Shell ovate-conical, whorls convex, periphery subangled to rounded; teleoconch with fine axial growth lines and very fine spiral grooves. Aperture ovate, outer lip slightly to moderately thickened, not reflected. Operculum yellow, paucispiral, flat, with several short, white pegs on inner surface head-foot unpigmented or black to dark grey; radula similar to Austropyrgus, Tatea and Fluvidona. Stomach with large posterior caecum. Penis with elbow in middle of distal part when at rest or evenly curved; pallial opening of female genital system placed at about middle or in anterior third of capsule gland and behind or close to anterior end of ventral channel.
Genus Westrapyrgus Ponder, Clark and Miller, 1999
Original reference: Ponder, W. F., Clark, S. A. & Miller, A. C. (1999). A new genus and two new species of Hydrobiidae (Mollusca: Gastropoda: Caenogastropoda) from south Western Australia. Journal of the Royal Society of Western Australia 82: 109–120.
Type locality: Leeuwin-Naturaliste National Park, Western Australia.
In seeps and springs at the base of limestone cliffs and around edges of lakes, pools and streams. On water weeds, bark and sticks, and under stones. Also found clogging water filters in some areas.
This genus is restricted to the southwest of Western Australia.
Westrapyrgus is morphologically most similar to the southeastern Australian freshwater genus Austropyrgus. However, the teleoconch of Westrapyrgus differs in possessing very fine spiral grooves over the entire surface.
Beesley, P. L., Ross, G. J. B. and Wells, A. (Eds). 1998. Mollusca: The Southern Synthesis. Fauna of Australia. Vol. 5. CSIRO Publishing, Melbourne. Part A. Pp. i-xvi,1-563, Part B i-viii, 565-1234.
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.
Ponder, W.F., Clark, S. A. & Miller, A. C. (1999). A new genus and two new species of Hydrobiidae (Mollusca: Gastropoda: Caenogastropoda) from south Western Australia. Journal of the Royal Society of Western Australia 82: 109–120.