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. In females, the coiled oviduct is of an inverted U-shape or with two or more bends, loops or twists.
Austropyrgus exiguus differs from other members of the group in the following combination of characters: shell small, with straight to weakly convex spire outline, slightly convex to convex whorls; outer lip heavily thickened; central teeth with 2 pairs of basal cusps; basal projection of lateral teeth U-shaped; inner marginal teeth with 11–14 cusps, outer marginal teeth with 18–24 cusps; seminal vesicle not conspicuously coiled on digestive gland behind stomach.
Austropyrgus exiguus Clark, Miller & Ponder, 2003
Class Gastropoda
Infraclass Caenogastropoda
Order Littorinida
Suborder Rissoidina
Superfamily Truncatelloidea
Family Tateidae
Genus Austropyrgus Cotton, 1942
Original name: Austropyrgus exiguus 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: Small tributary of Glenelg River, at Dartmoor, Victoria.
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 small springs and streams which flow into the lower part of the Glenelg River, western Victoria.
Most species of Austropyrgus are geographically isolated and have restricted ranges, and this one is no 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.
