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. pisinnus differs from other members of the group in the following combination of characters: shell small, with straight spire outline and convex whorls; ctenidium abutting anterior end or separated by short efferent branchial blood vessel; penis pigmented on the medial section only; capsule gland with indistinct glandular zones.
This species is not found together with any other species of Austropyrgus. However, A. salvus is found nearby and can be distinguished from A. pisinnus by its larger, broader shell.
Austropyrgus pisinnus Clark, Miller & Ponder, 2003
Class Gastropoda
Infraclass Caenogastropoda
Order Littorinida
Suborder Rissoidina
Superfamily Truncatelloidea
Family Tateidae
Genus Austropyrgus Cotton, 1942
Original name: Austropyrgus pisinnus Clark, Miller & Ponder, 2003. In 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 Supplement 28: 1–109.
Type locality: Tributary of Dismal Creek, tributary of Hardwood River, Tasmania.
In streams on water weeds, hard substrata (rocks etc.) and crawling on litter and sediment. Can be locally abundant. Assumed to feed by scraping bacteria and microalgae. Lay solitary capsules containing a single egg. Direct development.
This species is currently only known from the type locality in southwest Tasmania.
Most species of Austropyrgus are geographically isolated and have restricted ranges, and this one does not appear to be an exception.
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.
