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An isopod species, Cymodetta gambosa, found in brackish water in Tasmania
Invertebrata 6, Autumn/Winter 1996

In May, 1996, I finally made good my offer to examine Isopoda collected during the QVMAG Tamar intertidal survey. Most of the field work for this survey was done in 1993-1994 but some isopods obtained late in 1992 were included. A species of particular interest was not identified in time to be listed by Smith (1995:86).

Six specimens of Cymodetta gambosa Bowman and Kuhne, 1974, were collected on the western shore of Tamar Island, in the Tamar River, Tasmania on 12 March 1994, by Dr B.J. Smith et al. (grid reference: EQ 065 186). C. gambosa belongs to the suborder Flabellifera, Family Sphaeromatidae. Most flabelliferans are marine but C. gambosa lives in fresh or brackish water. The Tamar River is tidal for its whole length but its upper reaches are brackish due to fresh water received from the North Esk and South Esk Rivers which meet at its head. Tamar Island is only a few kilometres downstream from these tributaries.

In September 1989, one male and two females of C. gambosa were found in the Derwent River, Tasmania, at Murphys Flat (between New Norfolk and Granton), by J. Chapman and Dr P.H.J. Horwitz (grid reference EN 125 660). These specimens are now in the Tasmanian Museum and Art Gallery. At Murphys Flat the Derwent River is tidal but brackish, with the limit of tidal movement not far upstream.

Bowman and Kuhne (1974:239) recorded C. gambosa from New South Wales, Queensland and Victoria. The sample from the Derwent River was listed in the Tasmanian Museum and Art Gallery Annual Report 1989-1990 (Hobart, 1991:43). I have seen no other published record of C. gambosa from Tasmania.

Thank you to Dr T.J. Kingston, QVMAG for his help with information for this report.

Alison Green
Former Curator of Zoology, TMAG

References:

Bowman, J.E. and Kuhne, P. 1974. Records of the Australian Museum 29 (9): 235 - 244.

Smith, B.J. 1995. Tamar Intertidal Invertebrates: An Atlas of the Common Species. Launceston: Queen Victoria Museum and Art Gallery.

Two crab species from the Tamar River, Tasmania
Invertebrata 6, Autumn/Winter 1996

The two species of Brachyura examined for this report are:

PORTUNIDAE; Carcinus maenas (Linnaeus, 1758) European shore crab
PILUMNIDAE; Probably Pilumnus sp.; hairy crab

On 11 February, 1996, the Launceston Field Naturalists Club organised an excursion to the George Town Wildlife Sanctuary, on the eastern shore of the Tamar River. The main purpose was to observe wading birds but some people looked for invertebrates as well. Paul Cunningham and Sarah Tassell found and caught a large male of Carcinus maenas. It was under a stone, in a rock pool, at about mid-tide level (Green 1996). The specimen is now in the QVMAG collection. After this discovery of an introduced European shore crab, I checked the identity of the other crabs sighted that morning but they all belonged to native species.

C. maenas was first reported from Australia in 1900, from Port Phillip Bay, Victoria. Specimens from New South Wales, South Australia and Western Australia have been recorded since then. The species was first recognised in Tasmania in 1993, at Humbug Point, St. Helens. Gardner et al. (1994) recorded this and other east coast findings, while juveniles from Binalong Bay, eastern Tasmania were reported in 1995 (Invertebrata 4:6). There have been unpublished sightings of C. maenas from the Tamar River and from the North Coast of Tasmania as far west as Smithton (L. McGowan pers.comm., quoting information from CSIRO, Centre for Research on Introduced Marine Pests). Thus the male crab from George Town is not the first of its species found in the Tamar but, with a carapace 72 mm wide, it is a well-grown specimen.

No examples of C. maenas had been recognised among the crabs collected during the QVMAG survey of Tamar intertidal invertebrates, 1993-1995 (Smith,1995). However, in 1996 some samples still waited to be examined. The discovery at George Town in February stirred me to make time to finish identifying the survey crabs. This work confirmed that C. maenas was not collected during the 1993-1995 Tamar River survey. However, an Australian species which I examined in April and May, 1996, was not recognised in time to be listed by Smith (1995:86).

Five samples of a species of Pilumnidae were collected among rocks on mud: one male from Bell Bay, East Tamar, 16 January 1993; one male, one female from Middle Arm and one male from Richmond Hill, both West Tamar, 20 March 1993; one male from Donovans Bay, East Tamar, 23 October 1993; 6 males, 5 females from West Bay, Rowella, West Tamar, 16 July 1994. All five localities are in the survey's Zone B, between George Town and the Batman Bridge. The specimens from Bell Bay, Middle Arm and Richmond Hill were checked in April. In these four crabs the apparent distribution of hairs on the carapace is sparse. Because of this I thought that they might belong to Pilumnopeus serratifrons (Kinahan, 1856), the smooth-handed crab, a species for which I found no published record from Tasmania. However, among the samples checked in May were the Pilumnidae from Donovans Bay and West Bay. In these 12 crabs the carapace does bear conspicuous groups of long hairs, yet otherwise they agree with the earlier specimens. At this stage I abandoned thoughts of a new record for Tasmania and placed all of the Tamar survey's Pilumnidae, tentatively, in genus Pilumnus. Their specific identification now requires the attention of a specialist in Brachyura.

The QVMAG has one pre-survey specimen which has been registered as Pilumnopeus serratifrons. It was collected at Wilmores Bluff, West Tamar, on 28 September 1992, by M. Grubert (also in the Tamar survey's Zone B). I shall leave it to a specialist to assess this crab as well.

Thank you to Louise McGowan and Dr. Brian Smith, QVMAG, and Roger Buttermore, TMAG, for their help with information for this report.

Alison Green
Former Curator of Zoology, TMAG

References:

Gardner, N.C., Kwa, S. and Paturusi, A.1994. The Tasmanian Naturalist 116: 26-28.

Green, A.1996. The Launceston Naturalist 29(5 & 6): 6-7.

Smith, B.J. 1995. Tamar Intertidal Invertebrates: An Atlas of the Common Species. Launceston: Queen Victoria Museum and Art Gallery.

Chordeumatidan millipedes
Invertebrata 6, Autumn/Winter 1996

These small, curious millipedes live in loose forest litter (not in the soil) and in bark crevices on standing trees. They have large multi-faceted eyes, 30-32 body segments (in local species) and a pair of spinnerets at the tail end. Silk from the spinnerets is used to weave egg nests and to line the chambers in which the animals moult. Perhaps the most distinctive feature of chordeumatidans is a set of six long setae on the dorsal surface of each body segment (see illustration).

Eleven species in the Order Chordeumatida, in five genera and two families, have now been described from Tasmania (see references below). The most common is Australeuma jeekeli Golovatch, 1986, which is ca. 10 mm long and dark-brown to black above with pale paranota. A. jeekeli is widespread in eastern Tasmania and can be very abundant in wet sclerophyll forest. In a pitfall survey carried out recently by Forestry Tasmania in the Picton River area, 62% of all trapped millipede specimens were A. jeekeli. A yellow-coloured Australeuma species is sometimes extremely abundant in northwest Tasmanian rainforest; it emerges from hiding at night and can be collected in bulk from the surface of the moss-mat on tree trunks. Another chordeumatidan, Reginaterreuma tarkinensis Shear & Mesibov, 1995, is widespread in the west and can often be found sheltering by day under loose bits of bark and wood lying on the forest floor. This species is dark brown, up to 17 mm long, fast-walking (for a millipede!) and 'hairy-looking' thanks to its numerous dorsal setae.

The chordeumatidans are the best known of the Tasmanian millipedes, taxonomically speaking, but new locality records will always be welcome. Contact me or QVMAG Zoology staff for recommended storage, shipment and labelling procedures.

Bob Mesibov
Research Associate, QVMAG.

References:

Golovatch, S.I. 1986. The first Chordeumatida (Diplopoda) from Tasmania, with the description of a new genus and three new species. Zoologischer Jahrbucher, Abteilung fur Systematik 113: 251-264.

Shear, W.A. and Mesibov, R. 1994. Australian chordeumatidan millipeds. I. New observations on the genus Peterjohnsia Mauriès, with the description of a new species from Tasmania (Diplopoda, Chordeumatida, Peterjohnsiidae). Invertebrate Taxonomy 8: 535-544.

Shear, W.A. and Mesibov, R. 1995. Australian chordeumatidan millipeds. II. A new species of Reginaterreuma Mauriès from Tasmania (Diplopoda, Chordeumatida, Metopidiotrichidae). Myriapodologica 3: 71-77.

Shear, W.A. and Mesibov, R. (in press) Australian chordeumatidan millipedes. III. A review of the millipede family Metopidiotrichidae Attems in Australia (Diplopoda: Chordeumatida). Invertebrate Taxonomy.


Portion of the midbody dorsal surface of Australeuma simile Golovatch, 1986, showing paranota (p) and long dorsal setae. Anterior is towards the top. A number of Tasmanian chordeumatidans lack paranota and are more or less cylindrical, but the six segmental setae are always present in these species.

Observations of a breeding cockroach
Invertebrata 6, Autumn/Winter 1996

Since October 1995 we have been observing a cockroach which was found on the floor of our home in South Launceston. We suspect it came in with the firewood. It aroused our curiosity because it was in the process of laying an eggcase. It has been kept in a perspex tank (34 cm x 26 cm x 12 cm) with leaf litter, bark and dry wood, as well as some damp paper for moisture, and checked daily. While the cockroach has not yet been identified by an expert, it resembles specimens of Platyzosteria melanaria in the QVMAG collection. The cockroach is approximately 35 mm long and 12 mm wide. It is shiny black and wingless. It has appeared to show little interest in various things we put in as food, with the exception of dog biscuits and a sultana.

The following table represents the times taken to lay the eggcases and the time between each laying:

'Egg Laying Period' is the number of days between when the cockroach was first seen to be laying until laying was completed. 'Interval Between Eggcases' is the number of days between the completion of the laying of one eggcase and the first signs of the next.

The first eggcase to hatch was Eggcase 3. It hatched in February, 77 days after it was laid. Eggcase 4 hatched in March, after 68 days. Eggcase 1 was dissected after 180 days, and did not appear to have young in it. Eggcase 2 has not yet hatched after 145 days.

The first hatchlings were approximately 5 mm long by 3 mm wide and resembled the mother, though slightly pear-shaped. The empty eggcase was examined under a 'Maggy lamp' and the number of egg cells was found to be 24. From the 17 initial survivors from Eggcase 3, the numbers decreased over 28 days to six. The 14 survivors from Eggcase 4 were initially kept in a separate container with food and water. When, after 11 days, only three survived, these were put into the main tank. After 34 days, only three young from both eggcases survive. It is not clear why the survival rate has been so low. Those surviving are frequently seen on the sugar cube more recently placed in the tank.

As the tank is on the desk in my room, I have noticed that the cockroaches are most active at night. During the day the mother hides under the water container and the young under the bark and leaf litter, or under the sugar cube.

The cockroach surveillance continues......

Sophie Reid
Year 8 Student
South Launceston

The Leaf Beetle, Cadmus australis (Family Chrysomelidae)
Invertebrata 6, Autumn/Winter 1996

Chrysomelidae, containing more than 25 000 species, is the largest of three families forming the Superfamily Chrysomeloidea and totals about 4000 species. Distribution is cosmopolitan.

Chrysomelid beetles are primarily leaf eaters and are of economic concern as they attack a wide range of cultivated plants and trees. In Australia, numerous species are well known as pests of eucalypts. Cadmus australis is one of these and is common in forest areas, feeding on leaves of a variety of juvenile and advanced eucalyptus species.

Adults are small, mainly black with elongate bright yellow markings on the elytra. The male is approximately 6.6 mm long and the female 7.0 mm long. Mating pairs have been collected in March and are common in North Forests Products' reafforestation areas at Nunamara.

After mating the male dies and the female feeds continuously until and during the egg laying period. Eggs are laid singly. On emergence they are encapsulated in a bullet-shaped case with a sealed aperture, the female using the rear legs and abdominal plates to turn the egg and cover it with a special sticky faecal material. When covered the sealed cases are dropped into the forest litter where, upon hatching, the larvae feed on leaves, grasses, etc. Once hatched, the larva uses the utilitarian case as a portable home, enlarging as necessary and eventually sealing off the aperture for its final use as a pupal case.

Mike Tobias
Nunamara TAS 7259

Adult and larva of Cadmus. Drawing by Mike Tobias; scale bar = 10 mm.

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