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Austropyrgus colludens Clark, Miller & Ponder 2003

Diagnostic features

This species belongs to the Austropyrgus sparsus group, whose members are characterised by the following shell features: small to medium sized shells, conical, with convex to slightly convex whorls. Furthermore, in females, the coiled oviduct is of an inverted U-shape or with two or more bends, loops or twists.

Austropyrgus colludens differs from other members of the group in the following combination of characters: shell small; spire outline straight, whorls convex, outer lip with slight reflection; seminal vesicle slightly undulating over stomach; pallial vas deferens strongly undulating or longitudinally S-shaped between prostate gland and penis.

Classification

Austropyrgus colludens Clark, Miller & Ponder 2003

Class Gastropoda

Subclass Caenogastropoda

Order Littorinimorpha

Superfamily Truncatelloidea

Family Tateidae

Genus Austropyrgus Cotton, 1942

Original name: Austropyrgus colludens 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: Apsley River, at Lilla Villa bridge, southwest of Bicheno, Tasmania.

Biology and ecology

In streams on water weeds, hard substrate (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.

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 known from a number of the small coastal streams and rivers of eastern Tasmania.

Notes

While most species of Austropyrgus are geographically isolated and have restricted ranges,  A. colludens has a reasonably wide range in coastal drainages in the northern half of eastern Tasmania.

This species has been found in sympatry only with A. elongatus, and only at a single location. It is distinguished by its much smaller shell with a shorter spire.

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.