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Parastacoides tasmanicus LT (Family Parastacidae)

Distribution:

This freshwater crayfish species is widespread throughout western and northern Tasmania, with the exception of the far north-west. It is the only species of this new genus present in this region, however, it is often found in the same areas as species of another freshwater crayfish genus, Engaeus. (TAS).

Features:

A small (maximum length of 80 mm) burrowing crayfish found only in the north-west of Tasmania. The rostrum is distinctively concave in cross-section.

Ecology/Way of Life:

This is one of the many “burrowing” freshwater crayfish species found in Tasmania. It is relatively small, growing to approximately 80 mm in length. Although aquatic (uses gills to breathe) this freshwater crayfish, along with other species in this genus, can be found several kilometres from standing water. Its burrows extend down to the water table, terminating in a water-filled chamber; these burrows may extend for more than two metres. Burrowing freshwater crayfish are capable of surviving for extended periods out of water, and have been known to wander overland long distances from their burrows. The burrows can consist of mere runnels in mossy banks, to deep, ramifying structures occupying volumes of up to two cubic metres. While this species mainly lives in burrows, it is also often found in streams and lakes. They inhabit a wide range of vegetation types: rainforest, buttongrass plains, heathlands, melaleuca and eucalypt forest. In common with most Tasmanian “burrowing” crayfish, this species eats a combination of rotting vegetation, detritus, and small amounts of animal matter.

Females moult and produce young only every second year. There is some variation between species in this genus, however mating and spawning generally occurs between autumn and spring. The females carry the eggs from June to November and the eggs will hatch in early summer. The young remain attached to the female through two moults and are released in late summer, although they remain in the female's burrow system until her next hatchlings are released.

Recent research suggests that this is a very ancient species, along with others in the genus. It first appeared during the Miocene (more than eight million years ago). The species has therefore been able to survive through the glaciations associated with the Pleistocene ice-ages; some areas now occupied by this species had ice-caps up to 600 meters deep in the early Pleistocene. The animals probably survived in refugia in coastal river valleys, and migrated back to the present range as the ice melted.

Interaction with Humans/Threats:

Animals in this species are relatively slow-growing, reach a maximum size of only 80 mm and are burrowers. This combination means they are not suitable for intensive rearing for aquaculture. Although the range of this species extends into the Tasmanian World Heritage Area, large parts of the range lie outside this reserve. The northern-most part of its range has been greatly altered through land-clearing, both through forestry and for agriculture, and the species is vulnerable in these regions.

Other Comments:

Variations within the species yet to be formally described. Refer to Hansen and Richardson (2002).

Further Reading:

Crandall, K.A. & Fetzner, J.W. (2004). Crayfish Home Page. http://crayfish.byu.edu/

Hansen, B. and Richardson, A. M. M. (1999). Interpreting the geographic range, habitat and evolution of the Tasmanian freshwater crayfish genus Parastacoides from a museum collection. In: W. Ponder & D. Lunney, (eds) The Other 99% – the Conservation and Biodiversity of Invertebrates. Transactions of the Royal Society of New South Wales, Mosman. pp 210 – 218.

Hansen, B., Adams, M., Krasnicki, T. and Richardson, A. M. M. (2001). Substantial allozyme diversity in the freshwater crayfish Parastacoides tasmanicus supports extensive cryptic speciation. Invertebrate Taxonomy 15:667 – 679.

Hansen, B. & Richardson , A.M.M. (2002). Geographic ranges, sympatry and the influence of environmental factors on the distribution of species of an endemic Tasmanian freshwater crayfish. Invertebrate Systematics. 16(4) pp621 – 629.

Acknowledgments:

Text and distribution map by Brita Hansen. Photography by R. Mawbey.

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