This species belongs to the Austropyrgus sparsus group, with members characterised by the following shell features: small to medium-sized shells, conical, with convex to slightly convex whorls. 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.
Austropyrgus colludens Clark, Miller & Ponder, 2003
Class Gastropoda
Infraclass Caenogastropoda
Order Littorinida
Suborder Rissoidina
Superfamily Truncatelloidea
Family Tateidae
Genus Austropyrgus Cotton, 1942
Original name: Austropyrgus colludens 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: Apsley River, at Lilla Villa bridge, southwest of Bicheno, 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 known from a number of the small coastal streams and rivers of eastern Tasmania.
While most species of Austropyrgus are geographically isolated and have restricted ranges, this one 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.
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.
