This species belongs to the Austropyrgus petterdianus group, whose members are characterised by the following shell features: aperture slightly disjunct, with last whorl and base evenly convex; outer lip without reflection; shell colour yellow-brown and translucent.
A. nanoacuminatus differs from other members of the group in the following combination of characters: shell small, with elongated spire and straight to weakly convex spire outline; ctenidium with short efferent branchial blood vessel separating it from pericardium; prostate gland about 2/3 in pallial roof; pallial vas deferens strongly undulating at prostate gland; penis pigmented distally and medially; oviduct with one bend distal to seminal receptacle.
This species can be found in sympatry with three other species of Austropyrgus (A. lochi, A. conicus and A. smithii) throughout its currently recognized range and from which it can be distinguished by its small size, narrow elongate spire and slightly rounded whorls.
Austropyrgus nanoacuminatus Clark, Miller & Ponder, 2003
Class Gastropoda
Infraclass Caenogastropoda
Order Littorinida
Suborder Rissoidina
Superfamily Truncatelloidea
Family Tateidae
Genus Austropyrgus Cotton, 1942
Original name: Austropyrgus nanoacuminatus 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: Thirteen Mile Creek at Heazlewood Road, Mt Cleveland, 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 small streams, most of which are tributaries of the Arthur River, north-western Tasmania, as well as a few locations north and south of that area.
Although most species of Austropyrgus are geographically isolated and have restricted ranges, a few - such as A. nanoacuminatus - have wider ranges.
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.
