotheca straight to faintly rounded. Hydrothecal
margin elliptical (ventral view) with two long, pointed
lateral cusps shifted to adcauline side and a minute
adcauline cusp, a small submarginal knot of perisarc on
abcauline wall, operculum of two valves, adcauline valve
with a central rupture line. A cauline hydrotheca in axil
of hydrocladium, one above, almost level with di.stal node
and one opposite, halfway along internode. Perisarc of
hydrocladia and hydrothecae thin.

Gonothecae grouped on proximal stem, large, barrel
shaped, borne on a short, stout pedicel, body faintly
corrugated to almost smooth, perisarc moderately thick.

Beagle Gulf and Darwin Harbour hydroids

Fig. 11. Dynamena bilamellata sp. nov. A, stem from holotype colony with apical tendril. B, proximal stem internodes with proximal hinge
joint. C, hydrotheca with submarginal shelves. D, E, opercular structures. Scale bars: A, 1,000 pm; B, 500 pm; C, D, E, 200 pm.

Fig. 12. Dynamena mertoni: A, infertile stem. B, proximal stem with hinge joint and opposite basal hydrocladia. C, hydrocladial internode.
D, ventral view of operculate hydrothecae. E, lobate hydrothecal margin with entire operculum. F, gonothecae on proximal stem. G, gonotheca
with planula larva. Scale bars: A, B, F, G, 2,000 pm; C, D, 500 pm; E, 300 pm.

17

J.E. Watson

orifice distal, circular, inside a short, slightly everted
collar, a row of denticles within, operculum a thick,
dome-shaped plug. Gonotheca containing a single large
planula larva.

Colour. Stems white to almost colourless, go-
nophores white to pale pink.

Measurements (pm).

Stem

length of internode

720

-1,160

diameter of transverse node

200

- 360

Apophysis

length of adcauline side

40

- 152

width at transverse distal node

88

- 152

Hydrotheca

length of adnate adcauline wall

400

- 544

length of free adcauline wall

168

- 200

diagonal total length of abcauline

wall to embayment

520

- 544

maximum width of hydrotheca

120

- 160

width of margin

between embayments

120

- 156

width across marginal lobes

(ventral view)

220

- 268

Gonotheca

length, excluding pedicel

1,700

-1,780

length of pedicel

64

- 80

maximum diameter

800

- 900

diameter of marginal rim

480

- 496

Remarks. Although it is somewhat difficult to extract
critical characters and comparative dimensions from
Stechow and Muller’s (1923) description of Dynamena
mertoni, I believe the present material is that species.

The abundant present material shows the species
should be referred to Dynamena. As noted by Stechow
and Muller, the perisarc of the lower stem is quite thick
with no evidence of polysiphony. In some stems where
there are two sets of basal hinge joints there are also
two pairs of opposite hydrocladia. Frequently, these
hydrocladia are shed, leaving only paired apophyses. In
many respects D. mertoni resembles D. cornicina
McCrady, 1858, the differences being: 1) the complete
absence of simple stems from the colonies, 2) the grouped
overlapping pairs, rather than single pairs of hydrothecae,
and 3) opposite hydrocladia above the basal hinge joint.
The distal collar of the gonotheca also resembles that
figured by Billard (1925) for D. cornicina: however,
other authors (e.g. Gibbons and Ryland 1989, Millard
1975) have not shown this feature. Unfortunately few
authors have given measurements or illustrations of D.
cornicina thus impeding comparison with doubt arising
as to whether all material referred to D. cornicina indeed
belongs to that species.

There is a strong superficial resemblance between
infertile hydrocauli of D. mertoni and very young stems
of Idiellana pristis, especially as colonies of both species
often share the same habitat of Eunice tiibifex (J. E. W.,
pers. obsv).

This is the second record of D. mertoni and first
description of the gonotheca. The species is abundant in
Darwin Harbour.

Distribution. Previously known only from the Aru
Sea (Stechow and Muller 1923).

Genus Tridentata Stechow, 1920
Tridentata sp.

(Fig. 13A-C)

Record and material. NTM Cl2635, microslide,
one infertile stem on the polychaete Eunice tubifex, Stn
156.

Description. Hydrorhiza a knot of tubes. Stem 5 mm
high, monosiphonic, branched, proximal stem region
short, athecate, perisarc thick, ending in several
transverse constrictions. Proximal thecate region with
three pairs of hydrothecae to level of first branch,
branching thereafter sub-dichotomous, a hydrotheca in
axil of dichotomy; dichotomous internode with a V-
shaped to transverse distal node. Hydrothecae paired on
internode, subalternate to opposite, frontal on branch
internode, pairs separated by a long, slender infrathecal
part and a short suprathecal part with deep transverse
collar-shaped node. Hydrothecae tubular, narrowing to
an upwardly tilted margin; adcauline walls of pair in
contact, parallel to branch axis, adnate adcauline wall
shorter than free part, free wall convex to almost straight,
bent outwards at an angle of 30 - 40° to internode;
abcauline wall concave, contiguous with infrathecal
chamber, base of hydrotheca variable, flat, slightly
convex or concave. Margin with two lateral lobes with
deep embayments between and a small adcauline cusp;
aperture oval, operculum of two tent-shaped valves,
perisarc thin. Hydranth with abcauline caecum and c. 20
tentacles.

Colour. Colourless.

Measurements (pm).

Stem

width above base 180

Branch

length of internode 496 - 520

width at node 64 - 80

length of infrathecal part 240 - 256

Hydrotheca

length of adnate adcauline wall 168 - 200

length of free adcauline wall

(to embayment) 184 - 224

length of abcauline wall

(to embayment) 192 - 200

depth of margin (lateral view) 88 - 108

width at margin (ventral view) 120 - 140

Remarks. As the specimen has an abcauline caecum,
three marginal teeth, an operculum of two valves and
almost opposite hydrocladial hydrothecae it is referred
to Tridentata (for generic definition and discussion of
Tridentata see Calder 1991 and Cornelius 1995). In some

18

Beagle Gulf and Darwin Harbour hydroids

Fig. 13. Tridentata sp. A, part of stem. B, stem internodes and hydrothecae. C, hydrotheca, showing lobate margin. Scale bars: A, 1,000 pm;
B, C, 300 pm.

malayensis Billard, 1925; however, in that species the
lateral cusps are much sharper than those of the present
specimen.

Due to the paucity of material and lack of gonosome
the species cannot be confidently referred to any known
species of Tridentata. Neither for the same reasons can
it be described as new.

Genus Idiellana Cotton and Godfrey, 1942
Idiellana pristis (Lamouroux, 1816)

(Fig. 14A-E)

Idya pristis Lamouroux, 1816: 200. - Allman 1888:
85, 39. - Jaderholm 1916: 16. - Jtiderholm 1920: 4.

- Jarvis 1922: 344. - Bale 1924: 249.

Idiella pristis - Stechow 1919: 106. - Stechow and
Muller 1923: 469. - Briggs and Gardner 1931: 191.

- Blackburn 1942: 116. - Vervoort 1946: 306. - Buchanan
1957: 365. - Vervoort 1959: 252.

Idiellana pristis - Cotton and Godfrey 1942: 234.

- Pennycuik 1959: 193. - Ralph 1961: 766. - Van
Germeden-Hoogeveen 1965: 16. - Vervoort 1968: 36,
103. - Millard 1968: 266. - Hirohito 1969: 21. - Millard
and Bouillon 1974: 8. - Millard 1975: 269. - Millard
1978: 194. - Bandel and Wcdler 1987: 41. - Vervoort
1993: 188. - Migotto 1996: 65. - Watson 1996: 78.

Dynamena crisioides f. gigantea Vannucci, 1946:
558.

Pasythea philippina Marktanncr-Turneretscher, 1890:
234, 239.

Records and material. NTM Cl2874, alcohol
preserved material; NTM C12636, MV F86913,

microslides, colony, female colony detached from
substrate, Stn 74. NTM Cl2875, alcohol preserved
material, from Stn 7. NTM Cl2637 microslide, colony
on Eunice tiibifex, from Stn 161. NTM Cl2876, alcohol
preserved material, from Stn 48. MV F86942, alcohol
preserved material, from Stn 26. Other records. Stns 13,
20,27, 35, 36, 40, 50, 53, 57, 58, 78, 80, 81,82, 84, 85,
88, 97, 121, 122, 127, 129, 132, 136, 137, 140, 146,
147,148, 150, 154, 159, many colonies on Eunice tubifex
or detached from substrate. Wharf pilings, Darwin
Harbour, many colonies on Eunice tubifex, coll: J. E.
Watson depths 1-10 m, 15-20/8/1998. East Point reefs
and Plater Rock, abundant fertile colonies on Eunice
tubifex, other invertebrates and dead coral, coll: J. E.
Watson, depths 1-12 m, 19-22/9/1999.

Description. Hydrorhiza a fibrous mass of thin,
tangled stolons. Stems 40-170 mm high, monosiphonic,
pinnate, sometimes sparingly branched, more or less
straight, perisarc of older stems thick, proximal stem
region usually athecate with remnant hydrocladia and
hydrothecae; stem internodes short, nodes almost
transverse, constricted, a hydrotheca in aphophysal axis,
a hydrotheca above and one opposite. Hydrocladia
alternate, straight, given off at an angle of 70 - 80“ from
side of stem on lower third of internode; hydrocladial
apophysis short with narrow, transverse distal node,
hydrocladial internodes bearing up to 10 pairs of
hydrothecae, internode beneath hydrothecae inflated.

Hydrothecae biseriate, long, set in an imbricated
pattern on front of hydrocladium; adcauline wall convex
to sinuous, adnate part overlapping opposite hydrotheca.

19

J.E. Watson

Fig. 14. Idiellana pristis: A, stem from young colony. B, part of
stem and hydrocladia, C, hydrocladial intemode showing imbricated
pattern of hydrothecae. D, hydrotheca showing lateral lobes. E,
gonotheca. Scale bars: A, 10 mm, B, E, 1,000 pm; C, 500 pm; D,
300 pm.

free part projecting upwards or outwards from hydro-
cladium. Abcauline wall concave to sinuous, lower third
adnate to adcauline wall of hydrotheca below, usually a
knot of perisarc at point where wall bends away from
hydrocladium. Margin elongate oval with a pair of
sharply pointed lateral lobes, embayments between deep,
perisarc thin; operculum of two valves, often a pleat in
adcauline valve. Hydrothecal perisarc moderately thick.
Hydranth buried deep inside sinuous part of hydrotheca.

Gonothecae borne in longitudinal rows on lower to
mid-region of hydrocaulus, one on internode; gonothecal
pedicel short, wide, body of gonotheca large, urn-shaped,
with numerous longitudinal pleats to shoulder, merging
into a short, wide, neck, rim everted and sealed by a
dome-shaped plug; perisarc of gonotheca very thick.
Female gonophore ovoid, containing many large ova.

Colour. Dark honey brown.

Measurements (pm).

Stem

length of internode

1,300 -1,700

width at node

500 - 700

distal width of apophysis

160 - 192

Hydrocladium

length of internode

1,440 -4,000

width at node

120

- 160

Hydrotheca

overall length

560

- 768

width across margin (ventral view)

208

- 240

Gonotheca

overall length

1,700

-1,740

width across shoulder

940

-1,120

diameter of margin

580

- 600

Remarks. Due to their imbricating pattern and
thickening of the perisarc with age it is difficult to draw
or measure individual hydrothecae in older specimens.
The Beagle Gulf material includes many young colonies
comprising single stems with soft, flexuous perisarc.
These differ in so many respects (llexuose stems, axillar
hydrothecae on cauline internode and poorly developed
imbrication of hydrothecae) that they could well be
mistaken for smaller species such as Dynamena mertoni
(Stechow and Muller, 1923). Intergradations can,
however, usually be found among the large range of
material. Idiellana pristis is one of the most widespread
species in the Beagle Gulf.

Distribution. Circumtropical, especially the Indo-
Pacific. Recorded from Western Australia (Watson 1996)
and tropical Queensland (Pcnnycuik 1959).

Idiellana lepida sp. nov.

(Fig. 15A-E)

Record and material. Holotype, NTM Cl2954,
alcohol preserved colony, NTM Cl2638, MV F86915,
microslides from holotype, colony on Eunice tuhifex.
Plater Rock, coll: J. E. Watson, depth 3 m, 21/9/1999.

Description. Flydrorhiza tubular, thick, entwining
substrate. Stems to 90 mm long, monosiphonic,
gracefully plumose, proximal part of stem long,
ahydrocladiate, nodes if present, transverse, faint; lower
stem perisarc thick, thinning distally; two rows of
opposite hydrothecae on stem, a distinct internal
coenosarc tube running up centre of ahydrocladiate stem
region.

Hydrocladia alternate, close-set, up to 15 mm long,
borne on a short, distinct apophysis directed upwards at
an angle of 40° to cauline axis, distal apophysal node a
transverse constriction, this followed by an athecate
internode with strong hinge Joint. Most hydrocladia
unsegmented; if segmented, internodes with at least four
pairs of hydrothecae, nodes strongly oblique, constricted.

Hydrothecae biseriate, paired, not protruding,
tubiform, base of one of pair sometimes slightly
displaced downwards with respect to other, each pair
slightly overlapping that above, adcauline walls in
contact, straight to convex, free length of adcauline wall
minute, adcauline wall slightly inturned at base, ending
in a small knob of perisarc, abcauline wall almost
straight, a small internal submarginal thickening in
perisarc. Cauline hydrothecae alternate, same as those
on hydrocladia but separated laterally and vertically, one

20

Beagle Gulf and Darwin Harbour hydroids

beside apophysis and two or three in a row above. Margin
of hydrotheca facing outward and tilted slightly upwards;
margin with two prominent ear-shaped lateral cusps,
perisarc thin, aperture oval. Operculum a single very thin
adcauline valve. Hydranth without caecum and with 16
- 20 tentacles.

Gonothecae abundant throughout hydrocladiate part
of stem, borne on caulus or hydrocladia; cauline
gonotheca inserted just above hydrocladial apophysis,
hydrocladial gonothecae proximal on hydrocladia,
arising behind hydrothecal pairs; gonotheca standing
erect on a long, bent pedicel with basal constriction or
twist, body large, barrel-shaped, faintly undulated to
almost smooth, narrowing to a short, wide, slightly out-
turned collar, operculum a low domed plug. Perisarc of
gonotheca very thick, distal collar of thick, rough strands.

Colour. Pale brown.

Measurements (pm).

Stem

distance between hydrocladia on same sidel ,200 -

1,400

width below hydrocladium 320 - 500

width of apophysis at distal node 128 - 144

Fig. 15. Idiellana lepida sp. nov. A, fertile stem from holoytpe
colony. B, part of stem and hydrocladia. C, hydrocladial internode.
D, cuspate hydrothecal margin. E, gonotheca. Scale bars: A, 10 mm,
B, 1,000 pm; C, 200 pm; D, E, 500 pm.

Hydrocladium

maximum length of internode

5,000

width at node

120

- 160

Hydrotheca

length of adnate adcauline wall

212

- 240

length of free abcauline wall

184

- 224

maximum width

92

- 104

width across margin, between cusps

(ventral view)

296

- 312

width of aperture

204

- 212

length of marginal cusp

20

- 24

Gonotheca

overall length

1,060

-1,200

diameter of collar

400

- 500

length of pedicel

160

- 216

Remarks. Although the hydrothecae appear opposite
in front view, from other angles of view they may appear
to be subopposite. The adcauline opercular valve is very
fragile and although none were found intact, its adcauline
position is inferred from fragments of tissue adhering to
the adcauline margin, the abcauline margin being
invariably free of tissue. Most gonothecae contain a web
of strands of tissue throughout the body. The absence of
maturing gonophores and intact operculae suggests the
gonothecae are immature.

Although it differs in respects such as arrangement
and some structures of the hydrothecae, the lack of an
abcauline caecum, the paired marginal hydrothecal cusps
and an adcauline opercular valve indicates the species
should be referred to Idiellana, a hitherto monospecific
genus.

Only one colony of 24 stems was found, suggesting
that Idiellana lepida may be a rare species.

Etymology. Refers to the graceful, lax colonies.

Genus Salacia Lamouroux, 1816
Salacia hexodon (Busk, 1852)

(Fig. 16A, B)

Pasythea hexodon Busk, 1852: 395. - Bale 1884: 113.
- Bale 1888: 771. - Jaderholm 1916: 5.

Salacia hexodon - Billard 1925: 207. - Pennycuik
1959:194. - Watson 1996: 78.

Records and material. NTM C12928, alcohol
preserved material, from Stn 42. NTM Cl2929, alcohol
preserved material; NTM C12640, MV F86910,
microslides, colony from Stn 7. NTM Cl2927, alcohol
preserved material, colony from Stn 54. Sparse infertile
colonies 20 - 40 mm high, detached from substrate. Other
records. Stns 20, 89. Plater Rock, small colonies amongst
other hydroids on Eunice tubifex, coll: J. E. Watson,
depth 8 m. 22/9/1999.

Description. Stems monosiphonic, slender, lax,
branching irregularly dichotomous, so that no true stem
is present; a short internode above each dichotomy and
a partially adnate hydrotheca in each axil. Internodes
long, tubular, expanding a little distally to proximal

21

J.E. Watson

Fig. 16. Salacia hexodon: A, part of stem. B, lateral view of
operculate hydrotheca. Scale bars: A. 1,000 pm; B, 300 pm.

hydrothecae, nodes transverse, collar-like, perisarc
moderately thick and smooth throughout.

Hydrothecae biseriate, three to five overlapping sub¬
opposite pairs, in a crest-like group; hydrothecae
separated laterally, more or less tubular, widest about
middle, inclined outwards, adnate adcauline wall
moderately convex, free part almost same length or
shorter than adnate wall; abcauline wall concave, adnate
part about same length as free wall; margin slightly
sinuate, inclined downwards, closed by a thick abcauline
operculum attached to a small internal submarginal peg.

Colour. Colourless to brown.

Measurements (pm).

Internode

length

2,150

-2,300

diameter at node

no

- 180

Hydrotheca

length of adnate adcauline wall

350

- 500

length of free adcauline wall

280

- 380

length of adnate abcauline wall

300

- 380

length of free abcauline wall

140

- 180

width of margin

240

- 280

Remarks. The distalmost internodes often extend into
tendrils although without any evidence of re-attachment
to new substrate. This distinctive, straggling species
occurs in small colonies of a few stems.

Dhstribution. A tropical species known from Torres
Strait (Busk 1852, Kirkpatrick 1890), Queensland (Bale
1888, Pennycuik 1959), north-western Australia
(Jaderholm 1916, Watson 1996) and Indonesia (Billard
1925).

Salacia sinuosa (Bale, 1884)

(Fig. 17A-E)

Thuiaria sinuosa Bale, 1888: 772. - Ritchie 1911:
844. - Levinsen 1913: 271. - Bale: 1914: 12. - Briggs

1914: 294. - Bale 1915: 279. - Mulder and Trebilcock
1914: 9. - Briggs 1918: 38. - Hodgson 1950: 38.

Salacia sinuosa - Stechow 1922: 150. - Stechow
1923: 214. - Billard 1925: 204. - Blackburn 1942: 115.

- Rees and Thursfield 1965: 151. - Watson 1994: 66.

- Watson 1996: 78.

Records and material. NTM Cl2926, alcohol
preserved material, colony from Stn 156. NTM C12925,
MV F86929, alcohol preserved material; NTM C12641,
MV F8691I, microslides, colonies detached from
substrate, Stn 154. Other records. Stns 48, 100, 137,
139, 147, 155.

Description. Hydrorhiza a tough plug of perisarc up
to 20 mm wide. Stems long, the tallest 22 cm high,
supple, smooth, strongly fascicled by many fine tubes
running more or less parallel up stem to end of branches;
lower stem region up to 3 mm thick, unbranched, mid to
upper region dichotomously branched in three or more
orders of branching in several planes producing a sparse
canopy, ultimate branches pinnate, up to 50 mm long
and 1 mm diameter at dichotomy, a short proximal length
of each branch ahydrocladiate, thereafter hydrocladiate.

Hydrocladia inserted on prominent, twisted a-
pophyses; three hydrothecae between successive
hydrocladia, one axillar and two above, adcauline wall
of distalmost adnate to hydrocladium; internodes usually

Fig. 17. Salacia .dmiosa: A. colony of one main stem. B, branch
with hydrocladia. C, hydrocladial internode. D, hydrotheca with
internal submarginal shelf and operculum. E. gonotheca. Scale bars:
A, 100 mm, B 1, 000 pm; C, E, 500 pm; D, 200 pm.

22

Beagle Gulf and Darwin Harbour hydroids

hydrocladia, one axillar and two above, adcauline wall
of distalmost adnate to hydrocladium; internodes usually
absent but when present, of variable length, nodes
strongly constricted.

Hydrothecae biseriate, opposite to subopposite,
separated transversely, overlapping vertically, tubular,
sinuous, narrowing from floor to margin; adcauline wall
usually completely adnate, but sometimes a short length
free behind margin, a small shelf below margin and a
circular to pyriform fenestration below base; abcauline
wall almost straight to convex, a shelf in perisarc just
below margin. Margin narrow, beak-shaped, inclined
obliquely downwards, oblong to subcircular (frontal
view), operculum attached to submarginal abcauline
shelf. Perisarc of margin and operculum thin, perisarc
of branches, hydrocladia and hydrothecae very thick.
Hydranth without abcauline caecum.

Gonotheca large, loaf-shaped, inserted without
pedicel between rows of hydrothecae, up to six
gonothecae along hydrocladium; gonotheca adnate to
hydrocladium, sometimes a short part behind margin free,
distal end often in contact with base of next, wall smooth
(see remarks), orifice distal, circular to subcircular,
upturned with a raised thickened rim, a ring of
irregularly-shaped denticles inside, operculum a thick
plug of tissue.

Colour. Lower stems and branches dark brown to
almost black, upper branches and hydrocladia pale
brown.

Measurements (pm).

Hydrocladium

distance between hydrocladia

on same side

1,800

-2,000

apophysis, length adcauline side

240

- 280

apophysis, width at node

192

- 240

Hydrotheca

depth, adcauline margin to base

432

- 520

width at floor

120

- 176

width at margin (lateral view)

88

- 104

Gonotheca

length

1,340

-1,520

maximum width

460

- 540

diameter of aperture

256

- 360

Remarks. The colonies conform to descriptions and
dimensions given by previous authors. The tough, woody
appearance, thick perisarc and dichotomously branched
canopy is distinctive. The beak-shaped hydrothecal
margin and opercular valve may have up to seven
replications.

Billard (1925) could not find in his material the
transverse annulations on the gonotheca reported by Bale
(1888) and suggested that their absence from his female
material may be due to sexual dimorphism. Faint
annulations present on the abcauline walls of many
Beagle Gulf gonothecae can only be seen in preserved

material but become invisible in cleared and mounted
specimens.

This species is abundant in deeper water in Beagle
Gulf. It was not found in the shallower waters of Darwin
Harbour.

Distribution. Indonesia (Billard, 1925). Better
known from Australian waters; Queensland (Bale 1888),
central coast of New South Wales (Ritchie 1911), Great
Australian Bight and Tasmania (Briggs 1914, Hodgson
1950), Western Australia (Watson 1996).

Salacia tetracythara Lamouroux, 1816
(Fig. 18A-F)

Salacia tetracythara Lamouroux, 1816: 212.

- Lamouroux 1821: 15. - Stechow 1913: 30. - Stechow
1922: I50.-Thornely 1916: 146. -Thornley 1924: 54.-
Billard 1925: 202. - Mammen 1965: 54. - Pennycuik
1959: 194. - Rees and Vervoort 1987: 103. - Gibbons
and Ryland 1989: 414. - Hirohito 1995: 183.

Thiiiaria fenestrata Bale, 1884: 116. - Bale 1888: 773.

- Kirkpatrick 1890: 604. - Nutting 1905: 950.

Calyptothiiiaria opposita Von Campenhausen, 1896:
312.

Tliitiaria tetracythara - Billard 1909: 319.

Records and material. NTM Cl2930, MV F86943,
alcohol preserved material; NTM Cl2642, microslide,
colony from Stn 126. NTM Cl2932, alcohol preserved
material, colony from Stn 155. NTM Cl2931, alcohol
preserved material; NTM C12643, MV F86909,
microslides, colony from Stn 81. All fertile colonies, on
dead bryozoans, sponge and shale. Other record, Stn 152.

Description. Tangled colonies to 100 mm high and
100 mm wide ranging from groups of simple, stiffly
pinnate stems to a large fan-shaped colony of many
intergrown stems with one or two orders of branches
arising from a thick, ramified hydrorhiza. Stems up to 2
mm thick at base, stems and major branches fascicled,
perisarc thick. Branch internodes visible only on
younger, monosiphonic regions, nodes a transverse
constriction, each internode with a hydrocladium and
three hydrothecae, one axillar, one opposite and one
below hydrocladium.

Hydrocladia long, monosiphonic, held out stiffly at
an angle of c. 60° to axis of branch from a broad
apophysis; apophysis with an indistinct, constricted,
distal node; hydrocladial internodes usually absent but
when present, with 2-6 pairs of hydrothecae.

Hydrothecae biseriate, immersed in hydrocladium,
subopposite, laterally separated, overlapping vertically,
long, tubular, narrowing from floor to margin; adcauline
wall convex, convexity increasing distally, adcauline wall
almost entirely adnate to internode, a very short free part
just behind margin, abcauline wall straight to concave,
floor of hydrotheca incurved to accommodate a thin
circular to ovoid adcauline fenestration. Hydrothecal

23

J.E. Watson

one median adcauline cusp, in anterior view margin sub-
eircular; operculum a single abcauline flap attached to a
small internal submarginal peg, perisarc of operculum
delicate.

Gonotheca large, globular, up to six in an upright
row along hydrocladium, pedicel short, perisarc very
thick, smooth, aperture surmounted by a raised collar
with vertical striations and a basal ring of large, internal,
inwardly pointing denticles; operculum a thick plug of
tissue.

Colour. Pale brown.

Measurements (pm).

Branch

length of internode

800

- 980

width at node

168

- 208

Hydrocladial apophysis

length, adcauline side

80

- 88

width at node

88

- 144

Hydrotheca

depth abcauline margin to base

384

- 440

maximum width

128

- 136

width at margin (lateral view)

120

- 128

Gonotheca

overall length

1,040

-1,060

maximum width

760

- 860

diameter of aperture

520

- 540

Remarks. The material conforms to descriptions of
Salacia tetracyihara by previous authors. In mono-
siphonic parts of the branches the hydrocladial internodes
are faintly flexuose, but this character is lost in older,
polysiphonic parts of the stems. In younger branches the
hydrocladial apophyses are sometimes quite long,
extending 250 pm from the hydrocaulus to the base of
the first hydrothecal pair. In large colonies the branches
and hydrocladia are heavily intergrown and in some
instances hydrocladia have extended and reversed
direction of growth, becoming attached to the substrate.
The marginal cusps of the hydrotheca are frequently
damaged or obscured by opercular tissue and are thus
difficult to see. While many gonothecae are empty,
maturing gonophores suggest the colonies are probably
male.

The hydrothecae of Salacia tetracythara superficially
resemble those of S.sinuosa, however, the species are
easily distinguished by colony form and shape of the
gonotheca.

Distribution. Indian Ocean (Rees and Vervoort
1987), Indo-Pacific (Billard 1925; Ryland and Gibbons
1989), Japan (Hirohito 1995). Torres Strait (Kirkpatrick
1890), Australian tropical to temperate east and south¬
east coast (Bale 1884, 1888; Pennycuik 1959).

Salacia flavidula sp. nov.

(Fig. 19A-D)

Records and material. Holotype, NTM Cl2959,
aleohol preserved material; NTM Cl2644, microslide

from holotype colony. Paratypes, NTM Cl2645, alcohol
preserved material, MV F86925, microslide. Colonies
on Eunice tubifex. Plater Rock, coll: J. E. Watson, depth
3 m, 22/9/1999.

Description. Stems up to 20 mm long, plumose, lower
ahydrocladiate stem region short, perisarc thick, lightly
fascicled by two or three stolonal tubes which may reach
proximal node; proximal node a blunt hinge joint,
hydrocaulus thereafter monosiphonic, segmented,
hydrocladiate. Cauline internodes short, nodes trans¬
verse, deeply indented, a pair of opposite hydrocladia
inserted on a wide shoulder-like apophysis above
proximal node; two pairs of opposite or subopposite
hydrothecae above hydrocladia, bases of hydrothecae not
in contact across stem. Hydrocladial apophysis with a
deep transverse proximal node and usually a secondary
transverse node, sometimes a shallow V-shaped distal
node. Hydrocladium broad, inflated below hydrothecae,
perisarc very thin, ending in a blunt distal tip;
hydrocladium usually entirely lacking nodes, but if
present, represented only by a faint constriction in
perisarc.

Hydrothecae biseriate, alternate, sessile, frontal on
hydrocladium, tubiform, narrowing to margin, adcauline
wall convex, adnate to hydrotheca above, abcauline wall
concave to almost straight, base of hydrotheca flat,
concave or convex, partially overlapped by hydrotheca
above. Adcauline margin of hydrotheca almost straight,
a pair of lateral lobate cusps flanking margin, abcauline
marginal embayment with a thin opercular valve.

Hydrocladial coenosarc and hypostome of hydranth
containing numerous large bean-shaped haplonemes,
none discharged. Hydranth with c. 24 tentacles, no
abcauline caecum.

Colour. Brilliant lemon yellow in life; brown when
preserved.

Measurements (pm).

Stem

length of internode

960

- 100

width at node

224

- 352

Apophysis

length (adcauline side) to distal node

136

- 240

width at proximal node

184

- 200

Hydrocladium

maximum length

8,000

depth behind hydrothecae

168

- 296

length of internode

2,400

-3,700

width at node

160

- 176

Hydrotheca

length (diagonal) adcauline wall

margin to base

360

- 400

length free abcauline wall

(lateral view)

240

- 264

width margin across cusps

128

- 160

Nematocysts

length

22

- 28

width

8

- 10

24

Beagle Gulf and Darwin Harbour hydroids

Fig. 18. Salacia tetracythara: A, fertile colony. B, hydrocladiate part of stem. C, hydrocladial internode. D, ventral view of hydrotheca
showing marginal cusps. E, operculate hydrotheca. F, gonotheca with operculum. Scale bars: A, 10 mm, B, 1,000 pm; C, F, 500 pm; D, E,
200 pm.

Fig. 19. Salacia flaviclula sp. nov. A, stem from holotype colony from Plater Rock. B, part of stem with opposite hydrocladia. C, part of
hydrocladium. D, lateral view of hydrocladium showing overlapping hydrothecae. E, frontal view of hydrotheca showing lobate cusps.
Scale bars: A, 10 mm, B, 1,000 pm; C, D, 500 pm; E, 200 pm.

25

J.E. Watson

Fig. 20. Salacia alata sp. nov. A, stem from holotype colony. B,
stem intemodes. C, view of hydrothecae showing marginal cusps.
Scale bars: A, 1,000 pm; B, C, .SOO pm.

Remarks. Although the colonies are quite stiff in life,
the hydrocaulus becomes lax and fragile when preserved.
While some species of hydroids have opposite proximal
hydrocladia, few have opposite hydrocladia throughout
the entire hydrocaulus. The intense yellow colour is
imparted by an abundant flora of zooxanthallae in the
coenosarc; this flora was .so resistant that it was difficult
not to destroy important diagnostic features of the
perisarc by pre-mounting clearing agents. As the material
was initially preserved in formaldehyde solution the
nematocysts could not be discharged, and so could not
be further identified. While the hydrothecae have quite
distinct marginal cusps, a feature unusual in Salacia, the
absence of a caecum and presence of an abcauline
operculum indicate the species should be referred to that
genus.

Salacia flavidula forms spectacular yellow colonies
of up to 30 stems on tubes of the polychaete Eunice
tubifex growing on coralline boulders in shallow water,
the stems of the hydroid arching out gracefully from the
substrate. Salacia flavidula was found only at Plater
Rock.

Etymology. Refers to the distinctive pale yellow
colonies.

Salacia alata sp. nov.

(Fig. 20A-C)

Record and material. Holotype, NTM Cl2646,
NTM Cl2647, MV F86914, microslides from holotype;
infertile colony on red alga on Eunice tubifex, Stn 40.
(All material mounted on microslides: no preserved
holotype material remaining).

Description. Hydrorhiza tubular, reptant on alga.
Stems simple, to 12 mm high, monosiphonic, proximal
stem tubular, of same diameter as hydrorhiza, athecate.

of variable length, ending in a strong hinge joint; perisarc
moderately thick, smooth. Stem internodes short, nodes
transverse, collar-shaped, sometimes indistinct, a pair
of hydrothecae on each internode, infrathecal and
suprathecal parts short. Hydrothecae biseriate, opposite,
tubiform, narrowing distally, adcauline walls in contact
in front, separated behind, conjoined part straight to
convexly curved, of variable length, free adcauline wall
bending sharply outwards to become almost perpen¬
dicular or at obtuse angle to cauline axis, abcauline wall
straight, a thick shelf of perisarc in flexure. Margin of
hydrotheca tilted downwards at c. 45° to cauline axis
with two small opposite lateral cusps, aperture sub-
circular, sometimes a remnant of abcauline opercular flap
inside, marginal perisarc thin. Hydranth without caecum,
with 16-20 tentacles

Colour. Pale honey brown.

Measurements (pm).

Stem

length of athecate section
length of thecate section
diameter of athecate section
length of thecate internode
width at node
Hydrotheca

length of fused adcauline wall
length of free adcauline wall
width at margin (lateral view)
diameter of margin (frontal view)

Remarks. Salacia alata resembles Salacia dubia
Billard, 1922, but in that species the hydrothecae are
conical, not tubular, not bent acutely outwards and the
species lacks an internal abcauline shelf.

Etymology. Refers to the sharply bent wing-shaped
hydrothecae.

Salacia hidentata sp. nov.

(Fig. 21A, B)

Record and material. Holotype, NTM Cl2648,
microslide, a small colony of three stems on Eunice
tubifex, Stn 132 (All material mounted).

Description. Hydrorhiza reptant on substrate, stems
monosiphonic, straight, proximal athecate region long,
tubiform, perisarc smooth, moderately thick, ending in
a strong hinge Joint. Stem hydrothecate above Joint,
hydrothecae biseriate, opposite, proximal intemodes with
a pair of hydrothecae, succeeding intemodes bearing two
to four pairs of hydrothecae, nodes transverse to V-
shaped, infrathecal segment immediately above node
variable in length, others segments short. Hydrothecal
pairs laterally separated in proximal stem region,
adjoining walls becoming fused in distal part of stem.
Hydrothecae tubular, narrowing behind margin, floor
curved to straight, a small knot of perisarc at base of
adcauline wall; adnate adcauline wall straight to slightly
convex, free wall about one quarter length of adnate part.

560

-2,000

2,600

-9,000

120

- 128

560

- 600

88

- 112

304

- 376

200

- 272

112

- 140

120

- 160

26

Beagle Gulf and Darwin Harbour hydroids

curved upwards to margin, a small submarginal plug of
perisarc projecting into hydrotheca; proximal abcauline
wall straight to slightly concave, curvature increasing at
flexure, a large hook-shaped or triangular submarginal
shelf in bend projecting into hydrotheca. Margin with
two blunt, wing-shaped lateral cusps, perisarc very thin,
remnants of a thin abcauline opercular flap inside many
hydrothecae. Hydranths well preserved, without caecum,
deeply withdrawn into hydrotheca, body closely
transversely wrinkled, approximately eight tentacles with
distinct rings of nematocysts.

Colour. Pale transparent yellow (preserved material).

Measurements (pm).

Stem

length of athecate stem
diameter of athecate stem

96

1,500
- 112

diameter at node

56

- 112

Hydrotheca

width across pairs at base

144

- 240

length of adnate adcauline wall

256

- 320

length of free adcauline wall

64

- 88

width of margin

72

- 80

length of abcauline shelf

40

- 56

Remarks. Although the colony consists of only a few
stems the large abcauline submarginal shelf and
adcauline peg distinguishes Salacia hidentata from other
species of Salacia. One stem shows evidence of breakage
and regrowth below the hinge joint and another bears a
hinge joint in the mid-stem region (Fig. 21 A).

Etymology. Refers to the two internal submarginal
cusps.

Fig. 21. Salacia hidentata sp. nov. A, stem from holotype colony.
B, internode showing cuspate hydrothecal margin, opercular
structures and triangular submarginal shelf. Scale bars: A, 1,000
pm; B, 500 pm.

Genus Sertiilarella Gray, 1848

There are three closely related species of Sertularella
in the Beagle Gulf collection. These are: S. decipiens
Billard \ 9\ 9, Sertularella diaphana 1885) and

5. quadridens (Bale, 1884) These species are also closely
related to S. pinnata (Lamouroux, 1816), a southern
Australian species not found in the Beagle Gulf. The
type locality of S. diaphana and S. quadridens is Moreton
Bay on the subtropical Australian east coast, both species
now being widely reported from the Indo-Pacific and S.
decipiens has been previously reported from Indonesia
and the Arafura Sea. In order to form a basis for
distinction between the species of this group, material
from the Beagle Gulf and other Australian localities,
specimens in the collection of the Museum of Victoria,
Australia, and in the author’s private collection, were
examined.

Sertularella decipiens Billard, 1919
(Fig 22 A-E)

Sertularella decipiens Billard, 1919: 21. - Billard
1925:155.

Records and material. NTM Cl2916, MV F86932,
alcohol preserved material; NTM Cl2964, microslide,
colony from Stn 154. NTM Cl2918, alcohol preserved
material; NTM Cl2965, microslide, colony from Stn 40.
NTM Cl2917, alcohol preserved material; NTM
Cl2963, MV F86919, microslides, colony from Stn 147.
Fertile and infertile colonies on Eunice tubifex. Other
record, Stn 153.

Description. Hydrorhiza reptant on substrate, tubular,
smaller in diameter than hydrocaulus. Stems to 30 mm
high, stiffly pinnate, monosiphonic, perisarc thick,
sometimes secondary branching; stem thecate almost
from base, divided into short internodes, nodes oblique,
deep, tilted parallel with hydrocladium below; three
hydrothecae on internode, one axillar, one below
hydrocladium and one opposite. Hydrocladia to 12 mm
long, given off alternately at an angle of c. 60" halfway
up cauline internode from a short apophysis, usually
marked by a distinct constriction in perisarc, constriction
deeper on proximal side of hydrocladium. Hydrocladial
internodes may or may not be present, but if present,
bearing three to six hydrothecae on each side, node an
oblique constriction in perisarc.

Hydrothecae subopposite to almost opposite, immer¬
sed in internode, cauline hydrothecae well separated,
close, but not in contact on hydrocladium, margin of one
reaching about halfway along adcauline wall of that
opposite; hydrotheca more or less tubular, narrowing a
little to margin, adcauline wall shallowly convex, usually
completely adnate but sometimes a very short free part;
abcauline wall almost straight and parallel to hydro¬
cladial axis, bending outwards just below margin, a small
shelf of perisarc projecting into hydrotheca at point of

27

J.E. Watson

cladial axis, bending outwards just below margin, a small
shelf of perisarc projecting into hydrotheca at point of
flexure; ratio of length of abcauline to adcauline wall 1:
1.4 - 1.8, base of hydrotheca flat to slightly convex, a
knot of perisarc projecting downwards into internode
from base of wall. Margin tilted upwards at an angle of
25° - 30° to hydrocladial axis with four low, equidistant,
sharp cusps, one adcauline, one abcauline and two lateral,
separated by wide, shallow embayments; operculum of
four valves. Margin not replicated.

Gonothecae borne on hydrorhiza and lower stem,
long, sausage-shaped, straight or curved, perisarc very
thick, pedicel variable in length, crumpled to almost
straight, body of gonotheca encircled by 8 - 10 deep
corrugations usually deepest about middle, fading out
proximally but some gonothecae merely undulated
throughout; aperture a shallow, transverse depression
surrounded by four low cusps, operculum of four valves.
Female gonophore ovoid, containing many large ova.

Colour. Live colonies pale yellow.

Measurements (pm).

Hydrorhiza, diameter

160

Stem

diameter at node

340

- 640

Hydrocladium

length of apophysis, abcauline side

104

- 240

diameter at proximal node

200

- 280

Hydrotheca

length of adcauline wall

600

- 624

length of abcauline wall

336

- 448

maximum width

256

- 336

diameter at margin

200

- 216

Gonotheca

length excluding pedicel

2,580

-2,800

length of pedicel

100

- 600

maximum diameter

740

- 980

diameter of aperture

640

- 780

Remarks. In fertile colonies, ova are not only present
in the gonothecae but are also distributed throughout the
coenosarc; whether this is a normal character of the
species or occurred during preservation could not be
determined.

In absence of the gonosome, S. decipiens can be
distinguished from other members of the species group
by the longer hydrotheca with distal outward bend, the
small submarginal shelf at the point of flexure and the
low inclination of the margin to the hydrocladial axis.

Stechow and Muller (1923) doubted the validity of
S. decipiens suggesting it may be conspecific with S.
qiiadridens. While the gonotheca of S. decipiens closely
resembles that of S. qiiadridens it is almost twice as long
as that of S. qiiadridens figured by Weltner (1900) and
Billard (1925), and described by Stechow and Muller
(1923). For this reason S. decipiens is considered a valid
species, albeit closely related to S. qiiadridens. Stems of

5. decipiens are shorter, less tidily arranged and are a
paler yellow than those of S. quadridens and S. diaphana.
Colonies of S. decipiens usually comprise a few stems
in a preferred habitat near the base of the tubes of the
polychaete Eunice tiibife.x.

Distribution. Indonesia (Billard 1919, 1925). Not
previously recorded from Australia.

Sertularella quadridens (Bale, 1884)

(Fig. 23A-F, Table 3)

Thuiaria quadridens Bale, 1884: 119.-Bale 1888:
772. - Bale 1924: 242. - von Lendenfeld 1885b:
915. - Hartlaub 1900: 120. - Weltner 1900: 586. - Ritchie
1910: 818.-Billard 1910: 11.-Billard 1925: 150.
- Jaderholm 1916: 6. - Stechow and Muller 1923:
471.- Vervoort 1941: 214. - Vervoort 1946: 314. - Ralph
1961: 830. - Rees and Thursfield 1965: 135. - Mammen
1965: 38. - Pennycuik 1959: 195.

Thuiaria vincta Allman, 1888: 68.

Records and material. NTM C12919. MV F86941,
alcohol preserved material; NTM C12967, MV F86918,
microslides, colony from Stn 97. NTM C12968,
microslide, colony from Stn 138. NTM Cl 2966,
microslide, colony from Stn 136. NTM C12920, alcohol
preserved material. East Point reef, Darwin, depth 7 m,
coll: J. E. Watson, 19/9/1999. East Point reef, Darwin,
depth 7 m, coll: J. E. Watson 17/8/1998, large infertile
colony. NTM Cl3079, microslide. Plater Rock, coll: J.
E. Watson, depth 8-10 m, 21/9/1999, large fertile colonies
on Eunice tubifex. Other record. Stn 159.

Description. Hydrorhiza a bunch of tubular stolons;
stolons creeping up stems to proximal hydrothecae but
not forming fasciculations. Stems monosiphonic,
pinnately branched in one plane, to 110 mm high, lower
stem perisarc thick, thinning distally, hydrocladia up to
10 mm long, given off alternately from proximal part of
stem internode, nodes deep, transverse to oblique,
inclined opposite directions; three hydrothecae on
internode between each hydrocladium, one in axil below
node, one opposite and one below hydrocladium, axillar
hydrotheca narrow at base, adcauline wall becoming free
at or just below junction with cauline node.

Hydrocladia arising from apophysis in top third of
internode, proximal part with several constrictions in
perisarc. internodes variable in length bearing two to five
hydrothecae on each side, nodes deep, transverse to
slightly oblique. First hydrocladial hydrotheca on lower
side of hydrocladium. hydrothecae thereafter sub-
alternate, not in contact, tubiform to flask-shaped, widest
about middle, adcauline wall gently convex or sometimes
with a slight flexure where adcauline wall becomes free,
wall two thirds to almost entirely adnate; free wall (when
present) continuing curve of adnate part. Abcauline wall
almost straight or a shallow sinuous curve, a short
outward deflection of the wall just below margin; length:

28

Beagle Gulf and Darwin Harbour hydroids

Fig. 22. Sertularella decipiens: A, stem from fertile colony. B, hydrocladia. C, hydrothecae on hydrocladium. D, quadrate hydrothecal
margin and operculum. E, gonotheca. Scale bars: A, 10 mm, B, E, 1,000 pm; C, D, 500 pm.

Fig. 23. Sertularella quadridens: A, fertile colony from Plater Rock. B, hydrocladiate part of stem from same colony. C, hydrocladial
intemode from same colony. D, E, two hydrocladial internodes with differing hydrothecae from microslide from Peel Island, Queensland
(microslide from Bale collection. Museum of Victoria). F, gononotheca from colony from Plater Rock. Scale bars: A, 300 mm, B, F, 1,000
pm; C - E, 500 pm.

29

J.E. Watson

wall free than hydrocladiate hydrothecae. Floor of
hydrotheca flat, thick, in mature hydrothecae a knot of
perisarc at base of adcauline wall often extending into a
spur. Margin circular, tilted upwards at an angle of 30° -
45° to hydrocladial axis with four equidistant low,
pointed cusps, one adcauline, one abcauline and two
lateral, rim thickened, operculum of four equal triangular,
fairly thick flaps; margin not replicated.

Gonothecae large, borne below hydrothecae in mid¬
stem region; gonotheca slender, barrel-shaped, pedicel
contiguous with body, perisarc thick, with eight deep,
widely separated annular flanges passing around body,
these fading out proximally; body between flanges finely
vertically striated, distal end wide, tubular, orifice large,
depressed into apex with four prominent equidistant,
outwardly turned protuberances, operculum not visible,
gonophore female.

Colour. Live colonies golden yellow.

Remarks. I have compared microslides of Sertu-
larella quadridens Bale 1884 from Peel Island, Moreton
Bay, Queensland, held in the collection of the Museum
of Victoria, Melbourne with the Beagle Gulf specimens
(see Table 3). The Beagle Gulf specimens are micro¬
scopically identical with a microslide preparation
labelled “Thitiaria quadridens Bale, Near Peel Island,
Moreton Bay, 1886” held in the Bale collection of the
Museum of Victoria. Sertularella quadridens is

Table 3. Measurements (pm) for Sertularella quadridens'.
comparison of Beagle Gulf specimens with type from Queensland.

Type from Peel

Beagle Gulf

Island

and Darwin

Stem

Length of internode

1,560- 1,800

1,200-1,660

width at node

340 - 440

224 - 640

length adnate adcauline
wall stem hydrotheca

344 - 440

360 - 408

length free adcauline wall
stem hydrotheca

144-216

160-200

Hydrocladium

length of internode

1,740-2 ,000

980- 1,860

width at node

200 - 320

200 - 340

width at apophysis
distance to first hydrotheca

136-200

140-320

(proximal side)

Hydrothcca (hydrocladium)

600 - 760

280 - 700

length of adnate adcauline
wall

400 - 480

300 - 464

length of free adcauline
wall

40 - 144

120-200

length of abcauline wall

376 - 384

320 - 384

width at base

168 -200

144-184

maximum width

232-288

256 - 280

diameter at margin

240 - 280

192-224

Gonotheca

length including pedicel

-

1,960-2,200

maximum width

-

760 - 820

length of pedicel

-

220 - 240

width of pedicel, proximal

-

140-180

depth of ridge

-

120-152

redescribed from both the type and Beagle Gulf
specimens.

The Beagle Gulf specimens are taller than the 25 -
50 mm length of stems reported by Bale (1884) but are
within the size range given by Billard (1925) for material
from Indonesia. The Beagle Gulf specimens have stout
stems and thick perisarc, in younger stems the cauline
nodes are a shallow constriction and may be altogether
absent from older, thicker stems. The basal adcauline
spurs described by Bale (1884) and mentioned by Billard
(1925) are very well developed below some cauline
hydrothecae in the Beagle Gulf specimens. These finger¬
like spurs are extensions of the adcauline wall, are
sometimes forked and occasionally pass completely
across the hydrocaulus to connect with the hydrotheca
opposite. Both the type and present specimens have a
variable length of adcauline wall free of the internode,
ranging from none to one third of the total adcauline
length. The distance between successive hydrothecae
along the hydrocladium and laterally across the
hydrocladium is highly variable in the Beagle Gulf
material, in some colonies successive hydrothecae are
well separated while in others the margin of one overlaps
the base of that above. As in the type, some cauline
hydrothecae are outwardly bent, widest in the distal half
to one third and become decidedly narrow towards the
margin; the marginal rim is noticeably thicker in the
present specimens than in the type. The ratio of length
of abcauline to adcauline wall of 1:1.7 is greater in the
present material than in the type.

Bale’s type material is infertile, the gonotheca being
first described by von Lendenfeld (1885b) from Timaru,
New Zealand and later from Indonesia (Weltner 1900,
Billard 1925), the Arafura Sea (Stechow and Muller
1923) and Cape Jaubert, Western Australia (Jaderholm
1916).

Billard (1925) erected the variety Sertularella
quadridens van cornuta (for S. polyzonias van cornuta
Ritchie, 1910) which was also recognised by later authors
(e.g. Vervoort 1993), to accommodate the considerable
longitudinal separation of hydrothecae and greater length
of internode than present in typical S. quadridens. The
greatly elongated internode together with a much longer
free adcauline hydrothecal wall, replication of the margin
and absence of a knot of perisarc at the base of the
adcauline wall suggest that the van cornuta may actually
be a distinct species.

Fertile colonies from Darwin Harbour occurred
mainly on the tubes of the polychaete Eunice tuhifex on
which substrate their golden colour is quite distinctive.

Distribution. Sertularella quadridens is widely
distributed throughout the Indo-Pacific and Indonesia.
Australian distribution: Queensland (Bale 1884,
Pennycuik 1959), Cape Jaubert, Western Australia
(Jaderholm 1916).

30

Beagle Gulf and Darwin Harbour hydroids

Sertularella diaphana (Allman, 1885)

(Fig. 24A-E)

Thuiaria distans Allman, 1877: 27 [secondary
homonym; not Dynamena distans Lamouroux, 1816].

Thuiaria pinnata Allman, 1877; 28 [secondary
homonym; not Sertularella pinnata Clark, 1876],
Thuiaria diaphana Allman, 1885:145.

IThuiaria hyalina Allman, 1888: 69.

Sertularella distans Hartlaub, 1901: 100. - Nutting
1904: 88. - Vervoort 1968: 104.

Sertularella pinnigera Nutting, 1904: 86. - Hartlaub
1901: 113.-Deevey 1954: 270. - Vervoort 1968: 105.
Sertularella torreyi Nutting, 1905: 934, 949.
Sertularella speciosa Congdon, 1907: 463. - Bennitt
1922: 250. - Fraser 1943: 92. - Deevey, 1954: 270.
Vervoort 1968: 44, 105. - Wedler 1975: 333. - Cooke
1977: 96. - Colin 1978: 139. - Bandel and Wedler 1987;
38. - Florez-Gonzalez 1983: 120.

Sertularella tridentata Stechow, 1913: 137. - Stechow
1925: 226.

Sertularella diaphana - Bale, 1919: 337. - Jader-

holm 1920: 6. - Billard 1925: 157. - Stechow 1925:
226.-Billard 1931: 248. - Billard 1933: 12 -Dollfus
1933: 127.-Millard 1958: 188.-Yamada 1958: 58.
- Yamada 1959: 63. - Pennycuik 1959: 195. - Hirohito
1969: 21. - Millard 1970: 268. - Schmidt 1972:

Fig. 24. Sertularella diaphana: A, hydrocladiate part of stem from
colony on Eunice tubifex. B, part of hydrocladial internode. C,
gonotheca. D, colony corresponding to Sertularella diaphana var.
delicata from Gymnangium longirostre. E, liydrothecae from same
colony. Scale bars: A, E, 1,000 pm; B, D, 500 pm; C, 5,000 pm.

42. - Millard 1975: 285. - Millard and Bouillon 1975:
14. - Millard 1978: 197. - Gibbons and Ryland 1989:
414. - Calder 1991: 101. - Vervoort 1993: 214. - Hirohito
1995: 192. - Watson 1996: 78.

Sertularella sargassi Stechow, 1920, 37. - Stechow
1923:179.

Sertularella quadrilateralis Hargitt, 1924: 493.

Sertularella diaphana var orthogona Billard, 1925;
161. - Van Soest 1976: 83.

Sertularella diaphana var. delicata Billard, 1919, 21.

- Billard 1925: 161.

Records and material. NTM C12912, alcohol
preserved material; NTM C12972, MV F86922,
microslides, colony from Stn 87. NTM C12914, alcohol
preserved material NTM Cl2969, microslide, colony
from Stn 154. NTM Cl2913, MV F86933, alcohol
preserved material; NTM C12970, microslide, colony
from Stn 110. Infertile branch fragments and small
colonies. Other records. Stns 40, 113, 121, 131, 146,
156. East Point, Darwin, tall branched infertile colony,
coll: J. E. Watson, depth 7 m, 11/8/1998. Plater Rock,
large fertile colonies on coral boulders and Eunice
tubifex, coll J. E. Watson, depth 3 m, 22/9/1999.

Description. Stems to 100 mm high, pinnately
branched in one plane, lower stem thick, fascicled,
polysiphonic tubes a continuation of hydrorhizal
filaments, stems becoming monosiphonic distally. Stem
internodes short, broad, nodes transverse to slightly
oblique, sometimes indistinct. Hydrocladia distal on
cauline internodes, three hydrothecae on internode, one
below hydrocladium, one in, or in front of axil and one
opposite, axillar hydrothecae adnate to caulus and of
same shape as others. Hydrocladia alternate, on indistinct
apophysis, proximal part fairly long, slender, athecate,
the first hydrotheca on basal side of hydrocladium.

Hydrothecae alternate, immersed in internode, short,
widely separated laterally, base of each reaching about
halfway up wall of that opposite, widest in proximal
third, adcauline wall convexly curved, a small knot of
perisarc at base, floor a downwardly tilted shelf,
abcauline wall straight to slightly concave, contiguous
with hydrotheca below. Margin subcircular in frontal
view, tilted upwards at angle of 45° - 60° to hydrocladial
axis, rim distinctly thickened with four equidistant, low
rounded cusps, one abcauline, one adcauline and two
lateral, separated by shallow embayments, no replication
of margin, operculum of four fairly thick triangular flaps.
Hydranth with deep abcauline caecum and about 20
tentacles.

Gonothecae borne on stem and hydrocladia, inserted
without pedicel below a hydrotheca, a circular foramen
connecting with hydrocladium; gonotheca elongate
conical, adpressed to hydrocladium, perisarc thick, most
with several longitudinal pleats, some indistinctly
undulated.

31

J.E. Watson

Colour. Live colonies orange to honey brown.
Measurements (nm).

Stem

length of internode

900

- 112

diameter at node

460

- 600

Hydrocladium

internode length

880

-1,700

diameter at node

160

- 200

width of apophysis

180

- 200

distance from apophysis

to first hydrotheca

360

- 440

Hydrotheca

length of adnate adcauline wall

360

- 392

length of free adcauline wall

48

diameter at margin

200

- 224

Gonotheca

maximum length

2,060

-2,400

diameter at aperture

440

- 520

Remarks. Irregular transverse folds present in some
gonothecae appear not to be normal ornamentation but
are probably the result of interruptions or damage to
growth.

A single, white, infertile stem 12 mm high, on
Gymnangium longirostre from Stn 87, differs con¬
siderably from typical colonies of Sertidarella diaphana.
The slender, unfascicled stem has longer stem internode,
greater separation of the hydrothecae along the
hydrocladium, hydrothecae expanding to the margin and
shorter adcauline wall (Figs 24C, D) conform exactly
with S. diaphana var. delicata Billard, 1925. While
concurring with Vervoort’s (1993) rejection of the var.
delicata as simply one of a range of intergrading forms
of S. diaphana, it is possible that this variety may well
be a distinct species. However, until the finding of a
better range of fertile material the specimen is referred
to S. diaphana.

Distribution. Virtually circumglobal in tropical and
subtropical waters (Vervoort 1993). Tropical east and
north-west Australia (Pennycuik 1959, Watson 1996).

Sertularella pinnata (Lamouroux, 1816)

(Fig. 25 A, B)

Caberea pinnata Lamouroux, 1816: 130.

Thuiaria lata Bale, 1882: 26. - Bale 1884: 120. - Bale
1894: 103. - Bale 1915: 287.

Sertularella lata - Nutting, 1904: 85. - Nutting 1905:
948. - Stechow 1913: 137. - Stechow 1923: 14. - Bale
1919: 337. - Jarvis 1922: 342. - Blackburn 1942: 115.

Sertidarella tridentata iMe.vho\m, 1917: 13.

Sertidarella Idiaphana - Stechow 1924: 69. - Stechow
1925, 226.

Sertularella pinnata - Gordon et al. 1998: 413.

Description. The following description is from a
microslide held in the collection of the Museum of
Victoria, Melbourne (MV F58895), labelled Thuiaria
lata Bale, 1884 “co-type”, and thought to be probably

syntype (Stranks 1993) and specimens in author’s
collection consisting of a large fertile colonies from 1)
Crawfish Rock, Western Port, Victoria, depth 15 m, coll:
J. E. Watson 24/11/66, 2) Green Cape, New South Wales,
depth 17 m, coll: J. E. Watson 14/2/73.

Stems up to 200 mm high, 5 mm thick at base,
plumose, with several secondary and tertiary branches
given off in the same or nearly the same plane; stem and
lower branches heavily fascicled, ultimate branches
monosiphonic. Monosiphonic branch internodes short,
very wide, nodes oblique, tilted in opposite directions,
hydrocladium arising a little more than halfway up
internode; internode with three hydrothecae, one in axil
of hydrocladium, one below and one opposite.

Hydrocladia alternate on a short apophysis marked
by a constriction in perisarc, hydrocladial internodes
variable in length, two to five hydrothecae along each
side, nodes distinct, oblique. Hydrothecae seated on front
of hydrocladium, separated laterally, abcauline wall
slightly sinuous, hydrotheca widest about middle,
adcauline wall convex, completely adnate to internode;
length-width ratio of abcauline to adcauline wall 1: 1.2;
hydrotheca without true floor, a short spur of perisarc
extending inwards from base of adcauline wall. Margin
tilted upward at an angle of 55“ - 60“ to hydrocladial
axis, circular in frontal view, with four low equidistant
cusps, one abcauline, one adcauline and two lateral; rim
thickened, margin not replicated, operculum of four
flaps.

Gonotheca large, elongate conical, one to several
along hydrocladium inserted without pedicel at base of
a hydrotheca, connection with hydrocladium a wide
foramen, gonotheca adpressed to or laying close to

Fig. 25. Sertidarella pinnata: A, hydrocladial internode. B,
gonotheca. Scale bars: A, 500 pm; B, 1,000 pm.

32

Beagle Gulf and Darwin Harbour hydroids

hydrocladium, perisarc thick with up to 14 smooth, deep
transverse corrugations; corrugations less distinct on

adcauline side and fading out

proximally; orifice a

shallow, circular apical depression, transverse to slightly
oblique with a short adcauline lip; operculum a single

thick flap.

Colour. Live colonies deep yellow to orange.

Measurements (pm).

Stem

Length of internode

740 - 900

width at node

Hydrocladium

540 - 600

length of internode

1,720 -2,100

width at node

360 - 400

width at apophysis
distance to first hydrotheca

240 - 300

(proximal side)

140 - 200

Hydrotheca (hydrocladium)

length adcauline wall

456 - 464

length abcauline wall

376 - 456

maximum width

216 - 240

diameter at margin
Gonotheca

160 - 192

length

2,700 -2,840

width at aperture

820 -1,000

Remarks. The difficulty of distinguishing infertile

material of Sertularella pinnata from Sertularella
diaphana and other members of the group has been
discussed by previous authors (e.g. Bale 1919, Gordon
et ciL, 1998). Bale considered the hydrothecae of S.
pinnata to be “closer together, less laterally divergent,
do not face as much to the front of the hydrocladium
and the hydrothecal margins are more nearly vertical than
those of S. diaphana". Some of these supposed
differences may, however, be due as much to the angle
of presentation of the specimen on the microslide as to
actual orientation of the hydrothecae on the hydro¬
cladium.

Nutting (1904) considered the type of Thuiaria
hyalina Allman, 1888 from the coast of Brazil to be
conspecific with Sertularella lata (Bale, 1884). His
figure of the type clearly depicts the slight convexity
near the base of the hydrothecal abcauline wall typical
of S. pinnata. Jarvis (1922) reported S. pinnata from
several east African localities and although her
description is brief and lacks figures, the transversely
corrugated gonotheca with llattened distal end leaves
little doubt that the species is S. pinnata. Stechow (1925)
doubtfully assigned infertile material from Shark Bay,
Western Australia to S. diaphana-, the slight tumescence
of the abcauline hydrothecal wall (Stechow’s Fig. H, p.
Ill) suggests that the species is probably S. pinnata.

Distinction between species of the Sertularella
species group. Infertile material of Sertularella
quadridens, Sertularella diaphana and Sertularella
pinnata cannot be easily distinguished on microscopic
characters alone, a situation that has probably led to much

past misidentification of species. When fertile they are,
however, readily separated, the gonothecae of S.
quadridens (Fig. 23F) and S decipiens (Fig. 22E) being
more or less tubiform and ridged, that of S. diaphana is
conical with longitudinal pleats (Fig. 24E) while that of
S pinnata is conical and transversely corrugated (Fig.
25 B).

Ecology. In southern Australia, the large, plumose
orange-yellow colonies of Sertularella pinnata usually
grow in association with colonies of Plumularia
procumbens Spencer, 1891 or rarely, epilithically (J. E.
W., unpubl.). The tall, orange-coloured colonies are
unmistakable and cannot be confused with any other
southern Australian species.

As far as presently known all four species are
eipizooites, the tropical ones occurring chiefly on tubes
of the polychaete Eunice tubifex while Sertularella
pinnata is a virtual obligate on another hydroid.

Distribution. Southern Australia (Bale 1884, 1915;
Jiiderholm 1920; Gordon etal., 1998), East Africa (Jarvis
1922) and Brazil (Nutting 1904).

Genus Sertiilaria Linnaeus, 1758
Sertiilaria trigonostoma Busk, 1852
(Fig. 26A-E)

Sertiilaria trigonostoma Busk, 1852: 387-392.

- Kirkpatrick 1890: 604. - Billard 1925: 174. - Pennycuik
1959:198.

Sertiilaria trigonostoma var. alternata Vervoort,
1959: 284. - Mergner and Wedler 1977: 20.

Records and material. NTM C12903, alcohol
preserved material; NTM Cl2951 microslide, colony
from Stn 138. NTM Cl2904, alcohol preserved material;
NTM Cl2899, MV F86924, microslides, colony from
Stn 7. NTM Cl2905 alcohol preserved material, colony
from Stn 82. Sparse, sparingly fertile colonies on pebbles
and Eunice tubifex. Other records. Stns 84, 154.

Description. Hydrorhiza tubular, entwining substrate.
Stems to 85 mm long, pinnate, lax, monosiphonic,
cauline diameter decreasing distally, perisarc thick;
proximal region of longer stems ahydrocladiate, shorter
stems entirely hydrocladiate; cauline internodes
indistinct.

Hydrocladia alternate, arising at an angle of c. 40° to
cauline axis, longest in proximal stem region (up to 10
mm long on tallest stems), becoming .shorter distally;
hydrocladium inserted on long apophysis with distinct
transverse distal node; two hydrothecae between each
hydrocladium on same side, another in axil. Hydrocladial
internode with two hydrothecae, node transverse to
slightly oblique, distinct.

Hydrothecae biseriate, subopposite, seated on front
of internode, subopposite, slightly separated on proximal
region of hydrocladium, adcauline walls adjoined distally
along hydrocladium. Hydrotheca longer than wide,
adcauline wall convex, free part very short, abcauline

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34

Beagle Gulf and Darwin Harbour hydroids

wall straight to faintly sinuous or concave, contiguous
with internode, base of adcauline wall with an inturned
knot of perisarc, no true floor to hydrotheca, connection
with hydrocladium wide. Margin thickened with two
lobate lateral cusps and a much smaller adcauline cusp,
aperture elliptical, opercular remnants obscuring most
margins. Hydranths not well preserved, no caecum;
approximately 16 tentacles.

Gonotheca immature, balloon-shaped to irregularly
cylindrical, inserted without pedicel between two cauline
hydrothecae in mid to upper stem region, expanding a
little apically to a blunt distal end, gonophore an aborted
hydranth, perisarc extremely thin.

Colour. Pale yellow-brown.

Measurements (pm).

Stem

distance between successive hydrocladia on same

side

1,060

-1,100

length of apophysis (distal side)

112

- 128

width of apophysis at distal node

144

- 160

Hydrocladium

length of internode

296

- 336

width at node

120

- 128

Hydrotheca

length of adnate adcauline wall

184

- 228

length of free adcauline wall

(lateral view)

32

- 56

width between marginal cusps

88

- 112

Gonotheca

length 600

width 256

Remarks. Although the cauline perisarc is com¬
paratively thick the stems are quite lax. Many hydrocladia
are broken off at the distal apophysal node. The
hydrothecal aperture is small and frequently obscured
by adhering tissue and opercular remnants.

Vervoort (1959) erected the var. alternata to
accommodate specimens from west Africa with alternate
hydrothecae; the present material has subopposite
hydrothecae, thus conforming to Busk’s original
description of the species.

This first description of the gonotheca is based on
the single immature gonotheca present in the sample; it
is remarkably small and delicate in comparison with the
sturdy trophosome. As there is no sign of ova it is
probably male.

Distribution. Tropical Indo-Pacific and Red Sea
(Vervoort 1959, Mergner and Wedler 1977). Australian
distribution: Torres Strait (Busk 1852) and tropical
Queensland (Pennycuik 1959).

Genus Thuiaria Fleming, 1828
Thuiaria operculata sp. nov.

(Fig. 27A-D)

Records and material. Holotype, NTM Cl2956,
alcohol preserved material, NTM Cl2949, NTM

C12971, MV F86921, microslides from holotype colony.
East Arm port, concrete wall of berth, coll: J. E. Watson,
depth 5 m, 20/8/1998, colony of several infertile stems.
Paratype, NTM Cl2973, microslide, two infertile stems
on hydrorhiza of Idiellana pristis, Stn 146.

Description. Hydrorhiza thick, gnarled. Stems to 35
mm high, gracefully plumose, monosiphonic, proximal
stem robust, perisarc thick, thinning distally, a distinct
transverse node above base of stem, proximal cauline
internode athecate, cauline and hydrocladial internodes
thereafter thecate, nodes distinct to absent, slightly
oblique to transverse, perisarc tumid above and below
node.

Hydrocladium proximal on internode, a hydrotheca
deep in axil, one above, margin almost level with distal
node, another in alternate position, opposite on stem.
Hydrocladia alternate, long, upwardly directed at 60 -
70° to cauline axis, borne on a strong apophysis with
one or two transverse distal nodes, internodes thereafter
with two hydrothecae, nodes slightly oblique.

Hydrothecae frontal on internode, subaltemate, facing
forward, adnate adcauline wall smoothly convex, free
part short, a small hook-shaped knot of perisarc at base
of wall; abcauline wall contiguous with internode,
straight to slightly sinuous, maximum width of
hydrotheca in distal third, a bracket-like internal
submarginal shelf just below abcauline margin. Aperture
oval, facing upward with two large lateral lobes and a
very small adcauline cusp; operculum a strong flap with
outrolled rim, attached to abcauline submarginal shelf;
perisarc of operculum thick. Hydranth with c. 10
tentacles, abcauline caecum visible in some hydranths.

Colour. Live stems pale greenish-white.

Measurements (pm).

Stem

diameter of basal node

176 -

208

length of internodes

560 -

680

diameter at node

112 -

168

Branch

length of internode

400 -

520

diameter at node

72 -

96

abcauline length of apophysis

from stem node

180 -

208

length of first athecate internode

60 -

72

Hydrotheca

length of adnate adcauline wall

180 -

204

length of free adcauline wall

32 -

44

maximum width

96 -

100

Remarks. The abcauline operculum of one valve and
hydranth with abcauline caecum necessitates referral of
the species to Thuiaria. The operculum attached to the
knuckle-shaped submarginal shelf is quite delicate in
frontal view but in lateral view appears much thicker,
its outrolled upper edge being quite clear. In contracted
hydranths the small abcauline caecum is rather obscure,
being evident in extended hydranths.

35

J.E. Watson

Etymology. Named for the strongly developed
opercular flap.

Thuiaria plumularioides sp. nov.

(Fig. 28A-F)

Records and material. Holotype, NTM Cl2974,
NTM Cl2975, MV F86923, microslides, from infertile
colony on sponge, Stn 153. Paratypes, NTM Cl2976,
microslide, colony from Stn 110. NTM C12977,
microslide, colony from Stn 154. (All holotype and
paratype material mounted on microslides: no preserved
material remaining).

Description. Hydrorhiza a knot of tubes entwining
substrate. Stems to 25 mm high, straight, robust, pinnate,
proximal part of stem ahydrocladiate but with two rows
of opposite hydrothecae; ahydrocladiate paart of stem
usually with a strong distal hinge joint. Cauline nodes
of hydrocladiate part of stem distinct, slightly oblique
to transverse; internode with three hydrocladia, one to
three hydrothecae above hydrocladium, proximal one
axillar, di.stalmost level with node. Cauline perisarc very
thick proximally, thinning a little distally.

Hydrocladia close set, alternate, long, arching
gracefully upwards at an angle of c. 30“ to cauline axis
from a strong apophysis with an indistinct transverse
constriction and a pronounced distal hinge joint.
Hydrocladial internodes long, nodes distinct hinge joints.
Hydrothecae biseriate, frontal on hydrocladium, pro¬
ximal internodes bearing up to 10 pairs of hydrothecae,
pairs becoming fewer distally; hydrothecae overlapping,

facing upwards, sub-opposite on proximal region of
hydrocladium, becoming opposite distally, each pair
overlapping base of pair above. Hydrotheca long, tubular
(lateral view), almost vasiform (anterior view), slightly
tumid at base, narrowing just behind margin, adcauline
walls joined, straight, a short convex length free of
internode at a sharp outward distal bend; abcauline wall
almost straight, a prominent abcauline submarginal shelf,
a foramen at base of wall connecting with internode, base
of hydrotheca rounded. Aperture oval, margin thickened
with a pair of opposite laterally placed cusps and a
rounded adcauline lobe; opercular valve attached to
submarginal adcauline shelf. Hydranth with an abcauline
caecum and about 10 tentacles.

Colour. In life, pale yellow.
Measurements (pm).

Stem

maximum diameter at proximal node

850

length of internode

960

-1,960

diameter at node

220

- 500

apophysis, length of abcauline wall

280

- 360

apophysis, width at transverse node

144

- 184

Hydrotheca

length of adnate adcauline wall

184

- 240

length of free adcauline

wall to margin

100

- 160

length of abcauline

wall to top of margin

240

- 280

depth of margin, lateral view

60

- 64

width of margin, cusp to cusp.

frontal view

68

- 80

Fig. 28. Thuiaria plumularioides .sp. nov. A, stem from holotype colony. B, hydrocladia. C, frontal view of hydrocladium. D, hydrocladium,
lateral view. E, hydrotheca showing lobate margin. F, lateral view of hydrotheca showing submarginal abcauline thickening. Scale bars: A,
10 mm, B, 1,000 pm; C, D, 500 pm; E, F, 200 pm.

36

Beagle Gulf and Darwin Harbour hydroids

Remarks. The species is referred to Thitiaria on the
basis of the abcauline caecum in the hydranth and the
hydrotheca having an abcauline operculum. Colonies
may be sparingly branched, one stem of the holotype
colony having remnants of a branch near the base. The
overlapping hydrothecae and slightly tumid base of the
hydrothecae are characteristic.

Etymology. The species is named for its plumose
morphology.

Genus Thyroscyphus Allman, 1877
Thyroscyphus macrocytharus (Lamouroux, 1824)
(Fig. 29A)

Clytia macrocytharus Lamouroux, 1824: 647.
-Lamarck 1837: 199.

Campanularia marginata Bale, 1884: 54. - Bale 1888:
758. - Bartlett 1907: 62. - Levinsen 1913: 289.

Laomedea marginata - von Lendenfeld 1885a: 404.

Thyroscyphus marginatus - Bale 1914: 91. - Bale
1915: 245, 258. - Stechow 1924: 69. - Stechow 1925:
217. - Blackburn 1942: 112.-Watson 1973: 169.

Thyroscyphus balei Calder, 1983:16. - Watson 1992:

220 .

Thyroscyphus macrocytharus - Watson 1994: 156.
- Watson 1996: 78. - Watson 1997: 517.

Record and material. NTM Cl2987, MV F86893,
microslides, sparingly fertile colony of four straggling
stems on sponge, Stn 154.

Description. Hydrorhiza reptant on substrate,
hydrocaulus of same diameter as hydrorhiza, mono-
siphonic, perisarc very thick. Stems to 10 mm high,
internodes long, smooth, almost geniculate, nodes
oblique, deeply incised. Hydrothecae alternate, distal on
internode, borne on a moderately long pedicel either
smooth or with one or two constrictions; hydrotheca
campanulate, margin quadrate, conspicuously thickened,
with four pointed cusps and four shallow emarginations;
operculum of four equal valves. Gonotheca immature,
top-shaped, borne on a short pedicel inserted in
apophysis of stem beside hydrotheca.

Colour. Pale brown to colourless.

Measurements (pm).
Stem

length of internode

960

-1,320

width at node

168

- 256

Hydrotheca

length of pedicel

100

- 240

depth, diaphragm to margin

680

- 792

diameter at margin

528

- 568

Remarks. The specimen conforms to the description
of Thyroscyphus macrocytharus given by Watson (1994).
Most hydrothecal pedicels of the present material are
regenerated, some up to eight times. Thyroscyphus
macrocytharus is endemic to Australia, usually occurring
in shallow water; the present record from a depth of 30
m is the second deepest record for the species, the deepest
being 137 m off southern Australia (Bale 1915).

Distribution. The previous northernmost record of
T. macrocytharus is from Geraldton, Western Australia
(Stechow 1925). This is the first record of the species
from tropical Australia.

Thyroscyphus torresii (Busk, 1852)

(Fig. 29B-C)

Laomedea torresii Busk, 1852: 402.

Thyroscyphus simplex Allman, 1888: 25. - Jiiderholm
1903: 273. - Jaderholm 1916: 5. - Stechow and Muller,
1923: 466.

Campanularia torresii - Bale 1884: 52. - Kirkpatrick
1890: 604.

Thyroscyphus regularis Jaderholm, 1896: 9.

Thyroscyphus torresii - Jaderholm 1903: 273.
-Stechow 1913: 12. - Jaderholm 1916: 5. - Stechow
and Muller 1923: 466. - Redier 1963: 22. - Watson 1996:
78.

Cnidoscyphus torresii - Splettstdsser 1929: 70-82,
125. - Pennycuik 1959: 156. - Vervoort 1941: 204.

- Vervoort 1993: 104.

Records and material. NTM Cl2887, alcohol
preserved material, colony from Stn 110. NTM Cl2886
alcohol preserved material; NTM Cl2989, MV F86892,
microslides, colony from Stn 13. NTM C12888, alcohol
preserved material, colony from Stn 136. MV F86938,
alcohol preserved material, colony from Stn 137. NTM
Cl2988, microslide, colony from Stn 138. Many infertile
colonies, the largest of 20 stems on shell and grit,
Gymnangium longicorne and sponge. Other records. Stns
48, 67, 78, 87, 127, 136, 155. East Port channel and
wharf pilings, small and large colonies. Port of Darwin,
coll: J. E. Watson, depth 3 m, 16/8/1998. Plater Rock,
many sparsely fertile large and small colonies, coll J. E.
Wat.son, depth 3 - 10 m, 21/9/1999.

De.scription. Hydrorhizal stolons tightly entwining
substrate. Clusters of up to 20 pinnate stems to 100 mm
high arising from hydrorhiza, basal stem region lightly
fascicled by hydrorhizal stolons, stems thereafter
monosiphonic, tubular, stiff and robust, perisarc of basal
region very thick and smooth, thinning distally.
Hydrocladia pinnate, alternate, well separated, long, no
secondary branching, two alternate hydrothecae on stem
between each branch and one axillar. Stem and
hydrocladial internodes fairly long, nodes slightly
oblique to transverse, marked by a notch in perisarc.
Hydrocladial apophysis long, inclined upwards, proximal
side marked by an indentation in perisarc in stem; first
hydrocladial internode long, internodes shorter
thereafter, nodes transverse, usually distinct.

Hydrothecae alternate, pedicel short, thick, smooth
or with several ridges; hydrotheca asymmetrical,
abcauline wall straight, proximal third of adcauline wall
convex, the curve straightening out distally, diaphragm
distinct, down-curved, often asymmetrically tilted,
hydrothecal margin circular, rim quadrate with four low.

37

J.E. Watson

equidistant, sharply pointed cusps separated by four
shallow emarginations; operculum thin, of four triangular
flaps. Hydranths stubby, with at least 30 tentacles.

Gonothecae immature, top-shaped, arising in
proximal stem region beside a hydrotheca or on stem,
hydrocladium or apophysis from which a hydrotheca has
been shed; perisarc thin.

Colour. Live colonies golden-yellow to golden-

brown.

Measurements (pm).

Stem

diameter at base
distance between

successive branches
length stem internodes between
successive hydrothecae
Branch

length first internode
length succeeding internodes
width branch at base
width at node
Hydrotheca

length, including pedicel
length of pedicel apophysis
to diaphragm
width of pedicel
width at diaphragm
diameter at margin
width of marginal embayment
Remarks. The hydrothecal pedicels of younger
hydrocladia are usually smooth but in older stems are
often ridged from repeated breakage and regeneration.
There is no submarginal thickening of the hydrothecal
rim as in Thyroscyphus macrocytliarus, only a faint line
below the rim in some hydrothecae marking the junction
of the operculum with the body. Several colonies are
infested with Hebellopsis scandens, the hydrothecae of
which are invariably close beside those of Thyroscyphus.

The lower stem regions bearing developing gono¬
thecae are packed with globular white bodies, apparently
developing gonophores which are visible through the
stem perisarc. It is surprising that, as T. torresii is one of
the most abundant hydroids in both dredged and scuba
collections, only a few immature gonothecae were found.
The only description and figure of the mature gonotheca
of T. torresii is of a distally ridged gonotheca (Jaderholm

860

- 950

2,300

-2,800

800

-1,000

1,900

-2,040

700

-1,100

200

- 260

192

- 224

1,080

-1,200

120

- 152

160

- 192

240

- 280

472

- 576

232

- 320

Is of

younger

1903).

Distribution. Indonesia, China Sea, Mergui Archi¬
pelago (Vervoort 1993). Australian region: Torres Strait
(Busk 1852, Kirkpartick 1890) Aru Sea (Stechow and
Muller 1923), Fitzroy Island (Bale 1884), off Cape York
(Allman 1888), Cape Jaubert, Western Australia
(Jaderholm 1916), Queensland (Pennycuik, 1959).

Thyroscyphus fruticosus (Esper, 1793)
(Fig. 29D)

Spongia fruticosus Esper, 1793: 188.

Sertularellafruticosus-Thompson 1879: 100.

Campanularia fruticosus - Marktanner-Turneretscher
1890: 205.

Thyroscyphus vitiensis Marktanner-Turneretscher,
1890: 210. - Billard 1907: 343. - Jarvis 1922: 338.

Lytoscyphus fruticosus - Bedot 1905: 51. - Stechow
and Muller 1923: 465. - Stechow 1925: 215.

Thyroscyphus fruticosus - Splettstosser 1929: 7, 122.

- Billard 1933: II.- Vervoort 1941: 202. - Vervoort 1946:
306. - Millard 1952: 199. - Ralph 1961: 754. - Vervoort
1965: 35. - Vervoort 1967: 35. - Schmidt 1971:
35. - Millard and Bouillon 1973: 76. - Millard 1975: 323.

- Mergner and Wedler 1977: 18. - Gibbons and Ryland
1989: 425. - Watson 1996: 78.

Record and material. NTM Cl2889, MV F86945,
alcohol preserved material; NTM Cl2990, microslide.
Plater Rock, tall colonies on coral boulders and rock,
coll; J. E. Wat.son, depth 5-8 m. 22/9/1999.

Description. Colonies of up to 10 stems to 150 mm
high. Hydrorhiza a tangled mass of tough tubes
embedded in substrate. Stem and branches stiff,
monosiphonic, proximal part of stem athecate; branching
irregular, predominantly in one plane, usually almost
perpendicular to stem, no division into nodes, tubular in
section, each segment widening to a short, proximally
swollen apophysis supporting a hydrotheca. Perisarc of
stem and branches very thick and smooth.

Hydrothecae strictly alternate on opposite sides of
stem and branches, one in axil of branch; hydrotheca
inclined upwards on a short thick pedicel, smooth or with
one or two constrictions, tubular, asymmetrical,
abcauline wall straight, adcauline wall convex, widest
at proximal third, both walls narrowing slightly but
distinctly behind margin; diaphragm distinct, marked by
a circular shelf in perisarc tilted obliquely downwards;
margin circular, rim thickened, an internal band of tissue
below margin at narrowest point of hydrothecal body,
margin sometimes with four almost imperceptible
equidistant cusps, sometimes with one or two reno¬
vations. Operculum delicate, of four equal triangular
valves.

Gonothecae borne on a short, thick pedicel below
hydrothecal apophyses on stem and branches, larger than
hydrotheca, top-shaped, tilted downwards, perisarc thick,
smooth to rather lumpy, distal end obliquely truncated,
sealed by a plug of tissue. Gonophore (possibly female)
distal in gonothecal cavity.

Colour. Stem and branches of live colonies honey
brown, hydrothecae and gonothecae rose pink; colony
yellow-brown when preserved.

Measurements (pm).

Stem and branches

diameter above hydrothecal pedicel 340 - 380

distance between successive

hydrothecae on same side 1,480 -2,900

width below apophysis 400 - 540

38

Beagle Gulf and Darwin Harbour hydroids

Fig. 29. A, Thyroscyphus macrocytharus: part of stem with
developing gonotheca. B. C, Thyroscyphus torresii: B, fertile colony
from Plater Rock. C, branch internodes with hydrothecae and young
gonotheca. D, Thyroscyphus fruticosus: internodes from fertile
colony from Plater Rock. Scale bars: A, C, D, 1,000 pm; B, 5,000
pm.

width across distal node of apophysis 240 - 320
Hydrotheca

length (diagonal) of adcauline wall.

diaphragm to margin

1,300

-1,500

length of abcauline wall.

diaphragm to margin

1,140

-1,200

diameter of margin

488

- 536

length (abcauline side) of pedicel.

apophysis to diaphragm

280

- 320

width of pedicel above apophysis

208

- 240

Gonotheca

length 1,460 -1,760

maximum width 840 - 940

diameter at margin 640 - 720

Remarks. Thyroscyphus fruticosus and T. torresii

from the Beagle Gulf and Darwin share many characters,
particularly in size of colony, habit and choice of habitat.
The only reliable means of distinguishing between the
species in situ is in the slightly more straggling colonies
and pink colour of T. fruticosus while T. torresii is tidier
in aspect and is honey brown in colour. Gibbons and
Ryland (1989) reported very short (10-40 mm high)
violet-coloured colonies of T fruticosus from rock and
sandy habitats in Fiji. The pink colouration of T.

fruticosus is lost in preservation, a reaction also noted
by Millard (1975).

Confusing morphological similarities of T. fruticosus
with T. torresii have probably led to some past confusion
of the species, for example Gibbons and Ryland (1989,
fig. 40) depict asymmetrical hydrothecae, clearly those
of T fruticosus, but with marginal cu.sps more resembling
those of T torresii. In sterile material, the only reasonably
constant morphological differences are the absence of
internodes from stem and branches of T. fruticosus, the
usually larger hydrothecae and the sometimes almost
imperceptible narrowing of the adcauline wall behind
the margin.

Distribution. Mediterranean Sea, Indo-West Pacific
Timor Sea, New Zealand. Australian distribution, north¬
western Australia (Watson 1996).

Family Syntheciidae Marktanner-Ttirneretscher, 1890
Genus Syntheciiun Allman, 1872

Diagnosis. Colony with erect stem bearing hydro-
cladia in opposite pairs. Stem and hydrocladia bearing
hydrothecae in opposite pairs, the pairs always in the
same plane forming two longitudinal rows. Gonothecae
dioecious, springing from within hydrothecae.

Remarks. Seven species of Synthecium are reported
from Australia; Synthecium patulum (Busk, 1852),
Synthecium orthogonium (Busk, 1852), Synthecium
Allman, 1872 (see Jaderholm 1911), Synthecium
campylocarpum Allman ISSS, Synthecium suhventricosum
Bale, 1914 (recognised by Ralph (1958) as a small form
of Synthecium elegans), Synthecium megalothecum
Billard, 1924 (see Pennycuik 1959) and Synthecium
dentigerum Jarvis, 1922 (see Watson 1969).

Even with fertile material it can be difficult to
differentiate between species of Synthecium. Size
differences between hydrothecae in male and female
colonies reported in some species, are a further
complicating factor. Synthecium orthogonium and
Synthecium campylocarpum have been confused in the
past and as no type material of Synthecium patulum is
known to exist (see Totton 1930) concepts of the species
have varied widely. Bale (1888) reported Synthecium
orthogonium (here considered to be S. campylocarpum,
see discussion later) from off the coast of New South
Wales and Billard (1925) synonymised S. orthogonium
and S. campylocarpum in S. patulum. Synthecium
orthogonium from Indonesia was identified by Vervoort
(1941) as S. patulum while the description and figure of
a gonotheca identified as S. patulum by Millard and
Bouillon (1973, 1975) is clearly that of S. campylocarpum.

The Beagle Gulf and Darwin collection includes two
species, the most abundant of which is Synthecium
campylocarpum-, the other, less common, is here referred
to Synthecium orthogonium. Although Synthecium
patulum is not represented in the present collection, the

39

J.E. Watson

identity of other species rests largely upon establishment
of the true identity of S. patiilum. For comparison, a
redescription of S. patulum from southern Australia is
given, based on extensive material in the author’s
collection and holdings in the collection of the Museum
of Victoria.

Synthecium campylocarpum Allman, 1888
(Figs 30A-G, 31A-C)

Synthecium campylocarpum Allman, 1888: 78.

- Marktanner-Turneretscher 1890: 248. - Inaba 1890: 52-
54. - Farquhar 1896: 466. - Stechow 1913: 127.

- Jaderholm 1919: 14.-Totton 1930: 169.-Ralph 1958:
347. - Yamada 1959: 52. - Hirohito 1969: 18. - Watson
1996: 78.

Synthecium orthogonium (Busk, 1852). - Bale 1888:
767. - Bale 1924: 250.

Records and material. NTM Cl2933, MV F86946,
alcohol preserved material; NTM Cl2979, MV F86097,
microslides, colony from Stn 111. NTM C12980, NTM
Cl2981, microslides, colony from Stn 20. NTM Cl2983,
microslide, colony from Stn 13. NTM Cl2934, NTM
Cl2935 alcohol preserved material, colony from Stn 81.
Colonies in poor condition on digitate sponges and
Eunice tubifex. Plater Rock, large male colony on digitate
sponge, coll J. E. Watson, depth 5 m, 22/9/1999. East
Arm channel, large male colonies on Eunice tubifex, coll
J. E. Watson, depth 3 m, 17/8/1998. Other records. Stns

21, no, 26.

Description. Stems to 100 mm high. Hydrorhiza
tubular, reptant on host, perisarc of hydrorhiza and stems
thick. Stems wide proximally, narrowing distally,
proximal internodes usually athecate, internodes
thereafter long with one to three pairs of distal
hydrothecae; hydrocladia opposite, distal on internode,
given off at an angle of 60® - 90° to caulus above cauline
hydrothecal pair; nodes transverse, distinct in younger
parts of stems, indistinct to completely absent from older
parts, sometimes a secondary node between primary
nodes. Hydrocladia on a long vasiform apophysis,
sometimes a transverse distal node below first hydro¬
thecal pair. Hydrothecae opposite, occupying almost or
entire internode, nodes vestigial or absent, hydrothecae
often in contact vertically, a little separated in front, in
contact behind; hydrotheca tubular, adcauline wall
smoothly convex, one fifth to one quarter of wall free of
internode, abcauline wall straight or slightly tumescent
proximally, becoming concave, curvature increasing
distally, perisarc thinning a little towards margin. Margin
circular, sinuous, facing slightly forward, parallel to
hydrocladial axis or tilted slightly upward, rim outrolled,
sometimes up to four renovations from within hydro¬
theca.

Colonies dioecious, gonothecae borne on lower stem
and hydrocladia. Male gonotheca long, irregularly pod¬
shaped, usually widest about middle, pedicel inserted

Fig. 30. Synthecium campylocarpum from Beagle Gulf and Plater
Rock: A, hydrocladiate part of .stem. B, hydrocladial internode. C,
hydrotheca with everted marginal replications. D, male gonothecae.
E, lateral view of female gonotheca. F, frontal view of female
gonotheca. G, nematocyst (haplonemc?) from hydrocaulus. Scale
bars: A, B, 500 pm; C, 200 pm; D - F. 1,000 pm; G, 50 pm.

with a right-angled bend deep into hydrotheca, often
splitting hydrotheca; perisarc of gonotheca rather thin,
smooth to faintly undulated, orifice small, circular,
operculum a thin sheet of tissue, gonophore elongate.
Female gonotheca small, lenticular, one side usually flat,
other side convex, perisarc thicker than male, six to eight
transverse ribs crossing entire body, more deeply incised
on flatter side, ribs fading out proximally and distally,
orifice small, circular, on a short tubular neck, neck
foreshortening as gonotheca matures.

Cnidome of large /haplonemes with blunt ends,
capsule 62.5 x 17.5 pm, tubule coiled, in tentacles and
coenosarc of stems.

Colour. Live colonies yellow; female gonophore
orange.

Measurements (pm).

Hydrorhiza

diameter 350 - 450

Stern

length of internode

(distance between hydrocladia) 1,700 -2,000

diameter at node 240 - 320

Hydrocladium

maximum length 8,000

40

Beagle Gulf and Darwin Harbour hydroids

length of apophysis

to first hydrothecal pair

216

- 280

width across base of hydrothecal pair

296

- 336

Hydrotheca

length of adnate adcauline wall

448

- 480

length of free adcauline wall

96

- 168

length of abcauline wall

256

- 368

diameter of margin

184

- 208

Gonotheca

length of mature male

1,820

-2,200

maximum width of male

560

- 700

length of mature female

1,120

-1,600

width of female, frontal view

940

-1,100

width of female, side view

640

- 740

Remarks. Apical tendrils occur on several of the
longer stems. On some older stems, hydrocladial
apophyses are regenerated up to three times, each
regrowth marked by a shoulder-like node. The large
range of material examined revealed no difference in
height of stems nor in size of hydrothecae between sexes.

Bale (1888) referred to S. orthogoniiun a specimen
from Port Jackson, on the eastern Australian coast, later
finding nothing (Bale 1914, 1924) to distinguish it from
5. campylocarpum. His opinion was followed by many
later authors (e.g. Thornely 1904, Nutting 1905,
Jaderholm 1903, Jiiderholm 1916, Stechow and Muller
1923), none of whom described or figured their
specimens. Ritchie (1911) assigned specimens from the
eastern Australian coast to S. orthogonium noting that
their dimensions did not agree very well with Billard’s
(1910) measurements of the holotype of that species. His
description of the hydrotheca with sinuate margin is
undoubtedly of 5. campylocarpum.

1 have compared a microslide preparation of a syntype
of Syntliecium campylocarpum from the Challenger
collection, taken off the eastern Australian coast
(Museum of Victoria collection registered number MV
F58214), with a microslide specimen identified by Bale
(1888) as S. orthogonium (specimen also held in the
Museum of Victoria). The Challenger material is an
almost complete fertile stem with young male gonothecae
(Fig. 31D-F) and is almost identical with Bale’s
specimen, thus supporting Ralph’s (1958) view that
Bale’s specimen is not S. orthogonium but S. campylo¬
carpum.

When examined in isolation infertile material of S.
orthogonium may be confused with S. campylocarpum,
especially in colonies of S. campylocarpum in which the
hydrothecae are more outwardly bent than usual. They
are best distinguished by the larger and more robust stems
and distinctly sinuate margin of S. campylocarpum
compared with the smaller, more delicate stems and
sharply bent hydrotheca without marginal sinuosity of
S. orthogonium.

Distribution. Known from eastern subtropical to
tropical northern Australia (Watson 1996) New Zealand,
(Ralph 1958) Japan (Hirohito 1969).

Fig. 31. SynthecUim campylocarpum, syntype, from Port Jackson,
Challenger Expedition. MV F58214: A, part of fertile stem. B,
hydrocladial intemode, hydrothecae with replicated margin with
outrolled rim. C, male gonotheca. D, hydrocladial internode from a
microslide specimen from Port Jackson, identified by Bale (1888),
as Synthecium orthogonium held in Museum of Victoria. E, male
gonotheca from same specimen. F, female gonotheca from same
specimen. Scale bars; A, 5,000 pm; B, D, 500 pm; C, E, F, 1,000
pm.

Synthecium orthogonium (Busk, 1852)

(Fig. 32A-F, Table 4)

Sertularia orthogonia Busk. 1852: 390. - Bale 1884:
88. - Billard 1910: 25.

Not Synthecium orthogonium - Bale 1888: 767. - Bale
1924: 250.

ISynthecium orthogonium - Jaderholm 1903:
289. - Jaderholm 1916:6.- Thornely 1904: 119. - Nutting
1905: 950. - Stechow and Muller 1923: 465. - Pennycuik
1959: 190.-Watson 1996: 78.

Synthecium patulum (Bunk, 1852) - Billard 1925: 125.
- Vervoort 1941: 199.

Records and material. NTM Cl2936, alcohol
preserved material, colony from Stn 136. NTM Cl2984,
NTM C12985, MV F86890, microslides, infertile sparse
colony on Gymnangium long iconic from Stn 87. NTM
Cl2986, microslide, small fertile colony on aglaopheniid
hydroid. Plater Rock, coll: J. E. Watson, depth 4 m, 21/
9/1999.

41

J.E. Watson

Description. Hydrorhiza tubular, reptant; stems short,
to 35 mm high, lax, tubular, with two or three pairs of
opposite hydrocladia, proximal stem region athecate,
variable in length; diameter of stem diminishing and
thickness of perisarc reducing distally; stem internodes
long, nodes when present, a transverse constriction in
perisarc; one or two pairs of hydrothecae about halfway
to two thirds up internode; hydrocladia long and
flexuous, opposite or single, given off at a slight upward
angle from a strong shoulder-like apophysis.

Hydrocladial nodes marked by a pronounced
narrowing of perisarc or a transverse line, hydrothecae
paired, distal on internode, proximal pair displaced
slightly relative to one another; hydrothecae long,
tubular, pairs may or may not be conjoined, adnate
adcauline wall almost straight to faintly convex, free part
bending sharply outwards and slightly forward perpen¬
dicular to hydrocladial axis for one third to half adcauline
length, sometimes an internal thickening of perisarc at
junction of adnate and free wall; abcauline wall slightly
tumescent above base, almost straight to distal bend, then
either straight or concave to margin, often an internal
thickening of wall in bend. Margin parallel or almost
parallel to hydrocladial axis, circular, rim strongly
everted, some with up to seven marginal replications;
perisarc of hydrotheca smooth.

Gonotheca on a short pedicel issuing from a
hydrotheca in lower stem region, gonotheca sausage¬
shaped, tapering distally, body with two rows of 10 deep
corrugations along one side, corrugations smoothing out
behind; distal end obtuse, no orifice evident.

Colour. Live colony mauve, white or colourless when
preserved.

Comparison of Beagle Gulf specimens with
holotype. 1 have compared specimens from the Beagle
Gulf and Darwin Harbour with the holotype of
Syntliecium orthogonium (Busk, 1852) from the type
locality of Torres Strait, loaned by the Natural History
Museum, London (Fig. 32 E, F). The NHM microslide
preparation labelled "Sertularia orthogonia Australia,
Rattles, Holotype, Busk 1852, Busk Coll: 99. 7. 1.6367”
consists of two stem fragments, one 7 mm long and the
other 5 mm long, in good condition but without
hydrorhiza. There are several pairs of opposite
hydrocladia, one pair per internode, given off from just
below a node. The hydrocladia bear up to seven pairs of
opposite hydrothecae, one pair per internode; adcauline
walls of some pairs joined but others separated.
Hydrothecae tubular, distal on internode and sharply bent
outwards below node where adcauline wall becomes free.
Margin circular and parallel to hydrocladial axis; margins
of several hydrothecae arc sufficiently well preserved to
show replication of the rim. Internal thickening of the
abcauline wall is minimal, probably due to shrinkage
overtime. The Beagle Gulf and Darwin specimens almost
exactly conform with the type, the only difference being

the somewhat shorter stem internodes, a variable
character of little diagnostic value in the genus.
Dimensions of the Beagle Gulf and Darwin specimens
are compared in Table 4 with those of the holotype of S.
orthogonium.

Busk (1852) considered that the strong outward bend
of the hydrotheca of Synthecium orthogonium clearly
characterised the species but later speculated that S.
orthogonium may be a variety of Synthecium patulum
(Busk, 1852) from southern Australia. Bale (1884)
reported and figured S. patulum from Port Phillip Bay
in southern Australia but did not comment upon any
supposed relationship with S. orthogonium, continuing
to regard S. patulum a distinct species (Bale 1914a).
Billard (1925) described and accurately figured S.
orthogonium and its gonangium from Indonesia but, like
many other authors, assigned it to S. patulum. Compa¬
rison of dimensions tabulated above and dimensions
(Figs 32, 33) show that the free adcauline wall of S.
orthogonium is much longer and the hydrothecal margin
much narrower than that of 5. patulum. Fresh material
of 5. orthogonium is readily distinguishable from S.
patulum, colonies of 5. orthogonium being much smaller
and more delicate than S. patulum. Although closely
related, they are here regarded as distinct species.

Distribution. On present knowledge, Synthecium
orthogonium is a tropical species the only reliable records
of which are from Torres Strait (Busk 1852) and
Indonesia (Billard, 1910).

Table 4. Comparison of measurements (pm) of Beagle Gulf and
NHM Busk specimens of Synthecium orthogonium.

Beagle Gulf, NHM Busk
Darwin specimen

Hydrorhiza diameter

Stem

length of intemode (distance

112 -

200

between hydrocladia)

800 -

2,800

1,880 - 1,960

diameter a! node

140 -

160

152 - 176

diameter lower stem

260

200

diameter thecate part of stem
Hydrocladium

216 -

264

184 - 224

maximum length
length apophysis to first

4,000

"

hydrothecal pair
width across base of first

108 -

272

■

hydrothecal pair

Hydrotheca

length of adnate adcauline

256 -

320

wall

440 -

480

408 - 464

length of free adcauline wall
length of abcauline wall

208 -

320

192 - 240

(diagonal)

length of abcauline wall base

360 -

440

328 - 376

to bend

length of abcauline wall bend

320 -

326

■

to margin

136 -

160

-

diameter of margin

136 -

160

120 - 152

length of outrolled rim
Gonotheca

8 -

16

■

length

1,300 -

1,400

-

maximum width

360 -

376

-

42

Beagle Gulf and Darwin Harbour hydroids

Synthecium patulum (Busk, 1852)

(Fig. 33A-G, Table 5)

Sertiilaria patula Busk, 1852, 390. - Bale 1884: 88.

Synthecium patulum - Bale 1888: 766. - Hodgson
1950:18. - Watson 1975: 165.-Watson 1994: 66.

ISynthecium patulum - Jarvis 1922: 332, 345.

- Trebilcock 1928: 9. - Pennycuik 1959: 190.

Not Synthecium patulum - Billard 1925: 125.

- Vervoort 1941:199. - Millard and Bouillon 1973: 64. -
Millard 1975: 12. - Vervoort 1987: 94.

Description. Stems up to 50 mm high, occasionally
with secondary branching; hydrorhiza tubular, reptant,
perisarc of stems and hydrocladia fairly thick. Proximal
ahydrocladiate stem segment variable in length, some
stems with hydrocladia extending almost to base; stem
internodes long with one or two pairs of opposite
hydrothecae near middle of internode, node a constric¬
tion in perisarc. Hydrocladia up to 12 mm long, opposite,
given off at an angle of 45° - 50° to stem from distal end
of internode. Hydrocladial hydrothecae paired, distal on
internode, not conjoined; internode somewhat constricted
proximally, expanding to base of hydrothecae; hydro¬
thecae of first one or two pairs on internode a little
displaced relative to one another.

Hydrotheca tubular, expanding a little distally,
perisarc smooth, adcauline wall almost straight
proximally, gently convex distally, free part about one
quarter total length of wall, base rounded with a small
plug of perisarc; abcauline wall proximally tumescent,
becoming concave to margin. Margin tilted upwards at
an angle of 45° - 60° to hydrocladial axis, strongly
sinuate, rim moderately everted, sometimes replicated
several times. Hydranth small with about 10 tentacles.

Two kinds of nematocysts present:

- small ?mastigophores in tentacles, 9 pm long,
discharged with difficulty,

- large isorhizas 45 - 50 x 12 - 13 pm, tubule up to
500 pm long and 1 pm diameter, armed throughout with
spirals of short bristles; in hydranth and scattered
throughout coenosarc; easily discharged.

Colonies dioecious, gonotheca arising on a long
pedicel from deep within hydrotheca on stem and
proximal parts of hydrocladia; male gonotheca long,
straight to curved, elliptical, and llattened in frontal
aspect; narrow in side view with up to eight deep,
irregular corrugations fading proximally, corrugations
shallower in frontal view, perisarc very thick; orifice
circular, small, on a very short neck sealed by a plug of
tissue. Female gonothecae on different stems from male,
lenticular, shorter than male, with five or six irregular
corrugations, orifice small, circular, on a short neck,
sealed by a plug of tissue; gonophore one large or two
small ova covered by a thick gelatinous pellicle, almost
filling gonothecal cavity.

Colour. Living colonies reddish-purple.

Remarks. The above description is a composite from
colonies collected by the author from several localities
in Bass Strait, Victoria, Australia.

Apical stolonisation from stems and distally from the
hydrocladia commonly occur in some colonies, the
stolons often giving rise to new stems. While there is
some variation in diameter of the hydrothecal rim and in
length of the adcauline wall throughout the range of
colonies examined, the free wall is always one quarter
to one fifth of total wall length. There is no difference in
size of hydrothecae between male and female stems.
Large nematocysts are very abundant in most colonies.

Table 5. Measurements (pm) of specimens of Synthecium patulum from Bass Strait, southern Australia.

Eastern Bass Western Port Port Phillip Bay Range of

Strait dimensions

Hydrorhiza, diameter

Stem

300

300

maximum diameter

280

- 340

240

- 300

260

- 300

240

- 340

length of internode

2,060

-2,160

1,640

- 1,800

1,780

- 1,900

1,640

-2,160

diameter at node

260

240

- 260

240

- 280

240

- 280

Hydrocladium

intcmodc length

608

- 672

552

- 560

600

- 672

552

- 672

diameter at node

152

- 168

144

- 152

152

- 168

144

- 168

Hydrolheca

length of adnate adcauline wall

480

- 496

408

- 440

440

- 480

408

- 496

length of free adcauline wall

160

112

- 120

96

- 120

96

- 160

diagonal length abcauline wall

416

- 440

352

- 68

384

- 400

352

- 440

diameter at mtugin

192

- 216

144

128

- 184

128

- 216

Gonotheca

width of male (lateral view)

360

- 460

360

- 460

width of male (frontal view)

560

- 600

560

- 600

length of female

960

- 1,100

1,100

- 1,300

960

- 1,300

width of female (lateral view)

480

360

- 400

360

- 480

width of female (frontal view)

520

- 620

460

- 560

460

- 620

43

J.E. Watson

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44

Beagle Gulf and Darwin Harbour hydroids

Synthecium patulum is a common hydroid of south¬
eastern ocean, coastal and deep water embayments. The
distinctively purple-coloured colonies grow in tufts on
rock, bryozoans, sponge and dead shell in good current
flow. The species is fertile over the summer months.

Family Haloptcridae Millard, 1962
Genus Antennella Allman, 1877
Anlennella secundaria (Gmelin, 1791)

(Fig 34A-D)

Sertularia secundaria Gmelin, 1791: 3856.

Aglaophenia secundaria - Lamouroux 1824: 19.

Antennella secundaria - Pennycuik 1959: 176.

- Watson 1973: 183. - Millard 1975: 332. - Ryland and
Gibbons 1991: 525. - Ramil and Vervoort 1992: 143. -
Medel and Vervoort 1995: 35. - Schuchert 1997: 14.

- Calder 1997: 29 (full synonymy). - Watson 1996:
78. - Watson 1997: 522.

Antenella secundaria - Stechow and Muller 1923:
473.

Records and material. NTM Cl2993, microslide,
colony from Stn 95. NTM Cl3046, alcohol preserved
material; NTM Cl 2991, microslide, colony from Stn 136.
NTM C 13047, alcohol preserved material, colony from
Stn 84. NTM Cl2992, microslide, colony from Stn 111.
Sparse, fertile colonies on alcyonarians, bryozoans and
shellgrit. Other records. Stns 7, 37, 110, 82, 84, 95, 127.

Description. Hydrocladia up to 8 mm high, arising
from a tubular hydrorhiza replant on substrate; single
nematothecae arising at intervals from hydrorhiza.
Proximal part of hydrocladium with one to three athecate
internodes, nodes transverse, each internode bearing one
or two nematothecae, distalmost node strongly oblique.
Hydrocladial internodes thereafter of similar length,
alternately thecate and athecate, proximal node of thecate
internode strongly oblique, passing beneath hydrotheca,
distal node transverse below hydrothecal margin.
Hydrotheca occupying almost entire internode, facing
forward at an angle of c. 60° to hydrocladial axis, deep
cup-shaped, walls almost parallel but abcauline wall
sometimes faintly sinuate, free adcauline wall straight
to slightly concave, adnate part convex, curving back to
small hydropore at base of abcauline wall, perisarc
thickened around base; margin circular, slightly sinuous.

Nematothecae bithalamic, small, two on athecate
internode, basal chamber stout, cup small, foreshortened
on adcauline side; mesial inferior stout, adcauline side
of cup foreshortened, just reaching base of hydrotheca,
lateral nematotheca borne on a long, slender pedicel
where adcauline wall of hydrotheca becomes free, cup
broad and shallow, excavated on adcauline side, not quite
reaching hydrothecal margin; a small mesial superior
nematotheca inserted beneath hydrotheca.

Gonothecae of both sexes borne on same hydro¬
cladium, females in proximal region, males further along
hydrocladium; female slipper-shaped, somewhat

flattened, facing forward, borne on a short, thick pedicel
beside mesial inferior nematotheca; two large nemato¬
thecae at base of gonotheca; basal chamber of these long,
cup wide, shallow, excavated on side facing gonotheca.
Orifice of gonotheca distal, subcircular, closed by a thin
operculum, gonotheca containing a single planula larva
almost filling gonotheca at maturity. Male gonotheca
considerably smaller than female, borne behind
hydrotheca in same position as female, ovoid to kidney¬
shaped, flattened, apically blunt to rounded; no obvious
orifice; a single small nematotheca at base, cup deeper
and narrower than those on female; excavated on
adcauline side. Spermatogenic mass almost filling
gonothecal cavity.

Colour. Colourless, preserved material.

Measurements (nm).

Internode

length of athecate

(along base of hydrocladium)

328 -

400

length of thecate

(along base of hydrocladium)

168 -

272

diameter of transverse node

56 -

80

Hydrotheca

length of abcauline wall.

margin to hydropore

176 -

224

diameter of margin

208 -

240

Nematothecae

mesial nematotheca, overall length

70 -

80

diameter of cup

24 -

32

lateral, overall length

74 -

92

diameter of cup

42 -

44

Gonotheca

Fig. 34. Antennella secundaria: A, fertile hydroeladium. B, thecate
and athecate internodes. C, female gonotheca. D, male gonotheca.
Scale bars; A, 1,000 gm; B, 300 gm; C, D, 500 gm.

45

J.E. Watson

female, length of adcauline wall

544 -

632

maximum width

320 -

368

male, length of adcauline wall

280 -

344

maximum width

200 -

244

Remarks. The present material conforms with
descriptions and dimensions of Antennella secundaria
given by many authors (see Schuchert (1997).

Distribution. Cosmopolitan in temperate and tropical
seas.

Genus Halopteris Allman, 1877
Halopteris polymorpha (Billard, 1913)

(Fig. 35A-H)

Plumiilaria polymorpha Billard, 1913; 24.

Antennella polymorpha - Vervoort 1941; 218.

Plumularia buski Billard. 1913; 21. - Nutting 1927;
22. - Redier 1966; 90.

Halopteris buskii Rees and Thursfield, 1965; 160.

- Vervoort and Vasseur 1977; 72. - Gibbons and Ryland
1991; 527. - Rees and Vervoort 1987; 119.

Halopteris polymorpha - Pennycuik 1959; 178.

- Vervoort 1966; 132. - Millard and Bouillon 1973; 83. -
Millard 1975; 354. - Millard 1978; 193. - Hirohito 1983,
62. - Ryland and Gibbons 1991; 530. - Schuchert 1997;
64.

Records and material. NTM C12937, alcohol
preserved material; NTM Cl2995, microslide, colony
from Stn 138. NTM Cl2998, microslide, colony from
Stn 121. NTM Cl 2994, microslide, colony from Stn 129.
NTM C12996, microslide, colony from Stn 146.
Colonies on shell grit. NTM Cl2938, alcohol preserved
material; NTM Cl2997, MV F86902, microslides,
colony on sponge from East Point reef, coll; J. E. Watson,
depth 7 m, 17/81998.

Description. Hydrorhiza short, tubular, ramified, of
same diameter as stem. Stems to 20 mm high, mono-
siphonic, lower segments ahydrocladiate, perisarc thick
with irregularly spaced transverse nodes, distal lower
stem with scattered nematothecae; first hydrothecate
internode short with a strong proximal and V-shaped
distal node, a hydrotheca just above node; cauline nodes
thereafter oblique but less distinct, each with a
hydrocladium and basal hydrotheca in lower third.
Hydrocladial apophysis inserted alongside cauline
hydrotheca, long, with transverse distal node, first
hydrocladial internode athecatc, short, with one proximal
mesial nematotheca, distal node strongly oblique,
internodes thereafter alternately hydrothecate and
athecate, thecate internodes longer than athecate, two
partial intranodal septa superior to hydrotheca.
Hydrothecae variable in shape on different stems, from
deep to shallow cup-shaped, seated in proximal to mid¬
region of internode at an angle of c. 45° to hydrocladial
axis, free adcauline wall varying (on different stems)
from almost straight to distinctly concave, base convex,

Fig. 35. Halopteris polymorpha: A, colony from Darwin Harbour.
B. .stem intemode with hydrocladium. C, hydrocladial intemode with
cup-shaped hydrothecae. D, hydrocladial internode with cylindrical
hydrothecae. E. female gonothecae. F, lateral nematothecae with
short and long pedicels. G, mesial nematothecae. H, superior mesial
nematotheca from below hydrotheca. Scale bars: A, 2,000 pm; B,
E, 500 pm; F, G, H, 100 pm; C, D, 300 pm.

abcauline wall straight to slightly sinuous, expanding
just behind margin. Margin circular, perpendicular to
hydrothecal axis, perisarc rather thin.

Nematothecae all bithalamic; athecate internode with
one mesial nematotheca on centre of internode with short,
robust base, cup almost rectangular, adcauline side
excavated, clo.sely adpressed to hydrocladium; hydro¬
thecate internode with one inferior mesial nematotheca
similar to intersegmental nematotheca, not reaching base
of hydrotheca; lateral nematothecae bithalamic, seated
on pedicels of varying length, basal chamber moderately
long, cup reaching to or just above hydrothecal margin,
wide and shallow; adcauline side shallowly to deeply
excavated; a small, superior mesial nematotheca inserted
at base of hydrotheca. Cauline nematothecae same as
mesial superior.

Female gonotheca large, balloon-shaped, widest
distally, borne on a pedicel of one or two globular
internodes beside cauline hydrotheca; two nematothecae
similar to laterals side by side above pedicel; orifice
terminal, elliptical to circular, closed by a slightly domed
operculum.

46

Beagle Gulf and Darwin Harbour hydroids

Colour. Live colonies white.
Measurements (pm).

Stem

diameter of athecate stem
length of first stem internode
length of succeeding internodes

360

120
424
- 400

diameter of nodes

56

- 64

Apophysis

diameter at node

40

- 56

Hydrocladium

length thecate internode

288

- 352

length of first intersegment

136

- 176

length of succeeding intersegments

88

- 120

diameter of transverse node

32

- 40

Hydrotheca (tubular form)

length free adcauline wall

96

- 112

length abcauline wall

192

- 200

diameter of margin

160

- 168

Hydrotheca (cup-shaped form)

length free adcauline wall

96

- 112

length abcauline wall

192

- 200

diameter of margin

160

- 168

Nematotheca

length of pedicel of lateral

48

- 52

overall length of lateral

52

- 72

diameter of cup

44

- 52

Gonotheca

length including pedicel

800

- 880

maximum width

376

- 440

diameter of operculum

192

- 224

Remarks. Both stems and hydrocladia show evidence

of regeneration after breakage.

Colonies show two distinct hydrothecal morphologies
(Fig. 35C, D) but all fall within the range of variation of
Halopteris polymorplia defined by Schuchert (1997). The
form with wider, cup-shaped hydrothecae resembles
specimens from the Seychelles while those with more
tubular hydrothecae are similar to those from Billard’s
(1913) Siboga Station 80 (see Schuchert 1997).

Relationship between Halopteris buski, H. poly-
morpha and H. glutinosa (Laniouroux, 1816). In a
detailed study of the Halopterididae, Schuchert (1997)
found that several species, including Halopteris
polymorpha, have been confused with Halopteris buski
(Bale, 1884). Halopteris buski from southern Australia
can be confidently distinguished from Halopteris
polymorpha only in fertile material, the female gonotheca
of the former bearing up to 12 nematothecae in two rows
compared with only two nematothecae at the base of the
female of H. polymorpha. It is also clear from
Kirchenpauer’s figure of the female gonotheca of
Halopteris obconica (Kirchenpauer, 1876) from southern
Australia that H. buski is a synonym of that species.

Schuchert (1997) examined the remaining fragment
of the type of Halopteris glutinosa (Lamouroux, 1816)
from “mers des hides et TAustralie” and suggested the
possible conspecificity of H. buski with H. glutinosa.
Although the condition of the type specimen was too

poor for accurate description, Schuchert’s figure is
typical of specimens from southern Australia referred
by Bale (1884) to H. buski. Both Lamouroux (1816) and
Bale (1884) commented on the distinctive scarlet colour
of the species. Since only one species of hydroid from
southern Australia has such distinctive colouration (J.
E. W., pers. obsv.) it is certain that H. obconica and H
buski are conspecific with H. glutinosa.

Distribution. Indo-Pacific, Indian Ocean (Millard
and Bouillon 1973) (Billard 1913), (Vervoort 1966),
French Polynesia (Vervoort and Vasseur 1976). Tropical
eastern Australia (Pennycuik 1959).

Halopteris plagiocampa (Pictet, 1893)

(Fig. 36A-C)

Plumularia plagiocampa Pictet, 1893: 56. - Billard
1913: 31. - Jaderholm 1919: 21.

Halopteris plagiocampa - Schuchert 1997: 117.

Record and material. NTM Cl2998, microslide,
infertile stem fragment in poor condition broken off from
hydrorhiza, on Idiellana pristis from Stn 121.

Description. Stem 7 mm high, monosiphonic,
perisarc very thin, smooth, internodes tong with distinct
transverse nodes, a row of four equidistant nematothecae
on front of internode; opposite pairs of hydrocladia given
off distally on internode. Hydrocladial apophysis short,
with two transverse distal nodes; hydrocladia opposite,
directed upwards at 35° - 60“ to stem axis. Hydrocladial
internodes variable in length, usually long and slender,
proximal internode athecate with one small mesial
nematotheca close to transverse proximal node,
internodes thereafter with strongly oblique proximal node
and transverse distal node. Hydrothecate internode
shorter than proximal internode, hydrotheca seated on
distal half. Hydrotheca deep, almost tubular, set an angle
of 40“ to hydrocladial axis, floor shallowly convex, free
adcauline wall short, decidedly concave, abcauline wall
straight, margin circular, rim not everted.

Nematothecae all bithalamic, mesial proximal on
athecate internode, small, basal chamber stout, cup
shallow, broad, mesial inferior similar, basal chamber
more robust, nematotheca not reaching base of
hydrotheca; lateral nematotheca inserted without pedicel
below adnate adcauline wall, not reaching hydrothecal
margin, basal chamber long, cup shallow and broad, a
little excavated on adcauline side; cauline nematothecae
similar to mesials; no lateral nematothecae associated
with cauline hydrotheca.

Colour. Transparent to colourless (preserved
material).

Measurements (pm).

Stem

length of internode

800

-1,060

width at node

72

- 80

length of apophysis (abcauline side)

60

- 72

width of distal apophysal node

36

- 40

47

J.E. Watson

Fig. 36. Halopteris plagiocampa : A, part of stem. B, thecate hydrocladial intemode. C, thecate hydrocladial intemode with lateral nematothecae
removed to show concave adcauline wall. Scale bars: A, 500 pm; B, C, 300 pm.

Hydrocladium

length of athecate intersegment

208 -

312

length of thecate internode

184 -

272

diameter at transverse node
Hydrotheca

36 -

40

length of abcauline wall

140 -

148

length of free adcauline wall

60 -

64

diameter at margin

124 -

140

Nematotheca

length of pedicel

of intersegment mesial

24 -

28

diameter of cup

24 -

36

length of pedicel of lateral

40 -

46

diameter of cup

38 -

42

length of mesial inferior pedicel

32 -

38

diameter of cup

30 -

32

Remarks. Schuchert (1997) distinguished Halopteris

plagiocampa from its close congener Halopteris
zygocladia (Bale 1914) on the shorter basal chamber and
more inrolled cup of the lateral nematotheca of H.

zygocladia. As the few reasonably well preserved
nematothecae of the present material do not appear to
have inrolled cups the specimen is here referred to
Halopteris plagiocampa.

Distribution. Indonesia, Japan (Billard 1913,
Jaderholm 1919). A new record for Australia.

Family Plumulariidae Hincks, 1868
Genus Monotheca Nutting, 1900
Monotheca flexuosa (Bale, 1894)

(Fig. 37A, B)

Plumularia flexuosa Bale, 1894: 115. - Mulder and
Trebilcock 1916: 79. - Stechow 1925: 246. - Blackburn,
1938: 315. - Shepherd and Watson 1973: 140.-Watson
1973:188.

Monotheca flexuosa - Stechow 1921: 260. - Stechow
1925: 246.

Record and material. NTM C12999, microslide,
small infertile colony on shell grit, from Stn 87.

Description. Stems to 5 mm high, flexuous,
monosiphonic, unbranched, arising from a creeping
tubular hydrorhiza; perisarc of proximal stem fairly thick,
nodes distinct, without nematothecae; internodes of
hydrocladiate stem region slender, expanding a little
distally, nodes transverse, deeply incised, a nematotheca
halfway along internode, one or two in axil of apophysis
and one just below axil. Hydrocladia alternate, fairly
short, proximal internode athecate, node narrow, slightly
oblique, followed by hydrothecate internode; hydrotheca
sunk into and projecting beyond end of hydrocladium,
deeply campanulate, expanding to margin, abcauline wall
weakly concave, adcauline wall almost straight, base
rounded, margin circular, flaring but not everted.

Nematothecae all two-chambered, basal chamber of
mesial inferior short, cup reaching base of hydrotheca,
adcauline side foreshortened; twin laterals inserted in
blunt apex of hydrocladium below hydrotheca, basal
chamber long, cup circular, fairly wide and shallow;
cauline and axillary nematothecae same as mesial.

Colour. Colourless.

Measurements (pm).

Stem

length of internode

200 -

304

diameter of node

20 -

24

length of apophysis

20 -

32

Hydrocladium

length of athecate internode

68 -

80

length of hydrothecate internode

120 -

152

diameter of node

20 -

24

Hydrotheca

length of abcauline wall

92 -

100

diameter of margin

100 -

120

Remarks. One to three axillar nematothecae are
present in the specimens, thus differing from Monotheca

48

Beagle Gulf and Darwin Harbour hydroids

Fig. 37. Monotheca flexuosa: A, distal part of stem. B, hydroeladium.
Scale bars: A, 1,000 pm; B, 100 pm.

flexuosa from southern Australia which usually has only
one or two (J. E. W., pcrs. obsv.). While the significance
of the third axillar nematotheca is not known in this
tropical material, variation of the number of nemato-
thecae is not regarded as a reliable diagnostic character.

In the absence of gonothecae, Monotheca pulchella
(Bale, 1882) is virtually indistinguishable from M.
flexuosa. The gonotheca of M. pulchella is large with a
laterally directed terminal orifice and large internal
submarginal teeth while that of M. flexuosa is more
elongate with an axially directed terminal orifice and
sometimes a raised collar. This difference may possibly
be sexual as all gonophores of M. flexuosa so far found
in southern Australia are female (J. E. W., pers. obsv.);
the gonophore of M. pulchella is still unknown.

Distribution. Southern Au.stralia and South Africa.
Not previously recorded from tropical Australia.

Genus Nemertesia Lamouroux, 1812
Neinertesia cylindrica (Kirchenpauer, 1876)

(Fig. 38A-E)

Plumularia cylindrica Kirchenpauer, 1876: 45.

Antennularia cylindrica - Bale 1884: 146.

INemertesia cylindrica - Nutting 1927: 227.
- Pennycuik 1959: 178.

Records and material. NTM Cl2961, alcohol
preserved material; NTM Cl3000, NTM Cl3002, MV
F86906, microslides, colony from Stn 146. NTM C
13001, microslide, colony from Stn 121. NTM CI2962,
alcohol preserved material; NTM Cl3013, microslide,
colony from Stn 136. MV F86948, alcohol preserved
material, colony from Stn 147. Fertile and infertile small
to medium size colonies attached to rock. Other records,
Stns 91,137, 139. East Arm breakwater and channel bed.

many large colonies, coll: J. E. Watson depth 6 m, 20/8/
98. Plater Rock channel bed, many large colonies on
rock, coll: J. E. Watson, depth 15 m, 22/9/1999.

Description. Colonies to 200 mm high, up to 30 stems
arising from a large fibrous, hydrorhizal mat up to 50
mm wide; stolons also enmeshing basal region of stems
in a spongy sheath. Stems erect, long, monosiphonic,
single or forked at an acute angle more or less in the
same plane, internodes thick, short, nodes transverse,
deeply incised in proximal and distal stem regions, often
indistinct in mid-stem region.

Hydrocladia crowded, arising at an acute angle in
verticels of up to eight around each internode, reducing
to four or five in distal stem region. Apophyses with a
short, slightly oblique, often indistinct node, a truncated
tubular mamelon on adcauline side. Hydrocladial
internodes long, straight, nodes distinct, slightly oblique,
sometimes replicated. Hydrotheca occupying more than
half of internode, tubiform, adcauline wall completely
adnate, weakly convex, posterior wall slightly convex
to straight, abcauline wall slightly sinuous, margin
circular, cut obliquely away to join internode.

Mesial inferior nematotheca seated on a prominence
of the internode, lying along internode to touch base of
hydrotheca, bithalamic, basal chamber long, tapering,
freely movable, cup deep, excavated on adcauline side;
lateral nematotheca bithalamic, seated on a minute
pedicel at hydrothecal margin, basal chamber short,
inflated, side of cup deeply excavated and closely
adpressed on side facing hydrotheca, obscuring
hydrothecal margin. Cauline nematothecae same as
mesials, one on each side of stem internode, just proximal
to node, two or three flanking mamelon at base of
apophysis.

Female gonothecae large, distributed along entire
length of stem, several on internode, upwardly tilted,
without pedicel, irregularly saccate to sausage-shaped
(depending on angle of view), perisarc moderately thick,
up to eight nematothecae similar to laterals distributed
along frontal margin, orifice distal, subcircular to
elongate, flanked by two blunt lateral lobes, orifice
closed by a sheet of tissue, gonotheca containing three
globular planulae.

Colour, Stems of live colonies dark shining brown,
hydrocladia and gonothecae paler brown to almost white.

Measurements (pm).

Stem

length of internode

460

- 500

width at node

400

- 600

Hydroeladium

maximum length

5,000

length of internode

448

- 464

width at node

80

- 96

Hydrotheca

length of abcauline wall

224

- 256

49

J.E. Watson

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50

Beagle Gulf and Darwin Harbour hydroids

width at margin

80

- 96

Nematotheca

overall length of median

92

- 100

depth of cup

32

- 48

overall length of lateral

72

- 80

Gonotheca

length

800

-1,040

width (frontal view)

340

- 400

width (lateral view)

176

- 240

Remarks. The abundant fertile material in the Beagle
Gulf and Darwin Harbour collection led to re-appraisal
of Nemertesia cylindrica (Kirchenpauer, 1876) and N.
indivisa (Allman, 1883). Nemertesia cylindrica was
erected on infertile material from Java, and Allman
described N. indivisa from fertile specimens with lobate
gonothecae from Cape York, Australia. Billard (1913)
referred specimens from Indonesia with lobate gono¬
thecae to N. indivisa and included Antennularia
cylindrica Bale, 1884 from off Port Curtis, Queensland,
in its synonymy. After examination of type material of
N. indivisa. Bale (1919), following Billard (1913),
wrongly concluded that N. indivisa and N. cylindrica
were conspecific. Nutting (1927) and Pennycuik (1959)
recorded, without adequate description or figures, N.
cylindrica from the Philippines and Queensland
respectively; because of lack of description, their records
are doubtful. Billard (1913) described N. indivisa as
having two pairs of axilliary nematothecae and his figure
depicts a complex lobate gonotheca. The Beagle Gulf
material usually has two, sometimes three but never four
axillary nematothecae. This, together with the completely
different gonotheca shows that the material cannot be
N. indivisa. As comparative measurements of the Beagle
Gulf material agree with those extracted from Bale’s
(1884) figure of Antennularia cylindrica (pi. 10, fig. 7)
it is concluded that the two are conspecific. This is the
first record of the gonosome of N. cylindrica. Being very
difficult to distinguish when infertile, it is unfortunate
but understandable that A. cylindrica and Nemertesia
indivisa were confused by earlier authors; they are,
however, easily separated when fertile.

Colonies of Nemertesia cylindrica observed in
Darwin Harbour are distinctive in their large size, the
dark brown brush-like bunch of tall, straight stems
emerging from a large, spongy hydrorhizal mass which
sheaths and binds the lower stems firmly together, at the
same time anchoring it in situations of strong current
flow (J. E. W., pers. obsv.).

Distribution. Australian tropical east coast
(Pennycuik, 1959).

Genus Plumularia Lamarck, 1816
Plumularia badia Kirchenpauer, 1876
(Fig. 39A-E)

Plumularia badia Kirchenpauer, 1876: 45. - Bale
1884:128.-Bale 1913: I35.-Thomely 1916:149. - Jaderholm

1916: 7. - Stechow and Muller 1923: 473. - Vervoort
1941: 221.-Watson 1996: 79.

Plumularia ramsayi Bale, 1884: 131. - Kirkpatrick
1890: 604. - Billard 1913: 52.

Plumularia gracilis von Lendenfeld, 1885b: 476.

Records and material. NTM C13003, NTM C13004,
NTM Cl3005, NTM Cl3006, MV F86905, microslides,
colony from Stn 52. NTM Cl3007, microslide, colony
from Stn 95. NTM C12900, MV F86940, alcohol
preserved material, East Arm channel and breakwater,
coll: J. E. Watson, depth 7 m, 19/8/1998. NTM Cl2901,
alcohol preserved material. East Point reef, immature and
richly fertile mature colonies on dead coral boulders, coll
J. E. Watson, depth 6 m, 19/9/1999. Other records. Stns
58, 67, 101. Plater Rock, many large fertile colonies on
sponges, coll: J. E. Watson, depth 8 m, 21/9/1999.

Description. Hydrorhiza a tangle of narrow tubes
entwining substrate. Colonies ranging from single,
branched stems 20 mm high to large clusters of 60
complexly branched stems 240 mm high. Stems slender,
monosiphonic, more or less alternately branched in same
plane, lower stem region ahydrocladiate, hydrocaulus of
short stems stiff, branching pseudosympodial, almost
perpendicular to cauline axis; stems of taller colonies
long, flexuous, subdichotomous branching common to
second or third order, branches directed acutely upwards,
distally truncated. Stem and branch internodes short,
smooth, nodes transverse, deeply incised proximally,
fading distally, a node below and above origin of each
branch, branch apophysis with oblique distal node.
Perisarc of stem and branches smooth and thick.

Hydrocladia alternate, short, two on branch intemode,
in distal region of branch one row sometimes slightly
displaced to front of branch with a third above, forming
a verticel; hydrocladia backwardly curved, inserted on a
long, geniculate, upwardly directed apophysis with a
strong oblique distal node; two nematothecae in axil and
a mamelon with short neck on apophysis distal to
nematothecae. Hydrocladial internodes all hydrothecate,
variable in length, node deeply oblique, a weak septum
projecting downwards into internode from adcauline wall
of hydrotheca. Hydrotheca deep cup-shaped, centrally
placed on shorter internodes, proximal on longer
internodes, adcauline wall immersed in internode,
posterior wall perpendicular to internode, curved,
abcauline at an angle of 30° to internode, wall straight,
or with a slight concavity behind margin; margin sinuate,
base excavated back into internode.

Nematothecae bithalamic, large, moveable, mesial
inferior borne on a low prominence of internode, a deep
perisarc-infilled notch in front, basal chamber of
nematotheca long, cup foreshortened on adcauline side,
not reaching base of hydrotheca; twin laterals similar to
mesial, inserted on a prominence behind hydrothecal
margin, projecting forward from margin, facing inwards
towards axis of internode, cup shallowly excavated on

51

J.E. Watson

adcauline side. Cauline nematothecae same as laterals,
one beside apophysis (often absent) and one in axil, a
small mamelon or pore on base of apophysis between
nematothecae.

Gonotheca inserted without pedicel in axil of branch
apophysis, small, conical, distally truncated, terminal
orifice circular, sealed by a thin opercular flap, perisarc
very thin.

Colour, Stem and branches of live and preserved
specimens shining dark brown to black, hydrocladia
whitish, gonothecae transparent white.

Remarks. Variations in dimensions of hydrothecae
occur throughout the colonies, some having a longer
abcauline wall and a narrower margin than usual. The
thickened, truncated apex of the branches noted by
Kirchenpauer (1876) which suggests breakage occurs so
consi.stently that it must be a normal habit of growth.
While hydrocladia are alternate on older parts of the
stems, the distal regions of some branches have
hydrocladia in verticils of three, approaching the
structure of Nemertesia. The gonothecae are so delicate
that most collapse in mountant. There is some evidence
that the gonophore may be expelled as an acrocyst.

The large amount of material examined in the present
study and the wide range in some critical morphological
dimensions supports comments on the variability of
Plumularia badia by previous authors. But for the
finding of some colonies of intermediate size, the short¬
stemmed, pseudosympodially branched form of P. badia
could easily be mistaken for a different species from the
tall form (Table 6). Such structural differences may be a
response to ecological conditions, the simply branched,
shorter, presumably juvenile morphology being lost as
colonies increase in height and in number of stems. The

Table 6. Comparative measurements (pm) of short (simple) and tall
(multiple) forms of Plumularia badia.

Tall form

Short form

Stem, width at base

1,000

800

Branch

length of distal branch

272

- 520

560

- 936

internode

width at node

176

- 224

160

- 176

length of apophysis

120

- 136

72

- 104

(adcauline side)

Hydrocladium

maximum length

1,500

-1,720

1,400

-1,700

length of internode

236

- 280

296

- 352

width at node

36

- 60

36

- 40

Hydrotheca

length of abcauline wall

80

- 100

80

- 96

width of margin (lateral

56

- 88

64

- 72

view)

Nematotheca

mesial, length of pedicel

30

- 32

32

- 40

width of cup

30

24

- 26

lateral length of pedicel

40

- 50

32

- 40

width of cup

30

- 38

26

- 34

Gonotheca

length

256

- 336

480

- 560

distal width

136

- 160

200

- 240

long tresses of the tall form occur on sponges and other
invertebrate substrates in strong current flow of tidal
channels, whereas the shorter, pinnate colonies occupy
more sheltered habitats on reefs.

Plumularia badia is one of the most abundant species
in Darwin Harbour.

Distribution. Indonesia and Torres Strait, Australian
subtropical and tropical coasts (Bale 1884, Watson 1996).

Plumularia scabra Lamarck, 1816
(Fig. 40A-E)

Plumularia scabra Lamarck, 1816: 127. - Billard
1907: 322. - Billard 1913: 47. - Bale 1919: 342. -Rees
and Thursfield 1965: 164.

Plumularia effusa Busk, 1852: 388, 400. - Kirchen¬
pauer 1876: 46. - Bale 1884: 129. - Bale 1887: 22.

Acanthella effusa - Allman, 1883: 27. - Marktanner-
Turneretscher, 1890: 260. - Kirkpatrick, 1890: 610. - von
Campenhausen, 1897: 315. - Stechow and Muller, 1923:
474.

Records and material. NTM CI2897, alcohol
preserved material; NTM Cl 3008, MV F86903,
microslides, colony from Stn 147. NTM Cl2896, MV
F86930, alcohol preserved material, Stn 137. NTM
Cl3014, microslide, Stn 136. Infertile colonies of few
to many stems. NTM Cl2898, alcohol preserved
material. Plater Rock, large colonies on rock, coll: J. E.
Watson, depth 15 m, 22/9/1999. Other record, Stn 80.

Description. Hydrorhiza a knot of thin, tough tubes.
Colony consisting of up to 15 monosiphonic stems to
300 mm high, greater length of stems unbranched, distal
stem region a branched canopy with up to three orders
of branching into verticels, a deep hinge Joint above fork
on each branch. Branch internodes variable in length,
becoming shorter distally, nodes collar-shaped, deep,
internodes of younger branches bearing four hydrocladia,
older branches bearing up to 10; apices of some branches
with two or three thick, upwardly directed apophysal
spines without hydrocladia. Perisarc of stems and
branches very thick, thinning a little distally.

Hydrocladial apophyses very long, upwardly directed
with a strongly oblique distal node and deep crea.ses in
perisarc; hydrocladia alternate, short, on front of branch,
close-set on younger branches, directed forward and
slightly reflexed, older branches with whorls of up to
six hydrocladia. Hydrocladial internodes short, nodes
strongly oblique, narrow, one to four intranodal .septa,
one passing into hydrocladium midway along adcauline
wall of hydrotheca, another at base of lateral nema-
totheca, one, hook-shaped, below posterior margin of
hydrotheca and one, not always present, behind node.
Hydrotheca small, occupying almost entire internode,
tubiform, abcauline wall sinuous, curving upward to
margin, adcauline wall convex, immersed in hydro¬
cladium, margin broadly lobate, excavated back to
internode.

52

Beagle Gulf and Darwin Harbour hydroids

Fig. 40. Plumularia scabra: A, stem from colony from Beagle Gulf.
B, hydrocladiate part of stem with cauline spurs. C, hydrocladial
internodcs. D, apophysis of branch. E cauline spur. Scale bars: A,
50 mm, B. 1,000 pm; C, D, E, 200 pm.

Nematothecae large, all of similar shape, bithalamic,
movable, basal chamber long, one mesial inferior on
prominence of internode at base of hydrotheca, cup deep,
adcauline side slightly foreshortened, adpressed into
curve of abcauline hydrothecal wall or standing erect;
lateral nematotheca inserted without pedicel below
hydrothecal margin, basal chamber shorter than that of
mesial, cup level with hydrothecal margin; two or three
cauline nematothecae associated with apophysis - one
axillar, facing inwards to branch, another about halfway
along apophysis, the third (if present) at base of distal
apophysal node.

Colour. Stem and branches of live colonies grey-
brown, fading to lighter brown, hydrocladia grey-white.

Measurements (fim).

Branch

length, younger branch internode

760 -

800

width at node

96 -

136

Apophysis

length abcauline wall

216 -

240

Hydrocladium

length internode

200 -

216

width at node

40 -

52

Hydrotheca

length abcauline wall

88 -

100

width at margin

76 -

100

Nematotheca

length basal of chamber of mesial

48 -

64

marginal width of mesial cup

42

depth of cup (abcauline wall)

20 -

24

length of basal chamber of lateral

26 -

30

marginal width of lateral cup

24 -

26

depth of cup (abcauline wall)

26

Remarks. Although Lamarck’s brief description of
Plumularia scabra was accurate. Bale (1884) doubted
the validity of the species but Billard (1907) in
redescription of the type in the Lamarck collection of
the Museum du Paris confirmed the accuracy of
Lamarck’s description. Dimensions of the present
material fall within the range of variation of the type.
The apical apophysial spurs are diagnostic of the species.

Seen in situ, the colonies are tall with up to 15 stems
and a sparse, gracefully branching canopy. The species
prefers open, rocky habitat in good current flow at depths
greater than 15 m at the base of reefs.

Distribution. “South Seas’’ (Lamarck 1816),
Philippines, Indonesia (Billard 1913), Torres Strait (Busk
1852).

Plumularia setacea (Linnaeus, 1758)

(Fig. 41 A, B)

Sertularia setacea Linnaeus, 1758: 813.

Plumularia setacea - Lamarck 1816: 129. - Hincks
1868: 296.-Bale 1888: 778. - Billard 1913: 32. - Ritchie
1911: 851. - Bale 1915: 294. - Pennycuik 1959:
180. - Ralph 1961; 33. - Millard 1975; 399. - Watson
1994: 67. - Cornelius 1995: 158. - Watson 1996: 79.

Plumularia tripartita von Lendenfeld, 1885b: 477.

Record and material. NTM Cl3009, microslide,
damaged infertile stem on Eunice tubifex, Stn 40. Other
record. Fragmentary stem, Stn 137.

Description. Stems to 4 mm high, cauline internodes
long, slender, widening distally to a distinct, transverse
node; internode bearing one to three nematothecae, if
all three present, equally spaced along internode,
distalmost just below hydrocladial apophysis; if only one,
this usually proximal on internode. Perisarc of stem thick
proximally, thinning distally and along hydrocladia.
Hydrocladia alternate, inserted on an upwardly tilted
distal apophysis; apophysis with one or two strong
transverse nodes followed by a slightly oblique distal
node; first hydrocladial internode hydrothecate,
internodes thereafter alternately athecate and thecate; two
or three hydrothecate internodes on hydrocladium,
internodes long and slender, nodes slightly oblique,
distinct; thecate internode widening from proximal node
to base of hydrotheca

Hydrotheca on distal third of internode, abcauline
wall confluent with internode, adcauline wall almost
entirely adnate, convexly curved, free part short, straight,
margin circular, tilted distally at an angle of c. 105° to

53

J.E. Watson

Fig. 41. Plumularia setacea: A, stem from Beagle Gulf. B,
hydrocladial internodes. Scale bars: A, 1,000 gm; B, 300 gm.

hydrocladial axis; athecate internode with a small mesial
nematotheca at proximal third to centrally placed,
inclined towards hydrocladium, basal chamber short,
robust, cup a little foreshortened on adcauline side;
mesial nematotheca proximal on hydrothecate internode,
same as athecate mesial; lateral nematotheca small, freely
movable, facing outwards, basal chamber inserted
without pedicel in internode beneath hydrotheca, cup
small, circular; cauline nematothecae same as mesials.
Perisarc of hydrocladia and hydrotheca thin; hydranth
with 12-14 tentacles.

Colour. Colourless, preserved material.

Measurements (pm).

Stem

length of internode

416 -

504

diameter at node

40 -

48

Hydrocladium

length of athecate internode

200 -

240

length hydrothecate internode

336 -

400

diameter at node

32 -

40

Hydrotheca

length of abcauline wall

68 -

80

diameter of margin

100 -

104

Remarks. The specimen agrees with dimensions of
Plumularia setacea given by Ritchie (1911) for
specimens from the Australian east coast.

Distribution. Cosmopolitan. Recorded from east,
west and southern Australia.

Plumularia bedoti (Billard, 1911)
(Fig42A-D)

Plumularia bedoti Billard, 1911; 64. - Billard 1913:
27.

Record and material. NTM C13010, microslide, two
small, damaged infertile stems on Gymnangium
longicorne, Stn 136.

Description. Stems to 10 mm high, proximal half of
stems and lower branch lightly fascicled, becoming
monosiphonic in upper region, apophysis of branch with
transverse distal node, branch ahydrocladiate proximally,
internodes thereafter with strongly oblique nodes, each
internode with three alternate, equidistant hydrocladia,
one proximal, one in middle and one distal on internode.
Perisarc of stem and branches thick and smooth.
Hydrocladia frontal on stem and branches, internodes
slender, first internode athecate, distal node oblique,
internode with one mesial nematotheca, internodes
thereafter alternately thecate and athecate; thecate
internode with oblique proximal and transverse distal
node, transverse node sometimes indistinct; no intranodal
septa. Hydrothecae seated on upper side of internode,
tubular, deep, occupying almost entire internode, tilted
forward at an angle of c. 55° to internode, adnate
adcauline wall convex, short, free adcauline wall straight,
abcauline wall weakly convex, margin perpendicular to
hydrothecal axis, subcircular to oval, rim slightly everted.

Nematothecae bithalamic, mesial hydrothecate
inferior seated on a small prominence, a perisarc infilled
notch between basal chamber and proximal node, basal
ehamber short, robust, cup foreshortened on adcauline
side, just reaching base of hydrotheca; basal chamber of
lateral nematotheca long, conical, movable, cup broad
and shallow, reaching hydrothecal margin, excavated on
adcauline side. Athecate internode with one mesial
nematotheca similar to mesial inferior, proximal on
internode, bent forward. Cauline nematothecae similar
to mesials, a row of five on internode, one near base of
apophysis, one above and one in axil.

Colour. Colourless to white, preserved material.

Measurements (pm).

Stem, maximum width

160

Branch

diameter monosiphonic region

72 -

88

length apophysis abcauline wall

56 -

64

distance between hydrocladia

on same side

344 -

376

Hydrocladium

length along base intersegment

120 -

144

length along base hydrothecate

internode

88 -

100

width at transverse node

20 -

36

Hydrotheca

length free adcauline wall

60 -

76

length abcauline wall

104 -

128

diameter of margin

80 -

84

Nematotheca

mesial, length of basal chamber

18 -

24

mesial, diameter of cup

18 -

20

lateral, length basal chamber

(excluding pedicel)

28 -

34

lateral, diameter of cup

30 -

32

54

Beagle Gulf and Darwin Harbour hydroids

Fig. 42. Plumularia bedotv. A. stem from colony on Gymnangium
longicome. B. hydrocladiate part of stem. C, hydrocladial intemodes.
D, anterior view of hydrotheca. Scale bars: A, 3,000 pm; B, 300
pm; C, D, 200 pm.

Remarks. Although the colonies are much smaller
than those of Plumularia becloti described by Billard
(1913), they conform in morphological characters and
dimensions with that species. The apophysial mamelon
mentioned by Billard is not evident in the Beagle Gulf
specimens.

Distribution. Previously known only from Indonesia
(Billard 1913).

Plumularia tubacarpa sp. nov.

(Fig.43A-D)

Material and record. Holotype, NTM Cl3011,
microslide, infertile stem on sponge amongst shellgrit,
Stn 87. (No preserved material).

Description. Hydrorhiza a small knot of tubular
stolons. Stem 9 mm high, monosiphonic, slender, erect,
internodes long, smooth, increasing slightly in diameter
distally, nodes transverse, caulus slightly tumescent
above node, nodes becoming fainter distally along stem.
Hydrocladia alternate, one to four, usually two on
internode, given off from a long, slender upwardly
directed apophysis on side of stem; apophysis with an
oblique distal node and frequently a transverse septum
behind node; hydrocladia directed upwards at an angle
of c. 35“ to internode, with up to 10 hydrothecae.
Hydrocladial internodes all thecate, nodes strongly
oblique, an incipient septum passing into internode
between base of hydrotheca and mesial nematotheca.

Hydrotheca seated in middle of internode, deep cup¬
shaped, adcauline wall entirely adnate, convex, abcauline
wall contiguous at an angle of 20° with internode, straight
to faintly sinuous, concave just behind margin; margin

circular, rim slightly everted and inclined slightly to
hydrocladial axis. Nematothecae all same shape and size,
bithalamic, moveable, basal chamber long, cup
foreshortened on adcauline side; mesial inferior seated
on a prominence of internode, standing erect, not
reaching base of hydrotheca; lateral nematotheca inserted
on a minute pedicel behind hydrothecal margin,
extending well beyond hydrotheca. Cauline internodes
with variable number of nematothecae, one in axil of
apophysis, one beside apophysis, one halfway between
hydrocladia and sometimes one at side of internode just
above node.

Gonotheca long, tubular, pointing downward, inserted
without pedieel on proximal side of apophysis in lower
stem region, distal end domed, perisarc smooth.

Colour. Colourless.

Measurements (pm).

Stem

proximal diameter

88

distal diameter

168

distance between hydrocladia

on same side

640 -

768

apophysis, adcauline length

76 -

88

Hydrocladium

length of internode

376 -

416

width at node

24 -

32

Hydrotheca

length of abcauline wall

112 -

136

width at margin

96 -

112

Nematotheca

median, overall length

52 -

60

diameter of cup

24

Gonotheca

length

840

width

88

Fig. 4.3. Plumularia tubacarpa sp. nov. A, holotype colony. B,
hydrocladiate part of stem. C, hydrocladial internodes. D, gonotheca.
Scale bars: A, 2,000 pm; B, D, 500 pm; C 300 pm.

55

J.E. Watson

Remarks. The single stem of Plumularia tubacarpa
appears to be young, the distal cauline internodes still
being poorly developed and there is a distinct growing
apical tip. The long, tubiform gonotheca containing
coenosarcal tissue also appears to be immature.

Plumularia tubacarpa does not resemble any species
of Plumularia in available literature. While some species
reported from Indonesia have spatulate to rectangular
gonothecae (e.g. P. insignis var. gracilis Billard, 1913
and P. spiralis var. longitheca Billard, 1913) the absence
of intranodal septa in the hydrocladium distinguishes P.
tubacarpa from P. insignis and the presence of two, not
three axillar nematothecae distinguishes it from P.
spiralis. The hydrorhiza of P. tubacarpa is intergrown
with that of a young colony of Polyplumaria corniita
for which species it was originally mistaken.

Etymology. Refers to the long, tubular gonotheca.

Genus Polyplumaria G. O. Sars, 1874
Polyplumaria cornuta (Bale, 1884)

(Fig. 44A-F)

Plumularia cornuta Bale, 1884: 132.

Polyplumaria cornuta - Billard 1913: 53. - Briggs
and Gardner 1931: 191.

Record and material. NTM C12940 alcohol
preserved material, colony from Stn 67. NTM Cl2939,
alcohol preserved material; NTM Cl 3012, MV F86904,
microslides, colony from Stn 92. Sparse fertile colonies
on shellgrit and gravel. Other records. Stns 66, 87. East
Arm channel, infertile colony on coarse sand, coll: J. E.
Watson, depth 6 m, 21/8/1998.

Description. Hydrorhiza a tangle of thin colourless
stolons embedded in shellgrit. Stems solitary, to 280 mm
long, slender and flexuous, a proximal region short to
long and sometimes lightly fascicled, stem thereafter
hydrocladiate, monosiphonic; distal half to third of stem
branched in verticels of three, branches short, reflexed,
hydrocladiate. Perisarc of stem and branches thick,
smooth. Hydrocladia on branches alternate, on an
indistinct apophysis, hydrocladial internodes thecate,
short, nodes strongly oblique, deep, three strong septa
passing downwards from base of hydrotheca almost
through internode; two partial septa, one below mesial
nematotheca and between lateral nematotheca and node.
Apophyses of some branches with a spinous accessory
hydrocladium with several intrathecal septa, one or two
nematothecae near apex and one hydrotheca with twin
laterals but no mesial nematotheca. Hydrotheca adnate
to internode, adcauline wall obscured by three humps
associated with intranodal septa, abcauline wall weakly
sinuous with a small peak behind margin; margin strongly
sinuate, cut back to meet internode.

Nematothecae all bithalamic, movable, mesial inferior
on a small prominence of internode, an infilling of
perisarc at base, nematotheca standing almost erect, basal

chamber long, slender, cup shallow, foreshortened on
adcauline side to almost triangular; basal chamber of
lateral moderately long, inserted at base of hydrothecal
margin, cup rather shallow, broad, a little excavated on
adcauline side. Cauline nematothecae similar to mesial;
three on internode, one at base of apophysis and two in
axil.

Gonotheca inserted without pedicel in axil of
apophysis, small, almost triangular, widening distally,
no operculum, perisarc very thin.

Colour, In life, very pale yellow-brown, lower stems
darker brown.

Measurements (pm).

Branch

distance between hydrocladia

on same side

580

- 800

Hydrocladium

maximum length of hydrocladium

4,400

-6,000

length of internode

296

- 320

width at node

60

- 72

length of apophysial spine

260

- 280

Hydrotheca

length of abcauline wall

176

- 180

width of margin

140

- 148

Fig. 44. Polyplumaria cornuta: A. colony from East Arm channel,
Darwin Harbour. B, hydrocladial internodes. C, anterior view of
hydrocladium. 1), mesial nematotheca. E, lateral nematotheca. F,
cauline spur. Scale bars: A, 50 mm, B, C, 300 pm; D, E, 100 pm; F,
300 pm.

56

Beagle Gulf and Darwin Harbour hydroids

Nematothecae

mesial inferior, length of basal chamber 66 -

90

diameter of cup

30 -

40

lateral, length of basal chamber

64 -

76

diameter of cup

44 -

52

Gonotheca

length

66 -

100

distal width

40 -

54

Remarks. The graceful, slender colonies tend to
collapse out of fluid. The few gonothecae present on one
colony are too poorly preserved and obscured by
adventitious matter for determination of sex. Except for
the absence of the mesial nematotheca associated with
the hydrotheca on the accessory hydrocladium the present
material conforms with the detailed description and
dimensions of Polypliimaria coniuta given by Billard
(1913).

Colonies occur in sandy beds of channels in strong
current flow, their pale colour rendering them almost
invisible (J. E. W., pers. obsv.).

Distribution. Known only from Indonesia (Billard
1913) and Queensland (Bale 1884).

Family Kirchenpaueriidae Stechow, 1921
Genus Kirchenpaueria Jickeli, 1883
Kirchenpaiieria irregularis Millard, 1958
(Fig. 45A, B)

Kirchenpaueria irregularis Millard, 1958: 211.

- Millard 1975: 370. - Watson 1996: 79.

Kirchenpaueria sp. - Watson 1997: 530.

Record and material. NTM Cl3015, microslide,
small infertile colony on oyster shell attached to boat
mooring, Fannie Bay, near East Point, coll: K. Gowlett-
Holmes, depth 3 m, 17/8/1998.

Description. Stems to 15 mm high, arising irregularly
from a reptant hydrorhiza. Proximal stem region lightly
fascicled, stems sparsely branched with one or two orders
of branching. Cauline internodes long, narrow, smooth,
nodes transverse to slightly oblique, perisarc of
internodes thin; hydrocladia alternate, arching gracefully
away from a .short apophysis with transverse distal node.
Hydrocladial internodes long, slender, smooth, nodes
transverse to slightly oblique, no inlranodal septa; most
internodes thecate but some hydrocladia with an athecate
segment. Hydrotheca on distal third of internode, cup¬
shaped, adcauline wall lying parallel to but free of
internode; abcauline wall contiguous with internode,
curving upwards; margin circular, rim faintly everted,
perpendicular to hydrothecal axis and tilted proximally
away from axis of internode. Nematothecae all of same
size and shape, bithalamic, minute, mesial inferior distant
from hydrotheca, mesial superior near distal node; one
cauline nematotheca above axil of apophysis and one
on internode below apophysis, a small mamelon on distal
side of apophysis facing axillar nematotheca.

Fig. 45. Kirchenpaueria irregularis: A, stem from colony. East Point.
B, hydrocladium. Scale bars; A, 3,000 pm; B, 300 pm.

Colour. Live colonies transparent white.
Measurements (pm).

Stem

length of internode

304 -

656

diameter at node

56 -

104

length of apophysis

40 -

56

Hydrocladium

length of thecate internode

400 -

544

diameter at node

36 -

48

Hydrotheca

length abcauline wall

44 -

68

diameter of marginal rim

76 -

96

Remarks. Colonies of this small species are fragile
and lax, collapsing out of fluid. The specimens conform
in all respects (including the irregular internode length
and insertion of ancillary athecate internodes in the
hydrocladium) with Millard’s (1958, 1975) description
and dimensions of the species.

Distribution. South Africa (Millard 1975). Australia:
previously recorded from the Abrolhos Islands and
Australian west coast Watson (1996, 1997).

Family Aglaopbcniidac
Marktanner-Turneretscber, 1890
Genus Aglaophenia Lamouroux, 1812
Aglaophenia delicatula (Busk, 1852)

(Fig 46A-E)

Plumularia delicatula Busk, 1852: 396.
Aglaophenia delicatula - Bale 1884: 167.

- Kirkpatrick 1890: 604. - Borradaile 1905: 843. - Billard
1913; 106. - Jiiderholm 1920: 8. - Jarvis 1922: 350.

- Pennycuik 1959: 185.

57

J.E. Watson

Thecocarpus delicatulus - Millard and Bouillon 1973:
94.

Records and material. NTM Cl3017, microslide,
colony from Stn 81. NTM Cl2884, alcohol preserved
material, colony from Stn 154. NTM Cl2883, alcohol
preserved material; NTM Cl 3020, MV F87897,
microslides, colony from Stn 156. NTM C13019,
microslide, colony from Stn 153. MV F86931, alcohol
preserved material; NTM Cl3018, microslide, colony
from Stn 127. NTM Cl3016, MV F86896, microslides,
colony from Stn 40. Many infertile colonies, mostly on
Eunice tubifex', one colony on stem of sertulariid hydroid.
Other records. Stn 147. Plater Rock, colony on Eunice
tubifex, coll: J. E. Watson, depths 3 - 10 m, 22/9/1999.

Description. Hydrorhiza knotted; stems to 35 mm
high, plumose, monosiphonic, unbranched, narrowing
distally, prosegment ahydrocladiate, with strong distal
hinge joint; stem thereafter hydrocladiate. Hydrocladia
frontal on stem, closely alternate, one on internode,
cauline nodes transverse, indistinct or absent. Hydro-
cladial internodes short, nodes transverse, an intrathecal
septum passing almost vertically downwards from
posterior of hydrotheca to wall of internode opposite, a
weak partial or complete septum passing from base of
lateral nematotheca into internode. Hydrotheca conical,
adcauline wall flatly convex, adnate, abcauline wall
convex; a strong septum passing from abcauline wall to
base, connecting with intranodal septum; margin dentate
with a fairly long mesial abcauline cusp, an indentation
at base of cusp opposite mesial nematotheca; mesial
abcauline cusp flanked by a pair of blunt cusps, followed
a more rounded pair, a third very low pair and sometimes
a fourth posterior pair reduced to an mere undulation.

Mesial nematotheca tubular, free part short, not
reaching hydrothecal margin, terminal orifice circular
to canaliculate, an elliptical secondary orifice connecting
with hydrotheca at base of free part; lateral nematotheca
tubular, a little tumescent distally, bent forward beyond
hydrothecal margin, orifice circular, only slightly
excavated on adcauline side. Cauline nematothecae more
or less bean-shaped, with a single orifice, one in axil,
one of similar size below, both facing outwards and one
larger, above hydrocladium.

Colour. Stems brown, hydrocladia almost white.

Measurements (pm).

Stem

length of internode

224 -

232

width at node

84 -

88

Hydrocladium

length of internode

212 -

228

width at node

64 -

84

Hydrotheca

depth, mesial abcauline cusp to base

180 -

196

width of margin

120 -

128

Nematotheca

length of mesial

200 -

212

diameter at orifice

18 -

26

length of lateral

104 -

112

diameter at orifice

20 -

24

Remarks. The specimens do not entirely conform
with descriptions of Aglaophenia delicatula by Bale
(1884) and Billard (1913). Billard gives a length of 340
- 380 pm and 40 - 50 pm for width of the hydrocladial
internodes but these dimensions do not agree with an
internode length of 110 pm calculated from his figure
(Fig. 106). These dimensions differ considerably from
both Bale’s measurements (calculated from PI. 14, Fig.
4) and those of the present specimens. Nor does the
Beagle Gulf material agree with Bale’s description of
two cauline nematothecae below the hydrocladium, there
being only one, centrally placed on the internode Just
above the node; Billard (1913) does not mention cauline
nematothecae in his description. Despite these di¬
fferences 1 have no doubt that the Beagle Gulf material
is A. delicatula. The species may be an obligate epizooite
of Eunice tubifex.

Distribution. Tropical northern and eastern Australia
(Pennycuik 1959), Maidive Islands (Borradaile 1905).

Genus Gymnaiigium Hincks, 1874
Gymnangium liians (Busk, 1852)

(Fig 47A-E)

Plumularia hians Busk, 1852: 396.

Halicornaria hians - Bale 1884: 179. - Kirkpatrick
1890: 604. - Stechow 1909: 101. - Stechow 1913: 10,
94. - Billard 1913: 68. - Jaderholm 1916: 8. - Briggs
1918:47;-Stechow 1919: 425. - Bedot 1921: 347. - Jarvis
1922: 355. - Nutting 1927: 237. - Vervoort 1941:
222. - Millard 1958: 219. - Pennycuik 1959: 186.

Halicornaria haswelli Bale, 1884, 180.

Fig. 46. Aglaophenia delicatula: A, stem from colony from Beagle
Gulf. B, hydrocladial internode. C, hydrotheca, anterior view. D,
mesial nematotheca. E, cauline nematothecae. Scale bars: A, 10 mm,
B, C, D, 300 pm; E, 100 pm.

58

Beagle Gulf and Darwin Harbour hydroids

Aglaophenia balei Marktanner-Turneretscher, 1890:
272. - Billard 1905: 334.

Halicornaria balei - Ritchie 1910: 22.

Halicornaria flava Nutting, 1905: 955.

Halicornaria hians var laxa Ritchie, 1910: 835.
Halicornaria hians var. balei Billard, 1913: 70. -
Bedot 1921: 347. - Van Gemerden-Hoogeveen 1965: 70.

Gymnangium hians - Stechow 1923: 19. - Stechow
1924: 69. - Stechow 1925: 254. - Yamada 1958: 51, 61.

- Rees and Thursfield 1965: 171.-Millard and Bouillon
1973: 92. - Rho and Chang 1974: 147. - Millard 1975:
444 . - Rho 1977: 279, 425. - Vervoort 1977: 84.

- Vervoort and Vasseur 1977: 84. - Hirohito 1983: 77.

- Ryland and Gibbons 1991: 542. - Hirohito 1995: 287.

- Watson 1996: 79.

Gymnangium hians var. balei Mammen, 1967:
311.- Vervoort 1968: 114. - Schmidt 1972: 41. - Mergner
and Wedler 1977: 24. - Van Praet 1979: 912.

Not Gymnangium hians - Jaderholm 1916: 8.
Records and material. NTM Cl2948, alcohol
preserved material; NTM Cl3021, NTM Cl3022, MV
F86928, fertile colony of five damaged stems detached
from substrate, Stn 154. Other records. East Point, fertile
colonies on Eunice tubifex, coll: J. E. Watson, depth 8
m, 17/8/1998. Plater Rock, many fertile colonies on
Eunice tubifex, coll: J. E. Watson, depths 3-8 m 21/9/
1999.

Description. Hydrorhiza ramified, stems unbranched,
up to 40 mm long, stiffly plumose, monosiphonic,
proximal stem wide, prosegment bearing remnant spurs

from shed hydrocladia; stem narrowing distally, perisarc
thick and shining. Cauline nodes transverse, faint to
distinct, hydrocladia alternate, on opposite sides of stem,
directed upwards at an angle of c. 45° to axis, slightly
recurved, usually two, sometimes one on internode;
hydrocladia up to 20 mm long, internodes deep, nodes
slightly oblique, faint, no intranodal septa. Hydrothecae
saccate, contorted about middle, floor convex, proximal
part of wall sometimes extended downwards into a knot
of perisarc, free adcauline wall short, straight to slightly
convex, abcauline wall completely adnate to mesial
nematotheca, a thick hook-shaped intrathecal septum
passing forward into hydrotheca from mid-abcauline
wall, free end of septum a ragged edge (anterior view).
Margin tilted upwards, a pair of sharply pointed,
posteriorly pointing cusps in posterior third, margin
strongly everted into pair of broad cusps, a pair of small
cusps between lateral nematothecae, rarely a second pair
of small, poorly defined cusps between these and lateral
cusps.

Mesial nematotheca narrowing from base to apex, free
part long, arching over hydrotheca, abcauline wall
thickened, terminal orifice circular, a small secondary
orifice just above junction with hydrotheca. Lateral
nematothecae short, saccate, tubular, orifice large, open
down to hydrothecal margin. Cauline nematothecae same
as laterals, one above and one below hydrocladial
apophysis and one behind axil.

Gonothecae conical, perisarc thin, in a single crowded
row along stem, female containing a single planula larva.

Fig. 47. Gymnangium hians: A, fertile stem from colony on Eunice tubifex. East Point reef. B, hydrocladial internodes. C, anterior view of
hydrotheca. D, cauline nematothecae. E, intrathecal septum, showing ragged edge. Scale bars: A, 10 mm, B, C, D, 300 pm; E, 100 pm.

59

J.E. Watson

Colour. Stem shining dark brown, hydrocladia and
gonothecae paler brown to cream.

Measurements (pm).
Hydrocladium

length of internode

272

- 304

width of node

128

- 200

Hydrotheca

depth, anterior margin to floor

180

- 200

width at margin (lateral view)

148

- 160

width across marginal lobes (top view)

268

- 288

Nematotheca

mesial, length of free part

92

- 152

mesial, diameter of terminal orifice

16

- 18

lateral, length

84

- 100

Gonotheca

length

900

-1,000

width

520

- 680

Remarks. Ryland and Gibbons (1991) suggested a
likely relationship of Gymnangium haswelli with G.
Ilians. To investigate this, and relationships of G. Iiians
with other similar Australian species I examined
microslide preparations of putative type material of
Halicornaria haswelli Bale, 1884 (MV F58843), H.
baileyi Bale, 1884 (MV F58837) and H. furcata Bale,
1884 (MV F58839), held in the Museum of Victoria (see
Stranks, 1993). Gymnangium furcata and G. baileyi from
the temperate Australian east coast have similar bran¬
ching habit and there are no microscopic characters that
clearly differentiate them. Gymnangium haswelli and G.
Ilians, known from subtropical and tropical Australia
have unbranched plumose stems and also share similar
microscopical characters. The four species thus fall into
two distinct groups: G. furcata being conspecific with
G. baileyi-, and (supporting the suggestion of Ryland and
Gibbons (1991)) G. haswelli is conspecific with G. hians.
The Beagle Gulf and Darwin Harbour specimens
conform exactly with the type of G. hians from Torres
Strait.

It is possible that some of the many supposed variants
of Gymnangium hians reported from the Indo-Pacific and
other regions may be other, closely related species. For
example. Bale’s figure (1884, pi. 13, fig. 6) of the
cuspidate hydrothecal margin of a specimen of G. hians
exactly depicts the margin of a species, G. undulatiim,
described as new in this paper. Gymnangium undulatum
can be clearly differentiated from G. hians by the long,
undulated stems and cauline nematothecae. To establish
the taxonomic limits of G. hians there is need for critical
re-examination of preserved specimens of variants of the
species reported from geographically different localities.

Gymnangium hians is one of the most abundant
species in Darwin Harbour and environs, the colonies
occurring almost exclusively on Eunice tubifex. It is
surprising that the species was recovered from only one
locality (Stn 154) in the wider Beagle Gulf survey.

Distribution. Type locality, Torres Strait. Known
from tropical north-western Australia (Watson 1996) and
Indo-Pacific (Ryland and Gibbons 1991, Watson 1996).

Gymnangium longicorne (Busk, 1852)

(Fig. 48A-F)

Plumularia longicornis Busk, 1852: 399.

Aglaophenia longicornis - Kirchenpauer 1872:
47. - Bale 1884: 157. - Bale 1886: 25. - Kirkpatrick 1890:
604. - Marktanner-Tumeretschcr 1890: 267.

Halicornaria longicornis - Billard 1913: 67. - Briggs
and Gardner 1931: 195. - Pennycuik 1959: 186.

Halicornaria intermedia Billard, 1913: 65.

Halicornaria longicorne var. sibogae Billard, 1913:
67.

Lytocarpus longicornis - Bedot 1921: 315, 321.

Macrorhynchia longicornis - Stechow and Muller
1923: 474.

Macrorhynchia longicornia - Watson 1996: 79.

Records and material. NTM C12877, alcohol
preserved material, colony from Stn 7. NTM Cl2878,
alcohol preserved material colony from Stn 127. NTM
Cl2879, alcohol preserved material; NTM Cl3025,
NTM Cl3026, microslides, colony from Stn 87. NTM
Cl3024, MV F86916, microslides, colony from Stn 32.
Large and small colonies, some fertile, on pebbles,
bryozoans and ascidians. Other records. Stns 38, 40, 77,
78,81,91,97, 104, 110, 129, 136, 137, 144, 147, 149,
150, 152, 156, 157, 159, 160. East Arm port channel,
coll: J. E. Watson depth 4-6 m, 17/8/1998, Plater Rock,
coll: J. E. Watson, depth 3-6 m, 21/9/1999, many large,
fertile colonies on coral boulders and other invertebrate
substrate.

Description. Hydrorhiza a mass of tubular stolons
entwining substrate, stolonal filaments passing up into
strong cauline fascicular tubes. Stems to 3 mm in
diameter at base and 190 mm long, plumose, prosegment
ahydrocladiate, unbranched. Branches of up to three
orders given off in almost same plane from frontal tube
of stem, ultimate branches monosiphonic, a long, blade¬
shaped hinge joint separating monosiphonic branches
from preceding polysiphonic region, two short nema¬
tothecae on base of branch above joint. Branch
internodes short, visible only in distal region, nodes
transverse, distinct. Hydrocladium short, with up to six
hydrothecae, borne on short apophysis on front of branch,
hydrocladia alternate, crowded, recurved, two on
internode; internodes short, node almost transverse, two
strong, complete intranodal septa crossing internode,
proximal one passing into hydrotheca as a partial
intrathecal septum, distal node adjoining lateral
nematotheca. Hydrotheca long, saccate, occupying entire
internode, adcauline wall adnate to internode, abcauline
wall convex posteriorly, free half of wall saddle-shaped
and tilted upwards to margin, a deep wedge ot perisarc
passing into hydrotheca below margin. Margin parallel

60

Beagle Gulf and Darwin Harbour hydroids

with or inclined slightly to internode, a short mesial
abcauline cusp connecting with perisarcal flange; margin
circular with a pair of broad, centrally placed erect lateral
lobes.

Mesial nematotheca very variable in length from very
long, considerably overtopping hydrothecal margin to
shorter than hydrothecal margin, length increasing
distally along hydrocladium, longest nematothecae thin,
tubular, sometimes a little swollen in distal third, terminal
orifice small, circular, a larger secondary orifice on a
short neck above hydrotheca and a small internal foramen
connecting with hydrotheca. Shorter nematothecae with
same terminal and secondary orifices as on longer
nematothecae. Lateral nematotheca long, thin, tubular,
sinuous, adnate to hydrotheca and extending beyond
margin, terminal orifice circular. Two cauline nema¬
tothecae at hydrocladial apophysis, short, narrowing from
base to small terminal orifice, proximal one pointing
along hydrocladium, the other facing across branch.

Gonotheca inserted without pedicel in axil of
hydrocladium, large, leaf-shaped at maturity, perisarc
very thin, no terminal orifice, mature female gonophore
with many small ova, not filling cavity.

Stem and branches bearing structures termed here
“pseudophylactocarps” (see remarks) which usually
replace the first or second hydrocladium on a branch;
pseudophylactocarp long, lax, proximal two or three
hydrothecae normal, followed by up to eight internodes
each bearing two or three long, digitate nematothecae.

Colour. Live colonies dark grey-brown; preserved
stems shining golden-brown, branches and hydrocladia
paler brown.

Mea.surements (|ini).

Hydrocladium
length overall
length of internode
width at node
Hydrotheca

depth, margin to floor
width at margin
Nematotheca

mesial, free length (typical form)
mesial, diameter of terminal orifice
mesial, free length (intermedia form)
lateral, length
Gonotheca
length

maximum width
pseudophylactocarp
maximum length overall
length internode
length nematothecae

172

48

120

76

180

16

44

140

456

160

180

112

1,200
• 180
60

• 132

80

■ 220
18

• 60
■ 160

- 576

- 272

1,900

- 200
■ 152

Remarks. Some morphological variants in the large
sample of Gymnangium longicorne available for study
conform with descriptions of G. intermedium (Billard
1913) and G. longicorne var. sihogae (Billard, 1913).

Fig. 48. Gymnangium longicorne: A, small colony from Beagle Gulf.
B, hydrocladium with upwardly directed hydrothecae and long mesial
nematothecae. C, hydrocladium from different colony from Beagle
Gulf with parallel hydrothecae and short mesial nematothecae. D,
cauline nematothecae. E, pseudophylactocarp from proximal stem
region. F, female gonotheca. Scale bars: A, 50 mm, B, C, F, 300 pm;
D, 100 pm; E. 500 pm.

Billard (1913) described and figured “hydroclades
transformds” on the hydrocaulus of Lytocarpia angulosa.
These lax and extremely flexible structures, present on
several tropical species (J.E.W. pers. obsv.) are not true
phylactocarps since they bear neither hydrothecae nor
gonothecae and are defined here as “pseudophy¬
lactocarps”. Lower stems of G. longicorne which are
devoid of pseudophylactocarps are often invested with
epizootic communities of small hydroids and other
invertebrates but these epibionts are absent from regions
where there are pseudophylactocarps. The nematothecae
in the pseudophylactocarps are heavily armed, which,
together with the sweeping action of these structures, is
probably an adaptation to remove potential settlers from
the stems. Hydrocladia and distal branches are quite
deciduous, readily breaking off at hinge joints. Lateral
nematothecae on distal parts of the hydrocladia are
usually larger and more forwardly directed than those
proximal on the hydrocladium.

61

J.E. Watson

Briggs and Gardner (1931) first described the
gonotheca of G. longicorne from the Australian Great
Barrier Reef. The range of developing and mature
gonothecae in the present collection indicates that their
material was immature.

Gymnangiiim longicorne is one of the most abundant
hydroids in the Beagle Gulf collection and one of the
more con.spicuous species in Darwin Harbour.

Distribution. Indonesian region (Billard, 1913).
Australian distribution: Torres Strait (Busk 1852),
tropical Queensland (Pennycuik 1959). The locality of
Port Jackson given by Marktanner-Turneretscher (1890)
is probably incorrect.

Gymnangiiim undulatum sp. nov.

(Fig 49A-F)

Record and material. Holotype, NTM Cl2952,
alcohol preserved material; NTM C13027, NTM
Cl3048, MV F86901, microslides from holotype. Large
colonies on top of coral boulders, Plater Rock coll: J. E.
Watson, depth 4 m, 22/9/1999.

Description. Hydrorhiza composed of thick stolons
replant on substrate. Stems long, to 250 mm, plumose,
unbranched, monosiphonic, strongly undulated, bends
occurring every 15-25 mm along length, divided into
internodes by strong, slightly oblique nodes, a tu¬
mescence below each node, cauline perisarc very thick,
smooth. Prosegment ahydrocladiate, in hydrocladiate
region, hydrocladia close, alternate, directed slightly
forwards from opposite sides of stem on a moderately
long apophysis with distal hinge joint; two, occasionally
three, hydrocladia on internode, if two, proximal in lower
third to halfway along internode, upper one just below
distal node; sometimes two opposite hydrocladia and on
internode. Hydrocladial nodes slightly oblique, marked
only by a faint constriction and thinning of perisarc; no
intranodal septa. Hydrolhecae saccate, margin tilted
obliquely backwards at an angle of c. 40° to hydrocladial
axis, a strong septum passing forwards into body from
midway along abcauline wall, septum dividing wall into
two pronounced convexities, in ventral view septum seen
as a shelf with ragged edge; adcauline hydrothecal wall
gently convex, a small knot of perisarc at connection
with internode. Hydrothecal margin with three pairs of
equidistant, deeply scalloped cusps, no unpaired anterior
tooth, cusp of middle pair the largest (lateral view), often
pointing posteriorly; posterior cusp the broadest,
posterior margin of hydrotheca straight between lateral
nematothecae.

Mesial nematotheca digitate, just overtopping
hydrothecal margin, terminal orifice may be entirely
absent or with a small orifice on side facing hydrotheca,
orifice just above hydrothecal margin or a completely
open gutter from apex to hydrothecal margin. Lateral
nematothecae small, rectangular to elongate conical,
proximally rounded, distal end level with hydrocladium.

a large connection with internode and a large terminal
orifice. Three cauline nematothecae associated with
apophysis: two frontal, large, one in axil and one below
apophysis, the one below with two large excavated
orifices side by side, axillar one with a single orifice of
similar shape, orifices facing distally; rear nematotheca
behind axil, smaller, similar to laterals but with wider
orifice, facing distally.

Colour. Live colonies grey-brown.

Measurements (pm).

Stem

length of internode

576

-1,088

diameter at node

240

- 304

Hydrocladium

length of internode

280

- 336

width at node (lateral view)

120

- 152

Hydrotheca

depth, marginal cusp to floor

240

- 304

width at margin

172

- 180

height of middle marginal cusp

44

- 68

Nematotheca

mesial, free length

56

- 84

mesial, diameter of terminal orifice

lateral, length

80

- 86

lateral, width at orifice

52

- 72

cauline, maximum length

128

- 140

Remarks. While there is no discernible change in
size, shape or orientation of the cauline internodes at
the bends in the hydrocaulus, at each bend the
hydrocladia reverse their orientation, so that the group
facing the front is succeeded by a rear-facing group.

Although the colonies are infertile, 1 have little doubt
that the species should be referred to Gymnangiiim.
Jiiderholm (1916) briefly described G. hians (Busk,
1852) from a small specimen collected off Cape Jaubert,
north-western Australia. His description and figure
shows it to undoubtedly be G. undulatum. In micro¬
scopical characters, C. undulatum has much more deeply
scalloped marginal cusps than G. hians. In the field,
colonies of G. undulatum are unmistakable, growing in
thick groups of undulating stems 300 - 400 mm high
(extending to 500 - 600 mm when straightened out). In
situ, the species can deliver a painful, long-lasting sting.

Gymnangium undulatum was found only at Plater
Rock, where numerous large colonies occurred on upper
surfaces of coral rock in good current flow at 3 - 4 m depth.

Etymology. Named for the tall, undulating stems.

Gymnangium unjiiiense sp. nov.

(Fig. 50A-E)

Record and material. Holotype, NTM Cl3023,
NTM Cl 3028, MV F86898, microslides, infertile
colony from Stn 104. Paratype, NTM CI3029,
microslide, small infertile colony from Stn 110 (no
preserved material remaining).

Description, Stems simple, plumose, to 50 mm high,
arising from a thin, reptant hydrorhiza embedded in fine

Beagle Gulf and Darwin Harbour hydroids

Fig. 49. Gymnangium uiululatum sp. nov. A, stem from holotype colony from Plater Rock. B, hydrocladiate part of stem. C, hydrocladial
internodes. D, anterior view of hydrotheca. E, cauline nematothecae flanking apophysis, frontal view. F, cauline nematothecae, rear view.
Scale bars: A, 50 mm, B, 1,000 pm; C-F, 300 pm.

sediment. Stem fascicled, prosegment consisting of many
parallel tubes, becoming monosiphonic distally, pcrisarc
thick; proximal stem ending in a pronounced blade¬
shaped hinge joint, blades connected by a thin web of
perisarc. Entire length of fascicular tubes other than
axillar tube with a row of closely spaced ovoid
nematothecae; axillar tube unsegmented, giving off
hydrocladia at an angle of c. 30° to axis. Hydrocladial
apophysis short, distal node transverse, indistinct,
internodes thereafter moderately long, perisarc smooth,
thick, nodes merely a faint thinning of perisarc; three
equidistant partial intranodal septa below hydrotheca,
proximal septum short, mid-septum longer, curved
forwards, distal .septum straight or curved backwards
from base of lateral nematotheca.

Hydrotheca entirely adnate to internode, body semi-
ovoid, tilted upwards at an angle of c. 30° to internode,
posterior adcauline wall deeply sunk in intemode, a short
plug-like extension of the middle intranodal septum

passing into hydrotheca from summit of an upward bulge
in internode; abcauline wall weakly convex to sinuous,
a slight concavity behind margin. Margin transverse to
hydrothecal axis, mesial abcauline cusp prominent,
sharply pointed, followed by three pairs of very shallow,
scalloped cusps; margin straight between lateral
nematothecae; perisarc of hydrotheca thin, thickening a
little below margin.

Mesial nematotheca completely adnate to hydrotheca,
terminating below margin, orifice sinuate, open down
to hydrotheca; lateral nematotheca conical, widening to
deep gutter-shaped orifice, open to internode. Cauline
nematothecae same as laterals, orifice large, one above
hydrocladium, facing upwards along stem axis and one
below, facing along hydrocladium, a large circular
mamelon between; nematothecae on polysiphonic tubes
of stem ovoid.

Colour. Stem honey brown; hydrocladia lemon
yellow.

63

J.E. Watson

Fig. 50. Gymnangium unjinense sp. nov. A, whole stem from
holotype. Beagle Gulf. B, hydrocladium. C, anterior view of
hydrotheca. D, cauline nematothecae. E, ovoid nematothecae on
proximal stem. Scale bars: A, 10 mm, B-E, 300 pm.

Measurements (nm).

Stem

width at base

1,000

diameter of axial tube

128

- 176

distance between hydrocladia on same

side600

624

Hydrocladial internode

length

296

- 344

width at node

88

- 112

Hydrotheca

axial length margin to base

216

- 240

diameter at margin (lateral view)

160

- 176

length mesial cusp (lateral view)

48

- 56

Nematotheca

length mesial

232

- 272

height mesial apex above hydrotheca

44

- 52

length lateral

100

- 112

maximum width (lateral view)

44

- 52

Remarks. The distinctive ovoid cauline

nemato-

thecae appear as parallel series of closely spaced white
dots in the ahydrocladiate region of the stem. In some
morphological features Gymnangium unjinense is related
to Lytocarpia orienialis (Billard, 1913); however it
differs from that species in I) absence of a mamelon from
the base of the hydrocladium, 2) the hydrothecal margin
has three, not four pairs of cusps and 3) in the well
developed intranodal septa which are only incipient in
L. orientalis. The species is only provisionally assigned
to Gymnangium. When fertile material is found, it may
need to be transferred to another genus; if to Lytocarpia,
then its relationship with L. orientalis will need to be
re-examined.

Etymology. Named for the type locality off Unjin
Point in the Beagle Gulf.

Genus Lytocarpia Kirchenpauer, 1872
Lytocarpia angulosa (Lamarck, 1816)
(Fig51A-G)

Plumularia angulosa Lamarck, 1816: 126.

Aglaophenia angulosa - Lamouroux 1816: 166.
- Lamouroux 1924: 15

Plumularia huxleyi Busk, 1852: 395.

Thecocarpus angulosus - Billard 1913: 85.

Aglaophenia huxleyi - Bale 1884: 161. - Bale 1886:

26.

Acanthocladium huxleyi - Kirkpatrick 1890: 604.

Thecocarpus angulosus - Billard 1913: 85. - Briggs
and Gardner 1931: 192.

Acanthocladium angulosum - Bedot 1921: 335.
-Stechow and Muller 1923: 476.

Records and material. NTM Cl2880, alcohol
preserved material; NTM Cl3031, microslide, colony
from Stn 126. NTM C12882, alcohol preserved material,
colony from Stn 113. NTM Cl2881. alcohol preserved
material; NTM C13030, microslide, colony from Stn 93.
MV F86939, alcohol preserved material, colony from
Stn 120. NTM Cl3032, MV F86917, microslides, colony
from Stn 110. Infertile colonies on pebbles and shellgrit.
Other records. Stns 17, 27, 66, 67, 77, 82, 87, 89, 92,
100, 104, 105, 106, 111, 114, 115, 116, 118, 119, 127,
132, 136, 152, 159, 160, 161. East Port channel bed.
infertile colony on coarse sand, coll: J. E. Watson, depth
6 m, 20/9/1998.

Description. Hydrorhiza a bundle of thin, fibrous
stolons; colonies of single, straight stems to 500 mm high
and 2 mm wide at base, prosegment long, polysiphonic,
ahydrocladiate, comprising numerous parallel tubes,
some running almost to tips of branches; upper stem
region bearing single plumose hydrocladiate branches
to 30 mm long in verticels of three; branch internodes
short, nodes oblique, faint. Hydrocladia alternate, long,
close-set, inserted in front of frontal tube of branch,
internodes short, nodes slightly oblique, distinct to
absent; no intranodal septa. Hydrotheca irregularly
hemispherical, anterior adcauline wall strongly convex,
lower wall gently rounded, a concavity between two large
knots of perisarc .separating the two wall sections; a thick
intrathecal septum passing from base of mesial
nematotheca obliquely forward two thirds distance into
hydrotheca, terminating in a knot of perisarc. Margin
circular with a single, short mesial abcauline cusp
connecting with intrathecal septum followed by three
pairs of broad, low lobes, the first pair slightly more acute
than others.

Mesial nematothecae of two distinct lengths on
different colonies: long nematotheca tubular, arching
over hydrothecal margin, terminal orifice small,
excavated, base of nematotheca broad at junction with

64

Beagle Gulf and Darwin Harbour hydroids

hydrotheca, a secondary orifice, sometimes absent, just
above hydrotheca, a small foramen connecting base with
hydrotheca; short nematothecae may or may not overtop
hydrothecal margin, base same as that of long nema-
totheca, orifice excavated, often connecting with
secondary orifice above hydrotheca. Lateral nematotheca
triangular, extending to and sometimes overlapping
hydrocladial node; orifice broad, a small posterior
foramen connecting with hydrocladium. Polysiphonic
tubes of stem and branches with rows of oblong
nematothecae, each with a single terminal orifice.
Numerous pseudophylactocarps arising at intervals from
the outermo.st polysiphonic tubes of stem and branches
to just above first hydrocladium; pseudophylactocarps
short, lax, comprising up to 20 short segments separated
by deeply constricted nodes, each segment with three
long, tubular nematothecae, terminal orifice of
nematotheca sinuous, sometimes minutely crenulated;
nematotheca containing a battery of large nematocysts.

Colour. Stems light brown, hydrocladia pale yellow-
brown.

Measurements (pm).

Hydrocladium

overall length

2,900

-3,000

length of internode

200

- 224

width at node

96

- 112

Hydrotheca

depth

128

- 160

width at margin

136

- 144

Nematothecae

length of short mesial

240

- 280

width of orifice, short mesial

28

- 32

length of long mesial

280

- 320

width of orifice, long mesial

32

length of lateral

80

- 104

width of orifice, lateral

16

- 20

Pseudophylactocarp

maximum length

2,500

length of internode

160

- 180

Remarks. The present material conforms to the
redescription of Lamarck’s type material of Plumularia
angulosa by Billard (1909).

There is no lengthening of the mesial nematothecae
along the hydrocladium such as occurs in some
aglaopheniid species, the long and short forms of
nematothecae occurring on separate colonies, those with
long mesial nematothecae being the more common form.

The tall, single stems growing from a large bundle of
fibrous stolons are well adapted to life strong current
flow in beds of tidal channels. Lytocarpia angulosa is
one of the most abundant species in the Beagle Gulf
collection. The structure and presumed purpose of
pseudophylactocarps has been discussed previously.

Distribution. Indonesian region and Indian Ocean
(Millard and Bouillon 1973), Australian tropical east
coast (Pennycuik 1959).

Lytocarpia phyteuma (Kirchenpauer, 1876)

(Fig. 52A-G)

Aglaophenia phyteuma Kirchenpauer, 1876: 23.

Aglaophenia clavicula Whitelegge, 1899: 373.

Thecocarpus phyteuma - Stechow 1919: 139.
-Pennycuik 1959: 187. - Millard and Bouillon 1973:95.

IThecocarpusphyteuma - Vervoort and Vasseur 1977:

86

Thecocarpus leopoldi Le\oup, 1930: 1.

Lytocarpia phyteuma - Ryland and Gibbons 1991:
548.'

Records and material. NTM Cl2953, alcohol
preserved material; NTM Cl3033, NTM Cl3034, MV
F86899, microslides, fertile colony on Eunice tubifex,
Stn 154. NTM Cl3081, MV F86927, microslides. East
Point, fertile colony on Eunice tubifex, coll: J. E. Watson,
depth 7 m, 17/8/1998.

Description. Hydrorhiza tubular, entwining substrate.
Stems plumose, to 50 mm high, unbranched, mono-
siphonic, prosegment ahydrocladiate, divided thereafter
into short internodes by indistinct transverse nodes,
perisarc thick. Hydrocladia alternate, frontal on stem,
close, one on internode, held out stiffly at an angle of c.
45°; hydrocladia long with up to 30 hydrothecae, first
hydrothecate internode adpressed to hydrocaulus,
perisarc of internode thick, nodes marked by a notch and
a faint transverse line or thinning of perisarc, a short
intranodal .septum passing from posterior of hydrotheca.

Hydrotheca semi-ovoid, a strong partial to entire
septum passing from internode into hydrotheca at about
one third distance from posterior margin; margin inclined
backwards at c. 35° to internode, mesial abcauline cusp
tongue-shaped, prominent, flanked by three pairs of
rounded cusps of almost equal size and shape, not bent
outwards and a pair of smaller, sharper cusps, bent
slightly outwards behind lateral nematothecae. Perisarc
of hydrotheca moderately thick, thinner below margin
but thickened below marginal cusps.

Mesial nematotheca adnate to hydrotheca, not
reaching hydrothecal margin, abcauline wall weakly
convex to sinuous, narrowing to a gutter-shaped orifice
open down to hydrotheca. Lateral nematothecae ovoid,
facing outwards, narrowing distally, overlapping next
internode, orifice large, gutter-shaped, open down to
internode. Two nematothecae on each cauline internode,
pouch-shaped with wide orifice, one just above node,
the other at base of hydrocladium, facing outwards.

Corbula replacing a hydrocladium, proximal segment
hydrothecate followed by an internode bearing a small,
free leaflet; corbula with up to 20 ribs, corbula closed
but with a distinct thinning of perisarc at base of ribs,
free edges of ribs deep, upturned, no rachial internodes,
base of each rib hydrothecate, margin of hydrotheca
entire but without mesial or lateral nematothecae; rib with
at least 12 erect nematothecae similar to hydrothecal

65

J.E. Watson

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03 B

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111

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■ 5 . a

^ J= ta

'5 u M

•< o
u

« s

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--- «u

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■J'f •s

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66

Beagle Gulf and Darwin Harbour hydroids

laterals, orifice of nematothecae wide, gutter-shaped.
Gonophores probably female.

Colour. Stems deep honey brown, hydrocladia paler
brown.

Measurements (pm).

Stem

length of internode

304

- 344

width at node

128

- 144

Hydrocladium

maximum length

12,000

Hydrocladial internode

length

240

- 272

width at node

80

- 112

Hydrotheca

length along base

218

- 224

depth, behind margin to base

136

- 144

width at margin

160

- 176

length of anterior marginal cusp

28

- 40

Nematothecae

length of mesial

232

- 256

free height above hydrotheca

72

width of distal end (lateral view)

24

- 36

length of lateral

88

- 100

width at orifice (lateral view)

28

- 36

Corbula

maximum length

6,000

width (lateral view)

1,120

height of leaflets above body

344

- 400

Remarks. Specimens from Beagle Gulf and Darwin
Harbour generally conform to Stechow’s (1919)
description and figures of Lytocarpia phyteuma,
however, the free part of the corbula ribs appear to be
longer than shown by Stechow. The distinct partial
hydrocladial intranodal septum described by Whitelegge
(1899) for A. clavicula but not by Stechow is clear in
the present specimens. There is some doubt that Vervoort
and Vasseur’s (1977) specimens from French Polynesia
are indeed L. phyteuma because the hydrotheca shown
in their fig. 36a is longer, lies parallel to the internode
and the lateral nematothecae point downwards.

Colonies of L. phyteuma were found only on Eunice
tubifex.

Distribution. Pacific region, tropical eastern
Australia.

Genus Macrorhynchia Kirchenpauer, 1872

Macrorhynchia philippina Kirchenpauer, 1872
(Fig. 53A-D)

Macrorhynchia philippina Kirchenpauer, 1872;
19. - Stechow 1923: 241. - Stechow and Muller 1923:
475.-Stechow 1924: 69. - Stechow 1925: 258. - Hirohito
1983: 78.-Rees and Vervoort 1987: 177. - Watson, 1996:
79. - Migotto 1996: 40. -Watson 1997: 538. - Calder
1997: 62.

Aglaophenia philippina - Kirchenpauer 1872; 29,
45-46.

Lytocarpus philippinus - Kirkpatrick 1890: 604.
- Baie 1888: 786. - Billard 1913: 78. - Bale 1914: 6. -
Bale 1915: 293. - Jaderholm 1916: 7. - Briggs and
Gardner 1931: 193. - Millard 1958: 220. - Pennycuik
1959: 186. - Millard and Bouillon 1973: 93. - Millard
1975: 449.

Records and material. NTM Cl2894, alcohol
preserved material; NTM Cl3036, microslide, colony
from Stn 110. NTM Cl2893, alcohol preserved material;
NTM Cl3037, microslide, colony from Stn 49. NTM
Cl3035, microslide, colony from Stn 127. Large and
small infertile colonies on Eunice tubifex. NTM C12895,
MV F86936, alcohol preserved material, fertile colonies
on other invertebrates and Eunice tubifex on wharf
structures, Darwin Harbour, coll: J. E. Watson, depth 2-
12 m, 17/8/1998. 0//(er/-ecorJi'. Stn 61. East Point, coll:
J. E. Watson, depth 7 m, 19/8/1998. Plater Rock, colonies
on other invertebrates and Eunice tubifex, coll: J. E.
Watson depth 2-15 m 21/9/1999.

Description. Hydrorhiza reptant on substrate.
Colonies variable in size from single stems a few
centimetres long to large complex colonies of several
stems to 200 mm high. Stems erect, plumose, simple or
branched, if branched, up to 4 mm wide at base, fascicled,
polysiphonic tubes running parallel to near apex of
branches. Two or three orders of branching may be
present, branches straight, given off sparsely and
irregularly from stem, branch internodes indistinct.
Hydrocladia frontal on branch, alternate, one on
internode; hydrocladial internodes short, deep, nodes
slightly oblique; two partial intranodal septa, one passing

Fig. 53. Macrorhynchia philippina: A, small fertile colony from
wharf pilings, Darwin Harbour. B, hydrocladial internodes. C,
cauline nematotheca. D, phylactocarp with male and female
gonothecae. Scale bars: A, 50 mm, B, 300 pm; C, 100 pm; D, 1,000

67

J.E. Watson

down from base of hydrotheca, the other from base of
lateral nematotheca.

Hydrotheca saccate, adcauline wall flat or slightly
convex in contact with internode, where free of internode
attached to lateral nematotheca, a deep indentation in
base at proximal end of adcauline wall, abcauline sinuate,
rising abruptly behind margin, a deep V-shaped septum
penetrating hydrotheca between mesial nematotheca and
margin. Margin circular with a pair of opposite, tow
lobes.

Mesial nematotheca erect, tubular, parallel with
hydrothecal abcauline wall, reaching to or beyond
hydrothecal margin, tapering a little distally, terminal
orifice circular, a little excavated on adcauline side, a
secondary orifice above junction with hydrotheca and
another, internal, connecting with hydrotheca. Lateral
nematotheca long, tubular, inclined forward, overtopping
hydrothecal margin, orifice circular or slightly excavated.
A cauline nematotheca on branch at base of hydro-
cladium, short, body inflated, a circular orifice on a short
neck.

Phylactocarp a modified hydrocladium given off from
front of branch, phylactocarp about same length as
gonotheca; proximal internode with a hydrotheca, next
internode short, athecate, succeeding internode with two
nematothecae and pedicel of gonotheca, following three
to six internodes short with two long, digitate nema¬
tothecae with circular distal orifice. Gonothecae large,
lenticular, containing a degenerate medusa, one or two
gonothecae, sometimes a male and a female, on same
rachis, perisarc thin, female containing many small ova.
At release, medusa ovoid, without mouth or canals but
with a ring of strongly refringent granules around margin.

Colour. In life, stems and branches dark brown to
black, hydrocladia pale grey, male gonophore purple to
black, female cream to pale orange. The refringent
granules on the released medusa sparkle blue and white
under the microscope.

Measurements (^m).

Hydrocladium

maximum length

6,000

length of internode

280

- 320

width at node

64

- 88

Hydrotheca

length along base

136

- 160

depth, margin to base

180

- 200

width across margin

160

- 180

Nematotheca

maximum length of mesial

336

- 360

maximum free height

128

width acro.ss orifice

20

length of lateral

160

- 168

width across orifice

20

- 22

Phylactocarp

length

900

-1,100

Gonotheca

length

920

-1,200

Nematotheca

length 120 - 176

Remarks. Macrorhynchia philippina is a very
common tropical Australian species, colonies on the
Great Barrier Reef growing to very large size (J. E. W.,
pers obsv.). Colonies on the polychaete Eunice tubifex
in Beagle Gulf and Darwin Harbour were, however, quite
small. Gonophores of the present material conform
exactly with the description and figure of M. philippina
by Gravier (1970). Other authors (see Calder 1997) have
reported female gonophores containing one to three ova
or planulae. Colonies of M. philippina can deliver a
painful sting.

Distribution. Circumglobal tropical. Australian
distribution: tropical Queensland to Western Australia
(Pennycuik 1959, Watson 1997).

Macrorhynchia Phoenicia (Busk, 1852)

(Fig. 54A-E)

Plumularia phoenicia Busk, 1852:398.

Plumularia aurita Busk, 1852: 397:

Aglaophenia rostrata Kirchenpauer, 1872: 45.

Aglaophenia spectahilis Allman, 1883: 43.

Aglaophenia phoenicia - Bale 1884: 159. - Bale 1886:
15. - Bale 1887: 87. - Kirchenpauer 1892: 45. - Inaba
1892:347.

Lytocarpiis phoeniceus - Kirkpatrick 1890: 604.
- Nutting 1905: 954. - Ritchie 1910: 21. - Billard 1910:
48. - 1913: 74. - Bale 1913: 138. - Stechow 1913: 95. -
Jaderholm 1916: 7. - Jiiderholm 1919: 25. - Jiiderholm
1923: 5. - Bedot 1922: 181.- Jarvis 1922: 354. - Briggs
and Gardner 1931:194. - Vervoort 1946: 328. -
Pennycuik 1959: 187. - Millard 1968: 284. - Millard and
Bouillon 1973: 94. - Millard 1975: 451: 94.

Lytocarpiis phoenicea - Marktanner-Turneretscher
1890: 276.-Nutting 1927: 233. - Leloup 1930: 11.

Lytocarpiis aiiritis - Bale 1913: 138.

Macrorhynchia phoenicia - Stechow 1921: 232.
-Stechow 1923: 69. - Stechow 1925: 259. - Yamada
1959: 85. - Mammen 1965: 313. - Hirohito 1983:
80. - Ryland and Gibbons 1991: 555. - Hirohito 1995:
299. - Watson 1996: 79.

Records and material. NTM Cl2890, alcohol
preserved material; NTM Cl3039, microslide, colony
from Stn 136. NTM C12892, alcohol preserved material,
colony from Stn 138. NTM Cl2891, alcohol preserved
material, colony from Stn 7. NTM C13041, microslide,
colony from Stn 156. NTM Cl3038, microslide, colony
from Stn 137. Small unbranched colonies on Eunice
tubifex; larger branched fertile colonies on calcareous
bryozoans. MV F86935, alcohol preserved material,
sparsely fertile colonies on Eunice tubifex, Plater Rock,
coll: J. E. Watson, depth 12 m, 21/9/1999. Other records.
Stns 127, 154. East Arm port site, many large colonies
on rock and wharf structures, coll: J. E. Watson, depth
3-12 m, 20/9/1999.

68

Beagle Gulf and Darwin Harbour hydroids

Fig. 54. Macrorhynchia Phoenicia: A, branch from large colony from East Arm port, Darwin Harbour. B, hydrocladial internodes. C,
hydrotheca, anterior view. D, phylactocarps on distal part of branch. E, proximal part of phylactocarp. F, distal part of phylactocarp. Scale
bars: A, 10 mm, B, C, 300 pm; D, 3,000 pm; E, F, 500 pm.

Description. Colonies comprising three or four main
stems arising from a tubular hydrorhiza entwining
substrate. Tallest stems 200 mm, heavily fascicled,
parallel polysiphonic tubes passing almost to tips of
branches; branching fan-wise, primary branches given
off from posterior axillar tube, secondary and tertiary
branching common in large colonies. Branch prosegment
with a long, blade-shaped distal hinge joint, nodes
thereafter transverse, obscure, more distinct in mono-
siphonic distal region, perisarc of polysiphonic tubes
thick, thinning distally. Hydrocladia alternate to
subalternate, short, close, inserted on a cylindrical
apophysis on axillar tube of branch; nodes transverse,
internode with two strong partial to complete intranodal
septa, the strongest near ba.se of hydrotheca, the next,
partial, beneath mid-adcauline wall, and two, weak,
below walls of lateral nematotheca.

Hydrotheca short, ventricose, basal adcauline wall
convex, distal part fused to lateral nematotheca,
abcauline wall strongly convex, a short part free below

mesial nematotheca; body of hydrotheca divided by a
strong, narrow, partial septum passing down into
hydrotheca from free abcauline wall.

Margin tilted away from internode, mesial abcauline
cusp a small spine connecting with intrathecal septum;
margin subcircular, strongly everted, a pair of blunt cusps
in mid-lateral region, a smaller pair near base of lateral
nematothecae, a single, minute adcauline cusp between
lateral nematothecae.

Mesial nematotheca moderately long, erect, tubular,
tapering, usually considerably overtopping hydrothecal
margin; abcauline wall convex, terminal orifice small,
circular, a secondary orifice above junction with
hydrotheca; lateral nematotheca tubular, bent, narrowing
to margin, overlapping hydrocladial node, terminal
orifice small, circular, a large oval foramen connecting
with hydrotheca. Two cauline nematothecae at base of
hydrocladium, tubular, shorter than laterals, body
twisted, orifice circular, proximal nematotheca pointing
along hydrocladium, distal one facing along branch.

69

J.E. Watson

Phylactocarp replacing proximal hydrocladium on
branch; rachis long, arching, proximal internode with
normal hydrotheca, next internode long with an oblique
distal node and three short nematothecae similar to
caulines; succeeding intemodes with two or three digitate
nematothecae like mesials, terminal orifice circular, a
secondary orifice at base and a small internal foramen
connecting with inlernode.

Colour. Live colonies uniform golden brown to dark
brown.

Measurements (pm).

Branch (monosiphonic region)
distance between hydrocladia

on same side

376

- 480

Hydrocladium

length of internode

256

- 264

width at node

64

- 80

Hydrotheca

depth, floor to margin

136

- 140

width at margin

128

- 132

Nematotheca

length of mesial

200

- 220

width of terminal orifice

16

- 18

length of lateral

100

- 112

Phylactocarp

maximum length, mature

1,400

-2,000

length of internode

140

- 156

length of abcauline wall

of nematotheca

200

- 196

Remarks. The apical branches of larger colonies
sometimes end in long, tangled tendrils. Macrorhynchia
Phoenicia is easily recognised by its bristly appearance,
pinnate branching and uniformly brown colour. Short,
immature colonies occur in habitat such as wharf
structures and on Eunice tiibifex while larger, presumably
older, colonies occur in less disturbed habitat of natural
reefs. It is very abundant in Darwin Harbour and probably
more abundant in Beagle Gulf than suggested by the
survey data.

Distribution. Tropical Indian Ocean, Indonesia,
Japan (Millard 1975). Australian distribution: Torres
Strait (Busk 1852), tropical Queensland (Pennycuik
1959).

Macrorhynchia ambigua sp. nov.

(Fig. 55A-G)

Records and material. Holotype, NTM Cl2960,
alcohol preserved material, NTM C13080, NTM
Cl3046, microslides from holotype; colony detached
from substrate, Stn 154. Paratype, MV F86929,
microslide, colony from wharf piles. Port of Darwin, on
Eunice tubifex, coll: J. E. Watson, 5 m, 20/8/1998.

Description. Hydrorhiza a knot of tough stolons
entwining substrate. Stems stiff, to 100 mm high, heavily
fascicled, single stems branched irregularly alternate to
subopposite, or stems may be branched fan-wise from
hydrorhiza, secondary branching rare; polysiphonic tubes

of stem parallel, running along branches, but distal part
of branches monosiphonic; nodes if present, transverse,
prosegment ahydrocladiate with a central row of
nematothecae or oval foramen representing former sites
of cauline nematothecae.

Hydrocladia frontal on axial tubes of stem and
branches, short, alternate one per internode, inserted on
apophysis with transverse to slightly oblique distal node
and a reduced, central nematotheca. Hydrocladiate
internodes short, nodes transverse, indistinct, marked by
a notch in perisarc; internode with two strong septa, one
almost vertical below intrathecal septum, the other
sloping distally from base of lateral nematotheca.

Hydrothecae not immersed in internode, ventricose,
abcauline wall and proximal adcauline wall strongly
convex, base flatter, posterior adcauline wall free of
internode, a slightly oblique intrathecal septum passing
almost halfway into hydrotheca from proximal intranodal
septum. Margin inclined at an angle of 10 - 20° to
intemode with a prominent, blunt abcauline cusp passing
downward into hydrotheca as a wide hatchet-shaped
wedge; margin with a pair of low, central lobes,
sometimes reduced to mere undulations, in frontal view,
margin oval with smoothly everted rim, perisarc of
margin very thin.

Mesial nematotheca reaching abcauline cusp, usually
completely adnate, widening to orifice but with a short
narrow neck seen only in frontal view. Lateral nema¬
totheca on proximal hydrocladial internodes fairly short,
lengthening a little distally along internode, tubular,
reaching node but not reaching hydrothecal margin,
orifice circular, connection with internode large. A
cauline nematotheca at base of hydrocladial apophysis,
small, like proximal hydrocladial laterals but with shorter
orifice, facing upwards and outwards. Two large, tubular
cauline nematothecae flanking hydrocladium, terminal
orifice deeply excavated, a tumid mamelon with circular
orifice between.

Phylactocarp replacing a branch hydrocladium, borne
on a short apophysis, adcauline wall of basal internode
with a reduced nematotheca; next internode long,
upwardly curved below an unmodified hydrotheca,
followed by a long internode with hydrotheca with twin
lateral nematothecae and slightly reduced mesial
nematotheca, a single long nematotheca similar to laterals
above; phylactocarp thereafter directed upwards almost
parallel to axis of branch, bearing up to eight internodes,
nodes transverse, with two (sometimes one or three)
opposite nematothecae. Nematothecae short, stubby,
widest about middle, terminal orifice circular, a pore
without collar at junction with internode. A single
gonotheca borne frontally on a short pedicel on second
hydrothecate internode, gonotheca large, lenticular,
perisarc very thin and transparent, gonophore female,
packed with small ova.

Colour. Live colonies brown, gonophore cream.

70

Beagle Gulf and Darwin Harbour hydroids

Fig. 55. Macrorhynchia amhigua sp. nov. A, holotype colony from Beagle Gulf. B, branch from larger paratype colony from wharf piles.
Port of Darwin. C, part of stem with cauline nematothecae and hydrocladia. D, hydrocladial internodes. E. anterior view of hydrotheca. F,
cauline nematothecae, frontal view with tumid mamelon on apophysis. G, phylactocarp with gonotheca. Scale bars: A, B, 50 mm, C, G,
500 pm; D - F, 300 pm.

Measurements (pm).

Branch (monosiphonic region)

length of internode

200

- 272

width at node

136

- 160

length of apophysis, adcauline side

120

- 144

Hydrocladium

maximum length of hydrocladium

1,900

-2,100

length of internode

240

- 272

width at node

72

- 80

Hydrotheca

length parallel to internode

216

- 240

depth, floor to margin

172

- 180

width at margin

132

- 140

length of abcauline cusp

32

- 40

Nematotheca

length of mesial

192

- 212

width of terminal orifice

20

- 30

length of lateral

92

- 100

Phylactocarp

overall length, mature

1,760

-1,850

length of internode

140 -

160

width of node

72 -

100

length of abcauline wall

of nematotheca

144 -

160

width of terminal orifice

44 -

48

Remarks. Some colonies show a tendency towards
elongation of the mesial and lateral nematothecae along
the hydrocladium; this may also be accompanied by slight
exaggeration of the central (lateral) cusp on the
hydrothecal margin in which case the hydrothecae show
some resemblance to those of Macrorhynchia philippina.
However, the reproductive structures, habit and colour
of the colonies readily distinguish M. ambigua from M.
philippina. In many respects M. ambigua also resembles
M. Phoenicia, and as the species share the same habitat,
sterile colonies of M. ambigua can be easily mistaken
for a variant of M. phoenicia\ in fact it is likely that many
so-called variants of M. Phoenicia are actually M.
ambigua. Reliable differences between the two speeies

71

J.E. Watson

are: 1) the intrathecal septum of M. ambigua is much
wider in lateral view and more wedge-shaped than that
of M. Phoenicia, 2) the mesial nematotheca of M.
ambigua is shorter than that of M. phoenicia and is
completely adnate to the abcauline wall of the hydro¬
theca, 3) the mature phylactocarp differs significantly
from that of M. phoenicia and 4) mature colonies of M.
ambigua are much smaller and of paler brown colour
than those of M. phoenicia.

The stems of M. ambigua are rather brittle, showing
repeated regeneration after breakage above the
hydrorhiza. It may be a sparingly fertile species, there
being relatively few gonangia in the material examined.
M. ambigua was found only on tubes Eunice tubifex.
The bases of the stems are frequently overgrown by pale,
soft sponge.

Etymology. Refers to the difficulty in distinguishing
the species from M. phoenicia.

Macrorhynchia quadriarmata sp. nov.

(Fig 56A-G)

Record and material. Holotype, NTM Cl3043,
microslide, fragment of branched, infertile colony on
shellgrit from Stn 137. (No preserved material re¬
maining).

Description. Hydrorhiza of a few fragmentary
stolons. Colony 30 mm high, stem lightly fascicled,
polysiphonic tubes running almost to broken tip of stem;
prosegment long, lowest two branches broken off, a
hinge joint overgrown by fasciculations above stump of
proximal branch; six remaining branches regularly
alternate, distant, directed upwards, perisarc firm; frontal
tube of caulus hydrocladiate. Branches monosiphonic,
borne on a long apophysis, distal node of apophysis
transverse, followed by an athecate internode with a long
blade-shaped distal joint, the two sections joined by a
thin membrane, branch nodes thereafter transverse,
narrow, obscure proximally, becoming more pronounced
distally. Hydrocladia alternate, frontal on stem and
branches, one, sometimes two on branch internode,
inserted on a short apophysis with slender, acute distal
node, hydrocladia bearing up to six hydrothecae,
internodes rather long, nodes transverse, deeply
constricted, base of internode curving from node below
hydrotheca; two distinct, complete, almost vertical
intranodal septa, one at proximal third of hydrotheca and
one below lateral nematotheca.

Hydrotheca slipper-shaped, adcauline wall flat,
bisected by an inclined, almost complete intrathecal
septum connecting with intranodal septum, a small
proximal foramen in base of wall usually obscured by
tissue, abcauline wall convex to base of mesial
nematotheca then recurving to margin, a deep pocket of
perisarc behind margin. Margin almost parallel with
internodal axis with a pair of broad, sometimes

proximally displaced lateral lobes; lobes everted, a small,
blunt cusp between lateral nematothecae. Perisarc of
hydrocladia and hydrothecae thin.

Mesial nematotheca erect, increasing in length
distally along hydrocladium, proximal nematotheca on
hydrocladium not reaching hydrothecal margin,
distalmost nematotheca very long, thin, tubular,
considerably overtopping hydrothecal margin, distal end
swollen, terminal orifice of both forms small, circular, a
large secondary orifice on a short neck above junction
with hydrotheca. Lateral nematothecae bifid, superior
nematotheca long, thin, tubular, sinuous, extending
beyond hydrothecal margin, terminal orifice circular,
inferior nematotheca tubular, much shorter and wider
than superior, pointing obliquely downwards from
internode; openings of both nematothecae to internode
confluent through a small foramen.

Branch apophysis with one large cowl-shaped
adcauline nematotheca, a similar nematotheca on
succeeding athecate internode; orifice small, circular,
facing downwards to internode, both nematothecae with
a large foramen connecting with branch. A cauline
nematotheca on branch at base of hydrocladium, large,
like inferior lateral, pointing away from hydrocladium;
nematothecae also present on axillar tube of stem above
proximal hinge joint.

Pseudophylactocarps replacing first hydrocladium on
lowest branches, rachis unbranched, first two or three
internodes with normal hydrothecae followed by up to
six internodes with long, tubular nematothecae similar
to superior laterals, pointing obliquely forwards and
outwards, terminal orifice circular, a secondary orifice
just above base.

Colour. Honey brown.

Measurements (pm).

Stem

width at base

168

distal width

152

distance between

opposite hydrocladia

1,100

-1,560

Branch

length of adcauline wall of apophysis

112

- 160

width of apophysis at node

88

- 104

length of abcauline wall

athecate internode

320

- 440

Hydrocladium

maximum length

1,400

length of apophysis

88

- 92

length of internode

224

- 248

width at node

28

- 32

Hydrotheca

length of fixed adcauline wall

200

- 216

height, margin to base

128

- 160

width at margin

64

- 72

Mesial nematotheca

free length

144

- 140

72

Beagle Gulf and Darwin Harbour hydroids

diameter of terminal orifice

12 -

16

width of secondary orifice

32 -

48

Nematotheca

length of superior lateral

100 -

112

diameter of terminal orifice

12 -

16

length of inferior lateral

48 -

56

diameter of terminal orifice

16 -

20

Phylactocarp

length of nematothecate internode

168 -

176

length of nematotheca

112 -

136

Remarks. Several features characterise Macro-
rhyncliia quadriarmata: 1) the small size and graceful
habit of the colony which is more like that of a
plumulariid than an aglaopheniid hydroid, 2) the
exceptionally long mesial nematothecae, 3) the bifid
lateral nematothecae and 4) the long blade-shaped
proximal hinge joint of the branch with thin connecting
membrane.

Etymology. Named for the four lateral nematothecae
on the hydrocladial internode.

Family Campanulariidae Johnston, 1837
Genus Clytia Lamouroux, 1812
Clytia Iwarreni Stechow, 1919
(Fig. 57A-C)

Clytia elongata Warren, 1908: 338 [nomen nudum],

Clytia warreni Stechow, 1919: 48. - Millard 1975:

221 .

Record and material. NTM C12946, alcohol
preserved material; NTM Cl 3044, MV F86886,
microslides, sparsely fertile colony on stem of Pennaria
disticha, Stn 87.

Description. Hydrorhiza tubular, reptant on substrate.
Hydrothecal pedicels variable in length, simple, perisarc
smooth, hyaline, with up to eight proximal and eight
distal close annulations, sometimes a few annulations
mid-way along pedicel. Hydrothecae long, slender, sub-
cylindrical, widening above diaphragm in proximal third
and just below margin, diaphragm distinct. Hydrothecal
perisarc thinning distally; margin with six to 10 long,
obtuse cusps, a deep embayment between, cusps often
inclined inwards.

Gonotheca long, obconical, borne on an annulated
pedicel arising from the hydrorhiza, distal end truncate,
orifice circular, closed by a sheet of tissue; perisarc of
gonotheca thin and smooth.

Colour. Colourless.

Measurements (pm).

Hydrorhiza, diameter

48

- 56

Stem

length

424

-1,120

diameter

40

- 64

Hydrotheca

length, base to apex of cusp

448

- 496

diameter at diaphragm

64

diameter below marginal cusps

136

■ 224

height of cusp 32 - 60

distance between cusps 48 - 68

Gonotheca

length, base to apex 420

maximum width 170

Remarks. Because of thinning of the marginal
perisarc it is difficult to accurately count the number of
cusps in the few undamaged hydrothecae in the sample.
The hydrothecae are smaller than descriptions of Clytia
warreni, the number of marginal cusps variable and the
two immature gonothecae do not show the distal
narrowing as reported for that species. The material is
therefore referred with some doubt to C. warreni.

Distribution. This is the first record of C. warreni
outside South Africa.

Clytia linearis (Thornely, 1900)

(Fig.57D, E)

Obelia linearis Thornely, 1900: 453.

Campanularia gravieri Billard, 1904: 482. - Millard
and Bouillon 1973: 51. - Millard 1975: 215.

Campanularia obliqua Clarke, 1907: 9.

Clytia linearis - Cornelius 1982: 84. - Gibbons and
Ryland 1989: 404. - Calder 1991: 62. - Migotto 1996:
85.

Record and material. NTM Cl 2945, alcohol
preserved material; NTM Cl 3045, MV F86887,
microslides, small fertile colony on Pennaria disticha,
Stn. 56.

Description. Hydrorhiza reptant on substrate. Single
hydrothecae and erect stems to 10 mm given off
irregularly from hydrorhiza; stems monosiphonic,
subsympodially branched; stem and branch internodes
long, smooth, nodes a series of annulations. Hydrotheca
distal on internode, one, sometimes two on internode,
pedicel short, annulated proximally and distally or
completely throughout; hydrotheca slender, deeply
campanulate, expanding smoothly to margin, diaphragm
distinct, transverse, in empty hydrothecae marked by a
ring of thorn-shaped desmocytes pointing into hydro¬
theca. Margin denticulate with 10-12 long, sharp cusps
separated by deep embayments; perisarc thinning trough
hydrotheca to become almost invisible at margin.
Hydranth with 14-16 tentacles.

Gonotheca borne on an annulated pedicel in fork of
stem beside a hydrothecal pedicel; gonotheca long,
obconical, distally truncate, perisarc thin, enclosing up
to eight developing medusae, distal end of gonotheca
closed by a thin sheet of tissue; mature medusa (at point
of release) with 14 tentacles and inverted exumbrella.

Colour. White.

Measurements (pm).

Stem

diameter at base of erect stem 84 - 88

length of stem internode 520 - 672

73

J.E. Watson

74

Fi}>. 56. Macrorhynchia quadriarmata sp. nov. A, holotype colony from Beagle Gulf. B,

hydrotheca with truncated mesial nematotheca. C. hydrotheca with elongate mesial nematotheca. Fig. 57. A-C, Clytia ?warrenv. A, B, hydrothecae from colony from Beagle Gulf.

D, anterior view of hydrotheca. E, apophysis of stem with proximal hydrocladial internode and C, gonotheca from same colony. D, E, Clytia linearis: D, colony from Beagle

oblique hinge joint. F, cauline nematothecae. G, phylactocarp. H, distal end of phylactocarp Gulf. E, hydrotheca and gonotheca from same colony. Scale bars: A - C, E, 300

with three nematothecae. Scale bars: A, 10 mm, B, C, D, 200 pm; E - H, 300 pm. pm; D, 1,000 pm.

Beagle Gulf and Darwin Harbour hydroids

length of hydrothecal pedicel

200 -

880

diameter annulated hydrothecal pedicel 48 -

64

Hydrotheca

length, diaphragm to margin

624

diameter at diaphragm

72 -

100

diameter at margin

336

Gonotheca

length, excluding pedicel

488 -

640

distal diameter

120 -

200

Remarks. The specimens agree with dimensions of
C. linearis given by Gibbons and Ryland (1989) and
Migotto (1996). The perisarc is so frail that most
hydrothecae collapse in mountant. The slight narrowing
behind the distal end of the gonotheca shown by some
authors (e.g. Gibbons and Ryland 1989, Migotto 1996)
is not evident in the present material. There is a
remarkable range in size of hydrothecae and if
intergradations were not present on the same stem the
extremes in size could be easily mistaken for two
different species. The figured hydrotheca (Fig. 57E) was
one of the largest found on the colonies.

Distribution. Tropical to warm temperate oceans and
Fiji (Gibbons and Ryland 1989), Brazil (Migotto 1996).
Not previously recorded from Australia.

Clytia sp. 1

Record and material. Infertile colony on aglao-
pheniid hydroid, Stn. 61.

Remarks. The few remaining hydrothecae are too
badly crushed for identification.

Clytia sp. 2

Record and material. Infertile colony on bryozoan,
Stn. 38.

Remarks. Stems simple, unbranched, annulated
proximally and distally but the few remaining campa-
nulate hydrothecae are crushed beyond recognition.

ACKNOWLEDGMENTS

I thank the Parks and Wildlife Commission of the
Northern Territory and Director of the Museums and Art
Galleries of the Northern Territory, Darwin, for providing
the Beagle Gulf collection for examination; the CSIRO
Centre for Research on Introduced Marine Pests for the
invitation to participate in their 1998 survey of the Port
of Darwin, the Museums and Art Galleries of the
Northern Territory for providing facilities for SCUBA
diving and laboratory space in 1998 and 1999, and the
Zoologische Staalssamiung, Munich, Germany for loan
of type and voucher material; Dr Dale Calder of the Royal
Ontario Museum Canada for taxonomic advice. Dr Barry
Russell, Dr Philip Alderslade and Dr Richard Willan of
the Museums and Art Galleries of the Northern Territory
and Dr Chad Hewitt of the CSIRO Centre for Research
on Introduced Marine Pests for invaluable personal

support. In particular, 1 sincerely thank Dr Wim Vervoort
for his unfailing advice on difficult nomenclatural and
taxonomic problems and constructive criticism of the
manuscript. Lastly, I thank Karen Gowlett-Holmes of
CSIRO for underwater companionship during field work
in Darwin Harbour.

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Accepted 14 November 2000

81

J.E. Watson

Appendix 1. Taxonomic index of lepthothecate hydroids from the Beagle Gulf

Aglaophenia 57
AGLAOPHENIIDAE 57
alata sp. nov., Salacia 26
ambigua sp. nov., Macrorhynchia 70
amirantensis, Lafoeina 5
angiilosa, Lytocarpia 64
Antennella 45
Anthohebella 1

badia, Plumularia 51
bedoti, Plumularia 54
bidentata sp. nov., Salacia 26
bilamellata sp. nov., Dynamena 15

CAMPANULARIIDAE 73
CAMPANULINIDAE 5
campylocarpum, Synthecium 40
Clytia 73
Clytia sp. 1 75
Clytia sp. 2 75
cornuta, Polyplumaria 56
costata, Hebeliopsis 6
cylindrica, Nemertesia 49

darwinensis sp. nov., Anthohebella 8
decipiens, Sertularella 27
delicatula, Aglaophenia 57
diaphana, Sertularella 31
dichotomum, Hydrodendron 10
digitalis, Diphasia 14
Diphasia 12
Dynamena 15
dyssymetrum, Halecium 9

Filellum 5

flavidula sp. nov., Salacia 24
flexuosa, Monotheca 48
fruticosus, Thyroscyphus 38

Gymnangium 58

HALECIIDAE 9
Halecium 9
HALOPTERIDAE 45
Halopteris 46
Hebella 7
Hebeliopsis 6
hexodon, Salacia 21
Mans, Gymnangium 58
Hydrodendron 10

Idiellana 19

irregularis, Kirchenpaueria 57

Kirchenpaueria 57
Kirchenpaueriidae 57

LAFOEIDAE 5
Lafoeina 5

?laterocaudata, Hebella 1
lepida sp. nov., Idiellana 20

linearis, Clytia 73
longicorne, Gymnangium 60
Lytocarpia 64

macrocytharus, Thyroscyphus 31
Macrorhynchia 67
mertoni, Dynamena 16
Monotheca 48
mutulata, Diphasia 12

Nemertesia 49

operculata sp. nov., Thuiaria 35
orthogonium, Synthecium 41

parasitica, Anthohebella 8
patulum, Synthecium 43
philippina, Macrorhynchia 67
Phoenicia, Macrorhynchia 68
phyteuma, Lytocarpia 65
pinnata, Sertularella 32
plagiocampa, Halopteris 47
Plumularia 51
PLUMULARIIDAE 48
plumularioides sp. nov., Thuiaria 36
polymorpha, Halopteris 46
Polyplumaria 56
pri.stis, Idiellana 19

quadriarmata sp. nov., Macrorhynchia 72
quadridens, Sertularella 28
quadridentata, Dynamena 15

Salacia 21

scabra, Plumularia 52
scandens, Hebeliopsis 6
secundaria, Antennella 45
Iserratuni, Filellum 5
Sertularella 27
Sertularia 33
SERTULARIIDAE 12
setacea, Plumularia 53
sinuosa, Salacia 22
spatulum sp. nov., Halecium 10
SYNTHECIIDAE 39
Synthecium 39

tetracythara, Salacia 23
Thuiaria 35
Thyroscyphus 37
torresii, Thyroscyphus 37
Tridentata 18
Tridentata sp. 18
trigonostoma, Sertularia 33
tubacarpa sp. nov., Plumularia 55

undulatum sp. nov., Gymnangium 62
unjinense sp. nov., Gymnangium 62

?warreni, Clytia 73

82

The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 2000 16: 83-88

The rediscovery of Leandrites stenopus Holthuis, 1950 (Crustacea: Palaemoninae),

from Lucinda, Queensland

A.J. BRUCE

Research Associate, Museum and Art Gallery of the Northern Territory
GPO Box 4646, Darwin NT 0801, AUSTRALIA
abruce@ broad, net.au

ABSTRACT

A second specimen of the rare palaemonid shrimp Leandrites stenopus Holthuis, 1950, has been collected from
Lucinda harbour, northern Queensland. The only previous specimen was collected on the Siboga Expedition in 1899,
from Madura, Indonesia. This male specimen enables the generic placement to be confirmed and the geographic
distribution to be considerably extended.

Keywords: Leandrites stenopus, Crustacea, Palaemoninae, rediscovery, Queensland.

INTRODUCTION

The unique specimen of the small marine shrimp
Leandrites stenopus Holthuis was collected in 1899 but
was not described until 1950, half a century later. A
further half century has elapsed before a second specimen
was obtained. Despite innumerable marine faunistic
surveys in tropical Indo-West Pacific waters during the
last half century, it is still surprising that a species can
remain so apparently rare. The present specimen was
obtained during the course of a survey of the marine
faunas of northern Queensland harbours carried out by
the Department of Marine Biology and Aquaculture of
James Cook University of North Queensland for Ports
Corporation Queensland.

Abbreviations used: CL, post-orbital carapace length;
NTM, Northern Territory Museum, Darwin.

SYSTEMATICS

Leandrites stenopus Holthuis, 1950
(Figs 1-3)

Leandrites stenopus Holthuis, 1950: 40-42, fig. 6. -
Chace and Bruce 1993: 7-8.

Material examined. IcT, Lucinda, stn Sh 62, 18°
31' S, 148° 19' E, 7 July-1999, modified Ockelman sled,
15 m, coll. F. Hoedt, NTM Cr.012794.

Description. In poor condition, lacking both second
pereiopods and some other appendages.

Rostrum (Fig. lA) about 0.95 of CL, slightly
exceeding antennular peduncle, exceeded by scapho-
cerite, acute, tapering, horizontal, feebly developed
lateral carinae, with 11 acute teeth dorsally, first tooth

epigastric, second also situated on carapace, four small
ventral teeth distally, numerous median sparsely plumose
interdental setae dorsally, similar submedian marginal
setae ventrally; inferior orbital angle (Fig. 3B) well
developed, rounded, antennal spine lower, slightly
submarginal, branchiostegal suture absent,
branchiostegal spine similar to antennal, distinctly
postmarginal, pterygostomial angle rounded, sparsely
setose.

Ophthalmic somite without bee ocellaire, with small
pigment spot.

Eye (Fig. ID) with large globular cornea, diameter
about 0.25 of CL, feebly pigmented, with accessory
pigment spot, stalk about 0.8 of corneal width, slightly
longer than wide.

Antennule (Fig. IB) with proximal segment of
peduncle twice as long as width, distolateral angle
produced, rounded, with small acute distolateral tooth,
stylocerite acute, short, not reaching half segment length,
ventromedial border with small acute tooth at half length,
statocyst well developed, with large circular statolith;
intermediate and distal segments very obliquely
articulated, subequal in length; upper flagellum
biramous, proximal 5 segments of rami fused, short
ramus about 0.8 of CL, with 10 stout segments, lower
ramus long, filiform; lower flagellum long, filiform.

Antenna (Fig. 1B) with basicerite bearing small acute
lateral tooth; carpocerite about 0.3 of scaphocerite length,
subcylindrical, moderately compressed, merocerite short,
ischiocerite with acute medial process; flagellum long,
filiform; scaphocerite about 4 times longer than wide,
maximal width at 0.33 of length, lateral margin straight
with well developed distolateral tooth, not exceeding
distal border of broadly rounded lamella.

83

A.J. Bruce

Fig. 1. Leandrites stenopus Holthuis. Male, Lucinda, Queensland, NTM Cr.012794. A, carapace and rostrum. B, antennule. C, antenna.
D, eye. E, first pereiopod, chela. F, same, fingers. G, third pereiopod, dactyl and distal propod. H, telson. I, uropod.

Abdomen with sixth segment about 0.45 of CL, 1.3
times longer than deep; 2.3 times longer than fifth
segment, posterolateral angle well developed, acute,
posteroventral angle rounded, with small acute
preterminal tooth, fourth pleuron posteroventrally
rounded, fifth pleuron small, posteroventrally acute.

Telson (Fig. II) about 0.6 times sixth abdominal
segment length, 2.5 times longer than anterior width,
lateral margins straight, posteriorly convergent, dorsal
spines small, at about 0.5 and 0.8 of telson length,
anterior pair smaller, about 0.75, and further apart then
posterior pair, posterior width about 0.25 of anterior
width, acutely pointed (Fig. 3J), lateral spines small.

about size of anterior dorsal spines, marginal, medial
spines well developed, stout, about 0.3 of telson length,
subventral, submedian setae half length of medial spines,
slender, sparsely setulose, subventral.

Mandible (Fig. 2A) robust, without palp, with stout
four-toothed molar process, incisor process with three
large acute teeth distally. Maxillula (Fig. 2B) with
distinctly bilobed palp (Fig. 3C), lower lobe with small
distal tubercle bearing short hooked seta; upper lacinia
with about 12 stout simple spines distally; lower lacinia
with numerous shorter spiniform setae distally. Maxilla
(Fig. 2C) with basal endite bilobed, lobes slender,
subequal, with sparse slender setae distally, palp tapering

84

Palaemonid shrimp from northen Queensland

Fig. 2. Leandrites stenopus Holthuis. Male, Lucinda, Queensland, NTM Cr.012794. A, mandible. B, maxillula. C, maxilla. D. first
maxilliped. E. second maxilliped. F, third maxilliped.

distally with single terminal plumose seta, proximal
lateral border with short plumose setae, scaphognathite
2.7 times longer than wide, broad centrally, narrow
anteriorly, with small posterior lobe. First maxilliped
(Fig. 2D) with basal endite large, broad, distally rounded,
distal and medial borders with numerous fine, mainly
simple setae, coxal endite distinct, distomedially angular,
sparsely setose, palp tapering, distally angular, with long
preterminal plumose seta medially, short simple setae
distally, exopod well developed, with numerous plumose
setae distally, caridean lobe small, narrow, sparsely
setose, epipod large, deeply bilobed distal lobe much
larger, triangular, proximal lobe smaller rounded. Second

maxilliped (Fig. 2E) with dactylar segment short, broad,
about 3.0 times longer than width, 0.6 of propodal
segment length, with numerous long serrulate spines
along medial margin, propodal segment broadly
expanded distomedially, rounded, with numerous long
serrulate spines medially, carpus and ischiomerus
normal, exopod well developed, with numerous plumose
setae distally, ramus expanded proximolaterally, basis
medially produced, rounded, with small sub-oval epipod
laterally, with small multi-lamellar podobranch. Third
maxilliped (Fig. 2F) slender, ischiomerus completely
fused with basis, junction indicated by small medial
notch, about 15 times longer than central width, distally

85

A.J. Bruce

Fig. 3. Leandrites stenopus Hollhuis. Male, Lucinda, Queensland, NTM. Cr.0I2794. A, tip of rostrum. B, inferior orbital angle. C, maxillula,
palp. D, first pereiopod, distal dactylus. E, first pleopod. F, same, endopod. G, second pleopod. H, same, endopod. I, same, appendix
masculina. .1, telson, posterior spines.

broadened to about double central width, with three small
spinules distolaterally, medial margin sparsely setose,
carpal segment subcylindrical, about 12 times longer than
wide, sparsely setose medially, distal .segment about 0.6
of carpal segment length, with strong distal spine,
medially with nine transverse rows of spiniform setae;
endopod well developed, reaching to about 0.75 of
ischiomeral segment length, with numerous plumose
setae distally; coxa medially produced, sparsely setose,
lateral plate well developed, rounded, with small lamellar
arthrobranch proximally.

Pleurobranchs 5.

Fourth thoracic sternite with small acute medial
process.

First pereiopod as previously de.scribed. Slender, with
chela (Fig. 1E) about 0.75 of propod length, 0.68 of meral
length; chela with palm slightly compressed, about 3.5
times longer than depth, with six transverse rows of short
serrate setae proximally, fingers (Fig. IF) sparsely
setose, about 0.8 of palm length, similar, stout, feebly
hollowed medially, about 5.5 times longer than proximal
depth, with acute hooked tips, with small acute tooth
(Fig. 3D) proximally, rest of cutting edge laminar, entire.

Third pereiopod slender, dactyl (Fig. IG) about 0.33
of propod length, slightly curved, about 17 times longer
than proximal depth, unguis feebly demarcated, about
0.12 of corpus length, with two slender setae at half
dorsal margin length, smaller setae proximally, two

86

Palaemonid shrimp from northen Queensland

sensory setae distolaterally, propod subequal to CL, with
two small distoventral spinules, six smaller ventral
spinules. Fourth and fifth pereiopods generally similar.

First pleopod (Fig. 3E) with endopod (Fig. 3F) about
half exopod length, sub-oval, about 2.75 times longer
than central width, distal and lateral borders with short
plumose setae, proximal medial border with three
spiniform setae, with well developed appendix interna
arising at 0.5 of medial margin, not exceeding distal
border of ramus. Second pleopod (Fig. 3G) with endopod
(Fig. 3H) about 0.95 of exopod length, with numerous
long plumose marginal setae, appendices arising at about
0.3 of medial margin length, appendix masculina (Fig.
31) about 0.3 of endopod length, slender, subcylindrical,
12 times longer than proximal width with three slender
serrulate terminal spines, about half appendix length, 2
shorter simple distolateral spines.

Uropod (Fig. IFI) with rami distinctly exceeding
telson, protopodite posteriorly acute; exopod 3.4 times
longer than central width, lateral margin straight with
small distal tooth, with mobile spine medially, diaeresis
obsolete, distal lamella reduced.

Measurements. CL approx. 3.4 mm.

Colouration. Unknown.

Habitat. Water temperature 25.4°C; salinity 34.9 ppt;
sea floor firm, featureless sand/mud, 5.6 km offshore.

Remarks. The specimen generally agrees closely
with the original description. The type specimen has only
three ventral rostral teeth, in contrast with four in the
present specimen. The rostral dentition can therefore be
1 + 10/3-4. Not reported in the original description are
the small preterminal accessory teeth on each of the
fingers of the first pereiopods. No similar teeth have been
reported in other palaemonid genera.

Discussion. The original specimen was collected on
March 8, 1899 and no further specimens have been
subsequently described during the following century.
The discovery of a second specimen, albeit damaged and
incomplete, shows that the species is still extant and of
wider distribution. The assessment of rarity in marine
habitats remains an unsolved problem. A terrestrial
species that has not been observed over a period of 50
years is deemed extinct (Baillie and Groombridge 1996).
Li and Manning (1998) reported the presence of this
species in the northern South China Sea but provided no
further details.

The slender build and appendages of this shrimp
suggests that it is a free-living soft bottom species. The
holotype was collected from 56 m on a radiolarian ooze
substrate.

Chace and Bruce (1993) commented that the generic
position of this species could not be fully ascertained
until a male had been collected, enabling the condition
of the first pleopod to be determined. This has now been
rectified and the presence of an appendix interna on the

first pleopod endopod confirms that this species belongs
in the genus Leandrites. The presence of a median sternal
tooth on the fourth thoracic sternite is noted; a similar
tooth is also present in Leandrites ceiebensis (De Man,
1881), a feature that is probably another character of
generic value (Bruce 1987). It is found in some genera
in both the Palaemoninae and the Pontoniinae and its
phylogenetic importance is yet to be evaluated.

The fingers of the second pereiopod chela in
Leandrites stenopus appear to be unique amongst the
Palaemoninae, with the small acute preterminal teeth. It
remains possible that these may have been overlooked
in other species as, although distinctive, they are very
small and not readily discernible when the fingers are
closed.

Four species of the genus Leandrites are now known,
all from the central Indo-West Pacific region, and a key
for their identification is provided by Chace and Bruce
(1993). The commonest and most widely distributed is
L. ceiebensis, recorded from southern India, Indonesia
and tropical Australian waters, from shallow brackish
waters. The three other species are all south east Asian.
Leandrites indicus Holthuis, 1950, is known from the
type specimen from Sulawesi, Indonesia, and Vietnam
(Nguyen Van Xuan 1992), where it is common in
mangrove creeks and rivers; L. deschampsi (Nobili,
1903), from three specimens from the type locality,
Singapore, and one further specimen from China (Liu et
ai. 1990); L. stenopus is now definitely known from two
specimens only, from off Java, Indonesia, and north east
Queensland, Australia, and probably also the northern
South China Sea.

The present record also contrasts with the original
discovery and indicates that the species may also occur
in shallower water (15 m versus 56 m) and on non-
radiolarian substrates.

ACKNOWLEDGMENTS

I am most grateful to Dr Frank Hoedt for the
opportunity to examine the specimen on which this report
is based, and Dr C.H.J.M Fransen, for drawing my
attention to the abstract by Li and Manning. This study
was carried out with the support of the Australian
Biological Resources Study.

REFERENCES

Baillie, J. and Groombridge, B. 1996. The lUCN species survival
commission 1996 red list of threatened animals. lUCN:
Gland, Switzerland.

Bruce, A.J. 1987. Records of three palaemonid shrimps new to
the Australian Fauna. The Beagle, Records of the Northern
Territory Museum of Arts and Sciences 4: 57-60.

Chace, F.A., Jr., and A.J. Bruce. 1993. The Caridean Shrimps
(Crustacea: Decapoda) of the Albatross Philippine

87

A.J. Bruce

Expedition 1907-1910, Part 6: Superfamily Palaeinonoidea.
Smithsonian Contributions to Zoology 543: i-vii, 1-252,
figs 1-23.

Holthuis, L.B. 1950. The Decapoda of the Siboga Expedition.
Part XI. The Palaemonidae collected by the Siboga and
Snellius Expeditions with remarks on other species. II.
Subfamily Pontoniinae. Siboga Expedition Monograph
39a’: 1-268.

Li Xinzheng and R.B. Manning. 1998. Palaemonid shrimps from
the northern South China Sea, including new taxa and a
species list from Chinese waters. Poster abstract.
Proceedings and Abstracts, Fourth International Crustacean
Congress, Amsterdam 20-24 July 1998, 202-203.

Liu, J.Y, Liang, X.Q. and Yan, S.l. 1990. A study of the
Palaemoninae. (Crustacea Decapoda) from China 1.
Macrobrachium, Leander and Leandrites. Transactions of
the Chinese Crustacean Society 2: 102-134.

Man, J.G. de. 1881. Carcinological Studies in the Leyden
Museum, N° 1. Notes from the Leyden Museum 3: 121-144.

Nguyen Van Xuan. 1992. Review of the Palaemoninae
(Crustacea: Decapoda: Caridea) from Vietnam
{Macrobrachium excepted). Zoologische Mededelingen,
Leiden 66 (2): 19-47.

Nobili, G. 1903. Crostacei di Singapore. Bolletino dei Musei di
Zoologico ed Anatomia comparativo della R Universita di
Torino 18 (455): 1-39, 1 pi.

Accepted 8 August 2000

The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 2000 16: 89-90

Onycocaridella prima Bruce, 1981, a rare pontoniine shrimp from Darwin Harbour

(Crustacea: Decapoda: Pontoniinae)

A.J. BRUCE

Research Associate, Museum and Art Gallery of the Northern Territory
GPO Box 4646, Darwin NT 0801, AUSTRALIA
abruce@broad,net.au

ABSTRACT

The second occurrence of the pontoniine shrimp Onycocaridella prima Bruce, 1981 is recorded. The single
specimen was found in a sponge host collected from Darwin Harbour, Northern Territory, Australia. The species is
otherwise known only from the type specimens from Heron Island, Queensland.

Keywords. Onycocaridella prima, Crustacea, Pontoniinae, Darwin Harbour, sponge associate, Australia.

INTRODUCTION

In the course of a survey of the marine fauna of the
Port of Darwin, carried out by marine scientists from
CSIRO Centre for Research on Introduced Marine Pe.sts
(CRIMP) and staff of the Museums and Art Galleries of
the Northern Territory in 1998, a single specimen of a
small pontoniine shrimp was obtained from a sponge host
collected from harbour piles. The specimen was
identified as Onycocaridella prima, a species previously
known only from the two type specimens collected in
1979 from Heron Island in the Capricorn Islands of the
Great Barrier Reef. The new specimen of this apparently
rare shrimp is here described and compared with the type
material from Queensland.

Abbreviations used: CL, post orbital carapace length;
NTM, Museum and Art Gallery of the Northern
Territory.

SYSTEMATICS

Onycocaridella prima Bruce, 1981
(Fig. 1)

Onycocaridella prima Bruce, 1981a: 243-250, figs.
1 - 6 .

Material examined. 1 ovig. 9 , stn NTD FHI PI-3,
Fort Hill Wharf, Port of Darwin Harbour, I2°28.322’S
130°50.826’E. depth 3-9 m, collected by hand from pile
scrapings, 15 August 1998, coll. CSIRO CRIMP team,
NTM CrO 12795.

Description. A stout shrimp, with body sub-
cylindrical, slightly compressed anteriorly, with
relatively large abdomen. Generally as in original
description.

Rostrum about 0.22 of CL, acute, slender, depressed,
slightly up-turned, unarmed. Carapace (Fig. lA) about
as long as maximal depth, smooth, devoid of spines and
teeth. Abdomen slightly compressed, with first three
pleura broadly expanded.

Chelae of second pereiopods similar, only slightly
unequal; major chela (Fig. 1B) with fingers 0.47 of palm
length; minor chela (Fig. 1C) fingers 0.57 of palm length,
dactyls with sinuous entire cutting edges.

Third pereiopods with propod stout, bearing two short
stout distoventral spines; dactyl (Fig. 1D) with distinctly
demarcated unguis, corpus with ventral cutting edge
straight, without distal accessory tooth, with several
small denticles proximally.

Ova numerous, small.

Measurements. CL 3.3 mm; length of ovum 0.8 mm.

Host. Mycale sp., [Porifera: Mycalidae], possibly
Mycale (Aegagropila) cf. obscura (Carter).

Distribution. Previously reported only from the type
locality. Heron Island. Capricorn Islands, Queensland,
on the southern Great Barrier Reef, at 12 m depth.

Remarks. The single specimen is complete and in
good condition and in general agrees well with the
original description. With a CL of 3.3 mm, it is
considerably larger than both the type specimens (cf
allotype 1 .8 mm; 9 holotype 1.75 mm) sugge.sting that
both of these were juvenile specimens. With ova, the
present specimen is clearly an adult. In the adult, the
carapace length is less than the carapace depth, whereas
in the juvenile types it is greater (Fig. IE), the rostrum
is also more depressed, without a small preterminal
dorsal tooth as in the holotype. In the holotype female
the second pereiopod chelae are markedly unequal in
size ( 2 . 0 ; 1 . 0 ), in the present specimen they are only
slightly unequal (1.09:1.0), with the major chela

89

A. J. Bruce

Fig. 1. Onycocaridella prima Bruce, ovigerous female, Darwin Harbour, NTM Cr012795. A, carapace, lateral. B, second pereiopod, major
chela. C. same, minor chela. D, third pereiopod. distal propod and dactyl. E, comparison of carapace shapes in adult and juvenile (stippled)
specimens to show relative profiles (not to scale).

ACKNOWLEDGMENTS

relatively smaller, 1.29 times the CL, as opposed to 2.0
times the CL in the holotype. The ambulatory dactyl of
the third pereiopod is essentially as in the holotype but
lacks the small distoventral accessory tooth and the distal
ventral margin of the corpus appears unarmed. The
absence of these small denticles may be merely the result
of abrasion. The proximal ventral margin bears about
six minute denticles.

The host sponge has not been identified with full
certainty. The preserved sample contained repre¬
sentatives of several sponge genera (J.N.A. Hooper,
personal communication), but these included material
referrable to a Mycale, possibly Mycale {Aegagropila)
cf. obsciira (Carter). As the type specimens of O. prima
were found in association with Mycale sulcata Hentschcl,
it is most probable that this further Mycale was the host
of the present specimens.

The key to the genus Onycocaridella Bruce,
accompanying the original description of O. prima
remains valid (Bruce 1981a). The two other species of
U;e genus, O. stenolepis (Holthuis, 1952) and O.
monodoa (Fujino and Miyake, 1969) have also both been
recorded in Australian waters, also from Heron Island
(Bruce 1981b, 1983).

1 am most grateful to Helen Barnes for the opportunity
to examine the specimen on which this report is based
and to Dr J.N.A. Hooper for the identification of the
sponge host. This study was carried out with the support
of the Australian Biological Resources Survey.

REFERENCES

Bruce, A.J. 1981a. Onycocaridella prima gen. et sp. nov., a new
pontoniine sponge-associate from the Capricorn Islands,
Australia (Decapoda Caridea: Pontoniinae) Journal of
Crustacean Biology 1(2): 241-250.

Bruce, A.J. 1981b. Pontoniine shrimps of Heron Island. Atoll
Research Bulletin 245: 1-33.

Bruce, A.J. 1983. The pontoniine shrimp fauna of Australia.

Australian Museum Memoirs 18: 195-218.

Fujino, T. and Miyake, S. 1969. Studies on the genus Onycocaris
with descriptions of five new species (Crustacea, Decapoda,
Palaemonidae). Journal of the Faculty of Agriculture,
Kyushu University 15: 403-448.

Holthuis, L.B. 1952. The Decapoda of the Siboga Expedition.
Part XI. The Palaemonidae collected by the Siboga and
Snellius Expeditions with remarks on other species. II.
Subfamily Pontoniinae. Sihoga Expedition Monograph
39al0: 1-252.

Accepted 8 August 2000

90

The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 2000 16 : 91-96

Biological observations on the commensal shrimp Paranchistus armatus (H. Milne
Edwards) (Crustacea: Decapoda: Pontoniinae)

A.J. BRUCE

Research Associate, Museum and Art Gallery of the Northern Territory
GPO Box 4646, Darwin NT 0801, AUSTRALIA
abruce@broad.net.au

ABSTRACT

Some aspects of the biology of the commensal pontoniine shrimp, Paranchistus armatus (H. Milne Edwards), on the
Great Barrier Reef, are reported. The species is an obligatory commensal living as heterosexual pairs only in the giant
clam, Tridacna gigas (L.). Features of the morphology, fecundity, population structure, infection rate, and reproductive
mechanisms are described. It is considered possible that the species shows indications of serial male protandrous
hermaphroditism, not previously noted to occur in shrimps of the subfamily Pontoniinae. It may also be considered an
endangered species as its host animal is under threat.

Keywords: Paranchistus armatus, Pontoniinae, Decapoda, biology, possible hermaphroditism, Tridacna gigas
commensal, Australia, Great Barrier Reef, endangered species.

INTRODUCTION

The pontoniine shrimps associated with bivalve hosts
have attracted a certain amount of biological study,
particularly the species of the genera Anchistus,
Paranchistus and Conchodytes, found in association with
hosts in the family Pinnidae (Johnson and Liang, 1966;
Hipeau-Jacquotte 1974; Morton 1987). The species
associated with the family Tridacnidae have received
little attention, probably as the result of the clam’s legal
protection on most coral reefs and a reluctance to
sacrifice a significant number of these ho.sts.

The shrimp Paranchistus armatus is unusual in the
subfamily Pontoniinae, as it is one of the largest species
known, and is found only in association with the giant
clam Tridacna gigas (L.). The latter has a restricted
distribution in the Malaysian-Western Pacific region
(Rosewater 1965) and the shrimp, although first
described by Henri Milne Edwards in 1837, has so far
only been recorded from a relatively small number of
localities within that region. The giant clam is now a
protected species in Queensland waters, where spe¬
cimens can only be collected by special permit. The
Queensland Fisheries Service has been carrying out an
investigation of the biology of T. gigas, which has
enabled numerous specimens of P. armatus to be
examined without involving any unnecessary sampling
of the host animal. Previous reports on these shrimps
have generally been concerned with one to three
individuals and the present collection of 164 specimens

represents the first time that a small population, together
with some data concerning the hosts, have been available
for study. I am most grateful to Dr R.G. Pearson, of the
Queensland Fisheries Service, Department of Primary
Industry, and Dr V. Harriot, for this opportunity to report
upon these specimens.

Measurements (mm) refer to the postorbital carapace
length (CL) of the shrimps. Representative specimens
have been deposited in the collections of the Northern
Territory Museum, Darwin, (Cr.008674) and the
Queensland Museum, Brisbane (W25447).

DESCRIPTION

Paranchistus armatus (H. Milne Edwards, 1837)
(Figs 1-3)

Restricted synonymy:

Pontonia armata H. Milne Edwards, 1837: 359.

Anchistus biunguiculatus Borradaile, 1898: 387.

Tridacnocaris biunguiculatus - Nobili 1899: 235.

Anchistus oshimai Kubo, 1949: 26

Paranchistus biunguiculatus - Holthuis 1952: 13,
93-97, figs 36-38.

Anchistus armatus - Bruce 1967: 564-568.

Paranchi.stus armatus - Bruce 1975: 49-54, figs 1-3.

Material examined, (i) 61 adult pairs, 5 ovig.^, 2
9 , 4 cf, 3 immature, Arlington Reef, 16°45.0’S, 146°
00.0’E, from reef flat, 2 November 1978 to 12 November
1979. (ii) 4 pairs, 15 juveniles, Hastings Reef, 26
November 1979. (iii) 1 pair, I cf, 3 juveniles, Michaelmas
Cay, 5 December 1979.

91

A. J Bruce

Fig. 1. Paranchislus armatus (H. Milne Edwards). Arlington Reef, Queensland, Australia. A, left mandible. B, same, incisor process. C,
maxillula. D, same, palp. E, same, upper lacinia. P, maxilla. G, first maxilliped, palp and endites. H, paragnaths, ventral aspect. I, same,
left lateral. J, buccal region, left maxilla to third maxilliped removed. K. first pleopod, endopod. L, second pleopod, endopod, appendices.
A-J, ovigerous female. KL,. male.

Morphology. The present specimens agree closely
with the previously published descriptions given by
Kubo (1949, as Anchistus oshimai), Holthuis (1952, as
P. biungidculatus), and Bruce (1975).

In the large specimens, particularly the females, the
hepatic spine is very small and could only be identified
with considerable difficulty, even in dry specimens. The
dorsal rostral dentition on small specimens is relatively
conspicuous, in contrast to the condition in large females
in which it is obsolete.

The mouthparts correspond closely with the illustra¬
tions provided by Holthuis (1952). The maxillula has
short simple spines along the inner aspect and simple

setae on the outer side of the distal margin of the upper
lacinia (Figs 1 C, E). The palp is bilobcd, with a short
simple seta on the lower lobe (Fig. 1 D). The maxilla
has the basal endite bilobed, with the distal lobe larger
than the proximal and bearing six short setae, in contrast
to five (Fig. I F). The palp is broad and flattened, without
a subterminal seta but with a few short plumose setae
on the proximal lateral border. The setae on the endites
of the first maxilliped are simple. The coxal endite bears
a single long slender seta. The palp is non-setose and
the caridcan lobe of the exopod is fringed with short
plumose setae. The dactyl of the second maxilliped is
provided with numerous finely serrated spiniform setae

Commensal shrimp of the giant clam

Fig. 2. Paranchistus annatus (H. Milne Edwards), Arlington Reef, Queensland, Australia. Male, CL 8.0 mm. A, rostrum. B, chela of first
pereiopod. C, fingers of right second pereiopod. D, fingers of left second pereiopod. E, posterior telson spines. Female, CL 14.0 mm. F,
fingers of second pereiopod. G, posterior telson spines.

(Fig. 1 J). The anteromedial border of the propodal
segment bears long slender simple spines. The setae of
the third maxilliped are simple (Fig. 1 G). The epipods
of the three maxillipeds are deeply bilobed, sub-
rectangular and oval respectively (Figs 1 K, L). The third
maxilliped also bears a small six lamellar arthrobranch.
The flagella of all exopods are well developed and broad,
with numerous plumose setae along the margins of the
distal third.

The chelae of the first pereiopod are subspatulate,
with the laterally situated cutting edges of the fingers
fully finely pectinate (Fig. 2 B). The fourth thoracic
sternite bears a low transverse ridge with a small median
notch, and a similar but slightly large ridge is also present
on the fifth sternite.

The second pereiopods are generally subequal and
similar in both males and females, but relatively larger
in the former (Figs 2 C, D, F) The dactyl is generally
armed with 3-4 small acute teeth on the proximal cutting

edge and the fixed finger has 7-12, the most proximal of
which may be very small.

The telson is provided with three pairs of posterior
spines and two pairs of small dorsal spines (Figs 2 E,
G). The latter are situated at about 0.70 and 0.85 of the
telson length. The dorsal spines are relatively longer in
the males. The intermediate posterior spines are about
4.5 times longer than wide, about 0.1 of the telson length,
and about twice the length of the lateral spines. The
submedian spines are slender, feebly setulose and 0.4 -
0.7 of the length of the intermediate spines.

Colouration. The body, antennal peduncles,second
pereiopods and caudal fan are white, with the antennal
flagella purplish.

BIOLOGY

Fecundity. Of the 73 females over 11 mm CL, all
except four were ovigerous, and one of these appeared

A. J Bruce

to have just hatched its ova. The smallest ovigerous
female, CL 11 mm, carried 1,550 ova, and the largest,
CL 18mm, carried 8,901 ova. Intermediate size females
carried the following numbers of ova: (i) CL 13 mm,
4646; (ii) CL 15 mm, 5638; (iii) CL 17 mm, 7,788. The
ova are about 0.5 mm in length when freshly laid and
1.7 mm when about to hatch.

Population structure. Of the 138 specimens from
Arlington Reef, the males ranged in size from CL 7-11
mm and the females 8-18 mm. No Juveniles below CL 7
mm were found and the appendix masculina is re¬
cognisable in males of this carapace length. The
distribution of carapace length is shown in Figure 3.

It is noteworthy that no males occur with a CL of
over 12 mm and that very few females occur with a
carapace length below 11 mm, less than 3 %. As males
are readily identifiable from CL, 7-11 mm, it appears
that this population did not contain anyjuvenile females
and suggests that males of this species may be a
protandrous hermaphrodites, with the transition from
male to female occurring at about CL 11 mm.

In general the larger females are paired with the larger
males but considerable variation exists and a larger
sample is needed to clarify apparent discrepancies. The
relationships are summarised in Table 1.

Table 1. Range of carapace length (CL) in male.s paired with females
of specified CL

9 CL

cf CL,

range

n

mean

1 1

8-11

5

9.8

12

7 - 9

2

8.0

13

9-11

6

9.6

14

7 - 10

7

8.2

15

9-11

15

10.5

16

8-11

14

9.7

17

9-11

13

10.4

18

10-11

3

10.6

Almost all specimens were found as male-female
pairs. At Arlington Reef, 61 pairs were collected,
together with 6 six ovigerous females without male
partners and 2 non-ovigerous females, CL 16 and 8 mm.
It is most probable that the males of the six ovigerous
females were overlooked in dissection of the host clam,
or escaped during its removal from the reef. Of the four
cases where isolated females were found, three were
small, CL 8 mm, and could have been without males or
again, the males may have been overlooked during
collection.

In only one instance, at Arlington Reef, was more
than a pair of shrimps found in the host clam. In this
case a pair of small individuals, both of CL 10 mm were
accompanied by an additional small male of 7.5 mm CL,
the smallest identifiable male found. The female of this
association was without ova.

The two largest female shrimps (both 18 mm CL)
were found in two of the largest host clams, with shell
lengths of 83 cm and 95.5 cm. Two larger clams from
Hastings Reef were sampled, valve length 100 cm and

102.5 cm. both with a breeding pair of shrimps. The
smallest breeding pairs of shrimps were of 7.5 and 12
mm CL, and 10 and 11.5 mm CL in clams of 37.1 cm
and 43.0 cm respectively. The smallest pair of shrimps,
CLs 4.5 and 5.0 mm, were from Hastings Reef, from a
clam of 22.2 cm valve length.

Juveniles. The Arlington Reef population of P.
armatus is remarkable for the apparent absence of
juveniles, although sampling was carried out in the
months November, December, January, July, August,
September and October and ovigerous females were
found at all times, so that breeding may occur throughout
the year. Additional samples were also collected from
Hastings Reef, where clams of a larger size and smaller
size were sampled. At Hastings Reef two juveniles CL

4.5 and 5.0 mm, were found in clams of valve lengths

Commensal shrimp of the giant clam

28 and 23 cm respectively. A pair with an ovigerous
female were also found in a clam of valve length 43 cm.
At Michaelmas Cay, eight additional small specimens
of T. gigas were sampled, of which three contained
juveniles shrimps CL 4, 4, and 5 mm, clam valve lengths
30, 31 and 27 cm respectively. One clam, valve length
34 cm, contained a single male, CL 7 mm, and another,
valve length 37 cm., a small pair with an ovigerous
female, CLs 7.5 and 12 mm.

Two particularly large clams were also examined at
Hastings Reef in November 1979, valve lengths 100 and
102 cm. Each contained a male-female pair of adult
shrimp, CLs 11 and 15 mm and 11 and 17 mm. These
were accompanied by 7 and 6 juvenile shrimp res¬
pectively, CLs 1.5, 4, 4, 4, 5.5, 7, 7 mm and 4, 4.5, 5, 6,
7, 7 mm in each case. The 1.5 mm CL specimen was the
smallest found and is probably only a little over the first
post-larval stage size.

Autotomy. 89 specimens were examined in detail for
evidence for autotomy and limb regeneration. In not a
single example was there any evidence of limb loss,
injury or regeneration.

Host. All specimens were found in association with
the giant clam Tridacna gigas (L.). Hosts sampled ranged
in size from 22 - 102 cm in valve length. Small numbers
of Tridacna crocea, T. derasa, T. maxima, T. squamosa
and Hippopus hippopus were also sampled from
Michaelmas Cay but all were without associated P.
armatus (Pearson pers. comm.). The exact situation
within the host clam was not observable or recorded.

Infestation rate. Details are available of 91 clams
from Arlington Reef. Of these, 84 contained associated
shrimps, giving an infection rate of 92.3 %. Including
clams from other localities, 118 clams were infested on
100 occasions, with an overall infection rate of 84.7%.

Associated fauna. One specimen of Tridacna gigas,
valve length 18.2 cm, also contained two specimens of
the pinnotherid crab Xanthasia murigera White in addi¬
tion to Paranchistus armatus. No bopyrid parasitization
of the shrimps was found.

Distribution. Type locality: New Ireland, Papua New
Guinea. Also known from Indonesia: Batanta; Mefour
(Nobili 1899); Obi Latu (Holthuis 1952); Papua New
Guinea: New Ireland (H. Milne Edwards 1837);
Tubetube, Engineer Islands (Borradaile 1898); Hansa
Bay (De Grave 1999); Australia: Undine Reef (McNeill
1968); Chapman Island (Bruce 1975); Cairns; Arlington
Reef, Michaelmas Cay (Bruce 1983); Caroline Islands:
Helen Atoll, Palau (Kubo 1949); Ngadarak Reef and
Ngaianges Island (Miyake and Fujino 1968); Marshall
Islands: Ujae Atoll (Holthuis 1953); Eniwetak Atoll
(Rosewater 1965; Bruce 1975; Bruce 1979; Devaney and
Bruce 1989); Bikini Atoll (Chace and Bruce 1993);
Kiribati: Onotoa Atoll (Holthuis 1953).

Remarks. Giant clams are notorious for their
longevity and it may be safely assumed that each clam

provides a home for many generations of commensal
shrimp. No information is available on the life span of
the infesting shrimps. Their relatively large size, in
relation to other pontoniine shrimps, may indicate that
they live longer than about 12 months as suggested for
Periclimenes ornatus, a small pontoniine associate of
Japanese sea anemones (Omori et al. 1994). Morton
(1987) has discussed the biology of the commensal
pontoniine shrimps, Anchistus custos (Forsskal) and
Conchodytes rnonodactylus Holthuis, 1952, associated
with the pinnid bivalve Pinna hicolor Gmelin. This host
is comparatively short lived in comparison with T. gigas
and the situation is not comparable. No information is
available on the recruitment of these shrimps but it seems
likely that they arrive as post-larvae from the plankton.
In the present study the smallest individuals were little
above the typical size of pontoniine post-larvae. The
small ova indicate that there is no abbreviated larval
development that would enable recruitment to be derived
from the occupying pair of shrimps. The frequency of
heterosexual pairs of adult shrimps only akso suggests
that, in general, their presence suppresses or prevents
further colonisation by juveniles. The high infestation
rate suggests that replacement of shrimps is efficient and
quick. The range of shrimps sizes indicates a continuous
process without marked seasonality. Possibly the death
of an adult female results in the change of the male
partner into a female and the recruitment of a new shrimp
from the larvae in the plankton, which would develop
into a male. Death of a male would follow similar
recruitment, with the post-larva also developing into a
male. Protandrous and simultaneous hermaphroditism
have been reported in a number of caridean shrimp
families (Bauer and Holt 1998) but sex changes have so
far not been recorded in the Palaemonidae.

The absence of any signs of trauma or autotomy
suggests that life in Tridacna gigas represents a
particularly secure niche. This may be contrasted with
the situation reported in Coralliocaris graminea (Dana)
living in Acropora corals (Bruce 1976), where signs of
damage to the shrimp were frequent. In this species a
minimum of 23% of specimens examined showed signs
of significant regeneration after serious damage. The
species lives in small communities depending upon the
size of the coral host. The incidence of damage increases
with the size of the population, reaching up to 77% in
the larger populations. This damage was attributed to
intraspecific combat, particularly between females
(Bruce 1976), factors that would not be present in the
case of P. armatus.

The giant clam, Tridacna gigas (L.), was formerly
widely distributed in the Malaysian — northern
Australian — Western Pacific- region (Rosewater 1965)
but has recently been reported as “? extinct” in Taiwan,
Vanuatu, Fiji, Guam, New Caledonia and the Northern
Marianas (Wells 1997). Although unreported from these

A. J Bruce

localities, it is likely that P. armatiis was also present in
these regions but is now similarly extinct. All species of
Tridacnidae are listed in the Convention on International
Trade in Endangered Species of Wild Fauna and Flora,
APPENDICES I and II, as adopted by the Conference
of the Parties, valid from 16 February 1995 (http://
www.iwec.org/citesl.htm). If T. gigas is considered to
be an endangered species, logically its obligate
“commensal” associate, P. annatiis, must be in equal
danger.

Much remains to be studied in the life histories of
“commensal” shrimps such as Paranchistus annatus and
most others. Information on their food and feeding habits
is minimal, as is data on their larval stages and life
history, mechanism of host colonisation, longevity and
reproductive biology. The term “commensalism” is
frequently a euphemism for ignorance of details of the
lifestyle involved.

ACKNOWLEDGMENTS

I am grateful to Dr Richard Willan and Darryl Potter
for information on the present status of giant clams.

REFERENCES

Bauer, R.T. and Holt, G.J. 1998. Simultaneous hermaphroditism
in the marine shrimp Lysmata wurdemanni (Caridea:
Hippolytidae): an undescribed sexual system in the decapod
Crustacea. Marine Biology 132: 223-235.

Borradaile, L.A. 1898. A revision of the Pontoniidae. Annals and
Magazine of Natural History Series 7 2: 376-391.

Bruce, A.J. 1967. The results of the re-examination of the type
specimens of some pontoniid shrimps in the collection of
the Museum National d’Histoire Naturelle, Paris. Bulletin
dll Museum National d’Histoire Naturelle, Paris 2e Serie
39(3): 564-572.

Bruce, A.J. 1975. Pontonia armata H. Milne-Edwards (Decapoda
Natantia. Pontoniinae) - a correction. Criistaceana 29(1):
49-54.

Bruce, A.J. 1976. A report on some pontoniinid shrimps collected
from the Seychelle Islands by the F.R.N. Manihine, 1972,
with a review of the Seychelle pontoniinid shrimp fauna.
Zoological Journal of the Linnaean Society, London 59:
89-153.

Bruce, A.J. 1979. A report on a small collection of pontoniine
shrimps from Eniwetok Atoll. Crustaceana Supplement 5:
209-230.

Bruce, A.J. 1983. The pontoniine shrimp fauna of Australia.

Australian Museum Memoirs 18: 195-218. (1982).

Chace, F.A. Jr. and Bruce, A.J. 1993. The caridean shrimps
(Crustacea: Decapoda) of the Albatross Philippine
Expedition 1907-1910, Part 6: Superfamily Palaemonoidea.
Smithsonian Contributions to Zoology 543.

De Grave, S. 1999. Bivalvia associated with Pontoniinae
(Crustacea: Decapoda: Palaemonidae) from Hansa Bay,
Papua New Guinea. Bulletinde I’lnstitut Royal des Sciences
Naturelles de Belgique. Biologie 69: 161-177.

Devaney, D.M. and Bruce, A.J. 1987. Crustacea Decapoda
(Penaeidea, Stenopodidea, Caridea and Palinura) of
Eniwetak Atoll. 17. In: Devaney, D.M., Reese, E.S., Burch,
B.L. and Helfrich, P. (eds) The natural history of Eniwetak
Atoll. Part 2. Biogeography and systematics. Pp. 221-233.
U.S. Department of Energy: NTIS Energy Distribution
Centre, Oak Ridge, Tennessee.

Hipeau-Jacquotte, R. 1974. Etude des crevettes Pontoniinae
(Palaemonidae) associeds aux molluscs Pinnidae it Tuldar
(Madagascar). Archives de Zoologie Experimental et
Generale 115(3): 359-386.

Holthuis, L.B. 1952. The Decapoda of the Siboga Expedition.
The Palaemonidae collected by the Siboga and Snellius
Expeditions with remarks on other species. 2. The
subfamily Pontoniinae. Siboga Expedition Monograph
39*"': 1-252.

Holthuis, L.B. 1953. Enumeration of the decapod and stomatopod
Crustacea from Pacific coral islands. Atoll Research
Bulletin 24: 1-66.

Johnson, D.S. and Liang, M. 1966. On the biology of the
watchman prawn, Anchistus custos (Crustacea Decapoda
Palaemonidae), an Indo-West Pacific commensal of the
bivalve Pinna. Journal of Zoology, London 150: 433 455.

Kubo, 1. 1949. A new species of the genus Anchistus. Bulletin of
the Biogeographical Society of Japan 14: 26-29.

McNeill, F.A. 1968. Crustacea Decapoda & Stoinatopoda. Great
Barrier Reef E.xpedition, 1928-1929. Scientific Reports
7(1): 1-98.

Milne Edwards, H. 1837. Histoire naturelle des Crustaces,
comprenant I’anatomie, la physiologic et le classification
de ces animaux. Vol. 2: pp 1-532; atlas, 1-32, pis 1-42.
Paris: Librairie Encyclopedique de Rorel.

Miyake, S. and Fujino, T. 1968. Pontoniinid shrimps from the
Palau Islands (Crustacea, Decapoda, Palaemonidae).
Journal of the Faculty of Agriculture, Kyushu Imperial
University 10(3); 339-431.

Morton, B. 1987. Temporal host segregation by Anchistus custos
and Conchodytes monodactylus (Crustacea: Pontoniinae)
and Pinna bicolor (Bivalvia: Pinnidae) in Hong Kong.
Asian Marine Biology 4: 129-140.

Nobili, G. 1899. Contribuzioni alia Conoscenza della Fauna
carcinologica della Papuasia, delle Molucche e dell
Australia. Annali del Museum Civico di Storia Naturale di
Genova, Seiers 2 20(40): 230-282.

Omori, K., Yanagisawa, Y. and Hori, N. 1994. Life history of
the caridean shrimp Periclimenes ornatus Bruce associated
with a sea anemone in south west Japan. Journal of
Crustacean Biology 14(1); 132-145.

Rosewater, J. 1965. The family Tridacnidae. Indo-Pacific
Mollusca 1 (6): 347-393.

Wells, S. M. 1997. Giant clams: .status, trades and mariculture,
and the role of CITES in management. World Conservation
Union (lUCN).

Accepted 1 November 2000

96

The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 2000 16: 97-106

Vibration signals in Australian fiddler crabs - a first inventory

HEINRICH-OTTO VON HAGEN

Fachhereich Biologic, Zoologie, Philipps-Universitdt
D-35032 Marburg/Lahn, GERMANY

ABSTRACT

Vibration signals (often called sounds), which are components of the subterranean communication system of fiddler
crabs, were recorded in 14 of the 17 confirmed Uca species of Australia and analysed by use of oscillograms. Signals of
the related crab Heloechis cordiformis and two Asian species of Uca were used for comparisons. All crabs studied
produce “bounces”, i.e. burst-pulsed sounds corresponding to laterally directed jerks of the whole animal. All species
except H. cordiformis, U. dampieri and U. vomeris also emit “drumwhirls” or “rolls”, the familiar rapping sounds of the
major chelipcd. Parameters of these drumwhirls were compared using aquarium sound recordings of males competing
for a burrow. Indications of character displacement were found with regard to western and eastern samples of U.
signata. The most advanced rapping signals were recorded in U. signata and U.flammitla and in the two Asian species,
U. rosea and U. anmdipes', the most simple ones were recorded in U. longidigiium and U. polita. The two latter appear
to have pre.served early stages of drumwhirl evolution, contributing to the assumption of an Australian origin of the
genus Uca.

Keywords. Crustacea, Brachyura, Ocypodidae, Uca and Heloecius, vibration signals, survey, early stages of evolution,
Australian origin of Uca.

INTRODUCTION

Crabs inhabiting the semiterrestrial environment—
mainly Sesarminae (Grapsidae) and the subfamilies of
the Ocypodidae—are well-known examples of commu¬
nication by vibration signals. Various types of such
signals have been reported in literature (see preliminary
synopsis in von Hagen 1975), the most important ones
being generated by percussion and stridulation. Most
research on signal production, transmission and reception
has been done in tiddler crabs {Uca) and ghost crabs
iOcypode) (see Salmon 1983 for a review).

It is not clear to date, how often vibration signalling
arose independently in the two crab families mentioned.
It is certain, however, that vibration signals are used in
both agonistic and courtship situations and occur mostly
underground or at least in or near the mouth of the crab’s
burrow. Being short-range signals, vibrations appear to
play a major role in reproductive isolation. At least in
two West Indian sympatric and sibling species of Uca,
vibration signals were found to be much more species-
specific than the visual display (von Hagen 1984). As
the signals can also have group-specific characters, they
allow various phylogenetic inferences (von Hagen 1975,
1984), especially when these inferences are based on
quantitative data.

Until now, quantitative studies of Uca bioacoustics
have mainly dealt with the European fiddler crab U.
tangeri (von Hagen 1962; Altevogt 1963, 1970) and
American species of both the Atlantic (Salmon 1965,
1983; Salmon and Horch 1972; von Hagen 1984) and
Pacific coasts (Altevogt 1970; Muller 1989). R. Polivka
(pers. com.) started a bioacoustic project on fiddler crabs
of South East Asia, but did not complete and publish his
studies. With respect to Australia, pertinent research
seems to be lacking.

In the course of two visits to Australia, the author
had the opportunity to record subterranean vibration
signals of nearly all Australian species of Uca and of
the related ocypodid Heloecius cordiformis. The
recordings were obtained using a special aquarium that
allowed direct observation of the crabs during sound
production (cf. von Hagen 1970, 1984). The oscillo¬
graphic analyses published here are meant to serve as a
first survey or inventory and thus as a basis for more
specific research in future.

With a few exceptions, the vibration signals of
Australian fiddlers are simple, especially when compared
with the two Asian species included in this study. This
result allows certain speculations: that some Australian
Uca species have preserved an early stage of acoustic
communication (early with respect to the whole genus)
and that the genus probably originated in Australia.

97

H-O. von Hagen

Table 1. Abbreviations, systematic grouping, scientific names and Australian distribution of the species and origin of the samples studied.
Roman group numerals of Uca as in George and Jones (1982); in parentheses: subgeneric names from Crane (1975), invalid except A ustraluca.
Distribution in Australia: C circum-tropical, E eastern, W western.

Genus Heloecius:

He H. cordifonnis (H. Milne-Edwards) E Brisbane

Genus Uca, group IV ("Thalassuca"):

dp U. dampieri Crane W Darwin

vm U. vomeris McNeill E Bamaga, Brisbane

Genus Uca, group III (Australuca):

Ig

U. longidigitum (Kingsley)

E

Brisbane

pi

U. polita Crane

C

Broome, Cairns, Darwin

hs

U. hirsutimanus George and Jones

W

Broome, Darwin

sg

U. signala (Hess)

c

Cairns, Darwin

el

U. elegans George and Jones

w

Darwin

ss

U. seismella Crane

c

Broome, Darwin

Genus Uca, groups I and II {"Deltuca"):

cp

U. capricornis Crane

W

Bamaga, Darwin

ds

U. dussumieri (H. Milne-Edwards)

E

Bamaga, Cairns

fl

U. flammula Crane

W

Broome, Darwin

cc

U. coarctata (H. Milne-Edwards)

E

Brisbane

rs

U. rosea (Tweedie)

-

Penang and Malakka (Malaysia)

Genus Uca, group V ("Celuca"):

mb

U. mjoebergi Rathbun

W

Broome, Darwin

PP

U. perplexa (H. Milne-Edwards)

E

Bamaga, Cairns

an

U. annulipes (H. Milne-Edwards)

-

Bombay (India)

ANIMALS AND METHODS

Species names and localities of the specimens are
given in Table 1. The endemic Australian ocypodid crab
Heloecius cordifonnis, lately placed in a subfamily of
its own (Heloeciinae Tiirkay 1983), was studied in the
northern part of its range, which ends at Rockhampton
(Davie pers. comm). The present knowledge of the
geographic ranges of the Australian Uca, as specified in
von Hagen and Jones (1989), is also briefly indicated in
the Table.

Table 1 lists 14 of the 17 species of Uca confirmed
for the Australian fauna (only U. crassipes, U.
tetragonon and U. triangularis were not studied). As the
discussion about the extent and proper naming of the
species groups is not yet settled. Table 1 follows the
grouping of George and Jones (1982) by Roman
numerals; only U. elegans is transferred from group I to
group III and the order of groups has been altered (see
Discussion). In addition the subgeneric names from
Crane’s monograph (1975) are listed, which are widely
in use though mostly {except Austral uca) invalid because

of Bott (1973). The abbreviations of species names
(Table 1) are used also in Figures 1 and 2.

The two Asian species, U. rosea and U. annulipes,
included in the list, were collected by travelling students,
and the sounds were recorded in Germany. The
Australian species were studied at the places listed in
Table 1 during July and August of the years 1986 and
1988. Outdoor recordings of subterranean signals of
crabs are useful on certain occasions, but normally do
not allow statements on how the sounds are generated
(von Hagen 1975). Therefore, the signals were recorded
indoors in aquaria (12 1, height 20.5 cm), which, using
the technique of von Hagen (1970, 1984), allowed direct
observation of subterranean activities of the crabs. Bricks
were laid in the centre of the aquaria and only the narrow
gap between these bricks and the plastic walls were filled
with moist muddy sand from the habitat of the animals.
The crabs were forced to dig their burrows within this
thin vertical layer of soil and were observed, at very close
quarters, through the wall, which had to be kept clean.

Though also called “sounds”, the signals recorded
act as substrate-borne vibrations; the air-borne

98

Vibration signals in fiddler crabs

Table 2. Burst-pulsed sounds (“bounces”) measured in males of Heloecius cordiformis and four Australian Uca species (repetition rates
calculated from means of preceding column).

Species

One bounce: seconds

mean s.d.

Sequences:
maximum
number of
bounces

One bounce plus
subsequent silent interval:
seconds

mean s.d.

Repetition

rate:

bounces
per second

Number of bounces
measured (males)

H. cordifonnis

0.30

+ 0.10

3

0.64

+ 0.24

1.56

22

(2)

U. vomeris

0.12

+ 0.04

15

0.39

+ 0.19

2.56

23

(2)

U. seismella

0.07

+ 0.02

43

0.19

+ 0.02

5.26

64

(5)

U. coarctata

0.25

+ 0.08

4

0.57

+ 0.13

1.75

21

(3)

U. mjoebergi

0.20

+ 0.06

6

0.69

+ 0.14

1,45

64

(5)

components are only by-products. Therefore, a Briiel
and Kjaer accelerometer (type 4368) was used as a
vibration pick-up system. The accelerometer, screwed
to a 6.5 cm probing rod, was placed close to the crab’s
burrow and was connected to an Uher tape recorder
(type 4200 Report Stereo 1C) via a small preamplifier
designed by the Institute of Applied Physics, Marburg
(Dr. K.H. Wittich). The recordings were analysed in
Marburg by examination of oscillograms obtained from
a Philips oscilloscope PM 3231 in combination with a
camera (Tbnnies Recordine K-854).

The soil temperature ranged from 23 to 27.5 “C during
the recordings (including the ones in Marburg). All crab
individuals tested were of medium size when compared
with the figures of maximum carapace width for each
species (contained in Fig. 2). No special attempts were
made to detect signals of females, which tend to be rare
and more faint, when present (von Hagen 1984). Thus
all data given in this paper refer to males. Mean values
of the signals recorded were compared by a version of
Student’s t-test for heterogeneous variances and unequal
sample sizes (L-test, Graf et al. 1966; cf. Zofel 1992).

RESULTS

Main types of sounds. Nearly all of the signals
analysed in this paper were recorded in an agonistic
context, i.e. the accelerometer was placed close to the
mouth of a burrow occupied by a crab (“owner”). A
conspecific (“intruder”) wandering about in the aquarium
either detected the burrow spontaneously or was placed
into the mouth of the burrow by the experimenter. In
many of these situations one or both crabs emitted
vibration signals, sometimes in an antiphonal manner
(i.e. duetting with alternation). Sounds were either single
ones or sequences of sounds (Fig. 1).

Most of the species tested (though not all) produced
the usual percussive or rapping sounds or “rolls” of the

major cheliped, called “drumwhirls” in this paper and
also by Salmon and Atsaides (1968) and by Crane (1975),
who also speaks of “major-manus-drum”.

All species emitted signals that are regarded as
“additional components” of acoustic behaviour (von
Hagen 1984) and are, like respiration noises, normally
not specifically searched for by investigators. These
signals, called “bounces” in this paper and “leg-flicking”
by Salmon and Horch (1972), are “hoarse” burst-pulsed
sounds that correspond to laterally directed jerks of the
whole animal during its subterranean approach towards
an opponent, often in a “testing” manner. These sounds
are produced by the joint jerking motion of the flexed
ambulatories and are rather irregulary shaped and spaced
(e.g. Fig. 1 vm). By contrast, the drumwhirls of the major
cheliped are highly stylized and “elaborate” signals (e.g.
Fig. 1 sg) and are used not only in agonistic encounters,
but also as courtship display.

“Bounces” (burst-puLsed sounds). Examples of
sequences of bounces produced by H. cordiformis and
U. vomeris are given in Figure 1 (He, vm; cf. Table 2).
Bounces seem to form the only acoustic signals
detectable in these two species and U. dampieri (not
figured), though in H. cordiformis the bounces may be
superimposed by more evenly shaped short ambulatory
“trills”, visible in the first and last signal of Figure 1 He
and probably identical with the “ambulatory tapping”
that Griffin (1968) observed in the field.

Bounces were found in all species of Uca studied,
though not figured in all cases. Bounces (most often a
single one) frequently precede drumwhirls (Fig. 1 hSj,
dSj, flj, cc, rs, mb, pp, an), especially in the species of
group V (“Ce/HCfl”).

Some species (in addition to H. cordiformis, U.
vomeris and U. dampieri) produce bounces in short or
long sequences. Such sequences occur at least in U.
seismella, U. coarctata, U. mjoebergi and U. annulipes
(Fig. I SS|, CC|, mb|, an^). Of these, the Australian species

99

H-O. von Hagen

Fig. 1. Oscillographic samples of vibration signals of Australian Uca species, two Asian species {U. rosea, U. anniilipes) and Heloecius
cordiformis. Explanation of species name abbreviations given, in same order, in Table 1. Scale bars 0.5 seconds. Following part of legend
lists type and number of signals; B, bounces; D, drumwhirls (with number of strokes in parentheses): //c, and Hc^ 4 B, first and last
superimposed by ambulatory trills. - vm, 8 B. - /g^, 2 D (1 each); /g^, D (2). -p/,, D 3 D (2 each). - hs^, B + D (15); hs^, 2 D (7 and 8).

100

Vibration signals in fiddler crabs

Fig. 1 (cont.): Oscillographic samples of vibration signals. - sg^, D (35); sg^, D (14), (both from Darwin). - el^, D (9); el^, D (6). - 6 B;

ss^, D (12); Mj, D (5). - cp^, D (4); cp^, D (4). - ds^, D (2); ds^, B + D (3), arrow points to first stroke. D (21);/Zj, B + D (3). - cc,, 2 B
+ D (6); ccj, B + D (3). - B + D (26); rs^, D (5) + B + D (3). - m/t,, 3 B + D (7); mh^, B + D (16). -pp,, B + D (6) + B + D (5); pp^, B +
D (12). - an^, 2 B + D (14) + continuous ambulatory trill; cin^, B + D (10); an^, B + D (13) + B.

101

H-0. von Hagen

Table 3. Rapping sounds of Australian male fiddler crabs (results of oscillographic analysis of tape recordings, cf. Fig. 1). W, E: Samples
from western and eastern populations, respectively.

Species of

Uca

One (complex) sound
("drumwhirl"):

seconds

One sound plus
subsequent silent

interval: seconds

Strokes per sound: number

Period (one stroke
plus subsequent
pause):
milliseconds

Number of sounds
measured (males)

mean s.d

mean s.d

mean s.d range

mean s.d

longidigitum

0.18

±

0.16

1.33

±

0.34

1.87

±

0.87

(1-4)

159

+

34

23

(3)

polita

0.12

+

0.12

1.39

±

0.63

1.58

±

0.77

(1-5)

163

±

40

36

(4)

hirsutimanus

0.45

±

0.16

1.86

±

0.75

10.09

±

2.78

(5-16)

48

+

5

43

(4)

signata (W)

0.90

+

0.52

2.55

±

0.84

22.03

±

11.34

(7-45)

41

±

4

35

(2)

signata (E)

1.03

+

0.41

2.99

±

0.63

20.22

±

7.09

(8-38)

53

±

4

23

(3)

elegans

0.36

±

0.17

2.11

±

1.07

7.30

±

2.75

(2-11)

54

±

12

20

(3)

seismella

0.36

±

0.14

1.17

±

0.44

8.05

±

2.58

(5-14)

49

±

3

37

(4)

capricornis

0.22

+

0.13

1.71

±

0.41

3.10

±

0.97

(2-5)

90

±

23

20

(3)

dussumieri

0.12

±

0.04

3.24

±

1.04

2.06

±

0.44

(1-3)

98

+

25

16

(4)

flammula

0.84

±

0.53

2.36

±

0.77

13.40

±

8.89

(2-33)

69

±

12

57

(5)

coarctata

0.32

±

0.19

1.91

±

0.58

3.33

±

1.88

(1-11)

136

±

27

27

(3)

mjoebergi

0.49

+

0.23

2.33

±

0.80

9.42

+

3.71

(4-21)

56

±

6

64

(5)

perplexa

0.38

±

0.23

1.85

±

1.00

7.72

+

3.43

(3-15)

52

±

7

54

(5)

are included in Table 2, which presents some parameters
measured. Table 2 is mainly meant to illustrate the
speeialized charaeter of the bounces of U. seisniella (cf.
Fig. 1 sSj). Long .sequences of bounces (only comparable
with those of U. vomeris) are an essential part of its
acoustic communication. U. seismella is also cons¬
picuous by its extremely low means and low standard
deviations (differing from all other species, p < 0.001).

“Drumwhirls” (rapping sounds). Oscillographic
examples of rapping sounds are given in Figure 1 for 14
species including the Asian forms U. rosea and U.
annulipes. Three Australian species, namely H.
cordiformis, U. dampieri and U. vomeris, never emitted
rapping sounds.

Numbers of strokes listed in the legend of Figure 1
were verified by the running tape; the sudden extreme
decrease of pulse amplitude (e.g. Fig. 1 hs„ el, mb,, an|)
is due to reduced contact between chela and substratum.

Time patterns of the Australian species are to be
found in Table 3. The means given in this table are partly
based on up to five males (see last column of Table 3)
and different localities (Table 1). They have been united
after testing their statistical compatibility. In U. signata,
samples from Darwin and Cairns had to be treated
separately (see below). Species with small numbers of
sounds recorded (Table 3) reflect rarity of sound
production {U. longidigitum, U. capricornis, U.
dussumieri) or faintness of signals ((/. elegaus). Figure
2 and Table 4 were prepared to facilitate comparisons
within Table 3. The results can be summarized as
follows:

I) Relations of body size and repetition rate of
strokes. As the repetition rate of the rapping elements

(strokes per second, calculated from the period in Table
3) might simply reflect the species-specific body size,
the species were arranged according to the maximum
carapace width recorded for Australia (Fig. 2, left scale
and open circles). This arrangement is in accord with
the systematic grouping of Table 1.

As expected, the repetition rates (Fig. 2, right scale
and filled circles) mostly correspond to the body size
(though inversely): the broken line drawn at 17 strokes
per second divides the larger and thus “clumsier” and
slower species of group I and II from the smaller and
more agile species of group III and V. Within this scheme
the top positions are held by U. flamniula and the western
U. signata sample, respectively. The two species confirm
the advanced character of their acoustic signals also by
the high number of strokes per sound (Table 3 and Fig.
I sg|, n,).

On the other hand, the repetition rates of U.
longidigitum and U. polita do not fit the scheme at all:
the two species have the lowest repetition rates, though
they belong to the smaller species (middle and right
sections of Fig. 2). The exceptional status of the two
species is stressed by their low number of strokes per
sound (Table 3 and Fig. I Ig, pi). For a weighting of
these eharacters see below (Discussion).

2) In search of effects ofallopatry and sympatry. Most
of the 17 confirmed Australian species of Uca are
confined to one of the two northern zoogeographic
provinces: the Dampierian in the west and the Solan-
derian in the east, seen from the Torres Strait region (von
Hagen and Jones 1989; cf. Table 1 of the present paper).
Some of these allopatric species are still similar, i.e. they
form inter-provincial pairs or groups of relatives. The

102

Vibration signals in fiddler crabs

Maximum carapace width
in Australia (mm)

Repetition rate
(strokes per second)

Fig. 2. Body size (left scale, open circles) and repetition rate of rapping strokes (right scale, filled circles) in 12 species of Australian Uca
(abbreviations of species names and Roman group numerals as in Table I). Values of U. signata separated according to a western (W) and
eastern (E) sample. Maximum carapace widths in Australia after George and Jones (1982), except for U. seismella (Karumba sample of
author). Repetition rate calculated from the period of strokes in Table 3.

Table 4. Statistical comparison of allopatric and sympatric relatives
{Uca spp.) and populations of U. signata (W western, E eastern)
using two parameters of Table 3. ***, **, *: differences significant;
p < 0.001, < 0.01, •cO.05, respectively; n.s. not significant (L-test).
See Table 1 for geographic distribution of the species mentioned.

Strokes Period of
per sound strokes

Allopatric relatives:

U. capricornis

VS.

U. dussumieri

n.s

U. capricornis

vs.

U. coarctata

n.s.

***

U. flammula

vs.

U. coarctata

U. mjoehergi

vs.

U. perplexa

*

**

Svmoatric relative.s:

U. longidigitum

vs.

U. polita

n.s.

n.s.

U. elegans

vs.

U. hirsutimanus

*

U. seismella

vs.

U. polita

***

U. capricornis

vs.

U. flammula

***

U dussumieri

vs.

U. coarctata

Populations of U. sienata:

U. signata (W)

vs.

U. signata (E)

n.s.

U. signata (W)

vs.

U. hirsutimanus

***

U. signata (E)

vs.

U. hirsutimanus

***

***

U. signata (W)

vs.

U. elegans

***

U. signata (E)

vs.

U. elegans

***

n.s.

four species (U. polita, U. signata, U. seismella, U.
triangularis) that occur in both provinces appear to have
extended their range secondarily. They are one reason
for the fact that close relatives occur not only in allopatric
but also in sympatric distribution (Table 4).

It is to be expected that allopatric relatives are rather
“careless” of evolving species-specific vibration signals:
there is no selection against retaining signals that
antedate geographic separation. In fact three of the four
allopatric pairs listed in Table 4 are similar (differences
n.s. or p < 0.05 only) in one of the parameters chosen
for comparison (strokes per sound and period of strokes).

Sympatric relatives should reinforce selectivity of
their communication system, and the frequency of
significant differences in both parameters mainly appears
to fit this concept (Table 4). The pair U. longidigitum
vs. IJ. polita (Table 4) forms a puzzle, as both species
are reported from Sandgate and Shorncliffe in Moreton
Bay near Brisbane (George and Jones 1982). In 1986
the author found the two species at Shorncliffe on the
same mud-flat opposite to the mouth of Nundah Creek,
but not a single individual of U. polita in the many
longidigitum-hahitats of the Brisbane River itself.
Though both are members of the Solanderian province,
the two species seem to meet rarely in the field so that
their different time pattern of waving display (Pellikan
1990) may be sufficient as a behavioural isolating
mechanism.

103

H-0. von Hagen

The western and eastern samples of U. signata (from
Darwin and Cairns) were treated separately throughout
the paper, because they had clearly different periods of
strokes (p < 0.001, Table 4). Each population of U.
signata was compared with the two related western
(Dampierian) species U. hirsutimanus and U. elegans.
Indications of character displacement (i.e. the same two
species differ more in sympatry than in allopatry) were
not found between U. signata and U. hirsutimanus, but
between U. signata and U. elegans (Table 4). The latter
may be the closest relative of V. signata (Pellikan 1990).

3) Comparison with signals of two Asian species. The
two Uca species of South East Asia that were included
in this study fit easily into the systematic grouping of
the Australian species (Table 1). However, within these
groups the Asian species appear to be more specialized.

The number of strokes in isolated sounds of U. rosea
(e.g. 26 in Fig. 1 rs^ mean 17.06 ± 6.08, n = 17
drumwhirls of this long type) is only comparable with
that of U.flammula (Table 3). There are shorter sounds
in both species (Fig. I fl,, rs^), but only U. rosea can
“switch” to long .sequences of short drumwhirls (up to
12 sounds measured, instead of up to 3 in U.flammula).

Likewise, U. annulipes is more specialized than the
two related Australian species U. mjoebergi and U.
perplexa. The number of strokes per sound is similar to
that of U. mjoebergi and U. perple.xa, but the period of
strokes is more variable (cf. anj, with an^ and an^ in Fig.
1). In U. annulipes the drumwhirls are often followed
(or preceded) by continuous burst-pulsed “trills” (Fig. 1
aOj) of the walking legs, lasting up to about ten seconds.
These trills were also recorded in U. perplexa, but more
rarely, and they appear to be missing in U. mjoebergi.

DISCUSSION

In explaining the Figures and Tables in the section
on “drumwhirls”, a few conclusions were attempted that
are more or less well supported. It is clear that body size
and repetition rates of strokes are inversely related (with
a few striking exceptions), but the second idea that
sympatry and allopatry should inlTuence the signals
needs to be tested by closer pair-by-pair examinations
(cf. von Hagen 1984). A more detailed study of the U.
longidigitum-U. polita pair and of the western and eastern
populations of U. signata should be especially rewarding.
Work on U. signata should also include samples from
New Guinea, where the species occurs at least around
Merauke, Irian Jaya (Leiden Mu.seum, Netherlands: e.g.
No. D32522, D33526; von Hagen unpublished).

It is also premature to make general conclusions on
the advanced status of the signals of Asian fiddler crabs
(see third section). The two species chosen (U. rosea,
U. annulipes) might be specialized species by chance.
There exist, however, some additional bioacoustic data:

of U. paradussumieri Bott (= U. spinata Crane) and U.
dussumieri from Malaysia and Indonesia (R. Polivka
pers. com.). Judging only from their range of stroke
numbers per sound (3-21 and 2-6, respectively) these
Asian forms, too, appear to be more advanced than their
Australian relatives.

As is evident from examination of Figure I and Table
3 the sounds of Australian U. dussumieri as well as of
U. capricornis and U. coarctata are among the simplest
signals recorded. These species apparently hold a basal
position within the “De//HCfl”-group, with regard to its
Australian as well as to its Asian members.

Only members of Australuca (group Ill), namely U.
longidigitum and U. polita, are even simpler with respect
to their signals: by their mean number of strokes
(minimum in Table 3) and their long stroke period
(maximum in Table 3, resulting in an exceptional low
repetition rate. Fig. 2).

Especially U. longidigitum (Fig. I, Ig), with the
distribution pattern of a relict species (see George and
Jones 1982), could have preserved the earliest phylo¬
genetic stage of drumwhirl invention in Uca, namely
rapping as a by-product of waving the major cheliped.
Within Australuca, U. longidigitum is the only species
in which the length of one sound plus subsequent interval
(1.33 ± 0.34, n = 23, Table 3) is statistically not separable
from the length of one waving motion plus subsequent
pause (1.22 ± 0.11, n = 36, according to motion pictures
taken by the author and analysed by Pellikan 1990). Even
in the aquarium U. longidigitum tended to switch from
waving to rapping (and vice versa), the latter looking
like a reduced or weak waving movement.

Vibration components of visual display are well-
known in Uca (Altevogt 1964), but in U. tangeri, a
species that also possesses a complete system of
drumwhirls. U. longidigitum seems to have but one
gesture that serves two sen.sory channels - depending on
its intensity or completeness. It is important to note that
the nearly all Australian “Auslraluca”-group (which
includes U. longidigitum) retains, as a whole, some other
ancestral traits: above all, minor chelae with large teeth
(Crane 1975) and waving display of females (von Hagen
1993).

It is not clear, whether the “Thcdassuca”-gToup, which
also has waving females (von Hagen 1993), holds a still
more ancestral position with regard to sound evolution
in Uca. The two Australian members, U. dampieri and
U. vomeris, never emitted drumwhirls within the
experimental design of the present study, though they
should have: Crane (1975) recorded, in the field,
underground rapping sounds in the close relatives U.
hesperiae from East Africa and U. pacifensis from Fiji
(see her Plate 47 A) and even in U. vomeris from New
Caledonia; and Salmon (1984) describes a “shuttling”
motion of the major chela in U. vomeris from Townsville,

104

Vibration signals in fiddler crabs

used by intruders in the entrance of another crab’s
burrow. A gesture of this kind was filmed in Cairns in a
male of U. vomeris fighting on the surface of the ground
(von Hagen, unpublished). Furthermore, the American
narrow-fronts {Uca sensu stricto) are thought to be a
branch of “Thalasstica" (Crane 1975), and they have
genuine drumwhirls (e.g. von Hagen 1971, 1972).

However, even without certainty in the case of U.
dampieri and U. vomeris, Australia remains the continent
where all stages of sound evolution are to be found: H.
cordiformis without drumwhirls, U. dcimpieri and U.
vomeris apparently without proper drumwhirls or
normally not using them underground, U. longidigitum
and U. polita with drumwhirls of a very early stage, U.
capricornis, U. dussumieri and U. coarctata with simple
sounds not much more progressive than those of U.
polita, and after an intermediate stage two especially
advanced positions, which evolved independently out
ot'Australuca (U. signata) and “Deltuca” (U.flammula).
Among the intermediate forms (not specified here) two
species have, in addition to their drumwhirls, evolved
peculiarities: U. seismella has specialized in long
sequences of “hasty” bounces and U. perplexa (like U.
anniilipes) in continuous ambulatory trills.

Housing all stages of sound evolution, especially the
early ones, and also the early stages of waving evolution
(von Hagen 1993), Australia should be favoured as the
continent where the genus Uca first evolved.

The author is aware that directional change in
behavioural complexity cannot be the only indicator in
phylogenetic reasoning. A support at least by morpho¬
logical studies is necessary (Beinlich and von Hagen in
prep.). However, this holds true also for other ap¬
proaches. Two related papers, which were published
some years ago (Levinton et al. 1996, Sturmbauer et al.
1996), base their phylogenetic trees on certain analyses
of 16S rDNA alone. Their inferences, above all an
American centre of origin of Uca, should be treated with
reserve, as they lack a proper morphological background
for their discussions, which neglect for example, the most
reliable synapomorphy in Uca systematics: the unique
pleonal clasping apparatus identifying all broad-fronted
species as a monophylum (Guinot 1979, Beinlich and
von Hagen in prep.).

The assumption that Uca first evolved in Australia
is, furthermore, supported by an Australian origin of
certain mangrove taxa (palynological evidence compiled
in Specht 1981). As Uca is typically associated with
mangroves, it is essential that Rhizophora, Avicemiia and
Sonneratia first appeared in the late Eocene of West
Australia and colonized Indonesia not before Oligocene/
Miocene - probably accompanied by fiddler crabs, which
made South East Asia not their first, but their second
centre of evolution. Crane, who considers “Deltuca” the
subgenus “least specialized” (Crane 1975) and at first
supposed a Malaysian origin of the genus (Crane 1956),

finally called Australia’s northwest coast “the most
conservative area, judging by the morphology of the local
Uca" (Crane 1975). As the east coast has its ancestral
forms as well (H. cordiformis, U. longidigitum, U.
coarctata), one should extend Crane’s assessment to the
whole continent.

ACKNOWLEDGMENTS

The author wishes to thank the following persons and
institutions: the Northern Territory Museum (NTM,
Darwin) and Mr N. Roche (Police Station, Bamaga) for
generously providing a field vehicle; Dr A.J. Bruce and
Dr J.R. Hanley (formerly of NTM), Mr P. Davie
(Queensland Museum, Brisbane) and Mrs and Mr R. and
I. Vela (Bamaga) for their kind and constructive help,
e.g. in finding Uca habitats; Ms S. Dietrich and Mr P.
Heimes (Marburg) for providing live U. rosea and U.
annulipes', Mrs S. Gotzfried (Marburg) for many-faceted
technical assistance.

REFERENCES

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von Uca langeri. Verhandlungen der Deutschen
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Altevogt, R. 1970. Form und Funklion der vibratorischen
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Crane, J. 1975. Fiddler crabs of the world. Ocypodidae: genus
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crabs of Australia (Ocypodidae: Uca). Records of the
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Graf, U., Henning, H.J.. and Stange. K. 1966. Formeln und
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Guinot, D. 1979. Donnces nouvelles sur la morphologie, la
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Hagen, H.O. von 1962. Freilandstudien zur Sexual- und
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Hagen, H.O. von 1970. Die Balz von Uca vocator (Herbst) als
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Hagen, H.O. von 1975. Kla.ssifikation und phylogenetische
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zoologische Systematik und Evolutionsforschung 13: 300-
316.

Hagen, H.O. von 1984. Visual and acoustic display in Uca
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Accepted 4 June 2000

106

The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 2000 16: 107-122

Caetrathynnus, Nitidothynnus and Procerothynnus, new genera of Thynninae
(Hymenoptera: Tiphiidae) from northern Australia

G.R. BROWN

Museum and Art Gallery of the Northern Territory
GPO Box 4646, Darwin NT 0801, AUSTRALIA
Current address : Department of Primary Industry and Fisheries
GPO Box 990, Darwin NT0801, AUSTRALIA
graham.hrown @ nt.gov.au

ABSTRACT

Three new genera are erected to accommodate nine new species of thynnine wasps: Caetrathynnus for C. greggi sp.
nov. (type species), C galhinus sp. nov. and C. wesselensis sp. nov.; Nitidothynnus forN. purdiei sp. nov. (type species),
N. eheneus sp. nov. and N. .spinulus sp. nov.; and Procerothynnus forP. centralianus sp. nov. (type species), P. arnhemicus
sp. nov. and P. carpentarianus sp. nov. All the new species are described from males only, except Nitidothynnus spinulus
and N. purdiei, which are known from both males and females. Keys to species are given, as is a discussion of coupling
mechanisms in Nitidothynnus and the phenomenon of mixed species couples is considered in light of the biology of the
subfamily. Most of the new species are recorded only from the Top End of the Northern Territory, although Caetrathynnus
galhinus also occurs in adjacent areas of northern Western Australia and Procerothynnus carpentarianus also occurs in
adjacent areas of north-western Queensland. Procerothynnus centralianus is recorded from central Australia while
Nitidothynnus eheneus is known only from the holotype from northern Queensland.

Keywords. Tiphiidae, Thynninae, new genera, Caetrathynnus, Chilothynnus, Nitidothynnus, Procerothynnus,
Aspidothynnus, Australia, taxonomy, biogeography.

INTRODUCTION

Wasps of the subfamily Thynninae comprise a very
diverse group in Australia which includes many
undescribed species and genera (Brown 1998a). Some
600 species have been described, mostly from the
vicinity of the large coastal cities in eastern, south¬
eastern and south-western mainland Australia (Given
1954; Salter 1954). Very few have been described from
northern or inland Australia, and there are only 26 known
from the Northern Territory.

Adults are most commonly observed feeding on
flowers (hence the common name “flower wasps”) where
they often occur in copula. The main food source appears
to be nectar, although other plant and insect secretions
and exudates are also eaten (Tillyard 1926; Burrell 1935).

Nectar from flowers of the plant family Myrtaceae,
which includes eucalypts and tea trees, is particularly
attractive, and may attract these wasps in large numbers
at the height of the flowering season.

Male thynnines are fully-winged, while females are
smaller, wingless, and somewhat ant-like in appearance.

Because females are wingless, and cannot therefore
travel very far by themselves, they are dependant on
males for food. Feeding occurs during mating as pairs

couple for long periods during which the male carries
the female to flowers. Pairs remain coupled while both
are feeding, and there are morphological structures
present that assist pairs to remain coupled for prolonged
periods. Since the sexes are so different morphologically,
it is the convention to describe each separately.
Unfortunately in the de.scriptions that follow this is not
possible for every species because of the lack of females.

Females produce pheromones to attract males prior
to mating. However, on rare occasions when a
conspecific male never arrives, a female may couple with
a non-conspecific male (Brown 1993). This is a common
occurrence in this subfamily and is most probably a
mechanism that ensures a hungry female is carried to a
food source at the expense of successful mating. The
latter may be of little concern to the survival of the
species as a whole because unfertilised females of all
Hymenoptera (ants, bees and wasps) produce male
offspring which are haploid anyway (Naiimann 1991).
This phenomenon of miscoupling is mentioned spe¬
cifically under the descriptions of Nitidothynnus purdiei
and N. spinulus in this paper.

The Thynninae has not been revised taxonomically
since 1910 (Turner 1910) and the only critical
examinations since then have been revisions for the

107

G.R. Brown

genera Acanthothynniis Turner, Doratithynnus Turner,
Encopothynniis Turner and Macrothynnus Turner
(Brown 1987, 1989a, 1989b, 1995a). These revisions
indicated that, in at least these genera, between 50% and
75% of the fauna currently represented in collections
was undescribed and that many species were known from
only one or two specimens. This suggests that more
extensive collecting, especially in more remote areas
such as the Northern Territory of Australia, will reveal
even more new species.

Currently there are 37 genera considered to be valid
within the tribe Thynnini in Australia (Given 1954;
Brown 1983, 1992, 1995b, 1997a, 1997b, 1998b).
Studies by the present author indicate that these genera
form three distinct clusters. The first cluster contains the
genera Bifidothynmis Brown, Campylothynnits Turner,
Catocheilus Guerin, Elidothynnus Turner, Guerinius
Ashmead, Leptothynnus Turner, Lestricothynnus Turner,
Lophocheilus Gudrin, Macrothynnus Turner,
Megalothynnus Turner, Oncorhinolhynnus Salter,
Pogonothynmis Turner, Thynnoides Gudrin, Thynnus
Fabricius and Zaspilothynnus Ashmead. It is distin¬
guished from the other two generic clusters by numerous
characters including the labrum weakly rather than
strongly narrowed basally, the propodeum oblique in
profile, tergite 7 longitudinally multicarinate (except in
Bifidothynnus and Guerinius which have tergite 7
otherwise modified) and sternite 8 with prominent basal
angles or spines in the male, and sternite 5 rugose and/
or carinate in the female. Most Australasian species are
also larger in size than those found in the other two
clusters.

The second cluster inc\udes Acanthothvnnus Turner,
Arthrothynnus Brown, Aspidothynnus Turner,
Doratithynnus Turner, Encopothynniis Turner,
Epactiothynnus Turner, Gymnothynnus Turner,
Iswaroides Ashmead and Tmesothynnus Turner. It dif¬
fers from the subsequent cluster by having most
metasomal segments strongly constricted (and sometimes
spinose), and tergite 7 with a strong transverse apical
Carina.

The third generic cluster includes Aeolothynnus
Ashmead, Agriornyia Gudrin, Ariphron Erichson,
Chilothynnus Brown, Leiothynnus Turner, Neozelehoria
Rohwer, Pentazelehoria Brown, Phymatothynnus
Turner, Psammothynnus Ashmead, Tachynoides
Kimsey, Tachynomyia Gudrin, Tachyphron Brown, and
Zelehoria Saussure. This cluster is distinguished from
other Australian Thynnini (and Thynninae) by the
combination of: a relatively short, weakly protruding
sternite 8 that is not broadened into lobes or spines at
the base, and which may be armed apically with a narrow
spine (with or without lateral spines); the metasomal
segments are not strongly constricted or heavily
sclerotized; a convex tergite 7 that is uniformly punctate

with a medial impunctate area, but without a transversely
carinate apical margin; and the basiparameres are not
strongly developed ventrobasally such that the ventro-
basal angle (in profile) is well separated from the basal
ring. A key to genera in this cluster was given by Brown
(1998a), although Tachynoides was omitted. That genus
keys to Tachyphron in that key.

The three new genera described here belong to the
third cluster. Two of these were included in the key to
genera by Brown (1998a) and referred to as genus A
and genus B.

Terminology follows Snodgrass (1941), Brown
(1997a,b) and Naumann (1991). Relative terms relating
to microsculpture are interpreted as follows: sparsely
punctate = punctures greater than two puncture-
diameters apart; punctate = punctures at most two
puncture-diameters apart, but never confluent; closely
punctate = punctures almost confluent; rugosely punctate
= punctures partially confluent; finely punctate =
punctures small and shallow; coarsely punctate =
punctures large and deep; obscurely punctate = punctures
small, sparse, shallow and only visible at certain angles.

Abbreviations. Morphological characters: Tl-7,
metasomal tergites 1-7; SI-8, metasomal sternites 1-8;
POL:OOL, ratio of distance between posterior ocelli to
distance between eye and posterior ocellus. Specimen
repositories: AM, Australian Museum, Sydney; ANIC,
Australian National Insect Collection, CSIRO, Canberra;
BMNH, The Natural History Museum, London; MV,
Museum of Victoria, Melbourne; NTM, Museum and
Art Gallery of the Northern Territory, Darwin;
OTTAWA, Agriculture Canada, Ontario; QM, Queens¬
land Museum, Brisbane; SAM, South Australian
Museum, Adelaide; UQIC, University of Queensland,
Brisbane; WAM, Western Australian Museum, Perth.

SYSTEMATICS
Caetrathynnus gen. nov.

Type species. Here designated Caetrathynnus greggi
sp. nov.

Generic diagnosis. Male. Head, mesosoma and
metasoma strongly polished with metasoma shagreened.
Mandibles long, narrow and straight. Clypeus convex,
strongly produced and broadly truncate apically.
Antennal prominence long, narrowly U-shaped with
margins slightly emarginate dorsally, sagittally sulcate,
and with short oblique carina above antennal insertions.
Frons strongly and broadly depressed lateral to antennal
prominence. Antennae short and only just reaching
propodeum, apical 6 segments weakly arcuate. Pronotum
with anterior margin weakly raised not carinate, lateral
margins strongly convergent anteriorly. Mid femur
strongly and abruptly broadened at base. Metasoma

108

New thynnine wasp genera

fusiform, segment 1 subpetiolate, about as wide as long;
segments 3-4 widest, segments (apart from T2 and S2
anteriorly) not constricted. T7 convex, slightly produced
and membranous apically, not transversely apical
carinate. S8 subtriangular with a single narrow slightly
upturned apical spine, narrowly emarginate at base of
spine. Genitalia with basal ring cylindrical, not short;
basiparameres suborbicular to subtriangular (viewed
dorsally), not apically emarginate; parameres subparallel,
of moderate length and width, apex subtruncate; cuspides
of moderate length with opposing digitate digitus
apically.

Remarks. Caetratbynniis is most readily distin¬
guished from other thynnine genera (in particular, those
of the third cluster) by the structure of the mandibles
which are long, narrow and straight, and the clypeus
which is broadly convex without a sagittal carina, and
with the apical margin strongly produced and broadly
truncate. The broadly convex and broadly apically
truncate clypeus suggests a relationship with Psammo-
thynnus and Zeleboria. However, in both of these genera,
the mandible is shorter, broader and curved (as normally
found in other genera) and the clypeus is shorter, more
strongly convex and sagittally carinate. These differences
in clypeal shape suggest that an enlarged clypeus may
have arisen in Caetrathynnus independently to that of
Psammothynnus and Zeleboria, and is supported by
differences in the genitalia which differ from Caetra¬
thynnus by having the basal ring very short, the fused
basiparameres truncate to emarginate dorsoapically and,
in many species, the parameres with a ventroapical lobe.
These two genera also lack a single medial spine on S8
which occurs in Caetrathynnus and many other
Thynninae.

Caetrathynnus superficially resembles Aspidothynnus
Turner in that: the clypeus is broadly convex, and
strongly and broadly produced apically without a sagittal
Carina; and the metasoma is fusiform without spines on
the tergites or sternites. However, Aspidothynnus belongs
to the second generic cluster and as such differs by those
characters as listed in the Introduction. Aspidothynnus
also differs from Caetrathynnus by having the antennal
prominence weakly developed rather than long, narrowly
U-shaped with margins slightly emarginate dorsally; T1
wider than long rather than as approximately as wide as
long; and metasomal segments with spots rather than
lunulate marks.

The three species of Caetrathynnus are very similar
in appearance, but differ slightly in the punctation of
clypeus, gena and pronotum, and the shape of the fore
coxae, the depth of the anterior depression on S2 (typical
of all Thynninae), the base of the apical spine of S8, and
the genitalia. They are reliably distinguished by the
genitalia.

All three are recorded from the north of the Northern
Territory. Caetrathynnus galbinus sp. nov. is recorded
from near the Western Australian border while C.
wesselensis sp. nov. is known only from the holotype
from the Wessel Islands. C. greggi sp. nov. is the most
widely occurring species, and it ranges from Darwin to
Borroloola.

Caetrathynnus was referred to as genus “A” by
Brown (1998a) in a key to closely related genera.

Etymology. The generie name is masculine and is
derived from the Latin word caetra (also spelt cetra)
which is a type of shield. It is a reference to the shape of
the male clypeus.

Key to males of Caetrathynnus, (Females are
unknown.)

1. a Most sclerites predominantly yellow; prosterna
black with yellow spot; propodeum with U-shaped
lateral marks at least partially fused medially

.C. galbinus sp. nov.

b Sclerites predominantly black (may have exten¬
sive yellow marks but not distinctively more yellow
than black); prosterna black without yellow spot;
propodeum with U-shaped lateral marks not fused
medially.2

2. a Apex of parameres truncate (Fig. 3); base of cuspis

sinusoidal (in profile).

.C. wesselensis sp. nov.

b Apex of parameres rounded (Fig. 2); base of cuspis
rounded (in profile).C. greggi sp. nov.

Caetrathynnus galbinus sp. nov.

(Fig. 1)

Type material. HOLOTYPE cT - NTM (1911): Keep
River NP, Garrandalng, 15°53’S, 129°03’E, Northern
Territory, 30 April 1996, G.R. Brown. PARATYPES -
Western Australia’. UQIC (3d'), 14 mi. (22.5 km) S of
Kununurra, on Eucalyptus '/pruinosa, 5 March 1973,
E.M. Exiey.

Description of male. Body length 11 mm; fore wing
8 mm; hind wing 6 mm. Clypeus rugosely punctate,
punctures shallow and vertically aligned, apical margin
width to maximum width 1:2.0. POLiOOL 1:1.1. Frons
closely and shallowly punctate. Vertex obscurely
punctate. Gena shallowly and closely punctate. Pronotum
sparsely and shallowly punctate, punctures more distinct
posterolaterally. Mesoscutum and mesoscutellum
sparsely punctate medially, closely punctate laterally.
Metanotum punctate. Propodeum closely and shallowly
punctate, punctures deeper laterally, impunctate
anteriorly. Mesopleura closely to finely punctate. Fore
coxae flat. T1 width to length 1:0.9. T2 weakly depressed
anteriorly. Tergites and sternites closely and very
shallowly punctate such that most tergites and anterior
sternites almost appear impunctate, punctures coarser on
posterior tergites. SI not medially raised. S2 strongly

109

G.R. Brown

Figs 1-6. Caetrathvnnus spp., males: 1, C. galbinus sp. nov., genitalia, lateral and dorsal; 2, C. greggi sp. nov., genitalia, lateral and dorsal;
3, C. wesselensis sp. nov., genitalia, lateral and dorsal; 4, C. greggi sp. nov., habitus; 5, C. greggi sp. nov., S8; 6, C. greggi sp. nov., right
mid trochanter and femur. A, basal ring; B, basiparameres; C, cuspis; D, digitus; E, aedeagus; F, paramere. Scale lines = 0.5 mm.

no

New thynnine wasp genera

depressed anteriorly. S8 slightly emarginate at base of
spine. Genitalia as in Figure 1: basiparameres sub-
triangular (viewed dorsally) with each basiparamere
truncate apically; parameres relatively short, subtruncate
apically, weakly dorsally lobed (in profile) near base of
aedeagus; cuspis subparallel basally, apically triangular,
apex ending slightly beyond apex of digitus and
outwardly curved, base rounded and slightly visible in
profile.

Colour. Black; yellow colouration as follows:
mandibles (except apex), stipes, clypeus (except obscure
medial anchor-shaped mark), large longitudinal mark
(except very narrow sagittal line) above antennal
insertion, inner and outer orbits of eyes with outer orbit
almost continuous with inner orbits and extending
discontinuously across vertex, anterior margin of
pronotum broadly (very narrowly discontinuous
medially), posterior margin of pronotum broadly,
tegulae, mesoscutum with large spot on disc and
horizontal mark above fore wing, large spot on disc of
mesoscutellum, axillae, metanotum, metapleuron, broad
lateral U-shaped mark on propodeum, mesopleura
(except mesopleural groove), spot on prosterna, margins
of mesosternal lamellae, coxae (except base of mid and
hind coxae), outer surfaces of trochanters, femora and
fore tibiae, dorsal surface of fore femora, Tl-6 (except
anteromedially and posterolateral spot), .sagittal line on
SI, S2 (except anteromedial and posterolateral spots),
curved lateral mark on posterior margin of S3-6 (almost
confluent medially); orange colouration as follows: legs
(except coxae outer surfaces of trochanters, femora and
fore tibiae, dorsal surface of fore femora). Margin of
tegulae semitransparent. Wing membranes hyaline with
veins orange to brown. Setae white.

Distribution. Known only from the Northern
Territory-Western Australian border near Kununurra.

Remarks. This species is distinguished from other
species of Caetrathynnus by the extent of the yellow
colouration such that most sclerites are predominantly
yellow, including the presence of a spot on the prosterna,
and enlarged U-shaped lateral markings on the
propodeum which are at least partially fused medially.
It is also distinguished by having the fore coxae fiat, the
clypeus with punctures vertically aligned, and the
pronotum with punctures most distinct posterolaterally.

Yellow colouration may be expanded on the clypeus,
and on the propodeum so that marks are confluent
medially, or slightly reduced on the pronotum,
propodeum and metasoma. Black on the metasoma may
be partially replaced by brown, or it may be expanded
such that it is confluent with the black posterolateral spots
on some segments.

Etymology. The specific name is derived from the
Latin word galbinus (= yellowish) and it refers to the
extensive yellow colouration of the male.

Caetrathynnus greggi sp. nov.

(Figs 2, 4-6)

Type material. HOLOTYPE cf - NTM (1895): 17
Mile, Virginia, I2°33’S, 131°02’E, near Darwin,
Northern Territory, 28 April 1996, S. Gregg. PARA-
TYPES - Northern Territory: AM (K122050), BMNH
(E2000-27), MV (T17352), NTM (1896-1898), QM
(T57838), SAM (1 21437), WAM (26555) {9cf), same
data as holotype (3 NTM, 1 AM), 4 May 1996(1 BMNH,
1 MV), 19 May 1996 (I QM, 1 SAM), December 1997
(1 WAM); NTM (I899-I90I) (3cr), Arafura Swamp,
I2“16’S, 124°59’E, 9 June 1996, G.R. Brown; NTM
(1902-1903), OTTAWA (3cr), Berry Springs 50 km S
Darwin, rainforest. Malaise trap, 4-27 December 1993,
S. and J. Peck; ANIC (IcT), 12 km NNE of Borroloola,
15°58’S, 136°21’E, I November 1975, J.C. Cardale;
NTM (1904) (Icf), McMillans Rd [Berrimah] near
Darwin, eucalyptus woodland. Malaise trap, 1-25
December 1993, S. and J. Peck; NTM (1905), OTTAWA
(2cf), Berrimah near Darwin, mixed eucalyptus
woodland, 25 December 1993-10 January 1994, S. and
J. Peck; NTM (1906) (Icf), Mindil Beach near Darwin,
13 May 1996, S. Gregg; NTM (1907) (IcT), Melville I.,
swamp W of Taracumbi Falls, 1I°35’S, 130°40’E, 4
October 1996, G.R. Brown and G. Dally; NTM (1908)
(Icf), Melville I., Mirikau-Yunga Ck, ll°3rS,
130°4rE, 5 October 1996, G.R. Brown and G. Dally;
NTM (1909) (IcT), Melville I., 11°35’S, 130°40’E,
Malaise trap, 4-15 October 1996, G.R. Brown; NTM
(1910) (Icf), Mt Mortgage, Humpty Doo, 12°35’S,
131 °05’E, 28 February-31 March 1992, A. Wells and J.
Webber; ANIC(lcr), !9kmNE of Mt Cahill, 12°47’S,
l32°5rE, 16 November 1972, J.C. Cardale.

Description of male. Body length 8-12 mm; fore
wing 6-9 mm; hind wing 4.5-6 mm. Clypeus rugosely
and shallowly punctate, apical margin width to maximum
width 1:1.6. POL:OOL 1:0.9. Frons closely and
shallowly punctate. Vertex obscurely punctate. Gena
shallowly and closely to rugosely punctate. Pronotum
.sparsely and shallowly punctate, punctures more distinct
on anterior and posterior margins. Mesoscutum and
mesoscutellum sparsely punctate medially, closely
punctate laterally. Metanotum punctate. Propodeum
closely and shallowly punctate, punctures deeper
laterally, impunctate anteriorly. Mesopleura closely to
finely punctate. Fore coxae almost flat. T1 width to
length 1:1.0. T2 weakly depressed anteriorly. Tergites
and sternites closely and very shallowly punctate such
that most tergites and anterior sternites almost appear
impunctate, punctures coarser on posterior tergites. SI
not medially raised. S2 depressed anteriorly. S8
emarginate at base of spine. Genitalia as in Figure 2:
basiparameres broadly subtriangular (viewed dorsally)
with each basiparamere rounded apically; parameres
relatively long, rounded apically, distinctly dorsally

G.R. Brown

lobed (in profile) near base of aedeagus; cuspis
subparallel basally, apically triangular, apex ending
slightly beyond apex of digitus and outwardly curved,
base rounded and strongly visible in profile.

Colour. Black; yellow colouration as follows:
mandibles (except apex), clypeus (except medial anchor¬
shaped mark), large longitudinal mark (except very
narrow sagittal line) above antennal insertion, inner and
outer orbits of eyes almost continuous dorsally,
transverse line behind ocelli, margins of pronotum
(anterior margin very narrowly discontinuous medially,
and expanded ventrally), tegulae, mesoscutum with large
spot on disc and horizontal mark above fore wing, central
and anterolateral spots on mesoscutellum, axillae, disc
and anterolateral spot on metanotum, metapleuron, broad
lateral U-shaped mark on propodeum, anterior vertical
mark and small mark and adjacent spot near mid coxa
on mesopleura, margins of mesosternal lamellae, coxae
(except bases), extreme apices of femora, dorsal line on
fore femora, ventral margin of mid and hind femora,
lunulate lateral line on posterior margin of T1-6 and S3-

5 usually or virtually contiguous medially; orange
colouration as follows: legs (except coxae, apex of fore
trochanter, extreme apices of femora, dorsal line on fore
femora, ventral margin of mid and hind femora). Margin
of tegulae semitransparent. Wing membranes hyaline
with veins orange to dark brown. Setae white.

Distribution. Coastal Northern Territory from
Darwin to Borroloola.

Remarks. This species is distinguished from
Caetrathynnus galhimis by having less extensive yellow
colouration such that most sclerites are predonimantly
black. It is distinguished from C. wesselensis sp. nov.
by having the apex of the parameres rounded and the
base of the cuspis rounded in profile. It is distinguished
from both species by having S8 more emarginate at the
base of the apical spine, the gena with punctation more
rugose, and the pronotum with punctation more distinct
on the anterior and posterior margins.

The yellow colouration may be expanded on the
tergites to enclose a posterolateral spot, or reduced on
the mesoscutum and mesoscutellum such that the medial
spots are elongate marks. Black colouration on the
trochanters may be replaced by orange.

Etymology, This species is named after Steven Gregg
of the Museum and Art Gallery of the Northern Territory
who collected many of the type series, and who has a
great love of natural history.

Caetrathynnus wesselensis sp. nov.

(Fig. 3)

Type material. HOLOTYPE cT - ANIC : lUOl’S,
136°45’E, Rimbija Is., Wessel Islands, Northern
Territory, 3-14 February 1977, T.A. Weir.

Description of male. Body length 7 mm; fore wing

6 mm; hind wing 4 mm. Clypeus rugosely and shallowly

punctate, apical margin width to maximum width 1:1.8.
POL:OOL 1:0.9. Frons closely and shallowly punctate.
Vertex obscurely punctate. Gena shallowly and closely
punctate. Pronotum sparsely and shallowly punctate,
punctures more distinct posterolaterally and ventrally.
Mesoscutum and mesoscutellum sparsely punctate
medially, closely punctate laterally. Metanotum punctate.
Propodeum closely and shallowly punctate, punctures
deeper laterally, impunctate anteriorly. Mesopleura
closely to finely punctate. Fore coxae slightly convex.
T1 width to length 1:1.2. T2 weakly depressed anteriorly.
Tergites and sternites closely and very shallowly
punctate such that most tergites and anterior sternites
almo.st appear impunctate, punctures coarser on posterior
tergites. SI not medially raised. S2 depressed anteriorly.
S8 slightly emarginate at base of spine. Genitalia as in
Figure 3: basiparameres subtriangular (viewed dorsally)
with each basiparamere rounded apically; parameres
relatively short, distinctly truncate apically, weakly
dorsally lobed (in profile) near base of aedeagus; cuspis
subparallel basally, apically triangular, apex ending
slightly before apex of digitus and not outwardly curved,
base sinuate and strongly visible in profile.

Colour. Black; yellow colouration as follows:
mandibles (except apex), clypeus (except obscure medial
anchor-shaped mark), large longitudinal mark (except
very narrow sagittal line) above antennal insertion, inner
and outer orbits of eyes almost continuous dorsally,
margins of pronotum (anterior margin narrowly
discontinuous medially, and expanded and confluent
ventrally), tegulae, mesoscutum with spot on disc and
horizontal mark above fore wing, central and antero¬
lateral spots on mesoscutellum. axillae, disc and
anterolateral spot on metanotum, spot on metapleuron,
lateral U-shaped mark on propodeum, anterior vertical
mark and small mark and adjacent spot near mid coxa
on mesopleura, margins of mesosternal lamellae, apex
of fore coxae, mark on inner and outer margins of mid
and hind coxae apically, ventral surfaces and dorsal mark
apical mark on femora, lunulate lateral line on posterior
margin of T1-6 and S2-5 contiguous medially on tergites;
orange colouration as follows: legs (except coxae, apex
of fore trochanters, mid and hind trochanters, ventral
surfaces and dorsal mark apical mark on femora). Margin
of tegulae semitransparent. Wing membranes hyaline
with veins orange to brown. Setae white.

Distribution. Only known from a single specimen
from Rimbija I., Wessel Islands off the coast of Arnhem
Land, Northern Territory.

Remarks. This species is distinguished from other
species of Caetrathynnus by the apically truncate
parameres and the straight lateral margins of the
basiparameres. It also differs from C. greggi which has
the base of the cuspis rounded rather than sinusoidal in
profile and from C. galhimis which has more extensive

112

New thynnine wasp genera

yellow colouration such that the sclerites are more yel¬
low than black including a yellow spot on the prosterna
and the yellow U-shaped lateral marks on the propodeum
fused medially. This species is also distinguished by the
punctures on the pronotum being most distinct postero-
laterally and ventrally, and the fore coxae which are
slightly convex.

This species is similar in colouration to C. greggi.

Etymology. The species name is derived from the
type locality.

Nitidothynnus gen. nov.

Type species. Here designated Nitidothynnus purdiei
sp. nov.

Generic diagnosis. Male. Head, mesosoma and
metasoma (especially dorsally) strongly polished and
mostly obscurely punctate (such that punctures are
sparse, and very small and shallow giving the appearance
of the integument being impunctate especially on the
vertex and pronotum). Clypeus convex basomedially, not
carinate, narrowly truncate. Antennal prominence double
U-shaped, medially sulcate, above plane of clypeus.
Antennae long, longer than combined length of head and
mesosoma, flagellar (except basal) segments four times
longer than wide, apical six segments weakly arcuate.
Maxillary palps with apical 3 segments each longer than
basal 3 segments, fourth segment longest. Pronotum with
lateral margins strongly convergent anteriorly, anterior
margin raised but not carinate, anterior truncation
transversely carinate ventrally and produced laterally
such that the pronotum is produced anterolaterally.
Mesopleura with longitudinal median groove ventrally.
Fore trochanters long and strongly narrowed over most
of length from base. Metasoma elongate-fusiform,
sclerites weakly sclerotized (except SI and S8) and at
most slightly constricted (although more so basally on
S3-5 and especially S2 and T2). T7 convex, becoming
slightly produced and membranous apically, not carinate.
S8 with lateral margins curved, trispinose with medial
spine longest. Genitalia with basal ring of medium
length, subcylindrical and (in profile) slightly curved;
basiparameres subovate (viewed dorsally) and emar-
ginate medially, apices of individual basiparameres
produced and often acute; parameres long and narrow
especially apically, curved and convergent apically. All
species are extensively marked with yellow on a reddish
orange background although most of the reddish orange
is replaced with black on the meso- and metathorax in
some specimens.

Female. Mandible unidentate. Clypeus narrowly
truncate to slightly emarginate, medially raised. Frons
obscurely sagittally sulcate. Pronotum wider than long,
anterior margin clearly defined, longer than posterior
margin, anterolateral angles spinose, lateral margins
carinate on posterior half ending in a small tooth
anteriorly; disc slightly medially raised, raised area wider

posteriorly. Mesoscutellum narrow. Mesopleura with
slight dorsal surface. Propodeum projecting well above
level of mesoscutellum, oblique posteriorly becoming
flattened dorsally, apex directed anteriorly and narrowed.
Fore femur concave on apical half of ventral surface. T1
vertically truncate and setose anteriorly; dorsal surface
with carinate apical margin and curved impressed
preapical line. T2 impunctate with three to five transverse
carinae. T3-5 with impressed curved preapical line.
Pygidium (T6) curved in profile, posterior surface long
and narrow with carinate lateral margins, ventral margins
narrowly rounded, slightly emarginate laterally. Sternites
sparsely and shallowly punctate.

Remarks. The genus Nitidothynnus is most readily
distinguished from other genera of the generic cluster
by the microsculpture of the head, mesosoma and
metasoma which are distinctively polished and obscurely
punctate (particularly diagnostic on the vertex and
pronotum); the anterior truncated surface of the pronotum
transversely carinate ventrally and produced laterally and
visible laterally as a short truncated process; the antennae
relatively long; and the fore trochanters long and strongly
narrowed over most of their length from the base. A
convex, non-carinate clypeus that is below the plane of
the antennal prominence, and long apical maxillary palp
segments are similar to these states in Neozeleboria.
However, Neozeleboria has S8 subparallel to sub-
triangular with the apex ranging from rounded to slightly
emarginate but with only a single apical spine rather than
with lateral margins curved with the apex trispinose.

Antennae are characteristically long in Nitidothynnus
with antennae longer than the combined length of the
head and mesosoma, and most flagellar segments four
times longer than wide. In most other genera of the
generic cluster (except some species of Tachynomyia and
closely related genera) they are shorter but distinctly
longer than wide. This compares to the short antennae
found in Procerothynnus in which the antennal segments
are only slightly longer than wide, appearing virtually
as long as wide.

The three species placed in this genus are very similar
in appearance and are also best separated by the male
genitalia, although Nitidothynnus spinulus is distinguished
by the presence of a preapical spine on the fore and hind
trochanters. Only the females of A. purdiei and N. spinulus
are known, and these are distinguished by the shape of the
head and T6. Both species are widespread in the Top End
of the Northern Territory, and have overlapping distri¬
butions, while N. ebeneus is only known from the holotype
from north-eastern Queensland.

Nitidothynnus was referred to as genus “B” by Brown
(1998a) in a key to closely related genera.

Etymology. The generic name is masculine and is
derived from the Latin word nitidus (= shining), and is a
reference to the shining head, mesosoma and metasoma
of the male.

G.R. Brown

Figs 7-17. Nitidothynnus spp., males: 7, N. spinulus sp. nov., male carrying female (female except eye and antenna stippled); 8, N. purdiei
sp. nov., fore trochanter; 9, N. spinulus sp. nov., fore trochanter; 10, N. purdiei sp. nov., cuspis, ventral; 11, N. spinulus sp. nov., cuspis,
ventral; 12, N. ebeneus sp. nov., cuspis, ventral; 13, N. spinulus sp. nov., S8; 14, N. spinulus .sp. nov., prothorax lateral; 15, N. spinulus sp.
nov., genitalia, lateral and dorsal; 16, N. purdiei sp. nov.. genitalia, lateral and dorsal; 17, N. ebeneus sp. nov., genitalia, lateral and dorsal.
Scale lines = 0.25 mm.

114

New thynnine wasp genera

Key to species of Nitidothynnus. (The female of N.
eteneus is unknown)

1 . a Male (winged). 2

b Female (wingless). 4

2 . a Fore and hind trochanters with preapical spine on

ventral margin (most conspicuous if viewed post¬
eriorly) (Fig. 9). N. spiniilus sp. nov.

b Trochanters without preapical spine on ventral
margin (Fig. 8 ). 3

3 . a Genitalia (viewed dorsally) with each basi-
paramere with outer margin curved and ending in an
obtuse point (Fig. 16) and cu.spis (Fig. 10) with ventral
surface mostly horizontal becoming abruptly and
strongly concave apically (excluding lamellate

projection). N. purdiei sp. nov.

b Genitalia (viewed dorsally) with each basi-
paramere with outer margin sinusoidal and ending in
an acute point (Fig. 17) and cuspis (Fig. 12) with
ventral surface almost flat and sloping upwards
towards apex, not abruptly truncated or concave
apically (excluding lamellate projection).

. N. ebeneus sp. nov.

4. a Head with posterolateral angles emarginate (Fig.

20); T 6 subparallel dorsally (Fig. 23).

. N. spinulus sp. nov.

b Head with posterolateral angles rounded (Fig. 21);
T 6 broadened ventroapically(Fig. 22).

. N. purdiei sp. nov.

Nitidothynnus purdiei sp. nov,

(Figs 8 , 10, 16,21-22)

Type material. HOLOTYPEcT - NTM (1912): near
Oenpelli reservoir, campsite, 12°23’S, 133°05’E, 27
November 1997, G.R. Brown and J.E. Purdie. PARA-
TYPES - Northern Territory: NTM (1913-1916) (4cf),
same data as holotype; NTM (1917) (I cf), below Oenpelli
reservoir, 12°24’S, 133°05’E, 27 November 1996, G.R.
Brown and J.E. Purdie; NTM (1918) (I cf), near Oenpelli
reservoir, by sweeping, 12°22’S, I33°04’E, 27 No¬
vember 1996, G.R. Brown and J.E. Purdie; BMNH
(E2000-27), QM (57840), NTM (1919-1920) (4cf), near
OenpeWi, Aliosyncarpia forest, 12°23’S, 133°OrE, 28
November 1996, G.R. Brown and J.E. Purdie; NTM
(1921) (Icf), near Oenpelli, Allosyncarpia forest track,
12°23’S, 133°02’E, 30 November 1996, G.R. Brown and
J.E. Purdie; NTM (1922) (Icf), Oenpelli reservoir,
I2°24’S, 133°05’E, 26 November 1997, G.R. Brown and
J.E. Purdie; NTM (1923-1924) (2cr), Daly River rd,
Adelaide R. crossing, I3°29’S, 13r06’E, 24 October

1996, G.R. Brown; NTM (1925-1926) {Id), Blackfellow
Ck, Daly River rd, I3°32’S, 130°49’E, 19 November

1997, G.R. Brown; NTM (1927) (Icf), Groote Eyiandt,
in pit fall trap in open forest, 17-23 June 1982, J. Majer;
NTM (1928) (Icf), near Drovers Rest, Litchfield NP, 25
November 1993, G.R. Brown; NTM (1929) (Icf),
Maningrida, rubbish tip rd, 12°06’S, I34°13’E, 13 June

1996, G.R. Brown; NTM (1930) (IcT), Mataranka, by
sweeping, 1 January 1996, G.R. Brown; NTM (1931)
(Icf), 18°37’S, 137°59’E, Border Waterhole near
Musselbrook Reserve, 10-17 April 1995, G.R. Brown;
NTM (1932) (Icf), UDP Falls, 18-19 July 1980, M.B.
Malipatil. NTM (11166) (I 9 ) Virginia near Darwin,
12°33’S, 13r02’E, 28 October 1996, S.M. Gregg
(mounted with male paratype of N. spinulus).
Queensland: NTM 1933-1937 (5cf), Musselbrook
Reserve near Musselbrook Ck, 18°33’S, 138°irE, 18
April 1995, G.R. Brown; ANIC (Icf), Holts Ck, 18°33’S,
138.11’E, 15 May 1995, at light, l.D. Naumann.

Other material. Northern Territory: NTM (2cf), near
Oenpelli re.servoir, by sweeping, 12°22’S, 133°04’E, 27
November 1996, G.R. Brown and J.E. Purdie; NTM
(9cf), near Oenpelli reservoir, Allosyncarpia forest,
12°23’S, I33°02’E, 28 November 1996, 30 November
1996, G.R. Brown and J.E. Purdie; NTM (Icf), Oenpelli
area, November 1996, G.R. Brown and J.E. Purdie.
Queensland: NTM (4cf), Musselbrook Reserve near
Musselbrook Ck, 18°33’S, HSMl’E, 18 April 1995,
G.R. Brown.

Description of male. Body length 4.5-8 mm; fore
wing 4-7 mm; hind wing 2.5-4 mm. Clypeus shallowly
and closely punctate, apical margin width to maximum
width 1:4.3. POL:OOL 1:1.6. Frons, vertex, gena and
pronotum obscurely sparsely punctate. Lateral margins
of pronotum sightly curved and convergent anteriorly,
anterior truncation with ventral transverse carina almost
continuous medially. Mesoscutum closely punctate
anteriorly and laterally, punctures more conspicuous than
those on head and pronotum. Mesoscutellum and
metanotum obscurely sparsely punctate. Propodeum
transversely striate, longer than wide, lateral margins
parallel-sided anteriorly, dorsal margin in profile evenly
rounded down to metasoma. Mesopleura obscurely
sparsely punctate. Fore coxae, long, conical, ventral
surface flat. Fore trochanter (Fig. 8 ) not spined.
Metasoma almost impunctate, T1 closely punctate, T 6 -
7 and S 6-8 with conspicuous setiferous punctures and
setae long. T1 width to length 1:1.1. SI medially raised,
rounded in cross-section, T2 weakly and S2 strongly
depressed anteriorly, segments 1-5 Battened and wider
than high. Genitalia as in Figure 16: apex of each
basiparamere rounded dorsoapically; parameres narrow
and narrowly subtriangular; cuspis (Fig. 10) lamellate
apically, ventral surface mostly horizontal becoming
abruptly and strongly concave apically (excluding
lamellate projection).

Colour. Reddish orange; yellow colouration as
follows: mandibles (except apex), maxillary and labial
palps, clypeus (except medial anchor-shaped mark and
dorsolateral spots testaceous), antennal prominence,
inner orbits of eyes extending to behind vertex, outer
orbits sinusoidally extending across vertex and confluent
with inner orbits, margins of pronotum (broadly so

G.R. Brown

Figs 18-23. Nitidothynnus spp., females: 18, N. spinulus sp. nov., mesothorax; 19, N. spinulus sp. nov., habitus; 20, N. spinulus sp. nov.,
head; 21, N. piirdiei sp. nov., head; 22, N. purdiei sp. nov., T6; 23, N. spinulus sp. nov., T6. Scale lines = 0.25 mm.

ventrally), tegulae, mesoscutum with curved mark above
fore wing and central subrectangular marks, me-
soscutellum with anterolateral spot and central broad
trident-shaped mark; disc and anterolateral line on
metanotum, most of propodeum, mesopleuron (except
curved branched medial mark and ventral surface),
metapleuron (except extreme margins), coxae (except
extreme bases), margins of mesosternal lamellae, apical
margins of trochanters and inner surface of fore
trochanter, dorsal and ventral margins of femora
irregularly expanded on fore leg, outer surface of tibiae,
lateral irregular spots on Tl-6 and Sl-2; black
colouration as follows: ocellar triangle, posterior and
posteroventral surfaces of head, anterior truncation and
neck of pronotum, mesoscutum (except curved mark
above fore wing and central subrectangular marks),
mesoscutellum laterally and extreme anterior margin,
metanotum (except disc and anterolateral line), extreme
anterior margin of and pair of posteromedial spots on
propodeum, prosterna, mesopleuron ventrally, extreme
margins of metapleuron, SI, S8 and base of Tl; tarsi
brown especially apically. Wing membranes hyaline,
veins orangish brown.

Description of female. Body length 3 mm. Head (Fig.
21 ) rounded, as wide as long, sparsely punctate with large

semicircular closely punctate area occupying most of
vertex, posterolateral angles strongly emarginate. T2 with
3 transverse carinae, apical 2 strongest, basal 1 may be
obscured by Tl. Pygidium (T6) with lateral margins
slightly diverging ventrally, and slightly medially and
triangularly raised (Fig. 22).

Colour. Pale yellowish brown; head (except
appendages) greyer.

Distribution. Northern Territory from Daly River
south to Mataranka and east to the Queensland border.

Remarks. The male of this species is distinguished
from other species of Nitidothynnus by the structure of
the genitalia which (when viewed dorsally) has each
basiparamere with the outer margin curved and ending
in an obtuse point (Fig. 16) and cuspis (Fig. 10) with the
ventral surface mostly horizontal becoming abruptly and
strongly concave apically. The female is distinguished
by the structure of the head which has the posterolateral
angles rounded (Fig. 21) and T6 broadened ventro-
apically (Fig. 22). The only other known female of a
species in the genus Nitidothynnus has the posterolateral
angles of the head emarginate (Fig. 20) and T6
subparallel dorsally (Fig. 23).

The yellow markings may be expanded on the
posterior and anterior margins of the pronotum so that
116

New thynnine wasp genera

they are confluent each side of the sagittal line, or
confluent medially on SI. They may also be narrowly
discontinuous medially on the anterior margin of the
pronotum, reduced to a central spot on the pronotum or
split into 2 spots on the mesopleuron and replaced with
reddish orange, or reduced or absent on SI-2 and Tl.
Much of the reddish orange on the mesoscutum and
propodeum may be replaced with black. The apex of the
metasoma may be slightly darker.

The Musselbrook Reserve specimens tend to have the
mesosoma darker than the majority of the other
specimens, but fit within the range of colour variation
of these specimens. There are no noticeable differences
in the genitalia to Justify a separate species for the
Musselbrook material.

The specimen from Groote Eylandt is labelled as
coming from a pit fall trap. This is unusual, but it is
conceivable that a wingless female could have fallen into
such a trap, and, once there, attracted the male by
pheromones. I have never seen thynnines of either sex
in pit fall traps, although the wingless females of the
closely related family Mutillidae (“velvet ants”) are
frequently caught in such traps.

Etymology. This species is named after John Purdie
who collected many of the type series, and who is a keen
naturalist and a close friend.

Mating biology. As indicated in the Introduction,
mixed species pairs may be encountered occasionally.
This is indicated in museum collections when a series
consisting of a single species of male includes females
of two different species that have both been collected in
copula with this species of male. In the absence of
morphological structures that may, for example, be
adaptations to prolonged coupling, and therefore,
associate pairs, sexes may be associated on the
assumption that the majority of specimens couple
correctly. This is the case with Nitidothynniis purdiei
and N. spimilus.

Females of Nitidothynniis purdiei and N. spinulus are
associated with males on the basis of coincident
collecting data for four males and one female of N.
spinulus from Virginia, and two males and two females
N. spinulus from Berrimah. The Virginia specimens
include a pair collected in copula while the Berrimah
females include a pair grasping each other and which
had probably been in copula prior to being killed.

The Berrimah pair is interesting in the way the male
and female fit closely together. The male is clasping the
female with its legs such that: the hind trochantcral spine
fits into the groove before the apical carina on T2 of the
female; the fore trochanteral spine is holding the fore
femur of the female away from her body; and the male
head is deflexed so that the female head is held closely
between the mouthparts and the fore coxae of the male.
The female is clasping the male with her mouthparts and
has the fore femur overlapping the fore trochanter and

femur of the male, and has the protruding propodeum
slotted into the longitudinal ventral groove along suture
of the mesopleura of the male.

Contrary to this association of sexes is another female
in which the head is rounded posterolaterally and T6 is
broadened ventrally. This female was collected in copula
at Virginia with a male of N. spinulus. The female is
believed to be N. purdiei as it is the only other species
which overlaps in distribution with N. spinulus (although
there are no other coincident collecting records).

As pairs couple for prolonged periods, there is the
possibility that the shape of structures in the two sexes
that are juxtaposed as a result of this coupling, may be
correlated. The major differences in the shape of the
female head, and the juxtaposition of the female head
and male fore coxae in Figure 7 suggests that there may
be a correlation between these structures that permit the
association of sexes on morphological grounds.
However, no differences in the structure of the male fore
coxae could be found that would explain differences in
the female head shape.

Nitidothynniis ebeneus sp. nov.

(Figs 12, 17)

Type material. HOLOTYPF cT - QM (T57841): near
Granite Gorge, 17°0rS. 145°20’F, 21 May 1989, 12
km SW Mareeba, Queensland, G. and A. Daniels.

Description of male. Body length 7 mm; fore wing
5 mm; hind wing 4 mm. Clypeus with apical margin
width to maximum width 1:5.0. POL:OOL 1:1.5.
Anterior truncation of pronotum with ventral transverse
carina broadly discontinuous medially. Fore trochanter
not spined. Tl width to length 1:1.2. Genitalia as in
Figure 17: apex of each basiparamere narrow and acute
dorsoapically; parameres subtriangular, strongly
narrowed beyond level of apex of cuspis; cuspis (Fig.
12 ) lamellate apically, ventral surface almost flat and
sloping upwards towards apex, not abruptly truncated
or concave apically (excluding lamellate projection).
Otherwise as N. purdiei.

Colour. Black; yellow colouration as follows:
mandibles (except apex), maxillary and labial palps,
clypeus (except testaceous medial anchor-shaped),
antennal prominence, inner orbits of eyes extending to
behind vertex, outer orbits of eyes sinusoidally extending
across vertex and confluent with inner orbits, anterior
and posterior margins of pronotum, tegulae, mesoscutum
with curved mark above fore wing and central sub-
rectangular marks, mesoscutellum with anterolateral spot
and central broad inverted T-shaped mark, disc and
anterolateral line on metanotum, propodeum with medial
line strongly broadened anteriorly and lateral line
strongly broadened posteriorly, mesopleuron (except
curved branched medial mark and ventral surface), spot
on metapleuron, fore and mid coxae (except extreme
bases), outer margin of hind coxa, margins of mesosternal

G.R. Brown

lamellae, apical margins of trochanters, dorsal and
ventral margins of femora, outer surface of tibiae, lateral
irregular spots on Tl-5; reddish orange colouration as
follows: gena and vertex dorsally, legs (except coxa and
yellow marks on trochanters, femora, tibiae and tarsi)
and metasoma (except yellow spots on T1 -5, T1, S1, base
of S2 and S 8 ); S 8 dark brown. Wing membranes hyaline,
veins pale orange.

Distribution. Known only from near Granite Gorge,
12 km SW of Mareeba, North Queensland.

Remarks. The male of this species is readily
distinguishable from other species of the genus by the
absence of reddish orange colouration on the mesosoma
(excluding the legs) although this is based only on a
single specimen. It is also distinguished by the digiti
which are not visible ventrally and the cuspis (Fig. 12)
which has the ventral surface almost flat and sloping
upwards towards apex, not abruptly truncated or concave
apically. The female is unknown.

Etymology. The species name is derived from the
Latin word ebeneus (= black) and refers to the relatively
dark colour of the mesosoma.

Nitidothynnus spinulus sp. nov.

(Figs 7, 9, 1 1, 13-1.5, 18-20,23)

Type material. HOLOTYPE cf - NTM (1954):
Virginia near Darwin, 12°33’S, 131°02’E, Northern
Territory, 28 October 1996 S.M. Gregg. PARATYPES
- Northern Territory. NTM (1955-1958) (3d', 1 9 ), same
data as holotype (Icf, 1 9 1955-1956), or dated 12 July
1997 (1 cf 1957) or 16 November 1997 (1 cT 1958); NTM,
(1959-1962) (2d', 29 ), Berrimah near Darwin, 1-15
November 1996 (1 d" 1959), 16-30 November 1996 (1 cf,
29 1960-1962), A. Salvarani; NTM (1963-1965),
OTTAWA, WAM (26556) (5d'), Darwin, eucalypt
woodland. Malaise trap, (site 93-86), 1-25 December
1993, S. and J. Peck; NTM (1966-1967), QM (T57842)
(3d'), Anbangbang Billabong, Kakadu NP, 12°52’S,
132°48’S, 10 June 1996(1 NTM 1966), 17 January 1998
(1 NTM 1967), 1 QM), G.R. Brown; ANIC , NTM (1968-
1973), OTTAWA ( 8 d'), Kapalga Research Stn, Kakadu
NP, eucalypt woodland, Malaise trap, (site 93-117), 11-
25 December 1993, S. and J. Peck; NTM (1974-1975),
OTTAWA (3d'), Kapalga Research Stn, Kakadu NP,
North Point Rainforest, Malaise trap, (93-134), 24
December 1993-7 January 1994, S. and J. Peck; NTM
(1976) (Icf), Keep River National Park, Gurrandaing,
15°53’S, 129°03’E, 30 April 1996, G.R. Brown; NTM
(1977) (Icf), Keep River National Park, Gurrandaing,
15°53'S, 129°03’E, 29 April 1996, G.R. Brown.

Other material. NTM (Icf), Keep River National
Park, Gurrandaing, 15°53’S, 129°03’E, 29 April 1996,
G.R. Brown.

Description of male. Body length 5-7 mm; fore wing
4-6 mm; hind wing 3-4 mm. Clypeus with apical margin
width to maximum width 1:4.8. Anterior truncation of

pronotum with ventral transverse carina broadly
discontinuous medially. Fore and hind trochanters with
ventral preapical spine. Genitalia as in Figure 15: apex
of each basiparamere acute dorsoapically; parameres
narrow and narrowly subtriangular; cuspis (Fig. 11)
lamellate apically. ventral surface oblique. Otherwise as
N. piirdiei.

Colour. Similar to Nitidothynnus purdiei except that
at most S2 has a pair of pale spots, the apex of S1 is
reddish orange, and the basal three tarsomeres are
yellowish ventrally and brown dorsally with the apical
two tarsomeres uniformly dark brown.

Description of female. Body length 4 mm. Head
(Fig. 20) rounded, slightly wider than long, sparsely
punctate with semicircular closely punctate area on
vertex, posterolateral angles strongly emarginate. T2
with 5 transverse carinae, apical 3 strongest, basal 2 may
be obscured by T1. T3-5 with impressed curved preapical
line preceded by a curved line of punctures. Pygidium
(T 6 ) with lateral margins parallel (Fig. 23).

Colour, Orangish-brown; coxae, trochanters, femora
and mesosoma (except prothorax) slightly darker; tibiae
and tarsi slightly paler.

Distribution. Top End of Northern Territory between
Darwin and Kakadu National Park.

Remarks. This species is distinguished from all other
species of Nitidothynnus by the presence of a preapical
spine (most reliably viewed on the posterior surface) on
the ventral margin of the fore and hind trochanters of
the male. The female is distinguished by the structure of
the head which has the posterolateral angles emarginate
(Fig. 20) and T 6 which is subparallel dorsally (Fig. 23).
The only other known female in the genus, N. purdiei,
has the posterolateral angles of the head rounded (Fig.
21) and T 6 broadened ventroapically (Fig. 22).

Etymology. The species name is derived from the
Latin word for a spine, and refers to the preapical spine
on the fore and hind trochanters.

Procerothynnus gen. nov.

Type species. Here designated Procerothynnus
centralianus sp. nov.

Generic diagnosis. Male. Head, mesosoma and
metasoma polished. Clypeus closely and finely punctate,
sagittally carinate, narrowly produced, convex medially,
convexity extending medially almost to apical margin
of clypeus. Antennal prominence V-shaped, sagittally
sulcate, not carinate, not strongly raised, at level of
clypeus. Antenna very short, not reaching back to
propodeum, flagellar segments only slightly longer than
wide, apical six segments slightly arcuate. Maxillary palp
segments 2-6 subequal, segments 4 and 6 slightly longer.
Pronotum with lateral margins curved and convergent
anteriorly, anterior margin sharply raised and subcarinate.
Metasoma fusiform, segments 3-4 widest, segments
wider than high. T2 depressed anteriorly, T3 at most

118

New thynnine wasp genera

slightly depressed anteriorly. T7 convex becoming sligh¬
tly produced and membranous apically, not carinate. SI
broadly medially raised. S8 rounded apically, without
spines. Genitalia laterally compressed; basal ring short
and predominantly membranous with narrow, sclerotized
ring basally; basiparameres fusiform (viewed dorsally)
with apical margin sinusoidal, strongly rounded (viewed
laterally); paramere subtriangular to subquadrate;
aedeagus long and narrow.

Remarks. Procerothynnus is distinguished from
other genera of the generic cluster (and all other Aus¬
tralian Thynninae) by the combination of a medially
convex clypeus that is sagittally carinate; very short
antennae which do not reach back to the propodeum; S8
apically rounded and without spines; and the genitalia
laterally compressed. A convex clypeus with a sagittal
Carina and S8 that is not apically spinose suggest a
relationship with Zelehoria, Psammothynnus and
Chilothynmis. However, the former two have the clypeus
strongly convex and broadly produced and apically
truncate. Psammothynnus also has S8 apically e-
marginate. Chilothynmis is the closest genus, but differs
by having lateral spines on S8 (Brown 1997a), and
together with all other Thynninae lack very short
antennae and laterally compressed genitalia as found in
Procerothynnus.

The three species placed in this genus are similar in
appearance and are most reliably identified from the male
genitalia. However, head colour appears reliable in
distinguishing P. arnhemicus sp. nov. from other species
of Procerothynnus. All are known from relatively few
specimens from relatively few locations; P. centralianus
sp. nov. from four locations in the East MacDonnell
Ranges in central Australia; P. arnhemicus sp. nov. from
near Oenpelli in western Arnhemland and P. carpen-
tarianiis sp. nov. from Musselbrook Reserve near the
Northern Territory border in north-western Queensland.
Like Nitidothynnus, nothing is know about the biology
of Procerothynnus. All specimens were collected from
habitats with loamy or sandy soil and near water courses
(although all except the stream at Oenpelli, but including
the stream at Musselbrook Reserve, were dry at the time
at which specimens were collected).

Etymology. The generic name is masculine and is
derived from the Latin word procerus which means tall
and slender, and is a reference to the shape of the male
genitalia which are relatively high (in profile) and slender
(viewed dorsally).

Key to males of Procerothynnus. (Females are
unknown.)

1. a Yellow marks above each antennal insertion at
least partially confluent medially; mesoscutum above
fore wing with at most a small yellow spot; genitalia
with parameres broad and apex of basiparameres

weakly sinusoidal (Figs 27, 29).

. P. arnhemicus sp. nov.

1

b Antennal prominence with separate and discrete
spot above each antennal insertion; mesoscutum with
a longitudinal mark above fore wing; genitalia with
parameres subtriangular and apex of basiparameres

emarginate (Figs 25-7, 28).2

2. a Punctures on propodeum relatively deep, discrete
and distinct; genitalia as in Figure 25; apical margin
of basiparameres weakly sinusoidal, slightly

produced medially and apicolaterally.

. P. centralianus sp. nov.

b Punctures on propodeum shallow, often not
discrete; genitalia as in Figures 26; apical margin of
basiparameres (Fig. 28) strongly emarginate,
produced medially and strongly produced apico¬
laterally . P. carpentarianus sp. nov.

Procerothynnus centralianus sp. nov.

(Figs 25, 30)

Type material. HOLOTYPE cf - NTM (1979): near
Ghost Gum, 23°32’S, 134°23’E, Trephina Gorge Nature
Park, Northern Territory, 26 February 1997, G.R. Brown.
PARATYPES - Northern Territory. NTM (1980) (Icf),
Ross River Highway 23°38’S, 134°18’E, 6.2 km W of
Trephina Gorge Nature Park, 1 March 1997, G.R.
Brown; NTM (1981) (IcT), road to Ruby Gap Nature
Park, 23°29’S, 134°54’E, 2 March 1997, G.R. Brown;
NTM (1982) (Icf), Corroboree Rock Conservation
Reserve, 23MrS, 134°13’E, 1 March 1997, G.R.
Brown.

Description of male. Body length 6.5-7 mm; fore
wing 5-6 mm; hind wing 4-5 mm. Frons shallowly
punctate to shallowly closely punctate, punctures
becoming aligned longitudinally on antennal pro¬
minence. Clypeus with apical margin width to maximum
width 1:4.2. POL:OOL 1:0.9. Vertex and gena shallowly
rugosely punctate. Pronotum closely punctate. Me¬
soscutum punctate to sparsely punctate, closely punctate
near anterior margin. Mesoscutellum and metanotum
sparsely punctate. Propodeum closely to rugosely
punctate, punctures discrete. Mesopleuron closely to
rugosely punctate becoming, punctate ventrally. Fore
coxae with ventral surface almost flat, subparallel
basally, subtriangular apically. T1 width to length 1:1.0.
Tergites almost impunctate, punctures shallow, transverse
and slit-like on most segments, deeper and rounder on
T6-7. T3 not depressed anteriorly. Sternites almost
impunctate but with punctures aligned in transverse
straight or curved lines, S8 closely punctate. Genitalia
as in Figure 25; apical margin of basiparameres weakly
sinusoidal, slightly produced medially and apicolaterally.

Colour. Black; yellow colouration as follows: clypeus
(except medial anchor-shaped mark), mandibles (except
apex), large spot above each antennal insertion, inner
orbits continuous across vertex, outer orbits, margins of
pronotum broadly confluent medially (except small
central spot), tegulae, mesoscutum with curved mark
19

G.R, Brown

Figs 24-30. Procerothynnus spp., males; 24, P. arnhemicus sp. nov., habitus; 25, P. centralianus sp. nov., genitalia, lateral and dorsal; 26, P
carpentarkmus sp. nov., genitalia, lateral; 27, P. arnhemicus sp. nov., genitalia, lateral; 28, P. carpentarianus sp. nov., apical margin of
basiparameres; 29, P. arnhemicus sp. nov., apical margin of basiparameres; 30, P. centralianus sp. nov., S8. Scale lines = 0.25 mm.

120

New thynnine wasp genera

above fore wing and large medial subrectangular mark,
mesoscutellum with large medial mark and smaller
anterolateral spot, metanotum with disc, posterior margin
narrowly and mark on anterior margin, metapleuron with
large medial spot, broad sinusoidal transverse band on
propodeum, three dorsal spots on mesopleuron, anterior
spot largest, posterior spot near mid coxa smallest, coxae
(except basally), apices of femora extending along
ventral margin to base and along dorsal margin apically
especially on fore leg, line on outer surface of tibiae,
margins of mesosternal lamellae, lateral spot on Tl-6
and S2-5 (smaller or inconspicuous on sternites)
extending medially as a curved line near posterior margin
of sclerites, posteromedial spot on SI; orange colouration
as follows: apex of mandibles, lateral parts of anchor¬
shaped mark on clypeus, legs (except coxae and yellow
marks); much of T1 apically, T2-3 and S2-3, reddish
orange. Wing membranes hyaline, veins pale orange to
brown.

Distribution. Eastern MacDonnell Ranges, Northern
Territory.

Remarks. This species is distinguished from other
species of Procerothynniis by the presence of relatively
shallow punctures on the frons, a weakly developed
clypeal carina, and the genitalia (Fig. 25) which have
the apical margin of basiparameres weakly sinusoidal
and slightly produced medially and apicolaterally.

Yellow colouration may be reduced such that marks
and spots are smaller on some sclerites. In particular this
colouration may be limited on the clypeus to the apical
margin laterally, on the pronotum to the margins only,
on the propodeum as lateral spots, on the tergites and
sternites as a curved lateral line without a large lateral
spot, and reduced on the legs especially the femora. The
reddish orange colouration on the metasoma may be
replaced with black as may some of the orange
colouration on the legs. The Ruby Gap specimen is much
darker than the other specimens but there is no noticeable
difference in the genitalia.

Etymology. This specific name refers to the central
Australian distribution of this species. It is intended to
be construed as adjectival.

Procerothynniis arnhemiciis sp. nov.

(Figs 24. 27. 29)

Type material. HOLOTYPE cT - NTM (1983):
campsite near Oenpelli Reservoir, 12°23’S, 133°05’E,
Oenpelli, Northern Territory, 27 November 1997, G.R.
Brown and J.E. Purdie. PARATYPES - Northern
Territory. ANIC , NTM (1984) {2cf), data as holotype;
BMNH (E2000-27), NTM (1985-1986), WAM (26557)
(3d'), Leaning Tree Lagoon, I2°43’S, I31''25’E, II
December 1997, G.R. Brown and J.E. Purdie.

Other material. NTM (Icf), Leaning Tree Lagoon,
12°43’S, 131 °25’E, 11 December 1997, G.R. Brown and
J.E. Purdie.

Description of male. Body length 6 mm; fore wing
4.5 mm; hind wing 3.5 mm. Frons closely to rugosely
punctate. Clypeus with apical margin width to maximum
width 1:4.3. POL:OOL 1:1.2. Vertex and gena shallowly
rugosely punctate, punctures more discrete on gena.
Pronotum closely punctate becoming impunctate
ventrally. Mesoscutum punctate, punctures sparser
medially. Mesoscutellum and metanotum sparsely
punctate. Propodeum closely to rugosely punctate,
punctures discrete. Mesopleuron closely to rugosely
punctate becoming sparely punctate ventrally. Fore
coxae with ventral surface convex, subtriangular. T1
width to length 1:1.0. Tergites almost impunctate,
punctures shallow, transverse and slit-like on most
segments, deeper and rounder on T7 although punctures
sparser medially. T3 at most slightly depressed
anteriorly. Sternites almost impunctate, closely punctate
on S8. Genitalia as in Figure 27; apical margin of
basiparameres (Fig. 29) weakly sinusoidal, not produced
apically.

Colour. As in P. centralianus except spots above
antennal insertions partially confluent medially, mark
above fore wing reduced to a small inconspicuous spot
or absent, middle spot on mesopleuron small and
posterior post absent, marks on most metasomal
segments strongly curved, and metasoma without reddish
orange colouration. Wing veins generally paler except
subcosta.

Distribution. Known only from the vicinity of
Kakadu National Park, Northern Territory.

Remark.s. This species is readily distinguished from
other species of Procerothynniis by having separate
yellow spots above each antennal insertion, at most a
small yellow .spot on the mesoscutum immediately above
the base of the fore wing, and the structure of the
genitalia (Fig. 27), which have the apical margin of
basiparameres (Fig. 29) weakly sinusoidal and not
produced apically.

Etymology. This specific name is derived from the
type locality. It is intended to be construed as adjectival.

Procerothynniis carpentarianiis sp. nov.

(Figs 26, 28)

Type material. HOLOTYPE cT - UQIC; Murrays
Spring, I8°35’15”S, I38°04’28”E, 7km W of Mussel-
brook Resource Center, Lawn Hill National Park,
Queensland, 200 m, 10 May 1995, G. Daniels, M.A.
Schneider. PARATYPES - Queensland’. UQIC (Icf),
data as holotype dated 4 May 1995.

Description of male. Body length 6 mm; fore wing
4.5 mm; hind wing 3.5 mm. Frons shallowly rugosely
punctate. Clypeus with apical margin width to maximum
width 1:4.0. POL:OOL 1:1.2. Vertex and gena shallowly
punctate. Pronotum punctate becoming longitudinally
rugulose ventrally. Mesoscutum punctate.
Mesoscutellum and metanotum sparsely punctate.

121

G.R. Brown

Propodeum closely to rugosely punctate, punctures
shallow and not always discrete. Mesopleuron punctate.
Fore coxae with ventral surface almost flat, subtriangular.
T1 width to length 1:1.5. Tergites almost impunctate,
punctures shallow, transverse and slit-like on most
segments, deeper and rounder on T6-7 although
punctures sparser medially. T3 not depressed anteriorly.
Sternites almost impunctate, SI and S8 closely punctate.
Genitalia as in Figure 26; apical margin of basiparameres
(Fig. 28) strongly emarginate, produced medially and
strongly produced apicolaterally.

Colour. As in P. centralUinus except middle spot on
mesopleuron small and posterior spot absent, yellow
marks on sternites mostly absent, and metasomal
segment 3 is darker with less reddish orange. Wing veins
generally paler except subcosta.

Distribution. Known only from two specimens from
Musselbrook Reserve north-western Queensland on the
border of the Northern Territory.

Remarks. This species is easily distinguished from
the other two species of the genus by shallower and less
discrete punctures on propodeum, and the structure of
the genitalia (Fig. 26), which have the apical margin of
basiparameres strongly emarginate and produced
medially and strongly produced apicolaterally (Fig. 28).

Etymology. This specific name is derived from The
Gulf of Carpentaria which is the broader Australian
region from which the types were collected. It is intended
to be construed as adjectival.

ACKNOWLEDGMENTS

I thank Steven Gregg and John Purdie for their
interest in entomology in general and tiphiids in
particular, the curators of the above li.sted institutions
for the loan of material in their care, and the anonymous
referees for comments on an earlier version of this paper.
I also thank Dr Richard C. Willan for his comments and
eye for detail.

REFERENCES

Brown, G.R. 1983. Pentazelehoria, a new genu.s of Australian
Thynnini (Hymenoptera: Tiphiidae). Journal of the
Australian Entomological Society 22: 61-64.

Brown, G.R. 1987. Revision of the Australian genus Acantho-
thynnus Turner (Hymenoptera: Tiphiidae). Journal of the
Australian Entomological Society 26: 181-88.

Brown, G.R. 1989a. Revision of the Australian genus Dora-
tithynnus Turner (Hymenoptera: Tiphiidae). Journal of the
Australian Entomological Society 28: 1-17.

Brown, G.R. 1989b. The Australian genus Encopothynnus Turner
(Hymenoptera: Tiphiidae). Journal of the Australian
Entomological Society 28: 255-266.

Brown, G.R. 1992. Bifidothynnus wubiniensis, a new genus and
species of Australian Thynnini (Hymenoptera: Tiphiidae:
Thynninae), Journal of the Australian Entomological
Society 31: 215-217.

Brown, G.R. 1993. A new species of Lestricothynnus with notes
on miscoupling in Thynninae (Hymenoptea: Tiphiidae).
Journal of the Australian Entomological Society 32: 197-
199.

Brown, G.R. 1995a. Revision of the Australian wasp genus
Macrothynnus Turner (Hymenoptera: Tiphiidae: Thy¬
nninae). Records of the Western Australian Museum 17:
267-275.

Brown, G.R. 1995b. Tachyphron, a new genus of Australian
Thynninae (Hymenoptera: Tiphiidae). Journal of the
Australian Entomological Society 34: 241-246.

Brown, G.R. 1997a. Chilothynnus, a new genus of Australian
Thynninae (Hymenoptera: Tiphiidae) associated with
orchids. The Beagle. Records of the Museums and Art
Galleries of the Northern Territory 13: 61-71.

Brown, G.R. 1997b. Arihrothynnus, a new genus of orchid-
pollinating Thynninae (Hymenoptera: Tiphiidae). The
Beagle, Records of the Museums and Art Galleries of the
Northern Territory 13: 73-82.

Brown. G.R. 1998a. Revision of the Neozelehoria cryptoides
.species group of thynnine wa.sps (Hymenoptera: Tiphiidae):
pollinators of native orchids. Australian Journal of
Entomology yi\ 193-205.

Brown, G.R. 1998b. The generic status of Catocheilus Gudrin
and Hemithynnus Ashmead (Hymenoptera: Tiphiidae:
Thynnini). General and Applied Entomology 28: 89-92.

Burrell, R.W. 1935. Notes on the habits of certain Australian
Thynnidae. Journal of the New York Entomological Society
43: 19-28.

Given, B.B. 1954. A catalogue of the Thynninae (Tiphiidae,
Hymenoptera) of Australia and adjacent areas. New
Zealand Department of Scientific and Industrial Research
Bulletin 109: 1-89.

Naumann, l.D. 1991. Hymenoptera (Wasps, bees, ants, sawflies).
Pp. 916-1000. In Naumann, l.D. (ed). The insects of
Australia. A textbook for students and research workers.
Melbourne University Press: Carlton.

Salter, K.E.W. 1954. Studies on Australian Thynnidae. I. A check
list of the Australian and Austro-Malayan Thynnidae.
Proceedings of the Linnean Society of New South Wales
78(5-6): 276-315.

Snodgrass, R.E. 1941. The male genitalia of Hymenoptera.
Smithsonian Miscellaneous Collections 99: 1-86.

Tillyard, R.J. 1926. Insects of Australia and New Zealand. Angus
and Robertson: Sydney.

Turner, R.E. 1910. Hymenoptera Earn. Thynnidae. Genera
Insectorum 105: 1-62.

Accepted 8 August 2000

122

The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 2000 16: 123-126

A new bythitid genus and species, Acarobythites larsonae, from shallow rocky reefs
off northern Australia (Pisces, Ophidiiformes, Bythitidae)

YOSHIHIKO MACHIDA

Department of Natural Environmental Science, Faculty of Science, Kochi University
2-5-1 Akebono-cho, Kochi 780-8520, JAPAN
machida@cc.kochi-u.ac.jp

ABSTRACT

A new genus and species of the subfamily Bythitinae (Bythitidae), Acarobythites larsonae, is described from two
specimens, 25.2 mm and 18.6 mm standard length, collected from pools on rocky reefs in the Northern Territory,
Australia. This genus resembles Microhrotula Gosline, 1953 in the counts of pectoral and pelvic fin rays, branchiostegal
rays and developed rakers on the anterior arch, and in having a normal pectoral peduncle, lower angle of preopercle
without spines, sharp-pointed jaw teeth and vomerine and palatine teeth. However, it is clearly distinguishable from the
latter in the following characters: head and body scalcless, relatively small eyes (diameter 17.8-18.0 times in head
length), snout compressed, posterior end of maxillary rounded and lacking a ventrally-directed process near its postero-
ventral corner, opercular spine flat and weak, 11-12 caudal fin rays and 42-43 total vertebrae.

Keywords: Ophidiiformes, Bythitidae, Australia, new genus, Acarobythites.

INTRODUCTION

Cohen and Nielsen (1978) included 15 genera in the
subfamily Bythitinae of the viviparous fish family
Bythitidae. This subfamily is characterised by having
dorsal and anal fins continuous with the caudal fin, and
is separable from the free-tailed Brosmophycinae, the
other member of the family (Cohen and Nielsen 1978).
Since Cohen and Nielsen (1978), only Hastatohythites
Machida, 1977 has been added to the Bythitinae (Cohen
and Nielsen 1999).

Recently, two small hythitid specimens were sent to
the author for examination by Dr Helen K. Larson of
the Museum and Art Gallery of the Northern Territory
(NTM), Darwin, Australia. These specimens had dorsal
and anal fins continuous with the caudal fin. Although
they resembled the small-sized bythitine genus
Microhrotula Gosline, 1953, known from Hawaii
(Gosline 1953) and from Samoa and Vanuatu (Cohen
and Wourms 1976), they were easily distinguishable
from Microhrotula by the absence of scales on the head
and body. The specimens are here described as a new
genus and species.

Measurements and enumeration follow Machida
(1993). Standard length and head length are expressed
as SL and HL, respectively.

SYSTEMATICS

Family Bythitidae Gill, 1861
Subfamily Bythitinae Gill, 1861
Acarobythites new genus

'Fype species. Acarobythites larsonae new species,
by monotypy.

Diagnosis. A genus of the subfamily Bythitinae
(Cohen and Nielsen 1978: 42) with: head and body
scaleless; anal fin origin at about mid-body; eye diameter
17.8-18.0 times in HL, snout compressed; posterior end
of maxillary rounded, not sheathed by dermal cheek fold,
without ventrally-directed process near postero-ventral
corner; opercular spine flat and weak; no pore-bearing
skin flap on upper angle of opercle; lower angle of
preopercle smooth; pectoral peduncle normal, broader
than long; no spine on cleithrum; all teeth sharp-pointed,
some needle-like; teeth present in jaws and on vomer
and palatines; developed gill rakers on anterior arch 3;
pectoral fin rays 13-14; pelvic fin ray 1; caudal fin rays
11-12; branchiostegal rays 7; 12-13 precaudal vertebrae,
with sharp-pointed neural spines; and 42-43 total
vertebrae.

Description. See species description below.

Remarks. According to Cohen and Nielsen (1972,
1978), Cohen (1987), and Machida (1997), the following
genera in the subfamily Bythitinae are known to have

Y. Machida

Table 1. Comparison between Acarobythites gen. nov. and Microbrotula Gosline, 1953. * = orbit diameter.

Genus

(Source)

Acarobythites gen. nov.

(this work)

Microbrotula Gosline, 1953
(Gosline 1953; Cohen and Wourms 1976;
Cohen and Nielsen 1978)

Head squamation

scales absent

partly naked

Body squamation

scales absent

complete

Anal fin origin

at about mid-body

at about mid-body

Eye diameter

17.8-18.0 in HL

(6.4-15.4 in HL)*

Snout

compressed

depressed

Posterior end of maxillary

rounded, not sheathed, without ventrally-
directed process

expanded, not sheathed, with ventrally-
directed process

Pectoral peduncle

broader than long

broader than long

Opercular spine

flat and weak

sharp and needle-like

Lower angle of preopercle

smooth

smooth

Teeth

sharp-pointed

not all tiny and granular

Palatine teeth

present

present

Vomerine teeth

present

present

Developed rakers on anterior arch

3

3-4

Pectoral fin rays

13-14

10-14

Pelvic fin ray

1

1

Caudal fin rays

11-12

4-6

Branchiostegal rays

7

7

Precaudal vertebrae

12-13

11-13

Total vertebrae

42-43

51-56

seven branchiostegal rays; Bythites (7-8 rays),
Calamopteryx, Microbrotula, Saccogaster (7-9 rays),
Stygnobrotulo and Thalassobathia. Although Cohen and
Nielsen (1978) did not report the number of
branchiostegal rays for Bellotia, this genus apparently
differs from Acarobythites only in lacking pelvic fins.
Among these genera having seven branchiostegal rays,
two of them, Calamopteryx and Saccogaster, are well
characterized by having an elongated pectoral peduncle
(Cohen and Nielsen 1978). Stygnobrotula lacks palatine
teeth, and Thalassobathia has two rays in each pelvic
fin (Cohen and Nielsen 1978). Bythites has a scaleless
head, completely scaled body, 24-30 pectoral fin rays,
0-1 developed gill rakers on the anterior arch, and the
anal fin origin is positioned well behind the mid-body
(Nielsen and Cohen 1973; Cohen and Nielsen 1978).
Cohen and Wourms (1976) gave a revised diagnosis for

Microbrotula, when they described a new species,
M. randalli. They regarded small eyes, less than six times
in head length, as one of the diagnostic characteristics
of Microbrotula (Cohen and Wourms 1976). Orbit dia¬
meter ranges from 6.4 to 8.4 times and from 11.0 to 15.4
times in head length in M. randalli and in M. rubra,
respectively (Cohen and Wourms 1976). Table 1 com¬
pares Acarobythites and Microbrotula. Acarobythites
appears to be distinguishable from the latter by its naked
head and body, small eye, compressed snout, posterior
end of maxillary rounded, no ventrally-directed process
at the postero-ventral corner of maxillary, opercular spine
flat and weak, and 11-12 caudal fin rays.

Etymology. The generic name is derived from the
Latin, acaro (small), in reference to its small body,
combined with Bythites (gender: masculine), one of the
known genera in the family Bythitidae.

Fig. 1. Acarobythites larsonae sp. nov., NTM S. 14665-026, holotype, 25.2 mm SL, from Australia. Scale bar indicates 5 mm.

124

New bythitid fish from Australia

b

Fig. 2. Lateral (a) and ventral (b) views of anterior part of head of NTM S. 14665-026, holotype of Acarobythiles larsonae sp. nov. Scale bar
indicates 1 mm.

Acarobythites larsonae new species
(Figs 1-4)

Type material. HOLOTYPE - NTM S. 14665-026,
25.2 mm SL, sex unknown, northwestern side of Field
Island (12°04.20’S, 132°l9.3rE), Northern Territory,
Australia, rock pools on reef, depth 0.3 m, substrate sand,
mud, oyster covered rocks, coll. R. Williams and party,
5 June 1998. PARATYPE - NTM S. 10015-049, 18.6 mm
SL, sex unknown, on silty sand with isolated coral
clumps and rubble piles, off reef Hat on E side of Coral
Bay, Cobourg Peninsula, Northern Territory, depth 3-4
m, coll. H. K. Larson, 17 Oct. 1981.

Diagnosis. See generic diagnosis.

Description. Data on the holotype given first, data
on the paratype in parentheses when differing from
holotype.

Counts: dorsal fin rays 79 (73), anal fin rays 57 (53),
caudal fin rays 12(11), pectoral fin rays 14 (13), pel vie
fin ray 1, branchiostegal rays 7, developed gill rakers
on anterior arch 3, pseudobranchial filaments 0,
precaudal vertebrae 13(12), caudal vertebrae including
urostyle 29 (32). Measurements in % SL: HL 21.4 (24.2),
predorsal length 26.6 (29.3), preanal length 49.3 (46.2),
body depth at dorsal fin origin 13.5 (15.9), body depth
at vent 11.5 (13.7), head width 5.9 (8.6), pectoral fin
length 8.7 (11.3), pelvic fin length 11.9 (13.7).
Measurements in % HL: eye diameter 5.6 (5.6), snout
length 22.2 (21.1), maxillary length 48.1 (48.9), fleshy
interorbital width 18.5 (22.2).

Head and body compressed, tail not tapered
posteriorly (Fig. 1). Head small, slightly less than 1/2
preanal length. Snout round from lateral view, slightly
projecting beyond upper jaw (Fig. 2a). Eye small, about

1/4 snout length. Anterior nostril tubular, just above
upper lip. Posterior nostril small, rounded, slightly before
anterior margin of eye, at mid-eye level. Mouth large,
nearly horizontal. Maxillary extending backward far
behind posterior margin of eye, its posterior end rounded,
not sheathed by dermal cheek fold, without ventrally-
directed process near its postero-ventral corner. Lower
jaw included in upper jaw. Opercular spine flat and weak,
completely covered by skin. Posterior and lower margins
of preopercle smooth, completely covered by skin. Gill
opening wide; gill membranes united slightly behind
posterior margin of eye, free from isthmus. Pore-bearing
skin tlap absent from just above upper angle of gill
opening. A single pore with short tube in front of upper
angle of gill opening. Infraorbital pores four; three large,
slit-like pores between slightly behind anterior nostril
and just below posterior nostril, a single, small pore
above posterior end of maxillary. Supraorbital pore
single, large, on underside of snout tip before anterior
nostril (Fig. 2b). Two mandibular pores on each side;
left and right anterior pores separated, left and right
posterior pores united on ventral mid-line of head. A
single, .small pore near lower angle of preopercle.

All teeth sharp-pointed (Fig. 3). Upper jaw teeth
uniserial, becoming longer anteriorly, needle-like. Lower
jaw teeth biserial, inner teeth larger. About six teeth on
vomer, uniserial, well separated, nearly equal to inner
teeth on lower jaw. Palatine teeth about five, uniserial,
slightly shorter than vomerine teeth. Tongue short, its
tip bluntly pointed, free from mouth floor.

Developed rakers on anterior arch three, short, about
equal in length to eye diameter. Pseudobranchial
filaments absent.

125

Y. Machida

V V

V y

K V

Fig. 3. Upper and lower dentition of NTM S. 14665-026, holotype
of Acarobythites larsonae sp. nov. Scale bar indicates 0.5 mm.

Dorsal fin originating above mid-length of pectoral
fin. Origin of anal fin at about mid-body. Pectoral fin
short, no separated or free rays. Pectoral peduncle
normal, broader than long. No spine on posterior margin
of cleithrum. Pelvic fins not reaching to below tip of
pectoral fin, closely adjacent at their bases, inserted
slightly behind posterior margin of preopercle.

Head and body covered with mucous coating,
completely devoid of scales. Tiny papillae sparsely
present on anterior half of head. Lateral line indistinct.

Tips of neural spines of precaudal vertebrae pointed;
first neural spine short, 2nd spine longest, erect, 5th to
11th spines short, well depressed (Fig. 4).

In alcohol, head and body uniformly creamy-yellow,
slightly darker on dorsum of head and body, paler on
belly. All fins and buccal cavity pale.

Distribution. Known only from the type locality
(Field Island) and Cobourg Peninsula, western Arnhem
Land, Northern Territory, Australia.

Etymology. Named larsonae after Dr. Helen K.
Larson (NTM), who kindly sent me valuable bythitid
and ophidiid specimens for study.

ACKNOWLEDGMENTS

I thank the staff of the Ichthyology Department,

Museum and Art Gallery of the Northern Territory,

Darwin, Australia, for the loan of the specimens

described in this paper.

REFERENCES

Cohen, D.M. 1987. Notes on the bythitid fish genus Saccogaster
with a new species from the Gulf of Mexico. Natural
History Museum of Los Angeles County, Contributions in
Science 385: 1-4.

Cohen, D. M. and Nielsen, J.G. 1972. A review of the viviparous
ophidioid fishes of the genus Saccogaster. Proceedings of
the Biological Society of Washington 85: 445-468.

Cohen, D.M. and Nielsen, J.G. 1978. Guide to the identification
of genera of the fish order Ophidiiformes with a tentative
classification of the order. NOAA Technical Report, NMFS
Circular AM: 1-72.

Cohen, D.M. and Wourms, J.P. 1976. Microbrotula randalli, a
new viviparous ophidioid fish from Samoa and New
Hebrides, whose embryos bear trophotaeniae. Proceedings
of the Biological Society of Washington 89(5): 81-98.

Gill, T. N. 1861. Catalogue of the fishes of the eastern coast of
North America, from Greenland to Georgia. Proceedings
of the Academy of Natural Sciences of Philadelphia 13
(Supplement): 1-63.

Gosline, W.A. 1953. Hawaiian shallow-water fishes of the family
Brotulidae, with the de.scription of a new genus and notes
on brotulid anatomy. Copeia 1953(4): 215-225.

Machida, Y. 1993. Two new genera and species of the subfamily
Brosmophycinae (Bythitidae, Ophidiiformes) from
northern Australia. Japanese Journal of Ichthyology 39(4):
281-286.

Machida, Y. 1997. Hastatobythites arafurensis, a new bythitid
genus and species from Australia (Bythitidae,
Ophidiiformes). Ichthyological Research 44(4): 385-388.

Nielsen, J. G. and Cohen, D.M. 1973. A review of the viviparous
ophidioid fishes of the genera Bythites Reinhardt and
Abythites new (Pisces, Ophidioidei). Steenstriipia,
Zoological Museum, University of Copenhagen 3: 71-88.

Nielsen, J. G. and Cohen, D. M. 1999. Family Bythitidae. In:
Nielsen, J. G., Cohen, D. M., Markle, D. F. and Robins, C.
R. (eds) Ophidiiform fishes of the world (Order
Ophidiiformes}: an annotated and illustrated catalogue of
pearlfishes, cusk-eels, brotulas and other ophidiiform fishes
known to date. Pp. 94-135. FAO Fisheries Synopsis
125(18).

Accepted 1 November 2000

Fig. 4. Positive image of X-ray photograph of NTM S. 14665-026, holotype of Acarobythites larsonae sp. nov.

126

The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 2000 16: 127-144

Six new species of fork-tailed catfishes (Pisces, Teleostei, Ariidae)
from Australia and New Guinea

PATRICIA J. KAILOLA

19 Walkers Avenue, Newnham, TAS 7248, AUSTRALIA
pkailola @ CompuServe, com

ABSTRACT

Six new species of Arius (Teleostei: Ariidae) are described from estuarine waters of southern New Guinea and northern
Australia. Arius dioctes sp. nov. is pre,sent in both regions and is distinguished by its large maximum size, small eyes,
fixed (non-depressible) jaw teeth, broad mouth, and yellow lower body. Arius insidiator sp. nov. has a much depressed
body, long, angular ribs, small eyes covered by skin and fixed jaw teeth. It too has a yellow lower body. Arius pectoralis
sp. nov. is a slender catfish with strong, numerous serrae along the hind margin of the pectoral spines and dark margins
on the dorsal, pectoral and the caudal fins. Arius hainesi sp. nov. has fleshy lips, small mouth, partly restricted gill
openings, short barbels, ridges in the skin on the back below the dorsal fin, and often a dark mouth and branchial
chamber. The barbels of Arius hardenhergi sp. nov. are thick proximally. This species also has a fleshy snout, an
extensive head shield with broad supraoccipital process and a long-based adipose fin. Ariuspaucus sp. nov. is a freshwater
species very similar to Arius rnidgleyi Kailola and Pierce and inhabits the river systems draining into the Gulf of
Carpentaria.

Keywords: Ariidae; fork-tailed catfishes; new species; Australia; New Guinea; tropical marine; tropical freshwater.

INTRODUCTION

The isolation of the Sahul Shelf has enabled the
evolution of many endemic species of fork-tailed
catfishes (Ariidae). These fish inhabit the rivers, estuaries
and coastal waters of tropical (northern) Australia and
New Guinea. Earlier workers (e.g. Roberts 1978; Haines
1979; Coates 1983, 1988; Allen and Coates 1990) have
remarked on the adaptive characteristics of these ariids.

The Ariidae occurs worldwide in tropical and warm-
temperate regions. It comprises at least 80 valid species
and numerous nominal genera and species, many
confined to particular geographic regions (west Africa,
east Africa to India, South-east Asia, Australia-New
Guinea, eastern Pacific, western Atlantic). The
phylogenetic relationships of the family are under study.

Thirty-five species of ariid catfishes inhabit
Australian and New Guinea waters and only five of these,
all marine catfishes (Arius thalassinus Riippell, 1837;
A. bilineatus Valenciennes, 1840a; A. argyropleuron
Valenciennes, 1840b, A. /ie//a (Valenciennes, 1840b) and
A. polystaphylodon Bleeker, 1846), occur elsewhere: in
South-east Asian, Indian and east African (A.
thalassinus) seas (Kailola 1990b). Of the remaining 30
taxa, five species (A. nox Herre, 1935; A. solidus Herre,
1935; A. coatesi Kailola, 1990a; A. utarus Kailola,
1990a; and A. velutinus (Weber, 1908)) are endemic to

northern New Guinea fresh waters, and 12 species are
endemic to southern New Guinea fresh and saline waters
(Kailola 1990b). Eleven more species are common to
both northern Australia and southern New Guinea. Only
two species - Arius rnidgleyi Kailola and Pierce and a
new species - are endemic to Australia.

The Ariidae are under-represented in collections.
Most species attain moderately large size and it is
sometimes not easy for field workers to keep intact
material. Moreover, surveys have only been conducted
since the mid-1970s in some of the areas which now
reveal new species. The haphazard nature of ariid
collecting in often difficult environments has created the
paradox, however, that two of the endemic ariids from
New Guinea described in 1913 by Weber (Doiichthys
novaeguineae and Tetranesodon conorhynchus) are
represented today by less than ten specimens. Yet the
distribution of these taxa spans the most intensively
collected aquatic habitats of southern New Guinea.

I recognised nine Australo-Papuan ariid catfish taxa
as new several years ago and three of them were
described subsequently (Kailola and Pierce 1988; Kailola
1990a). Although I acknowledge the need of a
phylogenetic review and comprehensive key to the
species of this region, my objective here is to describe
six new species. The other information will be published
elsewhere.

127

P.J. Kailola

METHODS

Abbreviations (sucb as for bead length, standard
length, gill rakers) and definition of ariid features and
relevant osteology have been described in Kailola (1983).
Method of counting and measuring are defined in Kailola
(1983) and Kailola and Pierce (1988). The term ‘colour
of fresh material’ refers to freshly dead (just caught) or
chilled specimens except for A. insidiator, where ‘fresh
colour' refers to frozen specimens. The term ‘serrae’
refers to large, regularly-spaced serrations.

Institutional abbreviations follow Leviton et al.
(1985) and are: AMS (Australian Museum, Sydney);
CSIRO (Ian S.R. Munro Ichthyological Collection,
CSIRO, Hobart); KFRS (Kanudi Fisheries Research
Station collection. Port Moresby, Papua New Guinea);
NTM (Museum and Art Gallery of the Northern
Territory, Darwin); QM (Queensland Mu.seum and Art
Gallery, Brisbane); USNM (United States National
Museum, Smithsonian Institution, Washington); WAM
(Western Australian Museum, Perth); ZMA
(Zodlogische Museum, Universiteit van Amsterdam,
Amsterdam).

KFRS material of these new species identified ten
years ago generally is not included in the type series as
the present whereabouts and condition of the material is
unknown. However, an exception was made for two new
species because of the paucity of material.

SYSTEMATICS

Arius dioctes sp. nov.

(Figs 1-2; Tables 1-2)

Hexanematichthys sp - Kailola 1975: 41 (in part).

Hexanematichthys sp ‘Y’ - Kailola and Wilson 1978:
42.

Arius cf. stirlingi - Roberts 1978: 37, fig. 16a.

Arius sp. - Maunsell and Partners 1982: 181.- Allen
1991: 56, photo 14.

Arius (Hemiarius) species 1 - Kailola 1990b: 299.

Hemiarius sp.l - Blaber, Brewer and Salini 1994:
163, fig 3a.

Type material. HOLOTYPE - CSIRO C.3798, 430
mm SL, Norman River at Karumba (I7°29' S, 140‘’50'
E), Queensland, D. J. Turner, 1969. PARATYPES -
NTM S.l 1190-001, 2 (450-460 mm SL), Fog Bay
(12°54’S, 130°I4’E), Northern Territory, P. Mundy,
June 1983; AMS 1.15557-041,2 (103-172 mm SL), Gulf
of Carpentaria at 17‘’26’S, 140‘’40’E., l.S.R. Munro, 23
December 1963; AMS 1.29292-001, 159 mm SL, Gulf
of Papua (08°00' S, 145°00' E), S. Frusher, 11 July 1981;
CSIRO H.5154-01, 1050 mm SL, Papua (Irian Jaya) at
04°49’S, 137°00’E, K. Hortle and A. Haris, 7 December
1996; NTM S.l4828-005, 95.1 mm SL, Papua (Irian
Jaya) at 04°55'S, 137“15’E, K. Hortle and A. Haris, 28
May 1998; KFRS F.O4094, 200 mm SL, off Oreke River

mouth (08°42' S,146°29' E), Papua New Guinea, J.
Koaia, May 1973.

Additional material examined (non-type). KFRS
F.5627-01,350 mm SL, Tirere village, north side of Daru
Island (09‘’05' S, 143°12' E), Papua New Guinea, April
1988; KFRS F.5626-03, 330 mm SL, Sagero, north side
of Daru Island, Papua New Guinea, September 1988;
KFRS F.5729-03, 166 mm SL, Daru Island. Papua New
Guinea, 30 September 1983; KFRS F03992, 10 (84-89
mm SL), Pie River at Baimuru (07°33' S, 144‘’5r E),
Papua New Guinea, 28 September 1971 (juveniles from
mouth of an adult male. 104 cm SL); KFRS F04099,
328 mm SL, old Kukipi village, Lakekamu River mouth
(08°12' S, I46°10 E), Papua New Guinea, 18 October
1971; CSIRO H.4957-01,4 (86-94 mm SL), Papua (Irian
Jaya) at ()4°55’S, I37°03’E, K. Hortle and A. Haris, 28
May 1998; CSIRO H.4976-04, 325 mm SL. Papua (Irian
Jaya) at 04‘’53’S, 136°55’E, 6 September 1997.

Diagnosis. Teeth very strong, non-depressible; in
narrow bands in jaws and in four patches arranged across
front of palate. Snout prominent, jaw teeth exposed;
mouth wide. Head somewhat venulose, head shield
almost smooth. Eye small, free of head skin, 6-14 %
HL; few (10-11) first arch gill rakers; no rakers on
posterior face of first two arches; gill opening wide. Body
orange-yellow; lips, inside mouth and body usually
covered with orange or yellow mucus, and teeth
frequently reddish.

Description. D 1,7. P 1,11-12. A 17-21. GR (first
arch) 10-11 of which 3-4 on upper limb. GR (last arch)
9-11. Vertebrae 49-50 (42-43 free).

Body robust anteriorly, tapered, well compressed
posteriorly. Prcdorsal profile straight becoming convex
at nape. Snout prominent, well-rounded; inner lip margin
scalloped. Jaws strong; mouth wide, curved, subterminal
or inferior. When mouth closed, tooth band in upper jaw
almost completely exposed, outer rows of lower jaw teeth
also visible. Nostrils large, ovate, anterior one directly
before posterior one. Eye ovate, moderately small, border
completely free from head skin; eye dorsolateral, well
before mid-head length. Gill opening wide, membranes
broadly scalloped, meeting at sharp angle, leaving broad,
free margin.

All teeth sharp, strong, conical, not depressible.
Premaxillary tooth band with 4-6 irregular series of teeth;
mandibulary tooth band with 4-5 series of teeth, almost
continuous across symphysis. Four patches of teeth in
row across anterior of palate: two inner (vomerine)
patches separated by narrow gap at midline, half as wide
as outer, curved patches; 3-4 rows of teeth in each group.
Palate smooth anteriorly, longitudinally creased
posteriorly, with two long, low ridges ot epithelial tissue
before branchial chambers.

Head shield smooth anteriorly; several groups of
sharp granules laterally, distinct parallel striae adjacent
to distal third of dorsomedian head groove, striae

New catfish from Australia and New Guinea

Fig. 1. Arius dioctes sp. nov. lateral view, 200 mm SL paratype.

Fig. 2. Arius dioctes sp. nov. (all 200 mm SL paratype) A, dorsal head view; B, ventral head view; C, arrangement of upper tooth
patches; D, rubbing of head shield.

129

P.J. Kailola

Table 1. Principal meristics of six new species, n = number; x =
mean, SD = standard deviation; GR 1= rakers on first gill arch; GR
4 = rakers on last gill arch.

Species

variable

Anal

rays

Pectoral

rays

Total
GR 1

Total

GR4

A. dioctes

holotype

20

12

10

10

range, n = 9

17-21

11-12

10-11

9-11

X

18.7

11.6

10.3

10.0

SD

1.4

0.5

0.5

0.7

A. insidiator

holotype

20

10

12

12

range, n = 4

19-23

10

11-12

11-13

X

20.5

10.0

11.5

11.5

SD

1.7

0.0

0.6

0.8

A. pectoralis

holotype

18

8

15

15

range, n = 16

18-22

8-11

15-22

14-17

X

19.3

10.0

18.8

15.3

SD

1.2

0.9

1.8

1.1

A. hardenbergi holotype

18

10

14

13

range, n = 5

16-18

9-10

10-14

9-13

X

16.6

9.4

11.2

9.8

SD

0.9

0.5

1.6

1.8

A. hainesi

holotype

20

10

32

36

range, n = 14

20-23

8-11

32-37

31-37

X

21.7

9.6

34.3

33.5

SD

0.7

0.8

1.4

1.7

A. paucus

holotype

17

10

11

13

range, n = 16

16-18

9-10

10-11

11-14

X

17.3

9.9

10.7

12.8

SD

0.8

0.3

0.5

0.8

extending over supraoccipital process. Dorsomedian
groove narrow, lanceolate, flat, extending from between
nostrils to supraoccipital process base. Supraoccipital
process with sharp, distinct keel, straight to slightly
convex sides. Predorsal plate angular, striate. Numerous,
anastomising venules over anterior two-thirds and sides
of head, continuing onto shoulder. Rugose humeral
process anteroventrally well ossified, forming narrow
flange; acute, triangular shaft of process reaching one-
quarter to one-third along pectoral fin spine. Axillary
pore small and slit-like.

Barbels thin distally. Maxillary barbel attains end of
humeral process in juveniles, to well before opercular
margin in adults. Mandibulary barbel reaches opercular
margin in young, preopercular margin in adults. Mental
barbel extends short distance behind eye. Chin barbel
bases staggered.

Gill rakers rigid, pungent, half to two-thirds length
of opposing filaments. No rakers along posterior face
of first two gill arches, 9-11 along posterior face of third
arch. Low, muscular thickening posterodorsally on
smooth arches.

Fin spines thick, slightly curved, rounded, patterned
with fine rugae and granules. Anterior margin of spines
with distinct granules proximally, 6-10 antrorse, low

serrae distally; posterior margin with 8-30 serrae or
dentae. Short filament on spine tips. Longest dorsal ray
1.9-3.2 times longer than last ray. Pectoral fin low,
extending to below dorsal fin. Ventral fin narrow in
males, ending well before anal fin origin. Fin in females
broad, attains anal origin or beyond (inner rays thicken
and form pad of tissue in sexually mature individuals).
Adipose fin moderately high, oblong, originating
approximately opposite anal fin origin. Anal fin margin
almost truncate, longest ray 2.1-3.6 times last ray. Caudal
fin lobes broad-based, strongly tapered, upper lobe
slightly longer than lower.

Caudal peduncle shallow. Lateral line straight,
oblique below dorsal fin, strongly upturned at tail base.
Short lines and ascending rows of pores branch off from
lateral line, numerous and extensive anteriorly.

Colour of fresh material. Greenish or pale bluish grey
above; pale orange or yellow on sides and below, less
often cream or white. Bright yellowish orange mucus
over all of body; lips and inside of mouth also yellow.
Barbels and teeth reddish or yellow. Fins bluish grey,
green or yellowish, dusky towards margins. Snout and
head of some individuals blotched black.

Colour of preserved material. Pinkish brown or tan
above, cream or pale fawn below, top of head darker
brown. Fins brown or light tan, margin of dorsal fin and
caudal fin dark brown; upper aspect of pectoral fin,
ventral fin and mid-anai fin rays darker brown. Maxillary
barbel dark brown, others pale. Peritoneum grey.

Comparisons. Arius dioctes is similar to A. stormii
(Bleeker, 1858), a South-east Asian species growing to
over 50 cm long (Weber and de Beaufort 1913).
However, A. stormii possesses the following unique
features: dorsal spine subequal to head length (versus
equal to head length without snout in Arius dioctes)-,
caudal peduncle depth 2.6-2.8 in its length (versus 1.9-
2.3 in Arius dioctes)-, anterior nostrils lateral to posterior
ones (versus anterior to posterior nostrils in Arius
dioctes)-, total gill rakers on the first arch 17-18 (versus
10-11 in Arius dioctes)-, serrae on front margin of dorsal
spine directed upwards (versus directed downwards in
Arius dioctes); fin spines very broad (versus moderately
broad in Arius dioctes); adipose fin beginning before anal
origin (versus opposite or behind in Aius diocte.s).

The most phenotypically similar species to Arius
dioctes in Australia and New Guinea is /\. armiger De
Vis, 1884 (distinguished by its venulose head, small eye
and strong teeth). The taxa can easily be distinguished
however, on gill raker and anal fin meristics (A. armiger
has GR 16-22, first arch; A 22-25) and maxillary barbel
length (long maxillary barbel reaches at least to below
dorsal fin). Arius dioctes has similar colouration and
dentition to Arius insidiator sp. nov. However, the the
form of the body easily distinguishes these two taxa.

Distribution. New Guinea-, southern coast and rivers
from Kamora River to the Otokwa River, possibly also
130

New catfish from Australia and New Guinea

Table 2. Percent of head length (HL) and standard length (SL) for Arius dioctes sp. nov. and Arius insidiator sp. nov. n = sample size;
X = mean; SD = standard deviation.

Character

holotype

n

Arius dioctes

range

X

SD

holotype

n

Arius insidiator

range

X

SD

Percent of HL

head height

38.1

9

38.1

- 50.0

42.9

4.0

39.8

4

35.0

- 39.8

37.7

2.3

head width

66.3

9

61.3

- 71.3

66.3

2.9

64.1

4

61.9

- 64.9

64.4

2.0

eye diameter

6.8

9

5.7

- 13.2

8.8

2.5

6.0

4

5.6

- 6.8

6.0

0.5

mouth gape

47.3

9

44.7

- 52.3

47.4

2.5

44.3

4

42.8

- 45.8

44.0

1.2

intemostril distance

35.7

9

33.1

- 35.9

34.8

1.1

31.4

4

31.4

- 34.7

32.4

1.5

snout length

34.7

9

32.2

- 37.2

34.4

1.5

27.8

4

27.8

- 31.6

29.0

1.8

longest barbel length

54.4

9

40.7

- 77.4

61.3

13.2

32.4

4

32.4

- 52.0

40.1

8.5

bony interorbital width

33.1

8

26.6

- 35.4

31.7

3.2

25.8

4

25.8

- 27.8

26.5

0.9

occipital proc. length

28.1

9

25.5

- 34.4

29.6

2.6

28.8

4

28.8

- 36.9

33.0

3.5

occipital prix;. width

18.4

9

13.7

- 21.8

16.9

3.2

10.1

4

8.3

- 15.1

10.8

3.0

Percent of SL

HL

31.4

9

31.4

- 34.7

32.5

1.1

32.6

4

29.8

- 32.6

31.1

1.2

head height

12.0

8

12.0

- 16.3

14.0

1.4

13.0

4

10.6

- 13.0

11.7

1.0

head width

20.9

9

19.5

- 22.9

21.5

1.0

20.9

4

18.8

- 21.1

20.0

1.1

eye diameter

2.1

9

2.0

- 4.0

2.8

0.7

1.9

4

1.8

- 2.1

1.9

0.2

mouth gape

14.9

9

14.2

- 16.5

15.4

0.7

14.4

4

13.0

- 14.4

14.0

0.6

intemostil distance

11.2

9

10.7

- 12.3

11.3

0.5

10.2

4

9.4

- 11.0

10.1

0.7

snout length

10.9

9

10.5

- 12.3

11.2

0.6

9.1

4

8.5

- 10.0

9.0

0.7

longest barbel length

17.1

9

14.1

- 24.7

19.9

4.2

10.5

4

10.5

- 16.4

12.5

2.7

bony interorbital width

10.4

8

8.5

- 11.4

10.3

1.1

8.4

4

7.9

- 8.4

8.2

0.3

occipital proc. length

8.8

9

8.7

- 10.9

9.6

0.8

9.4

4

9.4

- 11.2

10.2

0.8

predorsal length

39.4

9

39.4

- 42.8

41.1

1.1

37.3

4

35.4

- 37.3

36.3

0.9

length dorsal f. base

10.8

9

10.0

- 13.2

11.6

0.9

10.3

4

10.3

- 12.2

10.3

0.9

interdorsal length

22.8

9

21.6

- 25.7

23.6

1.3

28.8

4

25.1

- 28.8

6.0

0.4

length adipose f. base

10.4

9

8.0

- 12.3

10.4

1.4

9.0

4

9.0

- 11.1

10.0

0.9

length anal f. base

16.9

9

13.3

- 16.9

15.3

1.3

15.1

4

15.1

- 17.0

16.0

0.9

caudal ped. depth

6.5

9

6.5

- 7.3

6.9

0.3

6.3

4

6.2

- 7.1

6.5

0.4

caudal ped. length

13.8

9

11.2

- 17.7

14.4

2.0

14.5

4

13.3

- 15.0

14.3

0.7

pectoral spine length

19.5

8

17.3

- 21.3

19.6

1.6

15.0

4

15.0

- 16.4

16.0

0.6

dorsal spine length

21.8

8

17.1

- 23.2

21.1

2.4

16.8

4

15.6

- 18.3

16.9

1.3

further westward and in intermediate rivers; from there
eastwards to the middle and lower river and delta of the
Fly, throughout the Gulf of Papua rivers including the
Kikori, Era, Pie and Purari systems and deltas, Vailala
River mouth, Murua River, Lakekamu and Oreke Rivers.
Australia: northern coast and rivers from the Adelaide
and Alligator Rivers to the Gulf of Carpentaria and the
Norman River.

Ecology. Coastal and lower mangrove areas, estuaries
into main rivers and lagoons; also freshwater.

Remarks. In late 1976, this species was the second
most important commercial species at Kikori (Papua
New Guinea) after barramundi (Lales calcarifer (Bloch)
(Haines 1979). Arius dioctes has been recorded to attain
1.2 m SL (Roberts 1978) and 19 kg whole weight (T.
Coleman pers. comm.). Papuan villagers report that this
species can attain 2 m in length. N. Haysom and T. Davis
(pers. comm.) have collected 1-2 m, ‘up to 40 kg’ fish
from the Alligator and Norman rivers. The 1050 mm SL
paratype from Papua (Irian Jaya) weighed c. 15 kg when
fresh.

Etymology, dioctes, masculine. From the Greek,
dioktes, meaning hunter or pursuer - in reference to the
species’ apparent hunting ability, diet and dentition.

Arius insidiator sp. nov.

(Figs 3-4; Tables 1-2)

Hexanematichthys sp - (in part) Kailola 1975: 41.

Hexanematichthys sp ‘D’ - Kailola and Wilson 1978:
40, 42.

Arius (Hemiarius) species 5 - Kailola 1990b: 306.

Type material. HOLOTYPE - NTM S. 11189-001,350
mm SL, mouth of Wildman River (12°26' S, 132‘’09' E),
Northern Territory, P. Mundy, 28 February 1984.
PARATYPES - AMS 1.28960-001, 282 mm SL, Gulf of
Papua (08‘’00' S, 145“00' E), S. Frusher, 1978; KFRS
F.O3302, 188 mm SL, half mile inside Pai’a Inlet (07‘’39'
S, 144°33' E), Papua New Guinea, F.R.V. Tagula, 6 May
1967; KFRS F.5526-01, 270 mm SL, off Kerema (07°58'
S, 145‘’43' E), D. Whitten, D. Coates and R. Watson, 11
October 1983.

Diagnosis. Head and anterior of body depressed; ribs
long, angular, impressed in abdominal body wall. Eye
covered with head skin; head smooth. Mouth wide,
terminal, jaws upturned at symphysis; teeth fixed,
cardiform, in 1-2 series on Jaws and palate; four elongate
patches of palatal teeth. No rakers on posterior of first
two arches; mandibulary barbel longest, reaching dorsal
fin. A 19-23; total gill rakers (first arch) 11-12; total
vertebrae 24+3+33. Fin spines slender, weak. Fresh

P.J. Kailola

Fig. 3. Arius insidiator sp. nov. lateral view, holotype

Fig. 4. Arius insidiator nov. A dorsal head view; B, ventral head view (both of holotype); C, arrangement of upper
tooth patches (188 mm SL paratype).

New catfish from Australia and New Guinea

colouration grey or yellowish, fins and mouth (bright)
yellow or orange.

Description. D 1,7. P 1,10. A 19-23. GR (first arch)
11-12, of which 5 on upper limb. GR (last arch) 11-13.
Vertebrae 58-60 (51-54 free).

Body moderately stout, anterior two-thirds depressed;
angular pleural ribs of trunk and anterior caudal vertebrae
apparent through body wall, forming a ‘shelf along
lower sides. Predorsal profile almost straight. Snout
evenly rounded; lips narrow, much thickened at corners,
scalloped along inner margin. Jaws strong, lower jaw
elevated at symphysis, slightly longer than upper; mouth
terminal to superior, broad, curved; teeth not visible
when mouth closed. Nostrils small, rounded, placed well
forward on snout; anterior one directly in front of
posterior one. Eye ovate, small, covered with head skin,
almost dorsally situated and about four eye diameters
before mid-head length. Gill opening wide, membranes
meeting well forward; distal margin broad.

Teeth fixed, strong, slightly curved, cardiform. Teeth
on both palate and upper jaw arranged in two (rarely
one) row(s) with distinct naked space between rows,
teeth in inner row longer. One row of teeth on lower
jaw; naked space at symphysis. Four elongate patches
of teeth across palate: inner pair adjoining and half as
wide as curved outer patches. Palate smooth; two long,
low ridges of epithelial tissue before branchial chamber.

Head shield completely smooth except for slightly
roughened lateral margins. Dorsomedian head groove
lanceolate, flat, beginning well forward on snout and
almost reaching base of supraoccipital process. Process
narrow, with straight sides, rounded from side to side.
Sides of head smooth. Broad-based, triangular humeral
process smooth, weakly ossified anteroventrally, its shaft
short, oblique, extending one quarter distance along
pectoral spine. Axillary pore small.

Barbels thin, flattened. Maxillary barbel short,
reaching only to preopercular margin. Mandibulary
barbel long, extending past head or as far as anterior
dorsal rays. Mental barbel reaches ventral head margin
or beyond pectoral base. Chin barbel bases elearly
staggered.

Gill rakers stiff, moderately pungent, half as long as
opposing gill filaments. Gill arches smooth; no rakers
on posterior face of first two; 10-12 rakers along back
of third arch. No thickened tissue postcrodorsally on
arches.

Fin spines feeble, rounded, pungent in smallest
specimen; smooth or roughened along anterior margin,
weakly serrated or roughened along posterior margin
(smallest specimen with 8-9 serrae along posterior
margin of pectoral spine). Dorsal fin truncate in outline,
longest ray 2.3-2.8 times longer than last ray. Pectoral
fin low on sides, its base in a horizontal plane; fin hind
margin truncate above, concave below. Pectoral fin
reaching to below dorsal. Ventral fin of both sexes broad.

terminating well short of anal fin origin. Adipose fin
above anterior two-thirds of anal. Anal fin margin almost
straight, longest ray 2.6-3.1 times last ray in length.
Caudal fin lobes broad and short.

Caudal peduncle stout. Lateral line straight, curved
dorsad at tail base. Numerous fine short lines emanate
from lateral line, forming dense, branehing network
anteriorly. Indistinct vertical series of pores ascend from
lateral line over upper sides.

Colour of fresh material. Pale grey to yellowish
above, white below; colours well-separated. Barbels grey
or cream; mouth ‘honey’-coloured. Dorsal, ventral, anal
and pectoral fins bright yellow-orange; caudal fin dull
yellow-orange.

Colour of preserved material. Charcoal or dark lilac-
brown above, upper jaw and undersides pale. Lower
sides and underside of head cream or pinkish, colour
extending dorsally along gill membranes; nostrils and
eyes also in pale streaks. Dorsal, pectoral and ventral
fins dusky yellow basally, charcoal distally or over dorsal
aspect; anal and caudal fins dull yellow or pale orange.
Peritoneum pale.

Comparisons. This species is distinct in dentition,
body form and colouration. Its colouration is similar to
that of Arius dioctes and its strong teeth and small eyes
link it to that species and to A. armiger De Vis, 1884.
The only other species with a skin-covered eye is
Doiichthys novaeguineae Weber, 1913 which also has
an upturned mouth. Nevertheless, none of them have A.
insidiator's flattened body, peculiar swimbladder form
(flattened and elongate versus cardiform and inflated)
and angular pleural ribs.

Distribution. New Guinea: southern coast along the
Gulf of Papua. Australia: northern coast east of Darwin.
Probably more widespread (for example, individuals
have been seined in the Fly River delta (C. Tenakanai,
pers. eomm.).

Ecology. Shallow mudflats and river mouths; muddy
coastal waters.

Remarks. The holotype is the largest specimen
known.

Etymology. Noun in apposition; from the Latin,
insidiator, meaning ambusher or lurker. The dorsally
placed eyes and depressed body form suggest that this
species’ habit is to lie half-hidden in sediment. Its strong
teeth and jaws indicate it is a predator. Although large
fish scales and detritus were adhering to the gills of the
largest specimen, the stomachs of all were empty.

Arius pectoralis sp. nov.

(Figs 5-6; Tables 1,3)

Arius species 3 - Kailola 1990b: 397.

Arius sp. 3 - Blaber, Brewer and Salini 1994: 168,
fig. 3m.

Type material. HOLOTYPE - AMS 1.27415-001,
226 mm SL, Chapman River, Queensland (14°56' S,

P.J. Kailola

Fig. S.Arius pectoralis sp. nov. lateral view, holotype.

Fig. 6.Arius pectoralis sp. nov. (all of holotype) A, dorsal head view; B, ventral head view; C, arrangement of upper tooth
patches, D, rubbing of head shield.

134

New catfish from Australia and New Guinea

141 °38' E), D.B. Carter, 21 December 1980. PARAT YPES
- NTM S. 13004-001, 127 mm SL, Chapman River,
Queensland, D.B. Carter, 5 March 1981; CSIRO A.3608,
112 mm SL, Norman River above Karumba, Queensland
(17°29’ S, 140°50' E), l.S.R. Munro, 22 October 1972;
CSIRO A.3609, 1 17 mm SL, same data as A.3608;
CSIRO A.3610, 116 mm SL, same data as A.3608; QM
1.14917, 105 mmSL, Darwin Harbour (12‘’27’S, 130“46'
E), November 1972; NTM S.10254-001,2 (94.5-101 mm
SL), Mickett Creek, Shoal Bay, Melville Island, Northern
Territory (12‘’2r S. 131°00' E), D. Grey, 16 December
1976; NTM S.10319-003, 56 mm SL, Shoal Bay,
Melville Island (11°48' S, 130“39' E), D. Grey, 19
October 1972; NTM S. 10235-001, 90 mm SL, Shoal
Bay, Melville Island, D. Grey, 1 August 1973; NTM
S.11507-004, 145 mm SL, Ludmilla Creek, Darwin
(12°27' S, 130°46' E), G. Cole and A. Howard, 19
December 1984; CSIRO H.5174-07, 4 (165-180 mm
SL), Papua (Irian Jaya) at 04°52’S, 136°57’E, K. Hortle
and A. Haris, 6 September 1997; CSIRO H.4937-02, 220
mm SL, Papua (Irian Jaya) at 04°52’S, ]36°57’E, K.
Hortle and A. Haris, 6 September 1997.

Additional material examined (non-type). CSIRO
H.4220-03, 230 mm SL, Papua (Irian Jaya) at 04'’52’S,
136°55’E, K. Hortle and A. Haris, 8 February 1996;
NTM S.14852-001, II (46-64 mm SL), Papua (Irian
Jaya) at 04°52’S, I36°57’E, K. Hortle and A. Haris, 1
June 1998.

Diagno.sis. Palatal teeth conical, in two oblique, oval
patches; one on each side of palate, well-separated. Snout
acute; lips fleshy, crenulate; lower jaw truncate. Head
shield finely granular; dorsomedian head groove
lanceolate, narrow distally. Eye large, 17-28 % HL.
Large, flattened serrae along inner margin of pectoral
spine; caudal fin lobes slender, acute. A 18-22; total first
arch GR 15-22; rakers present along posterior face of
all gill arches; vertebrae 18-l-6-t-27. Distinct, blackish
margin on dorsal, pectoral and inner caudal fins.

Description. D 1,7. P I, 8-11. A 18-22. GR (first arch)
15-22, of which 5-7 on upper limb. GR (last arch) 14-
17. Vertebrae 51 (44 free).

Body moderately slender; predorsal profile straight.
Snout moderately to slightly acute; lips fleshy, crenulate;
short, transverse crescent often present on dorsum of
snout between nostrils. Mouth subinferior, gape
moderately large; upper Jaw somewhat acute medially,
lower jaw almost truncate. Anterior nostril slightly
medial to posterior one. Eye large, border free from head
skin, dorsolateral and slightly before mid-head length.
Gill opening moderately wide, concave at isthmus,
margin moderately broad.

Teeth in jaws fine, sharp, depressible, forming 7-8
irregular series in upper jaw and 4-6 series in lower jaw,
bands either meeting or slightly separated at jaw
midlines. Single large, oval patch of conical, blunt teeth

on each side of palate anteriorly, obliquely situated, well-
separated. Palate smooth or slightly papillose; two
oblique, low to moderately developed epithelial ridges
posteriorly on palate.

Head shield finely granular. Dorsomedian head
groove originates between nostrils and reaches
supraoccipital process base. Groove flat, lanceolate
anteriorly, narrow and straight posteriorly. Supra¬
occipital process triangular, straight-sided, with median
keel. Triangular humeral process rugose, well-ossified
anteroventrally, its shaft oblique, extending one-third
along pectoral spine. Axillary pore small.

Barbels flattened, moderately thick, fleshy. Maxillary
barbel extends slightly beyond dorsal fin in juveniles,
to humeral process in adults. Mandibulary barbel usually
reaches pectoral fin spine base. Mental barbel reaches
ventral head margin. Chin barbel bases slightly
staggered.

Gill rakers short, one-third to half length of opposing
filaments. Rakers present along posterior aspect of all
arches: 6-7 (upper limb only) to 11-14 (total) on first arch;
13-18 along second; 11-16 along third. Often some papillae
on first two arches. Fleshy, scalloped epithelial folds
moderately developed posterodorsally on first two arches.

Fin spines strong, moderately long; sides with fine,
longitudinal striae. Short filament on tip of spines.
Anterior spine margin finely rugose with several sharp,
antrorse serrae near tip; posterior (trailing) margin with
low (dorsal spine) or large and flattened (pectoral spine)
serrae: 8-11 along dorsal, 12-13 along pectoral. Last
dorsal fin ray 2.9-3.4 times shorter than longest ray.
Pectoral fin extends to below posterior dorsal fin rays.
Ventral fin in males narrow, failing to reach anal origin
by distance of half eye diameter; in females, broad-based,
reaching to fourth anal ray (inner ventral fin rays
thickened to form a pad in sexually mature female fish).
Adipose fin rectangular, situated above middle of anal
fin. Anal fin margin slightly concave, last ray 2.5-3 times
shorter than longest ray. Caudal fin lobes slender,
tapered, acute, upper lobe slightly longer.

Caudal peduncle moderately stout. Lateral line
straight along sides, oblique below dorsal fin, turned
dorsad at tail base. Fine, short lines of pores diverge off
length of lateral line.

Colour of fresh material. Dark bluish brown or black
above, white to cream below. Charcoal or black margin
to fins (particularly caudal fin) and anterior two-thirds
of anal fin also charcoal.

Colour of preserved material. Dusky fawn to charcoal
above, creamy below; colours well-separated. Maxillary
barbel usually dark. Unpaired fins and dorsal aspect of
pectoral and ventral fins dusky or charcoal; distinct
charcoal or black margin to inner caudal, dorsal and
pectoral fins, and charcoal anal fin. Peritoneum pale,
occasionally with scattered, dark stipples.

135

P.J. Kailola

Fig. 7. Anus hardenbergi sp. nov. A, lateral view of 74.3 mm SL paratype; B, lateral head view of 253.8 mm SL
paratype.

Fig. 8. Arius hardenbergi sp. nov. A, dorsal head view sketch of 253.8 mm SL paratype; B, rubbing of head shield, same paratype; C,
arrangement of upper tooth patches, 74.3 mm SL paratype.

136

New catfish from Australia and New Guinea

Table 3. Percent of head length (HL) and standard length (SL) for Arius pectoralis sp. nov. and Arius hardenbergi sp. nov. n = sample size;
X = mean; SD = standard deviation.

Character

holotype

n

Arius pectoralis
range

X

SD

holotype

n

Arius hardenbergi
range

X

SD

Percent of SL

head height

60.9

16

51.0

- 64.4

58.9

4.8

47.0

5

47.0

- 55.6

51.0

3.1

head width

68.9

16

63.5

- 73.5

69.6

3.0

73.0

5

71.9

- 76.2

71.8

5.4

eye diameter

19.4

16

17.1

- 28.0

23.2

3.5

10.1

5

8.4

- 11.3

9.6

1.2

mouth gape

40.2

15

29.5

- 43.6

38.8

4.8

40.9

5

40.9

- 54.1

50.8

5.6

intemostril distance

25.0

15

20.6

- 28.4

25.0

2.2

25.9

5

25.9

- 35.5

30.4

3.4

snout length

38.5

16

33.5

- 41.2

37.5

2.2

35.6

5

34.5

- 39.3

37.1

2.0

longest barbel length

79.9

15

78.0

-121.7

101.0

13.1

76.7

5

76.7

-110.5

86.6

23.2

bony interorbital width

29.4

15

26.3

- 33.0

29.8

2.0

31.7

5

29.9

- 34.3

32.1

1.9

occipital proc. length

28.2

15

28.2

- 38.2

33.9

2.5

-

4

26.9

- 41.6

31.5

7.3

occipital proc. width

19.4

15

18.7

- 26.0

21.8

2.8

-

4

5.4

- 34.1

18.2

12.0

Percent of SL

HL

29.2

16

25.5

- 29.8

27.3

1.3

32.1

5

31.9

- 32.9

31.5

1.7

head height

17.8

16

14.4

- 17.8

16.1

1.0

15.1

5

15.1

- 17.9

16.5

1.1

head width

20.1

16

17.3

- 21.0

19.0

1.1

23.5

5

23.4

- 24.5

23.9

0.5

eye diameter

5.7

16

2.1

- 7.3

6.0

1.3

3.2

5

2.7

- 3.6

3.1

0.4

mouth gape

11.7

15

8.5

- 13.8

10.6

1.3

13.1

5

13.1

- 17.8

16.4

1.9

intemostil distance

7.3

15

5.7

- 8.0

6.8

0.6

8.3

5

8.3

- 11.3

9.8

1.1

snout length

11.2

16

9.1

- 11.7

10.2

0.8

11.4

5

11.3

- 12.7

12.0

0.7

longest barbel length

23.3

15

22.4

- 32.8

27.5

3.1

24.6

5

24.6

- 36.1

30.4

5.5

bony interorbital width

8.6

15

7.1

- 9.8

8.2

0.8

10.2

5

9.8

-11.0

10.4

0.5

occipital proc. length

8.2

15

8.2

- 10.6

9.3

0.8

-

4

3.0

- 14.1

8.5

4.5

predorsal length

37.9

16

35.2

- 40.0

36.9

1.5

42.0

5

39.2

- 42.0

40.5

1.3

length dorsal f. base

11.9

16

10.0

- 12.5

11.3

0.7

12.5

5

10.6

- 13.9

12.3

1.2

interdorsal length

27.7

16

16.5

- 33.7

28.2

3.7

26.2

5

14.3

- 26.2

18.5

5.1

length adipose f. base

8.5

16

6.7

- 11.5

8.5

1.3

12.1

5

11.7

- 18.9

16.0

3.7

length anal f. base

17.6

15

15.3

- 19.3

17.1

1.2

14.5

5

12.5

- 16.9

15.0

1.7

caudal ped. depth

8.0

16

7.1

- 8.7

7.9

0.5

7.6

5

6.9

- 7.8

7.4

0.4

caudal ped. length

15.9

16

15.2

- 20.2

17.0

1.2

14.8

5

14.6

- 17.8

15.9

1.3

pectoral spine length

19.8

15

19.5

- 26.0

21.4

1.7

21.8

3

17.3

- 21.8

19.9

2.3

dorsal spine length

21.7

14

19.0

- 27.3

21.9

2.0

15.3

4

15.3

- 18.8

16.9

1.5

Comparisons. Arius pectoralis is most similar to
Arius berneyi (Whitley, 1941) and A. graeffei Kner and
Steindachner, 1866, from which it can be distinguished
by its more acute snout, palatal dentition (almost always
a single patch on each side, compared with almost always
two patches each side in A. graeffei and A. berneyi', also,
palatal teeth finely conical instead of villiform in A.
graeffei and A. berneyi), its strong pectoral spine serrae,
very dark fin margins and slender caudal fin. Arius
pectoralis differs from the only other taxon in the area
with similar palatal dentition (Cinetodus froggatti
(Ramsay and Ogilby, 1886)) by its wide gill opening
and head shield form (restricted gill opening and very
broad and high head shield in C. froggatti).

Distribution. New Guinea', south coast and estuaries
of Papua (Irian Jaya) from the Kamora to Otokwa rivers.
Probably occurs more extensively, in pockets, including
the Port Moresby to the Kempwelch River area in central
southern Papua New Guinea. Australia: Darwin (harbour
and Ludmilla Creek) to Karumba and the Chapman River
in Queensland.

Ecology. Coastal waters, estuaries and rivers within
tidal influence; among mangroves.

Remarks. There are no literature records of this
species, which has probably been confused in the field
and earlier reports for Arius berneyi or A. graeffei. The
maximum recorded size for A. pectoralis is 393 mm FL
(Papua (Irian Jaya) specimen).

Etymology. From the Latin, pectoralis, meaning
shoulder: refers to the strong serrae along the inner
pectoral fin spine.

Arius hardenbergi sp. nov.

(Figs 7-8; Tables 1,3)

Arius species 6 - Kailola 1990b: 455.

Type material. HOLOTYPE - WAM P.29966-001,
260 mm SL, Manimeri River (02“06' S, 133°45' E),
Bintuni Bay, Papua (Irian Jaya), G.R. Allen, 28 March
1989. PARATYPES - NCIP 436, 254 mm SL, Merauke
(08°28'S, 140°20' E), Papua (Irian Jaya), J.D.F. Hardenberg,
4 August 1931; AMS 1.29291 -001,2 (59.5-74.5 mm SL),
delta of Fly River (08‘’22' S, 142°40' E), Papua New
Guinea, J. Watson, 16-22 July 1981; QM 1.26088, 56
mm SL, same data.

Additional material examined (non-type). NTM

S. 14873-001, 52 mm SL, Bamu River estuary, Papua
New Guinea, at c. ()8°08’S, 143°35’E, 21 June 1993.

137

P.J. Kailola

Diagnosis. Four patches of conical teeth across front
of palate: rounded vomerine patches well-separated;
outer patches oval or crescentic, 2-3 times larger than
inner patches. Snout fleshy, overhanging mouth. Low
papillae on palate and posterior face of gill arches; rakers
rarely on posterior face of first two gill arches. Barbels
thick proximally, thin distally. Head shield very granular,
extensive posteriorly; triangular supraoccipital process
short, broad. Eye small, dorsolateral, 8-12 % HL. A 16-
18; total gill rakers (first arch) 10-14; vertebrae 19+5+26.
Adipose fin large, base longer than anal fin base. Fresh
colouration dark grey; inner, dorsal aspect of paired fins
charcoal blue.

Description. D 1,7. P 1,9-10. A 16-18. GR (first arch)
10-14, of which 3-5 on upper limb. GR (last arch) 9-13.
Vertebrae 50-52 (43-46 free).

Body robust. Head broad, depressed; predorsal profile
almost straight, slightly convex at nape. Snout rounded
to slightly acute, prominent; lips moderately thick and
fleshy, inner margin crenulate. Tiny, fine papilla-like
structures on snout and around mouth in all specimens.
Mouth very broad, curved, more inferior than sub¬
terminal; one-quarter to half of upper jaw tooth band
exposed when mouth closed. Nostrils rounded, anterior
one slightly lateral to posterior one. Eye small, not
completely free of head skin, situated dorsolaterally, well
to slightly before mid-head length. Gill opening
moderately wide, united membrane concave over
isthmus, margin broad and free.

Teeth conical, tips sharp or compressed; very slightly
depressible; embedded in thick tissue. Five to eight
irregular series of teeth in premaxillary band. 4 to 6 in
lower band; narrow edentulous space at symphysis of
lower jaw. Four tooth patches across front of palate,
separated by narrow spaces. Vomerine patches rounded;
outer patches large, oval, at least twice as large as
vomerine patches. Palate smooth or with few scattered
low papillae; two low oblique ridges of epithelial tissue
before branchial chamber.

Head shield extensive, very granular, granules low,
coarse in large individuals. Ridges of striae flank
dorsomcdian head groove posteriorly; broader striae
extend over supraoccipital process. Groove lanceolate,
beginning on snout, extending to base of supraoccipital
process; groove flat anteriorly, narrow and deeply
excavated posteriorly. Supraoccipital process broad,
triangular; sides almost concave; strong median keel.
Sides of head slightly venulose; small, oval, naked space
in head shield above operculum. Humeral process broad-
based, heavily ossified anteroventrally; its triangular
shaft extending one-third distance along pectoral fin
spine. Axillary pore moderately large.

Barbels flat, thick proximally, thin and wisp-like
distally. Maxillary barbel extends to base of pectoral fin
or to below dorsal fin base (juveniles). Mandibulary
barbel reaches pectoral fin base. Mental barbel ends

midway between eye and pectoral fin base. Bases of chin
barbels moderately staggered.

Gill rakers well-spaced, half as long as opposing
filaments. Numerous, low papillae along back of first
two gill arches (fewer in larger fish); no rakers on poste¬
rior face of first arch; rarely 1-3 rakers posterodorsally
on second arch; 9-10 rakers on posterior face of third
arch. Narrow pads of epithelial tissue on gill arches
posterodorsally, best developed on second.

Fin spines robust, tips sharp. Outer spine margin with
low granules and 1-3 serrae distally; posterior margin
with 3-5 serrae (dorsal spine) or 5-10 large antrorse
serrae (pectoral). Longest dorsal ray 1.9-2.2 times last
ray. Pectoral fin extends to below mid-dorsal fin. Ventral
fin short of or reaches anal fin origin (condition in mature
females unknown). Adipose fin oblong, long-based,
beginning noticeably before anal fin origin, opposite all
of anal fin. Anal fin margin concave, longest ray 2.4-
3.2 times last ray. Caudal fin moderately short, lobes
broad, tapered.

Caudal peduncle moderately deep. Lateral line turned
dorsad at tail base, elevated below dorsal fin. Low, short
lines of pores diverge from length of lateral line, more
abundant anteriorly.

Colour of fresh material. Brown to dusky mauve
above, pale yellow or fawn below; iridescent gold on
sides. Fins dusky mauve or brown. Barbels pale yellow.

Colour of preserved material. Light brown or tan,
paler below; fins brown; barbels fawn. Peritoneum pale.

Comparisons. Arius hardenhergi can be distin¬
guished from the similar A/7 mx proximus (Ogilby, 1898)
by its larger adipose fin (12-19% SL, compared with 6-
12% in A. proximus). mouth shape, eye diameter
(8-12.5% HL, compared with 14-28% in A. proximus),
extent of head shield, supraoccipital process shape, and
swimbladder form (margins smooth versus scalloped in
A. proximus). The supraoccipital and mouth shapes,
paired fin colouration and adipose fin size of A.
hardenhergi are similar to those of Cinetodus (Kailola
1990b). However, the taxa belonging to that genus have
rakers along the posterior face of the first two gill arches,
different palatal dentition and more restricted gill
opening. Cinetodus carinatus (Weber, 1913) can be
confused with A. hardenhergi but C. carinatus has more
gill rakers on the first gill arch (15-19) and more and
.stronger .serrae along the inner pectoral spine.

Distribution. New Guinea: south coast. Vogelkop
Peninsula to the Fly River mouth.

Ecology. Muddy, shallow coastal waters and tidal rivers.

Remarks. On a label attached to the largest specimen
from Merauke, is written 'Arius uniformis Hardenberg’.
Hardenberg did not publish a description, and there is
no unpublished manuscript at the ZMA. This name is
therefore not available.

This species probably attains a larger size, although
the maximum size specimen 1 have measured is 254 mm

New catfish from Australia and New Guinea

SL. It could have been mistaken in collections for several
other species such as Arius proximus (Ogilby) and
members of the genus Cinetodus.

Etymology. I name this species after J.D.F.
Hardenberg, not only because he recognised that the
species was new but also as an acknowledgement of his
insightful contributions to Indo-Australian ichthyology
in the mid-twentieth century.

Arius hainesi sp. nov.

(Figs 9-11; Tables 1,4)

Nedystoma dayi - Tortonese 1964: 24.

Nedysloma dayi (in part) - Kailola 1975: 42.

Nedystoma sp. - Liem and Haines 1977: 25.

Arius species 4 - Kailola 1990b: 459.

Arius sp. 4 - Blaber, Brewer and Salini 1994: 168,
fig. 3n.

Type material. HOLOTYPE - NTM S. 11507-001,
304 mm SL, Ludmilla Creek (I2“27' S, 130“46' E),
Darwin, Northern Territory, G. Cole and A. Howard,
19 December 1984. PARATYPES - AMS 1.25995-001,
204 mm SL, Baimuru (07°33’ S, 144“5r E), Papua New
Guinea, A.K. Haines, 12-14 September 1974; QM
1.22657, 228 mm SL, Morowan (07'’35’ S,I44‘’58' E),
Ini Island, Papua New Guinea, A.K. Haines, 15 May
1975; AMS 1.27414-001, 237 mm SL, same data, 237
mm SL (cleared and stained); USNM 288553, 135 mm
SL, Gulf of Papua (OSW S, I45‘’00’ E), S. Frusher, 13
July 1981; AMS 1.25996-001, 136 mm SL, Gulf of
Papua, A.K. Haines, May 1975; CSIRO C.3799, 187 mm
SL, Norman River at Karumba (17“29' S, I4()‘’50' E),
Queensland, D.J. Turner, 1969; NTM S. 10190-002, 2

(88.0-88.2 mm SL), Mickett Creek (12“2r S, 131°00'
E), Melville Island, Northern Territory, D. Grey, 26 June
1975 (larger specimen cleared and stained); CSIRO
H.4545-01,2 (120.4-125.9 mm SL), Papua (Irian Jaya)
at 4°56.6’S, 137°03.2’E, K. Hortle and A. Haris, 4
September 1996; CSIRO H.4937-03, 222.5 mm SL,
Papua (Irian Jaya) at 4°52.rS, I35°57.7’E, K. Hortle
and A. Haris, 6 September 1997; CSIRO H.5252-01, 2
(210-234 mm SL), Papua (Irian Jaya) at 4°53.8’S,
136°54.6’E, K. Hortle and A. Haris, 6 September 1997.

Additional material examined (non type material).
KFRS F.O3990, 181.5 mm SL, Murua (07‘’52' S,
145°47' E), Matupi River, Papua New Guinea, October
1971; KFRS F.O4093, 3 (115-193 mm SL), off Oreke
River mouth (08°42' S, I46'’29' E), Papua New Guinea,
P. Kailola and J. Koaia, 3-4 May 1973; CSIRO H.4958-
01, 12 (33-42 mm SL), Papua (Irian Jaya) at 4°52.4’S,
136°57’E, K. Hortle and A. Haris, 1 June 1998 (mouth
juveniles); CSIRO H.5174-06, 210 mm SL, Papua (Irian
Jaya) at 4°52.6’S, 136°56.5’E, K. Hortle and A.Haris, 6
September 1997; WAM P.29965-002, 94 mm SL,
Manimeri River (02‘’06' S, 133°45’ E), Papua (Irian Jaya),
G.R. Allen, March 1989; AMS 1.27413-001,2 (108-151
mm SL), Arehava (07‘’35' S, I44“57' E), Papua New
Guinea, A.K. Haines, September 1974.

Diagnosis. Palate without teeth (but autogenous tooth
plates present); jaw teeth slender, in short, oblong band.
Lips fleshy, thin; mouth small, lower jaw truncate.
Barbels thin, short, maxillary barbel reaching only just
beyond eye; bases of chin barbels close together. Eye
large, 14-24 % HL, lateral. Dorsomedian head groove
elongate, deep posteriorly. Gill rakers along posterior

P.J. Kailola

Fig. 10. Arius hainesi sp. nov. A, dorsal head view (228 mm SL
paratype), B, ventral head view (holotype).

of all arches; gill opening slightly restricted; two large
epithelial flaps on palate posteriorly and double folds
on upper limb of first two gill arches. A 20-23; total gill
rakers (first arch) 32-37. Longitudinal furrows antero-
dorsally on body. Fin spines thin, long, slender; adipose
fin short-based, over posterior two-thirds of anal; ventral
fin pad of sexually mature females scalloped and tapered.
Fresh colouration dark grey above and iridescent purple;
palate and branchial chamber often purplish brown to
charcoal.

Description. D 1,7. P I, 8-11. A 20-23. GR (first arch)
32-37, of which 10-12 on upper limb. GR (last arch) 31-
37. Vertebrae 49-50 (43-44 free).

Body moderately elongate, cylindrical; head slightly
depressed. Predorsal profile straight, abruptly convex at
nape. Snout slightly rounded or truncate, curved ventrad,
overhanging subinferior mouth. Lips thin, fleshy or
‘rubbery’, inner aspect spongy and papillose. Mouth gape
moderately wide, lower jaw truncate or horizontal; all
of premaxillary tooth band visible when mouth closed.
Nostrils large, rounded, anterior nostril slightly median
to posterior one. Shallow groove usually present on snout
between posterior nostrils. Eye large, rounded.

Fig. 11. Arius hainesi sp. nov. A, rubbing of head shield (228 mm
SL paratype), B, arrangement of upper tooth patches (204 mm SL
paratype), C, ventral fin of mature female showing pad of epithelial
tissue.

prominent, situated laterally at or slightly before mid¬
head length, margin free of head skin; lateral ethmoid
prominent before eye. Gill openings somewhat restricted
ventrally, membranes attached broadly to isthmus,
margin concave.

Teeth in jaws slender, long, depressible; very fine;
embedded in tissue; in 5-6 series. Tooth band (both jaws)
interrupted at symphyses by edentulous space. Pre¬
maxillary bands elongate-oval. No teeth on palate. Palate
almost smooth or with low, scattered papillae. One large
pair of epithelial tissue folds hangs from palate into
anterior part of branchial chamber.

Head shield rugose or finely granular. Granules
conspicuous, usually .sharp, arranged in series along
dorsomedian head groove and along edge of shield in
larger specimens. Dorsomedian groove begins at level
of nostrils and continues to supraoccipital process base;
groove flat anteriorly, thence deeply excavated;
conspicuous. Rugose supraoccipital process triangular
with straight sides; sharp median keel prominent. Naked
space in head shield above gill opening. Large venules
on sides of head. Lateral head skin and ‘shoulder’ skin
develop 7-10 longitudinal furrows or ridges with age:
most apparent in individuals longer than about 150 mm
SL. Humeral process triangular, indented above, heavily
ossified anteroventrally, shaft oblique, acute; granules
arranged in series along process. Moderate sized, slit¬
like axillary pore present.

Barbels thin, rounded proximally, flattened and wisp¬
like distally. Maxillary barbel reaches to eye or halfway
between eye and gill opening (juveniles); mandibulary
barbel extends to below middle of eye; mental barbel
not or just reaches front eye margin. Chin barbel bases
close together, almost transversely aligned.

Gill rakers long, equal to gill filament length. Shorter
rakers along posterior face of all arches: 32-36 along
first arch, 33-40 on second. 30-34 on third. Curious large
double fold (or pouch) of epithelial tissue links upper
limb of first two arches.

Fin spines long, slender, rather compressed: sides
smooth to finely striate; anterior border with sharp
granules or ridges. Low serrae along distal part of dorsal
fin spine hind border and 25-35 sharp, large retrorse
serrae along pectoral fin spine hind border. Last dorsal
fin ray 3.0-3.7 times in longest ray. Pectoral fin reaches
just beyond dorsal fin. Ventral fin narrow in males,
reaching second or third anal fin ray; broad in females,
extending to about fifth anal fin ray; mature females with
curiously-shaped thickening along dorsal aspect of sixth
ray consisting of series of lobes and proximally a short,
lateral horizontal process (Fig. 11C). Adipose fin short-
based. oblong; above middle of anal fin. Outer margin
of anal fin truncate (adult) to deeply concave (juveniles),
last ray 2.8-3.2 times in longest ray. Caudal fin lobes
narrow, tapered, upper lobe slightly the longer.

140

New catfish from Australia and New Guinea

Caudal peduncle moderately deep. Lateral line
elevated below dorsal fin, curved dorsad at tail base.
Thin, dorsally-directed branchlets of lateral line
conspicuous; vertical series of fine pores diverging from
lateral line extend over upper body surface.

Colour of fresh material. Iridescent charcoal-purple
on head and back, otherwise dark grey or brown above,
white below. Sharp division between dorsal and ventral
colours. Fins pale. Lining of mouth and branchial
chamber either white to cream, or purplish brown to
charcoal.

Colour of preserved material. Dark brown or charcoal
grey over upper two-thirds of head and body, pale
orange-fawn or dusky grey below. Both lips pale. Dorsal,
adipose and caudal fins dusky tan with broad, brown
margins. Upper aspect of pectoral fin dark grey or brown;
upper ventral fin, anterior anal fin rays and anal fin
margin dusky. Palate and branchial chamber pale to dark
brown or charcoal. Barbels brown.

Comparison.s. Arius hainesi superficially re.sembles
Nedystoma dayi (Ramsay and Ogilby, 1886) in having a
toothless palate, epithelial folds around and before the
anterior gill arches, and many gill rakers. However, the

Table 4. Percent of head length (HL) and standard length (SL) for
Arius hainesi .sp. nov. n = sample size; x = mean; SD = standard
deviation.

Character

holotype

n

Arius hainesi
range

X

SD

Percent of HL

head height

54.8

14

45.6

-

65.1

55.2

5.5

head width

68.1

14

52.3

-

74.6

66.4

5.7

eye diameter

14.1

14

14.1

-

23.8

18.7

2.5

mouth gape

34.0

14

27.5

-

37.9

32.2

2.8

intemostril distance

18.4

14

15.6

-

19.1

18.2

0.9

snout length

43.3

14

38.2

-

43.3

40,6

1.7

longe.st barbel length

34.2

14

28.9

-

55.8

42.1

7.7

bony interorbital
width

28.0

14

27.0

•

42.6

30.1

3.7

occipital proc. length

28.0

14

22.9

-

50.0

30.3

6.6

occipital proc. width

12.1

14

12.1

-

20.5

16.6

2.3

Percent of SL

HL

32.1

14

27.7

-

33.0

30.4

1.9

head height

17.6

14

15.0

-

18.4

16.7

1.2

head width

21.9

14

17.3

-

21.9

20.1

1.4

eye diameter

4.5

14

4.5

-

6.6

5.7

0,6

mouth gape

10.9

14

8.4

-

12.1

9.8

l.l

intemostil distance

5.9

14

4.9

-

6.0

5.5

0,4

snout length

13.9

14

10.8

-

13.9

12.4

l.l

longest barbel length

11.0

14

9.5

-

15.8

12.7

1.9

bony interorbital
width

9.0

14

8.0

•

12.8

9.2

1.2

occipital proc. length

9.0

14

7.5

-

13.9

9.1

1.5

predorsal length

40.8

14

36.5

-

42.2

39.6

1.6

length dorsal f. base

11.6

14

9.9

-

12.3

11.2

0.6

interdorsal length

28.1

14

25.9

-

31.0

28.8

1.5

length adipose f. base

6.2

14

4.5

-

9.4

6.7

1.4

length anal f. base

17.0

14

17.0

-

19.9

18.5

1.0

caudal ped. depth

8.3

14

7.1

-

8.5

7.9

0.4

caudal ped. length

15.4

14

13.9

-

17.6

15.8

1.1

pectoral spine length

23.0

11

19.2

-

25.1

22.7

2.0

dorsal spine length

23.4

11

21.4

-

26.4

23.9

1.4

shapes of the posterior head groove and mature female
ventral fin, the short barbels (maxillary harbel 29-56 %
HL, compared with 46-76 % HL in N. dayi), longer snout
(38-43 % HL, compared with 30-36 % HL in N. dayi)
are among distinguishing characters. The two species
also apparently occupy different habitats {N. dayi is
almost strictly freshwater). Tortonese’s (1964) ‘Ne¬
dystoma dayi’ from Katau (09°08' S, I42°56' E) must be
referable to this species.

Distribution. New Guinea: southern coast from
Kamora to Otokwa rivers (Papua (Irian Jaya)) and from
Katau (west of Fly River delta) to Aird Hills and Oreke
River (Papua New Guinea); possibly continuous
distribution and more extensive westwards. Australia:
from vicinity of Darwin to the southern Gulf of
Carpentaria.

Ecology. Predominantly in marine waters of the lower
estuaries, along the coast and off river mouths. In Papua
New Guinea the species is common locally (such as the
Era River - Morowan area) (Haines 1979) although in
central-southern Papua (Irian Jaya), A. hainesi is
common in the estuaries.

Remarks. Arius hainesi attains a maximum size of
320 mm FL (Papua (Irian Jaya) material).

Etymology. Named for Alan K. Haines, who worked
in fisheries in Papua New Guinea between 1972 and
1976. He undertook several surveys of river systems
entering the Gulf of Papua (notably the Piirari) and de¬
veloped a sound appreciation of those river systems and
their aquatic fauna. Through his ability to distinguish
the species and his faithful recording of the biology and
ecology of the fork-tailed catfishes in the Gulf rivers,
Alan made a significant contribution to our knowledge
of this fish family in the Australian and New Guinea region.

Arius paiiciis sp. nov.

(Figs 12-13; Table 5)

Arius midgleyi Kailola and Pierce, 1988; 75 (in part).

Type material. HOLOTYPE - QM 1.12910, 326 mm
SL, Flinders River near Maxwellton (20°47' S, 142°43'
E), Queensland, H. and M. Midgley, 14 October 1974
(paratype of Arius midgleyi). PARATYPES - QM
1.12757, 310 mm SL, Flinders River near Maxwellton,

H. and M. Midgley, 14 October 1974 (paratype of Arius
midgleyi)-, QM 1.16730, 2 (315-329 mm SL), Flinders
River near Maxwellton, H. and M. Midgley, October
1974 (paratypes of Arius midgleyi)-, QM 1.11364, 205
mm SL, Forest Home Station (18°15' S, 143°02' E),
Gilbert River, Queensland, T.C. Marshall, 24 September
1953 (paratype of Arius midgleyi)-, AMS 1.25315-001
(previously IB.3159/2882), 171 mm SL, same data
(paratype of Arius midgleyi); QM 1.11990, 145.5 mm
SL, Mitchell River (16°00' S, 142°20' E), Queensland, 8
September 1959, (paratype of Arius midgleyi); QM

I. 16735, 240 mm SL, Hodgson River (14°54' S, 134‘’33'
E), Northern Territory, H. and M. Midgley, 17 September

141

P.J. Kailola

CO

Fig. 12. Range of total gill raker count (first arch) of Arius midgleyi and A. paucus sp. nov.(species combined) and 57 specimens of Arius
leptaspis (Bleeker) from northern Australia and southern New Guinea. Arius paucus sp. nov. counts are at the left of the figure.

1979 (paratype of Arius midgleyi)-, QM 1.16738, 2 ( 327
mm SL and 151.5 mm HL), Mannaburoo Hole (16°05'
S, 135°22' E), Limmen Bight River, Northern Territory,
H. and M. Midgley, 29-30 August 1979 (paratypes of
Arius midgleyi)', NTM S. 12070-001,2 (298-315 mm SL),
same data (paratypes of Arius midgleyi)-, QM 1.16737,
310 mm SL, same locality, H. and M. Midgley, 1
September 1979 (paratype of Arius midgleyi)-, NTM
S.12083-001, 331 mm SL, Wilton River (13“46' S,
134°28' E), H. and M. Midgley, 25-27 September 1979
(paratype of Arius midgleyi)', NTM S. 1775, 257 mm SL.
Wollogorang Station (17° 13' S, 137°57' E), Northern
Territory, D. Howe, 15 June 1974 (paratype of Arius
midgleyi)-, CAM F.36. 273 mm SL, same data (paratype
of Arius midgleyi).

Additional material (non-type). QM 1.16741, 2
(123.5-131 mm HL), McArthur River (24°46'S, 143°44'
E), Queensland, H. and M. Midgley, June 1975; NTM
S.12077-001, 107.5 mm HL, Roper River (14°46' S,
134°01' E), Northern Territory, H. and M. Midgley,
September 1979; NTM S.l 1153-001, 110 mm HL,
Mainoru River(14°0r S, 134°03’E), Northern Territory,
H. and M. Midgley, September 1979.

Diagnosis. Gill rakers total 10-11 on first gill arch,
11-14 on last arch. Eye diameter as percentage of head
length 9-15. In addition, the characters of Arius midgleyi
Kailola and Pierce: sleek body; strong jaws; jaws
upturned slightly at symphyses, mouth broad; snout
truncate in profile; head oblong, its width averaging 66%
HL. Supraoccipital process narrow with parallel margins.
Numerous fine, sharp teeth on palate in transverse band
of four oblong groups. No rakers on posterior aspect of
gill arches. A 16-19; vertebrae 20+7-8+28-29. Barbels
thin and short, rarely reaching beyond pectoral fin base
and less than 25% SL.

Comparisons. Arius paucus differs from A. midgleyi
in gill raker numbers (10-11 on first arch in A. paucus.

versus 15-17 on first arch in A. midgleyi) and eye size
(8.9-15.3% HL in A. paucus versus 12.9-21.8 % HL in
A. midgleyi) (Table 5). No other morphometric characters
distinguish these species, although juvenile colouration
may be important.

Furthermore, there is a clear disjunction in range of
the two species: A. midgleyi distributed in the west (the
Victoria, Katherine, Daly, Ord, remaining Kimberley and
northern river systems including the Alligator); and A.
paucus distributed in the east (the Roper and Flinders
River systems and all other rivers draining into the Gulf
of Carpentaria).

Distribution. River systems of the Roper (Limmen
Bight, Roper, Hodgson. Wilton and Mainoru), McArthur,
Tooganginie Creek, Robertson and Calvert (rare); south¬
east to the Flinders, Gilbert, Staaten and Edward River
systems (Strathgorden Lagoon) on Cape York Peninsula
(Midgley 1979, 1980, 1981, 1982, 1983, 1984, pers.
comm.).

Remarks. Arius paucus and A. midgleyi are most
closely related to Arius leptaspis (Bleeker) and less so,
to Arius latirostris Macleay, a Papuan endemic. The
distinguishing features of these fourtaxa were de.scribed

Table 5. Comparison of key characters between Arius paucus sp.
nov. and A. midgleyi. n = number; x = mean; SD = standard deviation;
GR 1 = rakers on first gill arch; GR 4 = rakers on last gill arch.

Specie.s

variable

Eye diam.

% HI.

Total
GR 1

Total

GR4

A. midgleyi

holotype

13.3

16

18

range, n = 14

I2.9-2I.8

15-17

16-19

X

17.1

15.8

17.3

SD

3.2

0.7

0.9

A. paucus

holotype

9.1

11

13

range, n = 16

8.9-15.3

10-11

11-14

X

11.0

10.7

12.8

SD

1.7

0.5

0.8

142

New catfish from Australia and New Guinea

22-1

20

18

c

0>

o

0 )

E

* 12 -
O
a>

uj 10-

8 -*

100

200

SL(mm)

300

Fig. 13. Comparison of eye size between Arius midgleyi (hollow circles) and A. paucus sp. nov. (solid circles).

by Kailola and Pierce (1988). Arius paucus and A.
midgleyi are common and widespread in river systems
of northern northern Australia, and attain a large size
(to about 28 kg and 1.3 m total length; A. midgleyi)
(Kailola 1990b).

Etymology. From the Latin, paucus, meaning few,
or less. Refers to the new species having fewer gill rakers
and a smaller eye than does A. midgleyi.

ACKNOWLEDGMENTS

1 am grateful to the many collectors and collection
managers of institutions who have sent me material. 1
appreciate the more recent support and assistance of
Helen Larson (NTM), Grant West, Alastair Graham and
Peter Last (CSIRO). Kent Hortle (P.T. Freeport
Indonesia, Papua (Irian Jaya)) enabled my access to west
New Guinea material and facilitated transfer of material.
I thank Hamar Midgley, Gerry Allen and Alan Haines
for their insights.

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Accepted 2 November 2000

144

The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 2000 16: 145-162

Two new genera and three new species of Thylacinidae (Marsupialia) from the
Miocene of the Northern Territory, Australia

PETER MURRAY' AND DIRK MEGIRIAN^

'Muaeum of Central Australia, PO Box 2108,

Alice Springs, NT0871, AUSTRALIA
peter, mu tray @ nt.gov. au

^Museum and Art Gallery of the Northern Territory, GPO Box 4646,
Darwin, NT0801, AUSTRALIA
dirk.megirian@nt.gov.au

ABSTRACT

Three new species and two new genera of Thylacinidae from the Northern Territory of Australia bring the total number
of known mid and late Tertiary species to 11 in eight genera. Tyarrpeciniis rothi gen. et sp. nov. from the Alcoota Local
Fauna (Waite Formation), and Ninibacinus richi sp. nov. and Mutpiiracimis archibaldi gen. et sp. nov. from the Bullock
Creek Local Fauna (Camfield Beds), are relatively small and amongst the more plesiomorphic members of the family.
Phytogeny reconstruction using cladistic methods and biochronological data indicate that a major radiation occurred
within the family in pre-Miocene times. Specialisation in the form of dental carnassiali.sation appears to have evolved
in parallel in at least two crown groups, one of which includes the recently extinct ‘Tasmanian wolf, Thylacinus
cynocephalus. The other, together with all the lineages represented by unspecialised species, apparently did not survive
into the late Miocene. However, insufficient data are available to show what the regional, let alone continental, pattern
of succession was during the Miocene.

Keywords. Marsupialia, Thylacinidae, Miilpuraciniis archibaldi gen. et sp. nov., Tyarrpecinus rothi gen. et sp. nov.,
Nimbacinus richi sp. nov., Alcoota Local Fauna, Bullock Creek Local Fauna, Camfield Beds, Waite Formation,
phylogeny, evolution, Miocene, Australia.

INTRODUCTION

The Thylacinidae is a family of dasyuromorphian
marsupials, the last member of which, the Tasmanian
wolf {Thylacinus cynocephalus (Harris)), was extin¬
guished by bounty hunters in the 1930s. Pliocene and
Pleistocene fossil .species have all been synonymised
with T. cynocephalus (Dawson 1982), and the fossil
record of the family was only extended into the late
Miocene with the discovery at Alcoota of Thylacinus
potens Woodburne, 1967. Thylacinus potens provided
the first indication that thylacinids were a radiated
family, as the species is derived dentally in ways that
precludes its direct ancestry of T. cynocephalus. In more
recent years, the fossil record has been greatly expanded
by new discoveries at Alcoota, Bullock Creek and
Riversleigh (Fig. 1), spanning the ?late Oligocene to late
Miocene (Muirhead and Archer 1990; Wroe 1996;
Muirhead 1997; Murray 1997; Muirhead and Wroe
1998). On the basis of the known diversity of thylacinids
in the central and northern Australian deposits, it might
be anticipated that similar diversity will eventually be
found in correlative deposits in the Lake Eyre and

Tarkarooloo Basins of South Australia. So far, only a
single premolar of unknown affinity has been listed from
Lake Ngapakaldi, South Australia (Kutjamarpu Local
Fauna. Wipijiri Formation of the Lake Eyre Basin)
(Archer 1982). Hypotheses of phylogeny within the
family are currently in a state of flux as each new
discovery adds to the diversity of fossil forms available
for analysis.

Tyarrpecinus rothi gen. et sp. nov. (Alcoota LF, late
Miocene), Mutpuracinus archibaldi gen. et sp. nov. and
Nimbacinus richi sp. nov. (both Bullock Creek LF, mid
Miocene) represent three new species and two new
genera of Thylacinidae, and raise the total number of
known Tertiary species to 11 in eight genera. The new
species are comparatively small members of the family
(small and medium-dog sized, compared to the wolf¬
sized T. cynocephalus, for example). Cladistic analysis
of dental characters resolves them as plesiomorphic
members of the family, closely related to certain
previously described forms (Muirhead 1992, 1997; Wroe
1996; Muirhead and Wroe 1998). Excellent preservation
of the maxilla of Mutpuracinus and a complete dentary
of Nimbacinus richi sp. nov. fill some important gaps in

145

Murray and Megirian

Fig. 1. ?Late Oligocene and Miocene localities that have produced
thylacines.

our knowledge of Tertiary thylacinid morphology. The
three new species and other recently reported late
Oligocene and Miocene finds exemplify a gradual
structural succession towards the genus Thylacinus.

The current consensus is that thylacinids are
dasyuromorphians derived from a dasyurid ancestor,
although a possible affinity with South American
borhyaenoids was a matter of prolonged debate from
1903 into the 1980s (e.g. references in Archer 1982;
Muirhead and Wroe 1998). We accept argument
presented by Wroe (1996) and Muirhead and Wroe
(1998) for the inclusion of Muribacinus gadiyuli Wroe,
1996, and Badjcimis tumhulli Muiihead and Wroe, 1998,
in the Thylacinidae (rather than in the Dasyuridae), and
offer no additional observations on the issue regarding
the thylacinid status of the similarly plesiomorphic
Miitpuracinus archibaldi gen. et sp. nov. Other than to
remark on the assumption that the metaconid reduces
uniformly along the tooth row in thylacinids, we support
the re-diagnosis of the family presented in Muirhead and
Wroe (1998).

METHODS

Adult dental terminology (Flower-Luckett) recognises
PI-3, Ml-4 (Flower 1869, Luckett 1993); all Archer
(1978, 1982) terminology in cited literature has been
converted. Specimens are Northern Territory Museum
(NTM) Palaeontological collection unless designated
QMF (Queensland Museum, Fossil collection). The
thylacinid-producing formations referred to are not
precisely dated, and their ages can at present only be
loosely expressed in terms of the standard geological
timescale. Con.sequently, modifiers such as ‘early’ and
‘late’ are left uncapitalised when attached to the standard

Tertiary epochs so as not to imply a geochronological
precision that does not exist. Stage-of-evolution
biochronological concepts and terminology follow
Megirian (1994).

Key to anatomical abbreviations.

A-E Stylar cusps

AC Anterior cingulum or precingulum

ALV Alveolus

ANP Angular process

CCR Centrocrista

CON Condyle

CRN Reception notch for canine

END Entoconid

HLD Hypoconulid

HYD Hypoconid

IFO Incisive foramen

lOF Infraorbital foramen

MAE Mandibular foramen

MCE Metaconule

MCR Submasseteric crest

MEC Metacone

MED Metaconid

MEF Mental foramen

MFO Masseteric fossa

MJS Maxillo-jugal suture

PAC Paracone

PAD Paraconid

PAF Palatal fenestra

PCD Precingulid

PCL Protoconule

PMF Posterior mental foramen

PMS Premaxillo-maxillary suture

PRC Protocone

PRD Protoconid

PSD Parastylid

SYSTEMATIC PALAEONTOLOGY

Order Dasyuromorpbia Gill, 1872
Superfamily Dasyuroidea Goldfuss, 1820
Family Thylacinidae Bonaparte, 1838
Miitpuracinus gen. nov.

Type species. Miitpuracinus archibaldi sp. nov. by
monotypy.

Diagnosis. Small thylacinid with strong expression
of stylar cusps on M''^; large, posteriorly directed P^;
infraorbital foramen not in contact with jugal and situated
over posterior root of M'. Size similar to holotype of
Muribacinus gadiyuli (QMF30386); lower position of
zygomatic root, more anterior position of infraorbital
foramen relative to the teeth (i.e. over anterior root of
M'); more posteriorly-directed premolar crowns; larger
posterolingual cuspule on P’; M^ narrower relative to
length; larger stylar cusp D on M'"^ and presence of stylar

146

Fossil thylacines from the Northern Territory

cusp C and E on M'’^; paracone more reduced relative to
metacone on M'"^; M 4 metaconid more reduced; narrower
cingulids and talonids on lower molars. Differs from
Badjcimis turnhuUi in which the jugal closely approaches
the infraorbital foramen opening above P'; the upper
premolar crowns are more slender, taller; M' lacks stylar
cusps on anterior lobe, preparacrista parallel to long axis
of tooth row and with minute stylar cusp D. Differs
from Nimhacinus dicksoni Muirhead and Archer, 1990,
which is significantly larger; the infraorbital foramen is
within the jugal and situated over anterior root of M^; in
which conules are more strongly expressed and
distinctly longer than Differs from Wabulacinus ridei
Muirhead, 1997, Ngamalacinus timmulvaneyi Muirhead,
1997, and species of Thylacinus in showing less
reduction of metaconids on M 2 - 4 ; absence of carnassial
notch in cristid obliqua and less reduetion of entoconid
and protocone.

Etymology. Miitpura is the tribal designation of the
Aboriginal people living in the Camfield district [=
Tjambutjamhulani - Tindale 1974] + kynos (Gr.) ‘dog’.

Mutpuracinus archihaldi sp. nov.

(Figs 2-4, Table I)

Diagnosis. As for genus.

Type material. HOLOTYPE - NTM P907-3 (Blast
Site), left maxilla with P--M'‘, missing canine and P'.
PARATYPE - NTM P9612-5 (Top Site), left dentary
fragment with M 3 . 4 , missing ascending ramus and
anterior part of horizontal ramus.

Referred material. All NTM: P9464-120 (Top Site),
right premaxilla with I'"' alveoli; P9464-119 (Top Site)
posterior fragment of horizontal ramus of right dentary
preserving submasseteric crest, part of condyle and part
of angular process; P87108-10 (Blast Site), isolated right
M4.

Type locality. ‘Blast Site’, Bullock Creek, Northern
Territory, Australia. Low limestone hill 1 km east of type
section of Camfield Beds; ISDSl’E, 17° 07’S; Wave
Hill 1:250 000 Map Sheet, SE/52-8.

Lithic unit, fauna and age. Camfield Beds, Bullock
Creek Local Fauna, middle Miocene on the basis of
marsupial stage-of-evolution biochronology (Woodburne
et al. 1985; Murray et al. 2000). Both fossil quarries
(sites) listed above are in the vicinity of the type locality
(Murray and Megirian 1992: fig. 2).

Description. Premaxilla (Fig. 2A,B). Edentulous,
13.0 mm anteroposteriorly by 11.5 mm dorsoventrally,
right premaxillary fragment P9464-I20 is missing the
ascending process. Four incisor alveoli are present: I' is
largest; are narrower; and 1 “ is slightly smaller than
I' but larger than P'^. The incisor arcade is nearly straight
and less acutely angled relative to the midline than in
Dasyurus hallucatus (Dasyuridae), for example. A large
reception socket for the lower canine measures 4.5 mm
anteroposteriorly by 6.5 mm dorsoventrally. The anterior
margin of the right incisive foramen indicates a narrow,
slot-like structure.

Maxilla (Fig. 3A,B). P907-3 preserves alveoli for
upper canine and P' and remainder of left cheek tooth

Table 1. Measurements (mm) of cheek teeth. L= length; W = width; AW = anterior width; PW = posterior width.

Mutpuracinus archihaldi gen, et sp. nov.lower cheek teeth

Pi

P2

Pi

Ml

M2

M.,

M4

L

W

L

PW

L

AW

PW

L

AW

PW

L

AW

PW

L

AW

PW

L

AW

PW

P9612-5

-

5.7

3.6

2.9

5.9

3.3

2.3

P87108-10

-

-

-

5.3

2.9

2.2

upper

cheek teeth

P'

P^

P’

m'

M^

M^

M^

L

W

L

PW

L

AW

PW

L

AW

PW

L

AW

PW

L

AW

PW

L

AW

PW

P907-3

-

-

4.5

1.8

5.5

2.4

3.0

5.8

4.1

6.2

5.7

5.0

6.5

5.4

5.7

7.0

6.0

4.7

3.5

Nimbacinus richi sp.

nov.

lower cheek teeth

Pi

P2

Pi

Ml

M2

M.,

M4

L

w

L

PW

L

AW

PW

L

AW

PW

L

AW

PW

L

AW

PW

L

AW

PW

P%12-4

5.0

2.0

6.1

2.8

7.2

2.1

3.1

7.0

3.3

4.2

8.3

4.5

4.4

8.2

5.0

4.0

8.7

4.2

2.5

P8695-92

-

-

5.8

2.8

-

-

-

6.2

2.9

3.2

-

-

-

-

4.3

3.6

7.2

-

3.0

P904-7

-

7.4

4.1

4.3

8.0

4.5

4.1

7.9

4.1

2.9

P85553-3

4.5

1.7

6.0

2.8

-

-

-

6.9

-

4.0

-

-

-

-

-

-

-

-

-

Tyarrpecinus rothi gen. et sp,

. nov.

upper cheek teeth

P'

p*

P’

m'

M^

M^

M^

L

W

L

PW

L

AW

PW

L

AW

PW

L

AW

PW

L

AW

PW

L

AW

PW

P9821I

-

-

6.5

2.5

-

-

-

4.8

7.0

7.3

-

-

-

7.7

7.9

9.8

-

-

-

Murray and Megirian

Fig. 2. Mutpuracinus archibaldi gen. et sp. nov. Referred right preinaxilla (P9464-120) in A, lateral, and B, occlusal views. Paratype left
dentary fragment (P9612-5) in C, lateral view; D, medial, E, lateral and F, occlusal, views of molars M3.4, Scale bars in mm.

148

Fossil thylacines from the Northern Territory

PAF

Fig. 3. Mutpuracinus archihaldi gen. ct .sp. nov. holotype left maxilla (P907-3) in: A. lateral view; B, occlusal view; and C, detailed
occlusal view of molars M'“'. Scale bars in mm.

row; premaxillary contact preserved anterodorsally and
nasal contact preserved dorsally; posterior (lacrimal)
process missing; jugal process intact. Canine alveolus
planoconvex, about 3.5 mm wide by 5.5 mm antero-
posteriorly. Alveolus for P' situated immediately
posterior to the canine alveolus, about 3.5 mm long,
oriented slightly obliquely to succeeding premolars. A
diastema 4.0 mm long separates P' from P^. Crown of P-
4.6 mm long, separated from P^ by narrow, but distinct,
slot that, while only 0.7 mm wide, is suggestive of

rudimentary diastema. P^ much larger than P‘ with crown
projecting well below occlusal line of the other cheek
teeth. Labial margin of molar row gently arcuate.
Interdental embrasures present between M'becoming
increasingly larger and distinct posteriorly. Anterior
margin of posterior palatal fenestra preserved at the level
of PVM'. Palatal processes thin posteriorly, thickening
anteriorly in front of fenestral margin towards PL Jugal
contact a shallow, crescentic depression extending to
within about 2.5 mm of infraorbital foramen dorsally

149

Murray and Megirian

Fig. 4. Comparison of maxillae of A, Mutpuracinus archihaldi gen.
et sp. nov. and B, Muribacinus gadiyuli drawn to the same scale,
showing differences in the position of the infraorbital foramen
relative to M'. (B reversed: after Wroe 1996: fig. I.)

and about 4.0 mm ventrally. Infraorbital foramen large,
about 5.0 mm vertically and 2.5 mm mediolaterally (Fig.
4), opening behind well-defined circular infraorbital
fossa, about 12 mm in diameter. The posterior margin
of the foramen is aligned with the distal root of M'. A
shallow depression extending anterodorsally from
infraorbital fossa is bounded dorsally by very distinct,
sinuous groove terminating about 12 mm above level of
canine alveolus. External surface of the canine alveolus
bulges conspicuously outwards from surrounding
contours of maxilla, resulting in a wide concavity in the
vertical profile of specimen. Lateral surface of alveolar
bulge rugose, with sharply defined posterior crest.

Incisors, Alveoli only (Fig. 2A,B): I' largest,
broadly oval, 2.0 mm wide, 2.1 mm anteroposteriorly; F
triangular, 1.5 mm wide, 1.8 mm long, slightly wider
than P; P narrow, slot-like; 1.3 mm wide, 2.1 mm long;
P, ovo-triangular, 1.8 mm wide, 2.0 mm antero¬
posteriorly.

Canine. Alveolus only (Fig. 2A,B), 5.5 mm antero¬
posteriorly; 3.5 mm mediolaterally; planoconvex shape;
root socket 14.0 mm deep, angled -30° to palatal plane.

Premolar, P' (Fig. 3A,B). Alveolus only, 3.5 mm
anteroposteriorly, anterior root socket 1.3 mm diameter;
angled about 12° from plane of P^’^.

(Fig. 3A,B). Crown 4.5 mm long, 1.8 mm
maximum width; low anterior basal crest, concave
anterior margin, tip directed posteriorly; slight
posterolingual expansion and small posterobasal cuspule;
posterior root larger than anterior.

(Fig. 3A,B). Much larger than P^, 5.5 mm
anteroposteriorly by 3.0 mm posterior width; low
anterobasal crest; concave, rounded anterior margin, tip
directed posteriorly; convex, crested posterior margin;
low, well-developed posterolingual cuspule developed
on thick basal cingulum, terminating in elevated postero¬
median cuspule; posterolabial cingulum poorly developed.

Molar, M' (Fig. 3C). Paracone situated much more
labially than metacone, very short transverse preparacrista;
centrocrista nearly parallel to axis of tooth row; metacone
large, premetacrista nearly transverse. Talon broad antero¬
posteriorly and short transversely; small metaconule and
protoconule present; protocone large. Stylarcusp B closely
adpressed to paracone; higher but slightly smaller than
the latter; vestigial stylar cusp C situated at base of stylar
cusp D, a large conical cuspule occupying about half the
posterior lobe of the crown. Well-developed ectoflexus
present, buccal occlusal profile of crown distinctly lobate.
Low swelling in the position of stylar cusp E (heavily
worn); weak precingulum present with shallow inter-
proximal notch for PL

M- (Fig. 3C). Larger, more equi-triangular crown;
paracone extends much further lingually than in M';
short, transverse preparacrista extends to stylar cusp B;
stylar cusp C well-developed, about equal in size to B;
stylar cusp D large, conical, occupies slightly less than
half of metastylar lobe of crown, slightly smaller but
nearly equal in height to metacone; small, distinct stylar
cusp E situated midway between D and metastylar tip.
Metacone much larger than paracone. Talon broad, but
more V-shaped than in M', conules small, protocone
narrow. Precingulum well-developed with notch for
metastyle of M'.

M^(Fig. 3C). Larger than M^ in occlusal aspect,
significantly wider transversely, equal in length labially
and slightly longer posterolingually; stylar cusp B
reduced; stylar cusp C well-developed but low; stylar
cusp D large, triangular, but considerably reduced in
height and transverse width; tiny cuspule present in
position of stylar cusp E. Ectoflexus strong, parastylar
and metastylar tips slender, lobate. Preparacrista long,
straight, transverse; paracone less reduced relative to
metacone; postmetacrista longer than in M^. Talon
narrow, distinctly V-shaped, small conules present, more
distinct than in M-; protocone reduced. Precingulum
longer than in M^ with V-shaped accommodation notch
for M’ metastyle.

M''(Fig. 3C). Tip of parastyle situated lingual to tip
of M’ metastyle; preparacrista slightly convex, about
equal in length to M^; metacone greatly reduced,
Protoconule better developed than on other molars;
metaconule absent; talon narrow; preprotocrista weak.
A tiny stylarcusp is situated midway between parastylar
tip and base of metacone.

Meristic gradients, M' "' (Fig. 3C). Preparacrista:
increases posteriorly, M^"'* about equal; postmetacrista:

Fossil thylacines from the Northern Territory

increases posteriorly except M'' where absent; paracone
height: increases posteriorly M''^, M"* equals or slightly
lower than M^; metacone height: increases posteriorly,
except where reduced; protocone height: decreases
posteriorly; talon surface: increases posteriorly M'^
decreases posteriorly stylar cusp B size: decreases
M'■*; stylar cusp C: increases M'"^, absent M"*; stylar cusp
D: decreases M' \ absent M''; stylar cusp E: decreases
M''^, possibly absent M'*.

Dentary (Fig. 2C). Medial surface flat, digastric fossa
faint, shallow; subalveolar fossa, lateral crest well-
defined. Masseteric fossa deep with prominent shelf-like
submasseteric crest. Depth of horizontal ramus below
M 4 14.0 mm; thickness of inferior border at same level,
5.5 mm.

A/j (Fig. 2C-F). Paraconid and protoconid bulky;
metacristid nearly perpendicular to long axis of crown;
talonid distinctly narrower than trigonid; metaconid
large, higher than paraconid, bulky at base. Entoconid
small but distinct; as high as hypoconulid; hypoconulid
merges labially with postcingulid. Hypoconid lowest
cusp on crown; pre- and postcingulids present but not
strongly developed. Cusp heights: protoconid>
metaconid> paraconid> entoconid= hypoconulid>
hypoconid.

M^fFig. 2C-F). Cusps of trigonid more slender,
talonid greatly reduced compared to Mj; metaconid and
paraconid similar in height to M 3 but more slender.
Entoconid reduced to thickening of preentocristid, lower
than hypoconulid; hypoconulid high pointed cusp,
continuous labially with postcingulid. Pre- and
postcingulids not strongly developed. Cusp heights:
protoconid> metaconid> paraconid> hypoconulid>
entoconid> hypoconid.

Meristic gradients M3.4 (Fig. 2C-F). protoconid,
paraconid and metaconid decrease in bulk posteriorly;
talonid decreases in width posteriorly; entoconid
decreases in size posteriorly; angle of paracristid to long
axis of crown more acute posteriorly.

Etymology. Named after Ian Archibald in honour of
his contributions to the natural hi.story of the Northern
Territory.

Niinbacinus Muirhead and Archer, 1990

Type species. Niinbacinus dicksoni Muirhead and
Archer, 1990, by original designation.

Niinbacinus riclii sp. nov.

(Fig. 5, Table 1)

Niinbacinus dicksoni - Muirhead and Archer 1990:
fig. 3 (in part).

Diagnosis. Medium-sized thylacinid with narrow
diastemata between premolars, P 3 much larger than P 2 ;
lower molars with well-developed metaconids and
entoconids. Differs from Niinbacinus dicksoni in
possessing well-developed metaconids on M 2-4 in

conjunction with reduced metaconid on Mi and large
conical entoconids on M 1 . 3 ; differs from Ngamalacinus
timinulvaneyi and Badjcinus turnbulli in lacking a
camassial notch in the hypocristid, and from Wabulacinus
ridei Muirhead, 1997, and species of Thylacinus in
having large metaconids.

Type material. HOLOTYPE - NTM P9612-4 (Top
Site), right dentary with P1-M4; canine, incisors missing.
PARATYPE - NTM P85553-3 (unrecorded quarry),
fragment of right dentary with P 1.2 and M| (also a
paratype of N. dicksoni Muirhead and Archer, 1990).

Type locality. ‘Top Site’, Bullock Creek, Northern
Territory (additional data as for Mutpuracinus archibaldi).

Referred material. NTM P8695-92 (Blast Site),
horizontal ramus of left dentary retaining P 2 , Mi, M 3.4
(M 3 lacking paraconid); P904-7 (Top Site), left dentary
fragment retaining M 2 - 4 .

Lithic unit, fauna and age. Camfield Beds, Bullock
Creek Local Fauna, mid Miocene (additional information
as for Mutpuracinus archibaldi).

Description. Dentary (Fig. 5A,B). P9612-4 is about
25% smaller than Thylacinus inacknessi Muirhead, 1992,
but relatively stouter anteriorly and more bowed along
inferior border; anterior margin of ascending ramus more
erect, condylar notch wider, more invasive. Diastema
between P 2 -P 3 very short, approximately 1.4 mm; large
mental foramen under posterior root of Pi, small posterior
mental foramen under posterior root of Mi. Masseteric
crest well developed, flange-like; masseteric fossa
relatively shallower and condyle; condyle transversely
elongate (14.0 mm wide), slightly flattened dorsally.
Mandibular foramen situated 22.0 mm from distal edge
of condyle; depth of ramus below M 4 is 15.6 mm;
thickness of inferior border at same level is 7.0 mm.

Incisors, I/.jiFig. 5A,B). Three incisor alveoli present
anteromedial to canine alveolus, arranged in a triangle,
I 3 ventrolaterally, I 2 lingually and L above I 2 but aligned
vertically with LTs socket smallest (1.3 mm x 1.5 mm)
followed by I 2 (1-3 mm x 2.5 mm) with L largest (1.5
mm X 3.0mm); lateral width of all three sockets about 3
mm, vertical extent about 4.8 mm.

Canine (Fig. 5A,B). Alveolus only (7.4 mm vertical,
4.0 mm mediolateral) oval socket, anterolaterally
directed.

Preinolars, P1.3 (Fig. 5A,B). P| oriented obliquely
(approximately 15°) to long axis of other premolars,
much smaller than P 2 (5.0 mm long, 2.0 mm wide) with
low, recurved protoconid and very elongated posterior
shelf lacking distinct cuspule. Protoconid of P 2 much
higher, longer than Pi; small anterobasal and posterobasal
cuspules present (6.1 mm long, 2.8 mm wide); P 3 ,
anterobasal cuspule more defined, posterior shelf more
talonid-like and elevated distally with small postero-
lingual and large posterobasal cuspules (7.2 mm long,
3.1 mm wide). Protoconids of all premolars directed
posteriorly.

Murray and Megirian

Fig. 5. Nimbacinus richi sp. nov. holotype right dentary (P9612-4) in: A, lateral view; B, occlusal view; C, molars M 1-4 in occlusal view;
and D, molars Mm in lateral view.

152

Fossil thylacines from the Northern Territory

Molar, M/(Fig. 5A-D). Subrectangular crown, rather
truncated anteriorly and markedly so posteriorly; talonid
wider than trigonid; short paracristid slightly angled
lingually, paraconid low, broad, conical with short
preparacristid terminating in small parastylid; protoconid
central, crown shallowly waisted on either side;
posterolingual corner of talonid forming right angle;
entoconid prominent, posteriorly-directed, conical cusp
about 1.5 mm in diameter, separated from base of
metaconid by deep, transverse groove; entoconid much
larger and higher than hypoconulid; hypoconid large,
triangular, lowest cusp on talonid. Small metaconid
represented by low, broad triangular bulge on postero¬
lingual side of protoconid. Pre- and postcingulids thick,
well developed anterolabially, terminating above middle
of anterior root; postcingulid ascends to just below
hypoconulid. Cusp heights; protoconid > metaconid >
entoconid > paraconid > hypoconulid = hypoconid.

MpCFig. 5A-D). Trigonid somewhat compressed,
much longer and slightly wider than talonid; paracristid
slightly less obtuse than in Mi; metaconid much larger
and more differentiated from protoconid; small carnassial
notch present in metacristid; entoconid slightly larger
and higher than in Mi; extending high above smaller,
flat, triangular hypoconulid and closely adpressed to
parastylid of M 3 . A short preentocristid developed.
Hypoconulid extending distolabially a short distance
beyond the entoconid where it is accommodated by
distinct C-shaped notch between precingulid and
parastylid. Hypoconid a broad, triangular cusp much
lower than hypoconulid. Crislid obliqua ascending base
of protoconid for short distance. Cusp heights:
protoconid > metaconid > paraconid > entoconid >
hypoconulid > hypoconid.

Afj(Fig. 5A-D). Protoconid more slender than in M 2 ,
paraconid higher, slightly more erect, metaconid also
higher, more differentiated, but more slender than in
preceding molar; talonid shorter and narrower relative
to trigonid than in M 2 . Entoconid reduced to small spur¬
like cusp on anterolingual margin of enlarged, triangular
hypoconulid; hypoconulid projects distally into
accommodation notch in M.i. Postcingulid reaches labial
side of hypoconulid; hypoconid situated much lower than
in M 2 and considerably reduced; cristid obliqua ascends
posterior face of protoconid about halfway up to
carnassial notch. Cusp heights: protoconid > metaconid
> paraconid > hypoconulid > entoconid > hypoconid.

A/.i(Fig. 5A-D). Paraconid directed slightly more to
lingual side than in M 3 ; para- and metacristids blade¬
like, with deep carnassial notches; metaconid greatly
reduced though fully differentiated from protoconid;
talonid width about half that of preceding molar;
entoconid reduced to thickening of the preentocristid,
hypoconulid formed as in preceding molar, but smaller,
succeeded anteriorly by strong posthypocristid;

po.stcingulid vestigial. Hypoconid small, situated low on
posterolabial margin of talonid basin; talonid basin open
labially; cristid obliqua strongly developed, ascends
posterior face of protoconid to base of carnassial notch
in metacristid. Cusp heights: protoconid > paraconid >
metaconid > hypoconulid > entoconid > hypoconid.

Meristic gradients, M 1.4 {Fig. 5A-D). Protoconid
decreases in bulk posteriorly; paraconid increases in
height and obliquity to long axis of crown posteriorly;
metaconid increases markedly in bulk from Mi to M 2
then gradually decreases; metaconid gradually increases
in height to M 3 then decreases in M^; entoconid increases
in size and height to M 2 then decreases M 3 to M 4 ;
hypoconulid increases in height po.steriorly; hypoconulid
increases in size posteriorly to M 3 then decreases in M 4 ;
talonid increases in width from M, to M 2 then decreases
from M3 to M4.

Remarks. Association of referred specimens of lower
molars with the uppers in Nimhacimis dicksoni was
problematic (Muirhead and Archer 1990). Muirhead and
Archer (1990) note several differences between the
hololype Mi (QMF16802, ‘Henk’s Hollow’, Carl Creek
Limestone) and the Bullock Creek Local Fauna specimen
(P85553-3). The latter specimen shows a stronger
entocristid and a more angular posterolingual corner,
resulting in greater posterior crown width and a more
rounded contour of the anterolingual surface. Although
very worn, the entoconid of P85553-3 (difficult to see
in their illustration) is somewhat larger and more distinct
than that of the holotype. The same differences are more
emphasised in less-worn P9612-4 in which a large,
conical entoconid is present. These distinctions appear
to be consistent and therefore not readily attributable to
individual variation. More important however, is the
status of paratype QMF16809 (Site D locality), identified
as a right M 2 (their M 3 in Archer (1978, 1982)
terminology). If this specimen, that has a greatly reduced
metaconid, represents N. dicksoni (as they argue at some
length), then P96I2-4, which has a large metaconid on
M 2 , could not represent this species. While a species-
level distinction could be made on the basis of this
technicality alone, the subsequent discovery of several
similar-sized thylacinid species increases the probability
that QMFI6809 might not represent N. dicksoni, and
therefore a systematic distinction made on this basis
could be phylogenetically misleading. While the
differences in M| morphology alone are sufficient to
indicate the existence of another species of the genus
Nimhacimis, this proposed revision leaves the states of
the M 2.4 metaconids of N. dicksoni in doubt.

Etymology. Named in honour of Thomas Rich for
his many important contributions to vertebrate pa¬
laeontology in Australia. Tom introduced us to the
Bullock Creek Local Fauna of the Northern Territory in
1984.

153

Murray and Megirian

Tyarrpecinus gen. nov.

Type species. Tyarrpecinus rothi sp. nov. by
monotypy.

Diagnosis. Medium-sized thylacinid with transversely
narrow, elongate M' and strong ectoflex and elongation
of metastylar spur on M^; differs from Muribacinus
gadiyuli and Mutpuracinus archihaldi in larger size,
narrower M', more elongate and slender metastylar wing;
wider angle between preparacrista and postmetacrista;
more closely approximated paracone and metacone on
differs from Badjcinus turnbulli in form of premolar
crown; in possessing stylar cusps and preparacrista on
the anterior lobe of M'; more reduced stylar cusp B and
relatively larger stylar cusp D on M’; differs from
Nimbacinus dicksoni and Ngamalacinus timmulvaneyi
in having a more slender, elongated M' with straighter
centrocrista and more reduced parastylar spur;
metastylar spur more elongate; narrower trigone basin,
metacone larger relative to paracone; conules where
present, extremely reduced; differs from Wabulacinus
ridei in more transverse orientation of preparacrista and
retention of stylar cusps B and D on M'; differs from
Thylacinus macknessi in reduction of precingulum but
retention of stylar shelf, otherwise showing conservative
Thylacinus-Vikc apomorphies.

Etymology. Eastern Arrente dialect tyarrpa ‘cracked’
-I- Kynos (Gr.) ‘dog’. Tyarrpa, pronounced char-puh,
(Henderson and Dobson 1994), is in reference to the state
of preservation of the type material.

Tyarrpecinus rothi sp. nov.

(Fig. 6, Table 1)

Diagnosis. As for genus.

Type material. HOLOTYPE - NTM P98211 (Main
Pit), fragment of left maxilla with P\ M''^'; M' and M’
complete but assembled from fragments; M^ and M‘'
represented by talons only; approximately 75 small
fragments consisting of isolated roots and bone and
enamel fragments.

Type locality. Alcoota Scientific Reserve, Northern
Territory, Australia. 22°52' S, 134‘’52' E; Alcoota
1:250,00() Map Sheet, SF/53-10.

Lithic unit, fauna and age. Waite Formation,
Alcoota Local Fauna, late Miocene on the basis of
marsupial stage-of-evolution biochronology (Woodburne
et al. 1985; Murray et al. 1993, Murray et al. 2000).

Description. The Tyarrpecinus rothi sp. nov.
holotype, P9821I, was reconstituted from a con¬
centration of small fragments of bone and teeth that may
represent the contents of a crocodilian coprolite. Many
of the fragments show chemical erosion and are coated
with a layer of calcite. Part of the left maxilla has been
assembled and, except for some conspicuous cracks and
a few missing chips of enamel, the M‘ and the M^ have
been adequately restored for description.

Maxilla. Maxilla contains P- and anterior alveolus of
P^. A 4.5 mm long section of the diastema anterior to P^
does not reach the P‘ alveolus. Palatal process extends
to median palatal suture and is about 7.0 mm wide
immediately anterior to P^. P’ alveolus situated
immediately posterior to P- and no diastema present.
Anterior root socket of P^ is about twice diameter of that
of P^.

Premolar, P-. P- crown low and elongate basally.
Cusp points posteriorly and anterior profile slightly
convex. Posterior margin of crown distinctly concave.
Surface of posterior shelf obscured by an obdurate calcite
encrustation. Posterior root about twice as wide mesio-
distally as anterior root. Crown length about 6.5 mm;
width, 2.5 mm.

P\ Alveolus only; at least 7.3 mm total length
(hypertrophied); anterior root socket about 3.0 mm long
and 2.0 mm wide; posterior root socket at least 4.0 mm
long, width unknown.

Molar, M‘. Reconstructed from three fragments;
heavily worn and thickly coated with calcrete. Crown
elongated, transversely narrow; short, distinct pre¬
cingulum pre.sent; deep cleft divides crown into two
lobes, shallow but distinct ectoflex. Stylar cusp B about
same size as paracone; metacone about half again larger
than paracone. Postmetacrista .straight, angles slightly
lingual to postprotocrista. Preparacrista short, extends
transversely to long axis of crown to stylar cusp B.
Centrocrista obtuse, essentially parallel to tooth row;
stylar cusp D much smaller than metacone, closely
situated distolabially and connected to it by low crest
with conspicuous groove labial to metacone and mesial
to stylar cusp D; small stylar cusp E heavily worn, but
faintly visible. Talon short transversely with U-shaped
profile. A very small metaconule represented. Cusp
heights: metacone > stylar cusp B > stylar cusp D >
paracone > protocone.

M\ Talon only, larger than .M' talon and more V-
shaped. Basin shallow, heavily worn on mesial side;
conules absent; crest of base of metacone confluent with
postprotocrista.

MT Complete crown and roots, reconstructed from
four fragments, moderate wear (slight misalignment of
fragments due to missing slivers of dentine at contacts).
Precingulum short, complete; parastylar spur much
shorter than metastylar spur, strong ectoflexus; stylar
cusp B connected to paracone by convex, mesially-
angled preparacrista; stylar cusp C reduced, but present;
low elongated stylar cusp D produces conspicuous labial
bulge; distinct, elliptical thickening ol enamel in region
of stylar cusp E, but no definite cusp structure visible.
Metacone much larger and higher than paracone. Angle
of centrocrista about 90“; angle between preparacrista
and postmetacrista slightly wider than in Nimbacinus
dicksoni and Ngamalcinus timmulvaneyi. Talon narrow.

154

Fossil thylacines from the Northern Territory

Fig. 6 . Tyarrpecinus rothi gen. et sp. nov. holotype left maxilla (P98211). Maxillary fragment in A, lateral and B, occlusal views; C,
reconstructed molar tooth row (M,. 4 from left to right) in occlusal view. Scale bars in mm.

V-shaped, very faint protoconule evident, metaconule
absent. Cusp heights: metacone > paracone > stylar cusp
D > ?stylar cusp E = stylar cusp B > stylar cusp C >
protoconule > protocone.

Talon only; greatly reduced compared to M^;
narrow, V-shaped, with low protoconule.

Etymology. Named in honour of Karl Roth for his
contributions to the natural history of Central Australia

and long career as Custodian of the Alice Springs branch
of the Museums and Art Galleries of the Northern
Territory, from which he recently retired.

PHYLOGENY RECONSTRUCTION

Muirhead and Wroe (1998) analysed shared, derived
character states amongst five thylacinid genera to

155

Murray and Megirian

reconstruct phylogeny in the family. Of 32 characters
analysed, 24 are dental, with the remainder pertaining
to the cranium. As a preliminary analysis, the states of
the three newly described species plus Muribacinus
gadiyuli Wroe, 1996, and Thylacinus megiriani Murray,
1997, were scored and added to their matrix (Table 2A -
necessarily omitting the eight cranial characters) and
analysed with Hennig86 version 1.5 (Farris 1988). One

Table 2. Thylacinid character expressions for phylogenetic analysis:
A, following Muirhead and Wroe (1998), cranial characters 1, 2
and 4-9 omitted; B, preferred matrix as discussed in the text.
Character definitions for matrices A and B given with Figures 7
and 8 respectively.

A

3:

•a

c

^ ^ Jv *2? ^

53

c

^ ^ S 5 2 ^

5 .

I

C5 ^ ^

Sr

^ ,5

*S *5 S a

f-, t-, h, s.

3

0

0

0

1

7

0

1

7

0

7

1

1

I

10

0

1

1

1

7

2

1

2

I

1

2

3

3

11

0

1

1

1

7

2

2

3

3

4

4

4

4

12

0

0

0

0

7

0

0

1

1

0

1

2

2

13

0

0

0

0

7

2

1

2

1

2

2

3

3

14

0

0

0

0

?

1

1

2

2

2

2

2

2

15

0

1

1

1

7

1

1

2

2

2

2

2

2

16

0

0

0

0

7

3

0

1

2

1

1

1

1

17

0

1

1

1

7

1

1

2

2

2

2

2

2

18

0

0

0

0

1

1

0

7

0

0

0

0

0

19

0

1

1

1

1

1

2

7

3

4

4

7

4

20

0

1

1

2

0

1

0

7

4

3

3

7

3

21

0

0

0

0

0

0

1

7

0

0

0

7

0

22

0

0

7

0

0

0

0

7

1

0

0

7

0

23

0

0

7

0

1

0

7

7

7

1

1

?

1

24

0

1

1

1

1

1

2

7

3

4

5

7

5

25

0

0

0

0

1

1

1

7

0

0

0

7

0

26

0

0

0

0

0

0

1

7

0

1

1

7

1

27

0

1

1

1

2

1

2

7

1

3

3

7

3

28

0

0

0

0

0

1

1

7

0

0

0

7

0

29

0

1

1

1

2

1

2

7

2

3

3

7

3

30

0

0

7

1

1

0

7

7

1

1

1

7

1

31

0

?

0

0

0

0

1

7

1

I

1

7

1

B

a?

u 0

2 ^

OT

JS s:
U Ct-

1

0

0

1

2

2

2

2

7

3

3

4

7

4

2

0

0

0

0

0

1

1

0

0

0

0

0

0

3

0

0

0

0

0

0

0

1

1

1

1

1

1

4

0

0

0

0

0

0

0

0

1

1

0

0

0

5

0

0

0

0

0

0

0

1

0

0

1

1

1

6

0

0

0

0

0

0

0

0

1

1

0

0

0

7

0

0

0

0

0

0

0

0

0

0

0

I

I

8

0

0

0

0

0

0

0

1

1

1

1

1

1

of eight equally parsimonious hypotheses selected for
discussion purposes is shown as Figure 7A, and the
Nelsen consensus tree is shown as Figure 7B.

In Figures 7A and 7B, the previously analysed species
branch consecutively in the same order as illustrated in
Muirhead and Wroe (1998). Of the new species,
Mutpuraciniis archibaldi aligns with the plesiomorphic
Muribacinus gadiyuli at the base, and Tyarrpecinus rotlii
branches off after Ngamalacinus ridei and Wabulacinus.

The emphasis in Muirhead and Wroe (1998) on
ordered multistate characters, postulating broad
morphoclines for the majority of character states, tends
to relegate resulting trees to a hierarchy of structural
grades. Notwithstanding, there are some promising
synapomorphic states that suggest clade formation within
the consecutively branched dendrogram. These include
the synapomorphic occurrence of a carnassial notch in
the hypocristid of Badjcinus and Ngamalacinus
(Character 28 in Table 2A) and mutual loss of stylar
cusp B accompanied by extreme reduction of the stylar
shelf in Wabulacinus ridei and Thylacinus macknessi
(Character 11); which, in combination with the strongly
morphoclinal expression of metaconid reduction
(Characters 18-19) result in the more resolved hypo¬
theses (Fig. 8 based on the character matrix in Table 2B)
preferred here.

Muirhead and Wroe (1998) divide the character of
metaconid reduction into two sets. Character 18, in which
a differential absence of metaconid on M, and presence
on the other molars is scored autapomorphically among
thylacinids i'or Badjcinus, and Character 19 in which the
size of metaconids on M 2 -t is scored as an independant
multistate set. The recognition of a unique differential
reduction of the metaconid in Badjcinus is apparently
based on the assumption of uniformly reducing
metaconids in Nimhacinus dicksoni, as indicated by the
D-Site M 2 paratype, QMFI6809.

However, Nimbacinus richi shows a similar degree
of differential metaconid expression to that of Badja-
cinus, in which the cusp is nearly obsolete on Mi, but
well-differentiated and large on M 2 . 3 , then reduced on
M 4 . Thus, while the extent of metaconid reduction on
M| in Badjacinus is more advanced than in Nimbacinus
richi, we do not consider the character of differential
expre.ssion of the metaconid to be unique to Badjcinus
(within the Thylacinidae). The states ot metaconids in
N. richi also negate the proposition that the expression
gradient of the metaconid along the molar row is
typically uniform in thylacinids. In any case, the
differential reduction of metaconids in Badjcinus
turnbulli, Nimbacinus richi and Ngamalcinus timmulvaneyi
may be the rule rather than the exception, and as such,
the basic similarity of the differentially reduced states
of the metaconids in these species is probably more
meaningful for thylacinid phylogeny than the autapo-
morphic absence of a metaconid on M' in Badjcinus.

Fossil thylacines from the Northern Territory

A

Dasyurid outgroup
Muribacinus gadiyuli
Mulpuracinus archibaldi
Badjcinus turnbulli
Nimbacinus dicksoni
Nimbadnus lichi
Ngamaladnus timmulvaneyi
Wabuladnus ridei
Tjarrpednus rothi

€

Thylacinus macknessi

i—

- Thyladnus potens

1— Thyladnus megiriani

B

Thyladnus cynocephalus

€

Dasyurid outgroup
Muribadnus gadiyuli
Mutpuradnus archibaldi
Badjcinus turnbulli
Nimbacinus dicksoni
Nimbacinus richi
Ngamaladnus timmulvaneyi
Wabuladnus ridei
Thyladnus macknessi
Tjarrpednus rothi
Thyladnus potens
Thyladnus megiriani
Thyladnus cynocephalus

Fig. 7. A, one of eight equally parsimonious trees depicting ihylacinid phylogeny using character matrix after Muirhead and Wroe (1998)
(see Table 2A of this work); B, Nelsen consensus of the eight equally parsimonious trees (Consistency Index = 0.73; Retention Index =
0.85: Hennig 86 version 1.5 (Farris 1988)). Abridged definitions of character expressions (see Muirhead and Wroe 1998 for details). 3,
infraorbital foramen; 0 , not bounded by jugal; 1 bounded by jugal. 10 , size of paracone: 0 , equivocal plesiomorphic state; 1 , slight reduction;
2, significant reduction; 3, extreme reduction. 11, stylarcusp B; 0, well developed; 1, slight reduction; 2, greater reduction; 3, more reduced
yet; dramatically reduced [Muirhead and Wroe (1998) include the stylar shelf and stylar cusp D in this morphocline: actual loss or extreme
reduction of stylar cusp B in thylacinids is confined to Thyladnus macknessi and Wabuladnus ridei (Muirhead 1992, 1997).] 12, anterior
cingulum: 0, complete; 1, incomplete. 13, protocone and conules: 0, well developed; 1, slightly reduced; 2, significant reduction; 3, conules
lost. 14, length postmetacrista: 0, as in dasyurids; I, slight elongation. 15, angle centrocrista: 0, acute; 1, more obtuse than in dasyurids; 2,
colinear. 16, direction of preparacrista: 0, perpendicular; 1, slightly oblique; 2, parallel to long axis; 3, directly anterior to paracone. 17,
angles preparacrista and po.stmctacrista: 0 , narrow; 1 , slightly widening; 2 , wider yet. 18, size of melaconid in Mi relative to Mj^: 0 ,
uniform reduction; 1, variably absent on Mi, present M 2 .<; 19, size metaconid M 24 : 0, plesiomorphic condition; 1, some reduction; 2 more
reduced; nearly lost; 4, lost. 20, size entoconid: 0, large; 1, slight reduction; 2, greater reduction; 3, very reduced: 4, absent. 21. morphology
entoconid: 0, plesiomorphic condition; 1. laterally compressed. 22. diastema PI-2: 0, present; 1, absent. 23, diastema P2-3: 0, present; 1,
absent. 24, hypoconulid / hypoconulid notch: 0, present; I, slightly diminished; 2, obvious reduction; 3, more reduced yet; 4, extremely
reduced; 5, notch absent. 25, posterior cingtilid and hypocristid: 0, separated; 1, joined. 26, cristid obliqua carnassial notch: 0, absent; 1,
present. 27, angle hypocristid: 0, parallel to transverse axis of dentary; I, moderate angle; 2, intermediate; 3, pronounced. 28, carnassial
notch in hypocristid: 0, absent; 1, present. 29, termination of cristid obliqua: 0, low; 1, higher; 2, stronger, higher; 3, principle posterior
shearing crest. 30-31, size P3, two pathways: 00, 01, plesiomorphic; 10 apomorphic [see Muirhead and Wroe (1998) for explanation.] 32,
length M4: 0, shorter than M3; longer than M3.

The inclusion of Muribacinus gadiyuli and Mutpu-
racinus archibaldi present a fairly complete picture of
the morphocline for metaconid reduction in thylacinids:
Muribacinus gadiylui shows gradual posterior en¬
largement of the metaconids ( 0 ); Mutpuradnus archibaldi
shows a slight reduction in the size of M 4 metaconid (I),
(M |.2 unknown); Ngamaladnus timmulvaneyi shows marked
reduction of metaconid on Mi and M4; Nimbacinus richi
shows further reduction of metaconid on M| with no further
reduction on M 4 than in the former species, and Badjcinus
turnbulli shows complete loss of metaconid on M| with no
further reduction on M 4 than in the former species ( 2 ); while
the metaconid is nearly obsolete on all molars of Wabuladnus
ridei and Thyladnus macknessi (3) and lost on all other
species of Thyladnus (4).

Resolution of clade formation is obscured by the
establishment of several interrelated morphoclines

(widened angle of preparacrista and postmetacrista,
straightened centrocrista, elongation of postmetacrista,
stylar shelf and cusp reduction) expressing progressive
states of carnassialisation in the Thylacinidae. These
overwhelm the otherwise compelling evidence for at
least two parallel trends in development of longer
shearing crests while simultaneously suppressing the
relatively few synapomorphic states that might otherwise
have been recognised by the algorithm. While it is true
that there is a general trend towards increased car-
nassialization signalled among these genera, and that the
structural changes that characterise these trends are
essentially indistinguishable (the possible exception
being T. macknessi - Muirhead 1992; 72), the disjunct
nature of the character combinations indicate that the
similarities in the states of carnassialization between
Thyladnus macknessi, Wabuladnus ridei and the comp-

157

Murray and Megirian

_r

J LJ

h-'

Dasyurid outgroup
Muiibacinus gadiyuli
Mutpuradnus archibaldi
Nimbadnus dicksoni
Nimbadnus richi
Badjdnus tumbulli
Ngamaladnus timmulvaneyi
Wabuladnus ridei
Thyladnus macknessi
Tjarrpednus rothi
Thyladnus patens
Thyladnus rnegiriani
Thyladnus cynocephalus

-c

B

Dasyurid outgroup
Muribadnus gadiyuli
Mutpuradnus archibaldi
Nimbadnus dicksoni
Nimbadnus richi
Badjdnus tumbulli
Ngamaladnus timmulvaneyi
Wabuladnus ridei
Thyladnus macknessi
Tjarrpednus rothi
Thyladnus potens
Thyladnus meginani
Thyladnus cynocephalus

Fig. 8. Dendrograms (A. more, and B, less, resolved) depicting preferred hypotheses of thylacinid phylogeny based on a restricted suite of
characters (Table 2B) which do not include the autapomorphous and discontinuous characters of Table 2A. (Hennig 86 version 1.5 (Farris
1988); 2 equally parsimonious trees; Consistency Index = 1.0; Retention Index = 1.0). Definitions of character expression. 1, pattern of
metaconid reduction: 0, slight, uniform; 1, slight M 4 ; 2, differential, marked on M|, slight M 4 ; 3, near obsole.scence on all molars; 4, entirely
lost on all molars. 2, carnassial notch in hypocristid: 0, absent; I, present. 3, elongation of postvallum, shearing surfaces: 0, slight; 1,
significant. 4, stylocone B: 0, present; 1 , extremely reduced or lost. 5, paracone reduction / hypertrophy of metacone: 0, slight - moderate;
1, conspicuous. 6 , ectoflexus; 0, strong expression; I, weak expression. 7, precingulum: 0, pre.sent, strong; 1, reduced - absent. 8 , entoconid:
0 , distinct; 1 , reduced - absent.

arably derived species of Thyladnus are phylogenetically
uninformative homoplasy.

As Muirhead (1992, 1997) and Muirhead and
Gillespie (1995) point out, both Wabuladnus ridei and
Thyladnus macknessi show progressive states of
carnassialization (loss of stylar cusps, extreme reduction-
loss of stylar shelf, lengthening, straightening of crests)
in combination with several autapomorphies and retained
plesiomorphies (relatively unreduced paracones).
Whereas in Tyarrpecinus and other members of
Thyladnus, carnassialization has proceeded in con¬
junction with plesiomorphous retention of the stylar
shelf, stylar cusps and apomorphous reduction of
paracone and/or enlargement of metacone. In other
words, the crown genera share an ancestor with states
close to Nimbadnus, rather than, as the Muirhead and
Wroe (1998) cladogram implies, direct, successive sister
relationships with Wabuladnus ridei and Thyladnus
macknessi.

Tyarrpecinus rothi is therefore considered to
represent the plesiomorphic sister-taxon of the Thyla-
cinus clade (T. potens + T. rnegiriani + T. cynocephalus,
but not T. macknessi) (Fig. 8A,B), as it is too derived
(more reduced M' paracone and precingulum) to have
given rise to Thyladnus macknessi and probably
Wabuladnus ridei (greater paracone reduction on M')
while lacking highly derived states of stylar cusp and
stylar shelf reduction/loss of the Thyladnus clade.
Tyarrpecinus rothi shows incipient to moderate

development of Thyladnus-iike states in the considerable
reduction of the parastylar spur, reduction of the
precingulum, elongation of the postmetacrista; mesial
obliquity of the preparacrista, reduction of the paracone,
extreme reduction to loss of conules and reduction of
the trigone basin on M^. Resemblance to particular
species of Thyladnus are evident, such as strong ectollex
present in T. potens and T. rnegiriani M^. There is also
the question of the expression of a tiny stylar cusp E
which appears to be pre.sent in the form of an elliptical
thickening of the stylar crest of in both Tyarrpecinus
and Thyladnus rnegiriani (Murray 1997). Although
Muirhead and Wroe (1998) have concluded that the tiny
stylar cusp on the M^ of Thyladnus cynocephalus
represents a distally-shifted stylar cusp D, we prefer to
wait for additional data.

Other than some minor shifts in emphasis on some
of the character states, the new data present no significant
points of disagreement with recently proposed hypo¬
theses of thylacinid phylogeny (Muirhead and Archer
1990, Muirhead 1992, Muirhead and Gillespie 1995,
Wroe 1996, Murray 1997, Muirhead and Wroe 1998).
However, the problem of association of the upper and
lower molars of Nimbadnus dicksoni creates an
ambiguity in character states of a pivotal group. The D-
Site M 2 (QMFI6809) has a much narrower paraconid
and much smaller metaconid than the equivalent molar
of the Bullock Creek LF Nimbadnus (P9612-4), so we
are certain that it represents a different taxon, probably

Fossil thylacines from the Northern Territory

another genus, in concert with the current level of
systematic discrimination. However, the Bullock Creek
LF specimens (P85553-3 and P9612-4) are sufficiently
close to the holotype M 2 (QMF16802) to indicate a
species-level distinction, and accordingly, we have
inferred that the unknown M 2-3 of N. dicksoni are as
similar to N. richi as is the Mi.

Although poorly represented, the Tyarrpecinus rothi
morphotype is sufficiently generalised to represent the
structural stage that may have given rise to all Thylacinus
species except T. macknessi, and perhaps to Wabulacinus
ridei. On the basis of present information, Thylacinus
macknessi branched off from a less derived form than
Tyarrpecinus. Taking the few synapomorphies between
Wabulacinus and Thylacinus macknessi at face value,
they become, more or less by default, sister taxa in a
minor clade (Fig. 8A,B) characterised by progressive,
predominantly homoplasious camassialization. Muirhead
and Archer’s (1990) observations on some strong si¬
milarities between N. dicksoni and T. potens Woodburne,
1967, become more pertinent here, because, as they
suggest, the well-developed ectoflexus in N. dicksoni
may constitute a synapomorphic condition. With the
additions of Mutpuracinus archibaldi, Tyarrpecinus
rothi and Thylacinus megiriani, all of which display
strong ectoflexus on M^, we are inclined to favour the
interpretation of a symplesiomorphy retained in a
conservative lineage culminating with the genus
Thylacinus.

STRATIGRAPHIC PALAEONTOLOGY AND
BIOCHRONOLOGY

The newly described Bullock Creek and Alcoota LF
species brings the total number of ?late Oligocene and

Miocene thylacinids to 11 species in eight genera, all
but Nimbacinus and Thylacinus being monospecific. No
species are represented by abundant material, and
thylacinids are presently of minimal use in
intraformational biocorrelation and of no use in
intracontinental correlation (Table 3). Even at the generic
level, a high degree of faunal regionalism is indicated,
which follows the general pattern observed by Rich
(1991) for the Australian mid Tertiary vertebrate record.

There is stratigraphic evidence of sympatry for:
Mutpuracinus archibaldi + Nimbacinus richi (‘Top Site’,
Camfield Beds); Ngamalacinus timmulvaneyi +
Wabulacinus ridei (‘Camel Sputum Site’, Carl Creek
Limestone); Thylacinus macknessi + Muribacinus
gadiyuli (‘Gag Site’, Carl Creek Limestone) and
Thylacinus potens + Tyarrpecinus rothi (Waite Formation
- two excavation sites, ‘Main Pit' and ‘Paine Quarry’,
sampling the Alcoota LF horizon) (Table 4). Although
the ‘Top Site’ (Camfield Beds) assemblage is drawn from
several lithofacies (Murray and Megirian 1992), and
therefore possibly different beds, P9215-4 (Nimbacinus
richi) and P9215-5 (Mutpuracinus archibaldi) were
found lying one upon the other in the same block of
limestone.

The only biostratigraphic evidence of temporal
succession amongst thylacinids comes from super¬
position in the Waite Formation of Thylacinus megiriani
(Ongeva LF) over Thylacinus potens and Tyarrpecinus
rothi (Alcoota LF) (Murray et al. 1993; Megirian et al.
1996; Murray 1997; Megirian 2000), but a broader
interpretive perspective is provided by zygomaturine
stage-of-evolution biochronology (Woodburne et al.
1985; Megirian 1994; Murray etal. 2000) (Table 5). The
as yet un-named species of Neohelos from the Camfield
Beds and Carl Creek Limestone ‘Gag’ and ‘Henks

Table 3. Stratigraphic di.stribution of ?late Oligocene and Miocene species of Thylacinidae. and biocorrelation of fossil a.s.semblages.

Formation (geographic location)

IxKal Fauna

Site / Quarry

Species

Waite Formation (Alcoota)

Ongeva

South Quarry

Thylacinus nwgiriani

Alcoota

Paine Quarry

Thylacinus potens

Alcoota

Main Pit

Tyarrpecinus rothi

Camfield Beds (Bullock Creek)

Bullock Creek

Top Site

Mutpuracinus archibaldi

Bullock Creek

Top Site

NimhaciniLS richi

Bullock Creek

Blast Site

Ninthacinus richi

Carl Creek Limestone (Riversleigh)

Camel Sputum

Ngarmilacinus tinunulvaneyi

Inabeyance

Ngamalacinus timmulvaneyi

Camel Sputum

Wabulacinus ridei

D-Site

Nimbacinus dicLsoni

Henks Hollow

Nimlxicinus dicksoni

Gag

Muribacinus gadiyuli

Gag

Thylacinus macknessi

Nevilles Garden

Thylacinus nuicknessi

Mikes Menagerie

Thylacinus mm:knessi

White Hunter

Badjcinus turnbulli

159

Murray and Megirian

Table 4. Stratigraphic evidence of sympatry amongst Miocene thylacinids.

Formation

Local Fauna

Site

Species

Waite Formation

Ongeva

South Quarry

Thylacinus megiriani

Alcoota

Paine Quarry

Thylacinus patens

Main Pit

Tyarrpecinus roihi

Camfield Beds

Bullock Creek

Top Site

Mutpuracinus archibaldi

Top Site

Nimbacinus richi

Blast Site

Nimbacinus richi

Carl Creek Limestone

Camel Sputum

NgamaUicinus timmulvaneyi

Camel Sputum

Wabulacinus ridei

White Hunter

Badjcinus turnbuUi

Gag

Muribacinus gadiyuli

Gag

Thylacinus macknessi

Inabeyance

Ngamalicinus timmulvaneyi

Henks Hollow

Nimbacinus dicksoni

D-Site

Nimbacinus dicksoni

Mikes Menagerie

Thylacinus macknessi

Nevilles Garden

Thylacinus macknessi

Hollow’ sites (Murray et al. 2000) is here identified as
"Neohelos sp. nov.’. The following conclusions can be
drawn from Table 5.

1. The apparent contemporaneity of Nimbacinus richi
(Camfield Beds) and Nimbacinus dicksoni (Carl Creek
Limestone) in Neohelos sp. nov. time suggests that these
were allopatric sibling species.

2. Thylacinus macknessi lived at Riversleigh from
Neohelos tirarensis to Neohelos sp. nov. time, which
Murray et al. (2000) suggest may have spanned the latest
Oligocene to mid Miocene. If ‘D-Site’ Nimbacinus
dicksoni is actually conspecific with ‘Henks Hollow’ N.
dicksoni as proposed by Muirhead and Archer (1990),
then this taxon may have had a similar temporal range.
Alternatively, the ‘D-Site’ Nimbacinus material may
represent a different species, as discussed in the
Systematics section above, which could conceivably
represent the ancestor of one or both of Nimbacinus
dicksoni and N. richi.

3. Five species of thylacinid may have co-existed at
Riversleigh during N. tirarensis time, supporting the
conclusions of Muirhead (1997), Muirhead and Wroe
(1998) and of this study that a major phylogenetic
radiation of thylacinids occurred before the ?late
Oligocene (= pre N. tirarensis time).

4. No potential ancestor-descendent relationships
have been identified amongst the 11 known Miocene
thylacinid species; Mutpuracinus archibatdi is identified
above as having structural states that may reflect the
ancestral conditions giving rise to Nimbacinus dicksoni,
but a phyletic succession from M. archibaldi to N.
dicksoni is not consistent with biochronological
indications in that Mutpuracinus archibaldi post-dates
the earliest record of Nimbacinus dicksoni.

Estimating changes in thylacinid diversity through
the Miocene is problematic due to different
taphonomic processes at the very few known fossil-
producing localities. Remains of small taxa are rare
in the ephemeral channel and overbank deposits of
the Waite Formation, and small terrestrial animals are
sparse in the billabong and channel deposits of the
Camfield Beds (Murray and Megirian 1992). Per¬
sistent sampling over many years produced the three
new species reported here. In contrast, the small-scale
cave-entrance/perched springline, fluvial tufa and
associated pond deposits of the N. tirarensis biochron
of the Carl Creek Limestone are noted for their
preservation of small and medium-sized animals (e.g.
Archer e/a/. 1989, 1991; Megirian 1992, 1997). The
apparent decline in diversity in the Carl Creek
Limestone from five species during Neohelos
tirarensis time to two species during Neohelos sp. nov.
time, with no species reported yet from apparently
younger zygomaturine biochrons, may also reflect
preservational and sampling biases.

The association of quite highly advanced and very
conservative forms in the Carl Creek Limestone during
N. tirarensis time (e.g. Thylacinus macknessi -i-
Muribacinus gadiyuli) reflects the extent of independent
(parallel) evolution of lineages which emerged in the
Paleogene, including the crown group comprising the
Waite Formation species and culminating in the recently
extinct ‘Tasmanian wolf’, T. cynocephalus. It appears,
from absence in the later fossil record, that by the late
Miocene (Kolopsis torus time), all the conservative
lineages as well as the quite advanced Thylacinus
macknessi + Wabulacinus ridei clade, had become
extinct, but the pattern of succession is not clear.

160

Fossil thylacines from the Northern Territory

Table 5. A, thylacinid biochronology in terms of zygomaturine stage-of-evolution (Murray et al. 2000): Neohelos tirarensis stage = latest
Oligocene / early Miocene; Neohelos sp. nov. stage = middle Miocene; Kolopsis torus stage = late Miocene; K. yperus stage = latest
Miocene. * No Neohelos has been described from Carl Creek Limestone White Hunter Site, which is here tied in by simple marsupial
biocorrelation, B, using burramyids (Brammall and Archer 1997), macropodids (Cooke 1997: table 1), phascolarctids (Black and Archer
1997) and the diprotodontoid Bematherium anguhtm (Black 1997: fig.l). White Hunter clusters with sites containing N. tirarensis, using
Bray and Curtis agglomeration analysis and flexible UPGMA (Un-weighted Pair Group Method, Arithmetic average) algorithms in PATN
(Belbin 1994).

A

Formation

Local Fauna

Site

Thylacinid species

Zygomaturine stage-of-evoIution

(Murray et al. 2000)

Waite Formation
-unconformity-

Ongeva

South Quarry

Thylacinus megiriani

Kolopsis yperus (-t- Kolopsis torus)

Waite Formation

Alcoota

Paine Quarry

Thylacinus potens

Kolopsis torus

Waite Formation

Alcoota

Main Pit

Tyarrpecinus rothi

Kolopsis torus

Camfield Beds

Bullock Creek

Top

Mutpuracinus archibaldi

Neohelos sp. nov.

Camfield Beds

Bullock Creek

Top

Nimbacinus richi

Neohelos sp. nov.

Camfield Beds

Bullock Creek

Blast

Nimbacinus richi

Neohelos sp. nov.

Carl Creek Limestone

Gag

Muribacinus gadiyuli

Neohelos sp. nov.

Carl Creek Limestone

Gag

Thylacinus macknessi

Neohelos sp. nov.

Carl Creek Limestone

Henks Hollow

Nimbacinus dicksoni

Neohelos sp. nov.

Carl Creek Limestone

Camel Sputum

Ngamalacinus timmulvatieyi

Neohelos tirarensis

Carl Creek Limestone

Camel Sputum

Wabulacinus ridei

Neohelos tirarensis

Carl Creek Limestone

Inabeyance

Ngamalacinus timmulvaneyi

Neohelos tirarensis

Carl Creek Limestone

D-Site

Nimbacinus dicksoni

Neohelos tirarensis

Carl Creek Limestone

Mikes Menagerie

Thylacinus macknessi

Neohelos tirarensis

Carl Creek Limestone

Nevilles Garden

Thylacinus macknessi

Neohelos tirarensis

Carl Creek Limestone

White Hunter

Badjeinus turnbulli

(Neohelos tirarensis)*

B

53

&

Site

Burramys

briityi

Bulungamay

delicata

Wabularoo

naughtoni

Ganawamayi

sp2

Balbaroo

gregoriensis

Nambaroo

sp5

Nowidgee

matrix

Litokoala

kanunkaensi

Nimiokoala

greystanesi

Bematheriui

angulum

Neohelos
sp. nov.

Neohelos

tirarensis

Gag

Henks Hollow

Mikes Menagerie
Camel Sputum
Nevilles Garden

1

1

1

1

I

1

1

1

1

1

1

1

1

1

1

1

I

1

1

1

1

1

1

1

1

1

Inabeyance

D-Site

White Hunter

1

1

1

1

1

1

1

1

1

1

1

1

*

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Accepted 21 November 2000

162

The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 2000 16: I63-I75

Records of cetacean strandings in the Northern Territory of Australia

RAY CHATTO' AND ROBERT M. WARNEKE^

'Parks and Wildlife Commission of the Northern Territory
Palmerston, NT0831, AUSTRALIA
ray. chatto@nt.gov. an

^ 1511 Mt Hicks Road, Yolla, TAS 7325, AUSTRALIA

ABSTRACT

Fifty-seven cetacean strandings are here documented for the Northern Territory (NT) coastline. This total includes
events discovered in the course of Parks and Wildlife surveys, chance encounters reported by a variety of observers, and
records held by various other government agencies and institutions. A total of 35 of these records are identified to
species, seven to genus (Globicephala, Balaenopiera), and the remainder can be listed only as ‘dolphin’ (3), ‘beaked
whale’ (l)or ‘not known’ (II). Of 26 species known to occur in Australia’s tropical waters only 12 had previously been
confirmed for the NT, and two others were provisionally listed on the basis of specimen material requiring further
analysis. Strandings reported here include 10 of those 12 species and verify the two previously listed as uncertain
(Globicephala macrorhynclius, Kogia simiisj. The total confirmed list for NT waters (within three nautical miles of the
coast) is further expanded to 16 species, now including the melon-headed whale Peponocephala electro (2 strandings)
and killer whale Orcinus orca (sighting). A further species, the .sei whale Balaenoptera borealis (trawled carcass), can
also be added to the Commonwealth waters (within two hundred nautical miles) off the NT coast.

Keywords, cetaceans, whales, dolphins, strandings. Northern Territory, Australia.

INTRODUCTION

With the inclusion of offshore islands and estuary
systems, the Northern Territory coastline is over 10,000
km in length. For the most part it is of low relief,
consisting mainly of sand beaches and mangrove flats,
interrupted by headlands which seldom rise above 30
m. Because much of this coast is remote and sparsely
inhabited, discoveries of stranded cetaceans are highly
fortuitous events, and often their remains are quickly lost
or scattered because under tropical conditions, carcasses
rapidly disintegrate. Aboriginals do encounter beached
cetaceans from time to time, but difficulties of
communication and traditional concerns mean that few
of these incidents are likely to be reported.

A potentially important source of sightings are
Coastwatch Bights, which are conducted along the entire
Northern Territory coast on a fairly frequent basis, but
the primary objective is surveillance of human activities.
Recently stranded single large whales, small groups and
schools are detected from time to time, and arc reported,
but decomposing and partly buried carcasses are likely
to be passed unnoticed.

Over the past ten years one of us (RC) has conducted
numerous surveys of terrestrial wildlife in coastal areas
on the ground and from the air. Incidental encounters
with stranded cetaceans were investigated as a matter of
routine, but were usually limited by the means then in
hand and unfortunately the salvage of specimen material

was generally impractical. This paper summarises these
direct observations on beached cetaceans or their
remains, as well as reliable reports received by wildlife
authorities from other observers, and documented records
held both by the Museum and Art Galleries of the
Northern Territory (MAGNT), Darwin, and by the
National Cetacean Stranding Database (NCSD) main¬
tained by Environment Australia, Canberra. Such a
summary of cetacean strandings in the Northern Territory
has not been attempted in the past.

METHODS

Information on strandings from all sources other than
newspapers, which have not been searched, has been
collated according to the following format: Species, Date,
Locality (including latitude/longitude) and Comments.
The primary date given is qualified by the term ‘stranded’
(which is either the known date of stranding or an
estimated recent date if the specimen(s) was found dead
in fresh condition), or the term ‘found’ in cases where
specimens were decomposing or skeletal; otherwise it is
simply the date a report was received. Doubtful
circumstances are explained under Comments. Locality
is given as a latitude and longitude and then described
with reference to named topographical features, although
in some instances this and the coordinates can only be
approximations. The systematic order of the records
listed in this paper follows Bannister et al. (1996).

Chatto and Warneke

Specimens retained by MAGNT and referred to in
this paper are listed using a reference number commen¬
cing with ‘U’. Records taken from the NCSD and used
in this paper are listed by NCSD followed by their
number on that database.

Other abbreviations used in this paper include: NT
(Northern Territory), PWCNT (Parks and Wildlife
Commission of the Northern Territory), DPIF (De¬
partment of Primary Industries and Fisheries) and NT
News {Northern Territory News).

SYSTEMATIC LIST OF CETACEANS STRANDED
IN THE NORTHERN TERRITORY

Family Delphinidae

Sousa chinensis - Indo-Pacific hump-backed
dolphin

Date. Eound August 1948.

Locality. I2°15’S, I36°54’E. Yirrkala, near Gove.

Comments. Johnson (1964) reports four mandibles,
likely of three different animals, that were picked up off
the beach by Aboriginal children during the American-
Australian scientific expedition to Arnhem Land.
Measurements and teeth counts are given in Johnson
(1964).

Date. Stranded 23 November 1985.

Locality. l2°2i’S, I30°52’E. Casuarina Beach,
Darwin.

Comments. Single carcass washed ashore in fresh
condition, male, length 2.08 m. Skull, mandibles and
teeth collected by B. Freeland, PWCNT. Condylobasal
length 510 mm, width 185 mm and height 175 mm; 30
teeth alveoli in one maxillary row and 32 teeth alveoli
in one mandible. Photographs in PWCNT file PI999/
629. Skull and mandibles in MAGNT, registered # U254.
NCSD# 180.

Date. Found 28 October 1988.

Locality. 13°10’S, 130°07’E. Channel Point, opposite
North Peron Island

Comments. Skull, lacking mandibles, condylobasal
length 505 mm, width 220 mm and height 190 mm; 30
tooth alveoli in maxillary row. Collected by D. Neal. No
further details. Skull in MAGNT, registered # U528.

Date. Stranded c. 2 March 1996.

Locality. 1I°20’S, 132°07’E. Knocker Bay, Cobourg
Peninsula.

Comments. Single carcass, in fresh condition, no
external injuries, c. 2 m in length and weight 69 kg.
Found 3 March by A. Withers, PWCNT. Collected entire
by MAGNT and has been processed (Temporary taxi¬
dermy ref. no. 342) to be accessioned as a disarticulated
skeleton.

Date. Stranded 28 October 2000.

Locality. 12°20’S, 130°53’E. Lee Point beach,
Darwin.

Comments. Single carcass washed ashore in rea¬
sonably fresh condition, female, length 2.1 m. There were
no obvious external injuries except a quite deep cut at
the base of the tail, which is sometimes indicative of
being caught in a mesh net. Thirty-one teeth in one
maxillary row and 29 teeth in one mandible. Photographs
(nos 6761-6756) and further measurements in PWCNT
file PI999/629. Entire specimen collected by MAGNT;
had not yet been registered at time of writing.

Tursiops truncatiis cf. aduncus - bottlenose dolphin

Remarks. It is likely that all Tursiops in NT waters
are referable to the subspecies aduncus (Banister etal.).
This species group was under taxonomic review at the
time of writing and aduncus may be elevated to full
species rank in the future (C. Kemper, South Australian
Museum, pers. comm.).

Date. Found 22 July 1972.

Locality. 14°53’S, 135°43’E. Maria Island, Gulf of
Carpentaria.

Comments. Partially weathered skull, lacking
mandibles, condylobasal length 420 mm, width 205 mm,
height 160 mm; 25 (+?1) teeth alveoli in one maxillary
row. Collected by D. Howe. No further details. Skull in
the MAGNT, registered # U3955.

Date. Found 6 October 1972.

Locality. 11°00’S, 136°46’E. Cape Wessel, Mar-
chinbar Island.

Comments. Partially weathered skull, lacking
mandibles, condylobasal length 420 mm, width 210 mm
and height 170 mm; 24 (+?1) teeth alveoli in one maxilla.
Collected by W. Dodd. No further details. Skull in the
MAGNT, registered # U3956.

Date. Found c. 1977 during the ‘dry’ season (May to
September).

Locality. 1I°47’S, 132°34’E. Mouth of Minimini
Creek, south of Cobourg Peninsula.

Comments. Carcass of an adult, badly decomposed.
Found by F. Woerle, PWCNT. Carcass left on site. No
further details.

Date. Found 5 June 1985.

Locality. 11°26’S, 132°58’E. North-east of Mur-
genella. Van Diemen Gulf.

Comments. Partially weathered skull, lacking
mandibles, condylobasal length 430 mm, width 210 mm
and height 160 mm; 24 teeth alveoli in one maxillary
row. Collected by W. H. Butler, 5 June 1985. No further
details. Skull in MAGNT, registered # U24L

Date. Found 30 November 1993.

Locality. 15°30’S, 136°57’E. Urquhart Island, Sir
Edward Pellew Islands.

Comments. Bleached disarticulated skeleton,
including skull and mandibles. Found by R. Chatto, 30
November 1993, lying among rocks. Condylobasal
length of skull c. 420 mm, mandibular tooth count (from

164

Whale and dolphin strandings in the Northern Territory

alveoli) 24 + 24; wear on Ihe only remaining tooth
indicates animal was fully mature. Measured and
photographed, but no material collected. Photographs
(nos 5253-57) in PWCNT file PI999/629.

Date. Found 29 September 1994.

Locality. 15°30’S, 136°55’E. Pearce Islet, Sir Edward
Pellew Islands.

Comments. Bleached skeleton, including skull and
mandibles, found on beach by R. Chatto. Condylobasal
length 400 mm; 22 (+2?) teeth alveoli in one maxillary
row and one mandibular row on one side. Photographed
and measured but no material collected. Photographs
(nos 5284 and 87) in PWCNT file PI999/629.

Date. Found May 1998.

Locality. 12°24’S, 136°55’E. 10 km south of Cape
Arnhem.

Comments. Weathered skull on beach; no other
skeletal remains. Found by M. Stevens, PWCNT. Skull
on display in the PWCNT office, Batchelor, NT.

Stenella attenuata - pan-tropical spotted dolphin

Date. Stranded. 20 October 1999.

Locality. 11°10’S, 132°09’E. Black Point, Cobourg
Peninsula.

Comments. Single adult female 2.15 m in length
stranded alive; emaciated. Examined same day by
PWCNT staff and euthanased on veterinary advice. Field
necropsy revealed old trauma to head, but no other
obvious injuries. Histology of internal organs showed
changes consistent with prolonged starvation, but no
evidence of disease. Whole specimen secured near site
for later retrieval of skeleton by MAGNT. Photographs
and report in NT News, 6 November 1999. Photographs
(nos 6536-54) and measurements in PWCNT file PI 999/629.

Stenella longirostris - spinner dolphin

Date. Found 5 June 1985.

Locality. 11° 26’S, 132° 58’E. North-east of
Murgenella, Van Diemen Gulf.

Comments. Weathered partial skull, lacking man¬
dibles and maxillae; condylobasal length >370 mm,
width 150 mm and height 130. Collected by W. H. Butler
on 5 June 1985. No further details. Specimen compared
with other S. longirostris skulls in MAGNT for
identification. Skull in MAGNT, registered # U242.

Date. Stranded c.l9 April 1994.

Locality. 11°I7’S. 132°43’E. Templer Island, off
Croker Island.

Comments. Single carcass, in fresh condition, no
external injuries. Found by R. Chatto, 19 April 1994, on
beach. Length of body 1.5 m, tip of upper Jaw to apex of
melon 150 mm, height of dorsal fin 150 mm; 43+
maxillary teeth and 45+ mandibular teeth on one side.
No material collected. Photographs (nos 5240, 41,45,
47, 49, and 51) in PWCNT file PI999/629.

Date. Found September 1998.

Locality. 11° 08’S, 132° lO’E. Just east of Smith
Point, Cobourg Peninsula.

Comments. Five decomposing carcasses found by A.
Withers, PWCNT, over a 30 m section of beach adjacent
to a broad tidal flat with rapid tidal flux. Carcasses left
on site. Single vertebra collected for display at Black
Point Ranger Station, Gurig National Park. No further
details

Peponocephala electra - melon-headed whale

Date. Stranded, from 21 to 26 March 1996.

Locality. 11°45’S, 135°54’E. Eastern end of Elcho
Island.

Comments. A mass stranding of 40 animals, occurred
over six days. Examined and photographed by R. Chatto;
one complete skull collected, condylobasal length 440
mm, width 250 and height 190 mm; 25 teeth alveoli in
one maxillary row and 24 teeth alveoli in one mandibular
row. Photographs (nos 4775, 77-79, 80, 82-85 and 91)
in PWCNT file PI999/629. Complete skull in MAGNT,
registered # U4438. See Chatto (2000c) for a detailed
description.

Date. Found 8 October 1996.

Locality. 15°35’S, 136°3rE. North-west side of West
Island, Sir Edward Pellew Islands.

Comments. Weathered skull, lacking mandibles,
found on beach by R. Chatto. Condylobasal length 300
mm, width 200 mm, 19+ teeth alveoli on either side.
Photographed and measured but no material collected.
Photographs (nos 5264 and 75) in PWCNT file P1999/
629. Identification confirmed with reference to MAGNT

# U4438.

Pseudorca crassidens - false killer whale

Date. Found 1968.

Locality. 11°13’S, 131 °59’E. Trepang Bay, Cobourg
Peninsula.

Comments. Bleached skull and mandibles, condy¬
lobasal length 620 mm, width 350 mm and height 260
mm; nine teeth in each maxillary row, eight in each
mandible. Collected by H. J. Frith, CSIRO. No further
details. Skull and mandibles in the Museum and Art
Galleries of the Northern Territory (MAGNT), registered

# U2056.

Date. Found 8 October 1996.

Locality. 15°35’S, 136°31’E. North-west side of West
Island, Sir Edward Pellew Islands.

Comments. Weathered skull, lacking mandibles,
found on beach by R. Chatto. Condylobasal length 560
mm, width 330 mm, height 260 mm, c. 9-10 pairs of
teeth in each Jaw. Photographed and measured, but no
material collected. Photographs (nos 5267, 69, 71-72)
in PWCNT file PI999/629.

165

Chatto and Warneke

Globicephala macrorhynchus - short-finned pilot
whale

Date. Stranded 18 March 1999.

Locality. 11°11’S, 130°22’E. Cape Van Diemen, NE
tip of Melville Island.

Comments. Three adults and two juveniles on beach,
reported by Coastwatch. When examined next day by R.
Chatto, only the smallest was still alive. It was
euthanased and all specimens were left on site. Reported
in NT News, 19 March 1999. Photographs (nos 5798-
5804) in PWCNT file PI999/629. See Chatto (2000d)
for a detailed description.

Globicephala sp. - pilot whale

Date. Found 1983.

Locality. 12°05’S, 135°22’E. Jigaimarea Point,
Howard Island, NW Arnhem Land.

Comments. A school of 30-50 ashore. Source of report
not stated, no further details. NCSD # 168.

Date. Found 1984.

Locality. 12°02’S, 134°58’E. Yabooma Island, off
Millingimbi, NE Arnhem Land.

Comments. A school of 20 animals reported to have
stranded - one died and the remainder escaped. Source
of report not stated, no further details. NCSD # 169.

Date. Found 1984.

Locality. 12°02’S, 134°58’E. Yabooma Island, off
Millingimbi, NE Arnhem Land.

Comments. Three animals reported to have stranded
- one died and two escaped. Source of report not stated,
no further details. NCSD # 170.

Date. Stranded c. 31 March 1985.

Locality. 15°24’S, 136°13’E. Rosie Creek, SW Gulf
of Carpentaria.

Comments. Group of eight animals seen on 1 April
1985 comprising six adults and two calves; one large
male still alive. Some whales on beach, some above high
tide mark and some washed inland of tree line by cyclone
surge. Source of report not stated, no further details.
NCSD# 173.

Date. Found 10 April 1985.

Locality. 16°04’S, 137° 17’E. Myoorlka Island, mouth
of the Robinson River, SW Gulf of Carpentaria.

Comments. Single animal on beach, partly covered
by sand and weed. Source of report not stated, no further
details. NCSD # 174.

Orcaella brevirostris - Irrawaddy dolphin

Date. Found 16 July 1948.

Locality. I2°15’S, 136°41’E. Melville Bay, near Gove.

Comments. Johnson (1964) reports two skulls of
unknown sex, one with a partial body skeleton, were
picked up at an Aboriginal campsite during the
American-Australian scientific expedition to Arnhem
Land. The skulls were likely to have been the remains

of dolphins eaten by Aboriginals and caught in Melville
Bay. Photographs and some skull measurements are
given in Johnson (1964).

Date. Found 12 June 1992.

Locality. 12°50’S, 130°16’E. Fog Bay, 70 km SW of
Darwin.

Comments. Single carcass, decomposing, c. 1.5 m in
length, with bulbous head partly eaten by dingos. Found
and examined by R. Chatto. No material collected.
Photographs in PWCNT file PI999/629.

Date. Found August 1997.

Locality. 12°37’S, 130°31’E. Indian Island, Bynoe
Harbour.

Comments. Weathered skull on beach, no other
skeletal remains. Collected by PWCNT staff. Skull on
display in the PWCNT Office, Batchelor, NT.

Date. Found 27 May 1999.

Locality. 13°22’S, 136°08’E. North-east side of Isle
Woodah, Gulf of Carpentaria.

Comments. Collapsed and dehydrated carcass, skin
and flippers still present, body length estimated 1.5 m.
Skull separate, clean, mandibles lacking, 18 tooth alveoli
in each maxilla. Found by R. Chatto, no material
collected. Photographs (nos 6110 and 6111) in PWCNT
file PI999/629.

Date. Stranded 1 October 1999.

Locality. 12°46’S, 130°22’E. Dundee Beach, Fog
Bay.

Comments. Single adult female 1.93 m in length,
washed ashore dead. Examined same day by PWCNT
staff; six 5 cm cuts in a line along its belly. These were
likely to have been done by a person with a knife,
probably alter death to cause the animal, which may have
been removed from a fishing net, to sink. Estimated to
have died 1-2 days previously. Necropsy indicated that
the animal was healthy and in good condition prior to
death. Specimen currently held frozen by MAGNT
(Temporary taxidermy ref. no. 1366) to be accessioned
as a disarticulated skeleton. Photographs (nos 6409-14)
and measurements in PWCNT file PI999/629.

Dolphin, unidentified

Date. Found June 1983.

Locality. 13°06’S, 130°07’E. Just north of Channel
Point, opposite North Peron Island.

Comments. Partly decomposed carcass lying in
intertidal zone, estimated length c. 2.5 m. Found by A.
Donati, Department of Primary Industries and Fisheries
(DPIF). Specimen left at site, no further details.

Date. Stranded 13 April 1985.

Locality. 13° 50’S, 136° OO’E. South of Cape Barrow,
west of Groote Eylandt.

Comments. Found alive, but rescue not attempted.
Possibly Tursiops but definitive details not recorded.
NCSD# 175.

Date. Found 17 May 1985.

166

Whale and dolphin strandings in the Northern Territory

Locality. 13°39’S, 129°48’E. c.l7 km south of Cape
Scott, 160 km SW of Darwin.

Comments. One animal ashore and a second floating
near shore c. 2 km to west. Source of report not stated,
no further details. NCSD # 179.

Family Ziphiidae
Ziphiiis cavirostris
Cuvier’s or goose-beaked whale

Date. Found 1969.

Locality. 11°22’S, 132°18’E. Cobourg Peninsula.

Comments. Weathered skull, lacking mandibles,
condylobasal length 910 mm, width 480 mm and height
500 mm. Collected by D. Lindner, PWCNT. No further
details. Photographs in PWCNT file PI999/629; skull
in MAGNT, registered # U2055.

Date. Found 30 July 1998.

Locality. 12°02’S, 134°57’E. Yabooma Island, off
Millingimbi.

Comments. Bleached skeletal remains including skull,
lacking mandibles, found high on beach adjacent to low
shrubs by R. Chatto. Condylobasal length c. 1000 mm,
width c. 500 mm, height c. 400 mm; c. 3 m portion of
vertebral column lying in situ. Photographed and a single
vertebra collected; retained in Darwin office of PWCNT.
Photographs (nos 5499, 5500 and 5501) in PWCNT file
P1999/629. Identified by G. J. B. Ross, who commented
that it was probably a mature female, based on fusion of
the epiphyses to the centra of the vertebrae and on skull
characters. Skull collected by R. Chatto on 18 November,
2000; deposited at MAGNT (not registered at time of
writing).

Beaked whale, probably Ziphius cavirostris

Date. Found 2 August 1984.

Locality. 12°03’S, 134°55’E. A small island (possibly
called Rakuna), just south of Yabooma Island off
Milingimbi.

Comments. Single animal, length 5.18 m stranded
alive but date uncertain. Reported by the Northern Land
Council to PWCNT. When examined by P. Whitehead,
PWCNT, on 2 August, the carcass had decomposed to
the point where the skull and mandibles were ‘clean’
except for some skin at the very tip; no sign of erupted
teeth or alveoli and deterioration of the genital/anrd area
precluded determination of sex. Specimen photographed
and measured, but no necropsy was performed and no
material was collected because of the totemic signi¬
ficance of the animal to the Aboriginal traditional
owners. Those who saw the whale alive identified it as
Z. cavirostris with reference to the illustration of the
Indo- Pacific form in Watson (1981:118). Measurements
and five photographs (un-numbered) on PWCNT file
PI999/629. NCSD #31.

Family Physeteridae
Physeter macrocephalus - sperm whale

Date. Stranded c.l7 November 1980.

Locality. 11°39’S, 133°22’E. Off north-west side of
South Goulburn Island, on a reef c. 2 km offshore.

Comments. Freshly dead when found by a fisherman
on 18 November 1980. Lodged among mangroves on
South Goulburn Island when investigated by MAGNT
staff on 24 November 1980, estimated length 13 m.
Reduced to a skeleton by late December. Substances from
rotting carcass had killed the mangroves over a radius
of 100 m (1. Archibald, MAGNT, pers. comm.).
Aboriginal traditional owners would not allow any part
of the specimen to be collected. NCSD # 166. See also
Hodgkinson (1987) for further details regarding the
Aboriginal issues concerning the stranding.

Date. Stranded c. 1987.

Locality. 14°13’S, 129°25’E. Beach near Port Keats.

Comments. Bleached skull observed from aircraft by
R. Chatto, 15 December 1992. Advised by Sgt. Kevin
Winzar of Port Keats police that the whale washed 9 km
to the NNW about 1987. It was not examined and was
left to disintegrate on site. Sgt. Winzar photographed
the skull on 17 December 1992 and measured the width
at 120 cm and height at 70 cm. No further details.
Photographs in PWCNT file PI999/629.

Date. Stranded 22 January 1993.

Locality. 12°2rS, 130°52’E. Casuarina Beach,
Darwin.

Comments. Single, adult male stranded alive, 15.4 m
in length. Grounded in shallows and died soon after.
Skeleton collected for display by MAGNT (file BP2000/
793); not registered in scientific collection. Photographs
and report in NT News, 23 January, pp 1,14,15. See also
Chatto (2000a) for more detailed description.

Date. Stranded between 3 and 6 August 2000.

Locality. 11°34’S, 133°05’E. 1 km south of Brodgen
Point, east of Murgenella.

Comments. Freshly dead male lying in the intertidal
zone, length c. 15 m. Found by P. Luton, PWCNT, on 6
August 2000. It had not been there on 3 August 2000.
Examined and photographed by R. Chatto on 17 August
2000; no external injuries; 24+ teeth in one mandibular
row, several broken. Carcass left on site. Site revisited
by R. Chatto on 17 November, 2000. Skull (minus all
teeth), some vertebrae and a rib bone still present.
Additional measurements and photographs taken, and
rib collected and deposited in MAGNT (not yet
registered at time of writing). Photographs (nos 6742-
48 and 6844-52) and measurements in PWCNT file
PI 999/629.

Family Kogiidae

Kogia simus - dwarf sperm whale

Date. Stranded 19 August 1995.

167

Chatto and Warneke

Locality. 12°22’S, 130°5rE. Nightcliff Beach,
Darwin.

Comments. Adult male, length 2.1 m, stranded alive
late afternoon. Towed out to sea and released. Stranded
next day on Mindil Beach, where it died during rescue
attempts. Photographs and report in NT News, 21 August
1995, p 1. Necropsy performed, photographs and
measurements taken; details in PWCNT file PI999/629.
Specimen currently in MAGNT freezer (Temporary
taxidermy ref. no. 126); to be accessioned as a
disarticulated skeleton. See Chatto (2000b) for a detailed
description.

Family Balaenopteridae
Balaenoptera musculus - blue whale

Date. Found 19 December 1980.

Locality. 12°04’S, 131°18’E. Beach on the east side
of Cape Hotham.

Comments. Specimen in skeletal condition, estimated
length c. 25 m. Found by a fisherman who removed and
sold some vertebrae as garden seats. Remainder of
skeleton collected by MAGNT staff some months later
and put on public display at MAGNT; not registered in
scientific collection. Identification confirmed by S. Van
Dyck, Queensland Museum, on the basis of skull
measurements. NCSD # 165.

Megaptera novaeangliae - humpback whale

Date. Found 1981.

Locality. 11°59’S, 135°49’E. Napier Peninsula, NE
Arnhem Eand.

Comments. Found dead with a hole in its side,
estimated length 10 m. Source of report not stated, no
further details. NCSD# 167.

Balaenoptera sp.

Date. Stranded January 1996.

Locality. 13°10’S, 136°17’E. Western point of
entrance to Myoola Bay, Gulf of Carpentaria.

Comments. Carcass washed ashore, estimated length
10+ m. Found February 1 and photographed by Waka,
an Aboriginal traditional owner from the Banyalla
community. Carcass lodged near mangroves in an
advanced state of decomposition, but numerous throat
grooves still evident. R. Chatto visited site with Waka
in May 1999, at high tide, but no remains could be seen.
No further details. Photograph in PWCNT file P1999/629.

Date. Stranded c. 19 April 1999.

Locality. 12°24’S, 136°55’E. 15 km south of Cape
Arnhem, near Gove.

Comments. Decomposed carca.ss, estimated length
10+ m washed ashore on or just before 19 April 1999.
Dhimurru Fand Management Aboriginal Corporation
provided photographs and video taken 10 May 1999,
which show a flipper of moderate length, numerous
throat grooves and the skull missing. Remains left on
site, and were still present but very decomposed when

examined and photographed by R. Chatto on 27 May
1999. No further details. Photographs (nos 6117-6120)
in PWCNT file PI999/629, copy of video in Darwin
office of PWCNT.

Family and species unknown

Date. Found February 1984.

Locality. I5°40’S, 137°00’E. Vanderlin Island, Sir
Edward Pellew Islands.

Comments. A group of six whales ashore. Reported
by Coastwatch whose observers supposed that they could
have been driven ashore by cyclone ‘Kathy’. No further
details.

Date. Stranded 1 August 1984.

Locality. I2°02’S, 134°56’E. Yabooma Island off
Millingimbi.

Comments. Alive when seen by Coastwatch; length
estimated at 4.5 m. Coastwatch observers commented
that the weather was rough at the time and described the
whale as black with white marks on the head, a colour
pattern suggestive of Z. cavirostris. No further details.
NCSD# 171.

Date, Found April 1985.

Locality. 15°36’S, 137°I0’E. 2 nautical miles SSE
of Cape Vanderlin, Sir Edward Pellew Islands.

Comments. Two animals, possibly a mother and calf.
Observer in aircraft thought they were too large for
dolphins. Source of report not stated, no further details.
NCSD# 172.

Date. Found 16 April 1985.

Locality. 15°02’S, 135°34’E. North of mouth of
Limmen River, Gulf of Carpentaria.

Comments. Single animal on beach, dead. Reported
by Coastwatch. No further details. NCSD # 176.

Date. Found 16 April 1985.

Locality. I5°36’S, 136°33’E. West Island, Sir Edward
Pellew Islands.

Comments. At least one animal on beach, dead. Re¬
ported by Coastwatch. No further details. NCSD # 177.

Date. Found 1985 during ‘dry’ season (May to
September).

Locality. ll‘’20’S, 132°56’E. Just east of De Courcy
Head, north of Murgenella.

Comments. Decomposing carcass, estimated length
5 m. Observed from aircraft by A. Donati, DPIF. No
further details.

Date. Found 9 May 1985.

Locality. 16°00’S, 137°12’E. 2 nautical miles north
of Robinson River mouth, SW Gulf of Carpentaria.

Comments. Single animal, decomposing, estimated
dead for 2-3 weeks. Length said to be approximately 6-
7 m. Reported by Coastwatch, who said it appeared to
be unlike Globicephala and was possibly a baleen whale.
However, this is very small for such. No further details.
NCSD# 178.

Date. Found pre 1990.

168

Whale and dolphin strandings in the Northern Territory

Locality. I2°54’S, 130°20’E. Just south of Finniss
River mouth.

Comments. Skeletal remains of large whale, one rib
c. 3 m in length, possibly either a large Physeter or a
large baleen whale. Reported to R. Chatto in June 1999
by Aboriginal traditional owner. No further details.

Date. Found early 1990s, in month of February.

Locality. 12°13’S, 136°15’F. North-east part of
Arnhem Bay.

Comments. Bleached skeletal remains of a whale c.
5 m in length, but possibly longer. Observed from aircraft
by M. Stevens, PWCNT. Reported to R. Chatto, June
1999. No further details.

Date. Stranded December 1994.

Locality. 11° 57’S, 134° lO’F. West Point, near
Maningrida.

Comments. Farge individual washed ashore, left
untouched. Reported to R. Chatto by Northern Fand
Council in 1995. Site visited by R. Chatto on 17
November, 2000. One mandible (no teeth alveoli; curved
length 2.97 m), on vertebra and two ribs remaining. The
specimen can now be confirmed as a baleen whale. The
vertebra was collected and deposited in MAGNT; not
yet registered at time of writing. Photographs (nos 6866-
72)and measurements in PWCNT file PI999/629.

Date. Stranded January 1998.

Locality. II°()2’S, 132°35’F. North-east side of
Croker Island.

Comments. Five small black whales stranded on
beach; four c. 1.5 m and one c. 1.0 m in length. Report
by Aboriginal traditional owners via Northern Fand
Council to R. Chatto stated that the animals “had a dorsal
fin but a blunt nose, not like normal dolphins”. Two were
returned to the sea but the others persistently re-stranded,
and were left on site. One had cuts to the belly area. No
further details.

DISCUSSION

There is scant information on the occurrence of
cetaceans in NT waters. This unsatisfactory situation is
the result of many factors, including the remoteness of
much of the Territory’s coastline, the sparse and non-
randomly distributed human population, the sporadic
nature of human activity in inshore waters, poor
communication, historical disinterest and continuing low
levels of scientific inquiry. These latter two issues are
due in part to the cost and logistical difficulties of survey
and salvaging specimens from remote areas.

Thus when Banister et al. (1996) prepared the first
comprehensive review of Australia’s cetaceans, they
could confidently list for the Northern Territory only 12
(inclusion of Mesoploclon layardii in their Table I is an
error) of the 26 species known to occur in Australia’s
tropical waters. They provisionally included two others
on the basis of uncertain identification of specimen

material. Records based on strandings, accumulated from
a variety of sources and summarised here, include ten of
those 12 species, while the two provisionally included
{Globicephala macrorhynclnts, Kogia sirniis), are now
confirmed. The melon-headed whale Peponocephala
elecira, can now also be added to the Northern Territory
list. Two species listed from the NT by Bannister et al.
(1996), but yet to be recorded by strandings are the
rough-toothed dolphin Steno brenadensis and common
dolphin Delphinus delphis.

In addition, another species can now be confirmed
for NT waters and an additional species to Common¬
wealth waters off the NT coast. Confirmation of the killer
whale, Orcinus orca, in NT waters is based on a sighting
made on 7 April 1999 at Yirrkala(12° 15’S, 136° 54’F)
by C. Fane, and reported by the Dhimurru Fand
Management Aboriginal Corporation. At least one
animal was seen from shore at around 12.30 h approx¬
imately I km out to sea and heading south. The animal
was described as 3-4 times the size of a dolphin,
strikingly marked with black on top and white below,
and with a very large dorsal fin. (The dolphins most
frequently seen in this area are Sousa cbinensis and
Tursiops truncatus cf. aduncus, i.e. individuals about 2.5
m in length (Chatto, pers. obs.).) One old Aboriginal
lady said that she had not seen this species for 20 years,
but does remember seeing them from time to time when
her children were young. Confirmation of the sei whale,
Balaenoptera borealis, in Commonwealth waters off the
NT coast is based on a sample of baleen from a dead
specimen c. 15 m in length, trawled up from 113 m by a
Thai fishing vessel on 1 September 1989 at 10° 21’S,
133° 55’F, approximately 160 kilometres north-east of
Croker Island. The specimen of baleen was donated to
MAGNT where it is on display but it has not been
registered in the scientific collection.

Of the total series of 57 stranding events reported on
here (Table 1), 35 were identifiable to species, seven to
genus {Globicephala, Balaenoptera), and the remainder
could be described only as ‘dolphin’ (3), ‘beaked whale’
(1) or ‘unknown’ (II).

This series is loo small and the data available for most
events too meagre for intra- and inter-species compa¬
risons. Similarly, there are too many confounding factors
and biases to search for any patterns in geographic
distribution of the 57 events. For instance, there is no
way of telling whether any of the singletons found dead
were alive when they beached, or if they died at sea and
their floating carcasses had been transported by current,
wind and tide over considerable distances before they
eventually washed ashore.

However, it is appropriate to consider the results of
this study in terms of the known distributions of these
13 species and their habitat preferences, seasonal
movements or migrations. We have grouped them
according to broad oceanographic categories based on

169

Chatto and Warneke

Table 1. Species, number of stranding events and number of individuals per event

Species

Common name

No. of stranding
events

No. of individuals
per event

Balaenoptera musculus

blue whale

1

1

Balaenoptera sp.

baleen whale sp.

2

1 (x2)

Globicephala macrorhynchus

short-finned pilot whale

1

5

Globicephala sp.

pilot whale sp.

5

1,3,8, 20,30-50

Kogia siina

dwarf sperm whale

1

1

Megaptera novaeangliae

humpback whale

1

1

Orcaella brevirostris

Irrawaddy dolphin

5

1 (x4), 2

Peponocephala electro

melon-headed whale

2

1,40

Physeter macrocephalus

sperm whale

4

1 (x4)

Pseudorca crassidens

false killer whale

2

1 (x2)

Sousa chinensis

Indo-Pacific hump-backed dolphin

5

1 (X 4), 3

Stenella attenaata

pan-tropical spotted dolphin

1

1

Stenella longirostris

spinner dolphin

3

1, 1,5

Tiirsiops truncatus cf. aduncus

bottlenose dolphin

7

1 (x7)

Ziphius cavirostris

Cuvier’s beaked whale

2

1 (x2)

'beaked whale'

beaked whale sp.

1

1

'dolphin'

dolphin sp.

3

1 (x3)

'unknown cetacean'

unknown cetacean sp.

11

1 (x7), l+, 2,5,6

water temperature and commonly used to define
distributions, as follows.

Tropical - subtropical. Includes two inshore species
(Indo-Pacific hump-backed dolphin and Irrawaddy
dolphin), and two offshore species (melon-headed whale
and the spinner dolphin), both of which range into coastal
waters.

The Indo-Pacific hump-backed dolphin is restricted
to coastal, inshore and estuarine habitats throughout
northern Australia, ranging south along the WA coast to
about 24°S, and to Moreton Bay in Queensland, at
27°30’S (Bannister et al. 1996). Stragglers have been
recorded as far south as Sydney (Llewellyn et al. 1994).
This species is not known to be migratory, but individuals
may move about a great deal along-shore and between
islands. It appears to be loosely social in small groups
(Ross et al. 1994) and is not prone to strand. This species
is often seen in very shallow water in large tidal variation
areas and does not become stranded (Chatto pers. obs.).
G. Ross (pers. comm.) has also seen this species school
fish up onto sandbanks and then slide up to grab them
without becoming stuck. Thus all five NT records listed
here probably represent mortality at sea rather than active
strandings.

The Irrawaddy dolphin has a similar but slightly more
restricted distribution in northern Australia, occurring
on the WA coast north of Broome (18° S), throughout
the NT and to Gladstone (23° 50’S) on the Queensland
coast (Banister et al. 1996). It is usually encountered in
groups of less than 6 animals, but groups of 10-15
animals have been reported (Marsh et al. 1989). As this
species is not prone to strand, the five NT records listed
here probably also represent mortality at sea.

The spinner dolphin inhabiting NT waters has
recently been described as a subspecies - Stenella

longirostris roseiventris (Perrin et al. 1999). It is a small
form restricted to the shallow inner waters of South-east
Asia, including the Gulf of Thailand, Timor and Arafura
Seas, and similar waters of Indonesia, Malaysia and
northern Australia; it is not known to be migratory. In
deeper oceanic waters it is replaced by the typical and
larger pelagic form, S. 1. longirostris (Perrin and
Gilpatrick 1994). Little is known of the occurrence of
spinner dolphins in northern Australia, even though they
were commonly caught by accident in the Taiwanese
gillnet fishery for sharks in the Timor and Arafura Seas
(Harwood and Hembree 1987). Stenella /. roseiventris
is known, however, to feed on shallow water benthic
and reef dwelling fish, squid, cuttlefish and shrimp (G.
Hembree, cited in Perrin et al. 1999). More southern
records, to Bunbury in WA (30°19’S, Bannister et al.

1996) , from the Great Barrier Reef and in NSW to
Uranga (30°31’ S, Llewellyn et al. 1994) appear to be of
the pelagic form. The close grouping of the three NT
records listed here over less than 1 degree of longitude,
and including a mass stranding, may indicate a centre of
activity for S. 1. roseiventris in that region, as there is no
reason to suspect it may be attributable to greater
observer activity.

The melon-headed whale is a highly social deep-water
species, occurring in large schools and often associated
with other oceanic dolphins and small whales (Leather-
wood and Reeves 1983; Perryman et al. 1994). Schools
have been sighted over the continental slope off northern
NSW (Dawbin et al. 1970) and several mass strandings
have occurred in southern Queensland (Bryden et al.

1997) and NSW (Dawbin et al. 1970; Smith 1997). The
small .school that stranded on Elcho Island in the NT in
1996 may have become disorientated when navigating
in unfamiliar shallows, however little is known about

170

Whale and dolphin strandings in the Northern Territory

this species which may not be restricted to deep waters
only (Ross pers. comm.).

Tropical - temperate. Four ecologically very
different species fit this general category - pan-tropical
spotted dolphin, bottlenose dolphin, false killer whale
and dwarf sperm whale.

The spotted dolphin occurs circumglobally in deep
offshore waters, most frequently where sea surface
temperatures exceed 25° C and overlie a sharp thermo-
cline at depths less than 50 m (Perrin and Hohn 1994).
It is often encountered in large schools and is often
associated with spinner dolphins. In Australia, spotted
dolphins are known to occur north of Augusta in WA
(38° 20’S) and north of Sydney on the east coast
(34° GO’S, Bannister etal. 1996). Their activity patterns
in Australian waters are not known, but elsewhere,
seasonal inshore-offshore movements occur in spring
(Leatherwood and Reeves 1983). The timing of the one
NT record of a compromised adult fits this pattern.

The adiincus form of bottlenose dolphin is very
widely distributed in tropical, subtropical and temperate
Australian waters, ranging south to about 32° S. Where
it occurs sympatrically with the hump-backed dolphin it
tends to be active slightly further offshore, but often in
depths of less than 10 m, and may range to about 10 km
beyond the shelf (Bannister et al. 1996). Because
bottlenose dolphins navigate confidently in shallow and
confined waters, the seven NT records, all singleton
events, probably represent mortality at sea. This appears
to be the case with the typical Inincalus form in Victoria
where many events involve aged, diseased, injured and
very young animals (Warneke, unpublished data).

The false killer whale is an oceanic species, rarely
approaching land except where the continental shelf is
narrow. In Australia, false killers have been widely
recorded by some sightings and strandings in all slates.
Strandings occur throughout the year, but the majority
of mass events occur from May to September on south
and south-east coasts, indicating a seasonal movement
inshore or along the continental shelf (Bannister et al.
1996), possibly associated with abundances of prey. The
two singleton events in the NT are unrevealing, but
probably represent mortality at sea.

The short-finned pilot whale occurs throughout
tropical and warm temperate regions of Indian, Pacific
and Atlantic Oceans, but the southern limits of its range
are poorly known, partly because of the difficulty of
distinguishing it from the closely similar long-finned
pilot whale, Globicephala melas, at sea. The short-finned
pilot whale appears to be widely distributed off
Australia’s northern coast where it ranges into con¬
tinental seas. Records from temperate waters on the
southern coast (South Australia, Tasmania) probably
reflect the influence of the south-flowing, warm Leeuwin
Current and/or East Australia Current (Bannister et al.
1996). Because G. melas is restricted to temperate waters

(the most northern record in Australia is of a straggler at
Point Lookout in Qld (27° 26’S, Paterson 1986) it is
reasonable to assume that the five NT ‘pilot whale’
records are of this species, making six in total. The high
proportion of school strandings (5) in this series and their
wide geographic spread indicate considerable activity
in NT waters and that this species is at high risk when
navigating near the shore in those areas. The large and
fast tidal variations of the NT may also be influential in
this regard.

The dwarf sperm whale is primarily oceanic and
occurs world wide within about 40° N and S of the
equator. The frequency and distribution of strandings in
some regions appears to correlate with continental shelf
width and important current systems, and suggests that
the species might be more abundant in the warmer parts
of its range (Caldwell and Caldwell 1989). It feeds
primarily on benthic and demersal organisms. Dietary
studies in southern Africa (Ross 1984) indicate that
Juveniles and immatures are active over the outer
continental shelf and slope where suitable prey is often
more abundant and that adults feed in deeper waters
beyond the shelf. Comparative data suggest that dwarf
sperm whale is more active nearer to coasts than the
pygmy sperm whale, Kogia breviceps, but in Australia
the former strands very rarely by comparison, with single
records only in WA, SA, NSW and now the NT.

Tropical - subantarctic. Cuvier’s beaked whale
occurs world-wide within this broad latitudinal range. It
is a true oceanic species, normally ranging far from land.
It is thought to be resident in some areas, e.g. off Japan,
where it is most common in waters deeper than 1000 m
(Nishiwaki and Oguro 1972). In the Australian region it
is known from a few strandings in all mainland states,
but many more (15) in Tasmania (Bannister et al. 1996).
Strandings have been recorded in all months except
September to January, but this indication of seasonality
of occurrence may be an artefact of the small series of
Just 12 dateable events. No pattern of seasonality has
been detected in strandings elsewhere (Heyning 1989).
The two certain and one probable NT events listed here
suggest that the species is not uncommon in the region,
but otherwise are unrevealing.

Tropical - Antarctic. Sperm whales range widely in
all oceans and tend to concentrate in the vicinity of steep
continental shelves, oceanic islands and sea mounts
where favoured prey are more abundant. Breeding
females form stable nursery schools, while adult males
are solitary or associate in temporary bachelor schools.
Judging by the frequency of strandings, sperm whales
are common in Australian waters. The majority of events
have occurred in the south-east and most involved single
animals, 75% of which were male. In striking contrast
mass strandings are rare, except in Tasmania (15 events,
Warneke, unpublished data). The series shows a strong
seasonal bias, with most singleton events occurring in

Chatto and Warneke

spring to autumn, and mass events in January - March,
September and October. While this pattern accords with
the known generalised open ocean movement of the
species southwards in summer (Rice 1989; Bannister et
al. 1996), very little is known of its activities near-shore.
The four NT singleton events listed here of known date
indicate that sperm whales, probably only adult males,
are present in the region during summer.

Two forms of blue whale are recognised - the world
wide ‘true’ blue, Balaenopterci miisculus intermedia, and
the southern hemisphere pygmy blue, B. in. brevicauda,
which is most abundant in the Indian Ocean (Yochem
and Leatherwood 1985). Both forms migrate between
warm water breeding grounds at low latitudes and cold
water feeding grounds at high latitudes - the blue
penetrating to the Antarctic ice edge, whereas the pygmy
blue normally feeds north of 55° S. In recent years blue
whales have been encountered relatively clo.se to the
Australian coast at various places, mainly in southern
waters from Rottnest Island WA to southern NSW; the
most northern records being sightings off the Dampier
Archipelago in WA at about 20° S (Bannister et al. 1996)
and a stranding at Couti Uti in Qld (22°20’S, Paterson
1986). The single confirmed record for the NT extends
the known range in the Australian region by 8 degrees
of latitude. At the time this paper was going to print, a
21 m blue whale washed up dead on to Troughton Island
(13°45’S, 126°09’E) in NW Western Australia on
November 7, 2000 (Chatto pers. obs.).

Two relatively discrete Australian populations of
humpbacked whales undertake a seasonal north-south
migration similar to that of the blue whale, but between
breeding grounds on either side of the continent at about
15-20°S and feeding grounds at about 60-70°S; some
individuals may remain in the tropics, e.g. in Torres Strait
(Bannister et al. 1996). Migrating animals generally pass
close to the coast at various points, and stragglers may
enter bays and inlets where they navigate confidently in
confined shallow waters, e.g. in Victoria (Warneke
1995a). Consequently strandings are rare and apart from
live animals entangled in netting they almost invariably
involve individuals that have died at sea from natural
causes. The NT stranding appears to be one such natural
event.

Other species likely to strand in the Northern
Territory. Finally, it remains to consider what species
might in future strand in NT waters and to emphasise
the importance of investigating as many events as
possible to obtain authentic identifications and to
document little known aspects of the species’ biology.
Bannister et al. (1996) lists 14 species that are widely
distributed in the tropical region and are likely to range
into the tropical waters of the Australian region, but
which have not been authentically recorded in the NT.
We provide brief comment on each of these, as well as

the rough-toothed dolphin, killer whale and Bryde’s
whale not included in the review above.

The rough-toothed dolphin, Steno bredanensis, is
widely distributed in deep offshore waters in tropical to
warm temperate latitudes, including the Indo-Australian
Archipelago, but it is not known to be numerous. It is
social and gregarious, and associates with pilot whales
and bottlenose dolphins (Leatherwood and Reeves 1983).
It was listed for the NT by Bannister et al. (1996).

Risso’s dolphin. Grampus griseiis, is abundant and
cosmopolitan in tropical to warm temperate waters
(Leatherwood and Reeves 1983) and although an oceanic
species it is frequently seen over the continental slope
and ranges onto the shelf in parts of Australia (e.g.
Corkeron and Bryden 1992).

The striped dolphin, Stenella coeruleoalba, is widely
distributed in deep waters in tropical to warm temperate
latitudes, ranging to the outer edge of the continental
slope. It is social and gregarious, and is known to be
migratory in some regions (Perrin et al. 1994). In
Australia, southernmost records are strandings and may
be related to the south-flowing warm Leeuwin and East
Australia Currents - at Augusta WA (34° 20’S, Bannister
et al. 1996) and at Woolongong NSW (34° 23’S,
Llewellyn et al. 1994).

The common dolphin, Delphiniis delphis, is very
widely distributed and abundant in tropical to temperate
latitudes, but there are very few records from Australian
tropical waters (Bannister et al. 1996), which may reflect
its preference for areas of high topographical relief and
upwellings (Evans 1994) and the very wide continental
shelf around northern Australia. The species is often
encountered over the narrow continental shelf in south¬
eastern Australia, where many singleton strandings have
been recorded (Nicol 1987; Kemper and Ling 1991;
Warneke 1995b); mass strandings are rare, except in
Tasmania. The species Delphiniis iropicalis is more
likely to occur in waters off the NT coast than D. delphis
(Ross pers. comm.).

Fraser’s dolphin, Lagenodelphis hosei, is abundant
and widely distributed in oceanic tropical waters (Perrin,
Leatherwood and Collet 1994) and could be expected in
waters off the NT coast (Ross pers. comm). This species
occasionally strays into temperate regions, where single
and mass strandings have occurred, e.g. in NSW
(Llewellyn et al. 1994) and Victoria (Warneke 1995c).

The pygmy killer whale, Feresa attenuata, is
primarily tropical in distribution; records from higher
latitudes being associated with warm boundary currents
(Ross and Leatherwood 1994). In Australia it is known
from sightings in north-eastern waters and several
strandings in NSW (Llewellyn et al. 1994) and WA
(Bannister ct a/. 1996).

The killer whale, Orcinus area, is cosmopolitan,
occurring from the equator to polar seas. In Australia

172

Whale and dolphin strandings in the Northern Territory

this species is often seen along the continental slope
and on the shelf, and has been recorded from all states,
but more commonly in the southern waters (Bannister
et al. 1996). Killer whales navigate confidently in very
shallow waters, consequently live strandings are rare.
Several singleton events in Victoria and Tasmania
involved very old and juvenile individuals and one neonate
that had died at sea, or were moribund when they beached
(Warneke, unpublished data), ie they were instances of
natural mortality. Similar events can be expected in the
NT.

Longman’s beaked whale, Indopacetiis pacificus
(Moore \ 96i){-Mesoplodonpacificushongmm 1926),
is known only from two skulls, one from Mackay, Qld,
at 21‘’09’S and the other from Danane, Just north of the
equator in Somalia — points which suggest an Indo-
Pacific distribution. At an estimated length of c. 7.5 m it
is by far the largest me.soplodontid. Intriguingly during
the past three decades there have been numerous
sightings of large beaked whales very similar in form to
the southern bottlenose whale Hyperoodon planifrons
(see below), in tropical waters of the Indian and Pacific
Oceans. A recent review of these sightings and some
associated photographs by Pitman et al. (1999) indicates
that this ‘tropical bottlenose whale’ differs from H.
planifrons in several respects and that it is almost
certainly the elusive I. pacificus. Any report of a large
beaked whale stranded in the NT should be promptly
investigated.

Blainville’s beaked whale, Mesoplodon densirostris,
is an oceanic species widely distributed in tropical to
temperate waters world wide. In Australia it is known
only from strandings, in most of the southern states and
from WA and Qld south of 20° lO’S (Mead 1989).
Records in NSW, Victoria and on the west coast of
Tasmania may be of stragglers ranging southwards in
the warm Leeuwin and East Australia Currents.

The southern bottlenose whale, Hyperoodon plani¬
frons, is included here only on the basis of the proximity
of a record (the type specimen) from Lewis Island in the
Dampier Archipelago (20° 35’S) in WA. The normal
range of this species is considered to be south of 30“ S
to the Antarctic ice edge (Bannister et al. 1996).
Although commonly and widely encountered in deep
oceanic waters (Ross 1984) this species appears to avoid
continental seas and strands infrequently (Baker 1983).

The pygmy sperm whale, Kogia breviceps, has a
similar world wide distribution to its congener K. siniiis,
but tends to remain in deeper waters further offshore
(Caldwell and Caldwell 1989). However, in Australia
K. breviceps strands much more frequently and most
records are concentrated on the east and south-east
coasts, especially in NSW (38 records to 1992, Llewellyn
et al. 1994), possibly because of the relatively narrow
continental shelf in much of that region.

Two rorquals - minke whale, Balaenoptera acuto-
rostrata, and Bryde’s whale, B. edeni, are known from
tropical waters. In the Australian region their status and
movements are not well understood, and the situation is
further complicated by the presence of two forms of each
species. An ‘inshore’ Bryde’s whale is confined to the
tropics, whereas a larger ‘offshore’ form ranges into
temperate waters, where it has been recorded as far south
as Bass Strait (Dixon and Frigo 1994). Similarly, a
diminutive form of minke occurs mainly in the tropical
- subtropical region north to at least 12“ S, although there
are records as far as 58-65“ S, while a ‘dark shoulder
form’, B. bonaerensis, ranges not quite so far north in
winter as the diminutive form (recorded at 21° S), but
migrates to the Antarctic ice edge during summer
(Banni.ster et al. 1996). Two other migratory rorquals -
the fin whale, B. physalus, and the sei whale, B. borealis,
overwinter in subtropical to temperate waters in the
Australian region, but they tend to remain well offshore
and it is not known whether either species ranges into
NT waters (Bannister etal. 1996); in any case they rarely
strand.

ACKNOWLEDGMENTS

Environment Australia, Canberra, provided data
from the National Cetacean Stranding Database.
Several strandings were reported by Coastwatch,
Darwin, the Northern Land Council, Darwin, and the
Dhimurru Land Management Aboriginal Corporation,
Nhulunbuy, NT. Access to specimens and/or additional
reports of strandings were provided by Paul Horner,
Ian and Jared Archibald of the Museums and Art
Galleries of the Northern Territory; Stuart Woerle, Mark
Stevens and Alan Withers of the Parks and Wildlife
Commission of the NT; Bryan Walsh, Frank Woerle and
Peter Whitehead, formerly with the Parks and Wildlife
Commission of the NT; Adrian Donati of the Department
of Primary Industries and Fisheries of the NT; and
Sergeant Kevin Winzar, Port Keats Police. Dr Catherine
Kemper, South Australia Museum, Dr Stephen Van Dyck,
Queensland Museum and Dr Graham Ross, Australian
Biological Resources Survey, Canberra, confirmed some
of the identifications. Dr Peter Whitehead, Dr John
Woinarski and Dr David Cheal of the Parks and Wildlife
Commission of the NT, Palmerston, commented on the
manuscript.

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Accepted 14 November 2000

175

i

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Brake, B., McNeish, J. and Simmons, D. 1979. Art of the Pacific. Oxford University Press: Wellington, New Zealand.

Callen, R.A. 1984. Clays of the palygorskile-sepiolite group: depositional environment, age and distribution. In: Singer, A. and Galan, E.

(eds) Palygorskite-sepioUte occurrence, genesis and uses. Pp 1-38. Elsevier: Amsterdam.

Crowley, L.M. 1949. Working class conditions in Australia, 1788-1851. Unpublished PhD thesis. University of Melbourne.

Sadlier, R.A. 1990. A new .species of scincid lizard from western Arnhem Land, Northern Territory. The Beagle. Records of the Northern
Territory Museum of Arts and Sciences 7(2); 29-33.

The Beagle

Records of the Museums and Art Galleries
OF THE Northern Territory

Volume 16, December 2000

CONTENTS ^

WATSON, J.E. - Hydroids (Hydrozoa; Leptothecatae) from the Beagle Gulf and Darwin Harbour,

northern Australia. 1

BRUCE, A. J. - The rediscovery of Leandrites stenopus Holthuis, 1950 (Crustacea: Palaemoninae),

from Lucinda, Queensland.83

BRUCE, A. J. - Onycocaridella priina Bruce, 1981, a rare pontoniine shrimp from Darwin Harbour

(Crustacea: Decapoda: Pontoniinae).89

BRUCE, A. J. - Biological observations on the commensal shrimp Paranchistus armatus (H. Milne

Edwards) (Crustacea: Decapoda: Pontoniinae).91

VON HAGEN, H.-O.- Vibration signals in Australian fiddler crabs - a first inventory.97

BROWN, G. R. - Caetrathynnus, Nilidothymnis and Procerothynnus, new genera of Thynninae

(Hymenoptcra: Tiphiidae) from northern Australia. 107

MACHIDA, Y. - A new bythitid genus and species, Acarobythites larsonae, from shallow rocky reefs

off northern Australia (Pisces, Ophidiiformes, Bythitidae). 123

KAILOLA, P. J. - Six new species of fork-tailed catfishes (Pisces, Teleostei, Ariidae) from Australia

and New Guinea. 127

MURRAY, P. and MEGIRIAN, D. Two new genera and three new species of Thylacinidae

(Marsupialia) from the Miocene of the Northern Territory, Australia. 145

CHATTO, R. and WARNEKE, R. M. - Records of cetacean standings in the Northern Territory

of Australia. 163