Print Fact Sheet

Austropyrgus nanus Clark, Miller & Ponder 2003

Diagnostic features

This species belongs to the Austropyrgus cooma group, whose members are characterised by generally pupiform to conical, small to medium sized shells, where the last whorl and base are evenly convex. A. nanus differs from other members of the group in the following combination of characters: shell small, with convex spire outline; outer lip weakly thickened and without reflection; bursa copulatrix ovoid; capsule gland with anterior end tapering and compressed-oval in cross section.

This species is the smallest member of the genus and among the few that exhibit obvious sexual dimorphism in shell size, with the females significantly larger than the males.

Classification

Austropyrgus nanus Clark, Miller & Ponder 2003

Class Gastropoda

Subclass Caenogastropoda

Order Littorinimorpha

Superfamily Truncatelloidea

Family Tateidae

Genus Austropyrgus Cotton, 1942

Original name: Austropyrgus nanus Clark, Miller & Ponder 2003. Clark, S. A., Miller, A. C. and Ponder, W. F. (2003). Revision of the snail genus Austropyrgus (Gastropoda: Hydrobiidae): A morphostatic radiation of freshwater gastropods in southeastern Australia.  Records of the Australian Museum Supplement 28: 1–109.

Type locality: Natural thermal spring, south of dam and pool, Hastings Thermal Springs, west of Hastings, Tasmania.

Biology and ecology

Occurs in thermal springs, and can be extremely abundant throughout the very small area of the springs. It can be found crawling on all substrates. This species and A. solitarius are the only two hydrobiids to be found in this habitat in Tasmania.

Additional information on the biology and ecology of members of this family can be found in Fauna of Australia, vol. 5B, p. 752-755.

Distribution

This species is found in a number of small thermal springs (25°C), which are part of Hastings Hot Springs group, south-eastern Tasmania.

Notes

Most members of Austropyrgus, including this species, are geographically isolated and have restricted ranges.

Further reading

Clark, S. A., Miller, A. C. & Ponder, W. F. (2003). Revision of the snail genus Austropyrgus (Gastropoda: Hydrobiidae): a morphostatic radiation of freshwater gastropods in southeastern Australia. Records of the Australian Museum 28: 1–109.