Shells of this monotypic genus are small, globose to conical, thin, and bright reddish-orange to pale brown. The whorls are weakly convex whorls, and sculptured with fine but distinct axial riblets and irregular microscopic spiral threads. The outer lip of the rounded aperture is prosocline and the columellar lip is thick, and gently curved and there is a narrow, open umbilicus.
The operculum is semicircular and paucispiral, thin, horny, yellowish, transparent. The cephalic tentacles are moderately long with the eyes in lateral bulges at their outer bases. The snout is simple, rather long, and bilobed distally. The foot is large, wide, and rounded anteriorly and posteriorly.
Austroassiminea letha Solem, Girardi, Slack-Smith & Kendrick, 1982
Original name: Austroassiminea letha Solem, Girardi, Slack-Smith & Kendrick, 1982. Solem. A, Girardi, E. L., Slack-Smith, S. and Kendrick, G. W. 1982. Austroassiminea letha gen. nov. a rare and endangered prosobranch snail from south-western Australia (Mollusca; Prosobranchia; Assimineidae) Journal of the Royal Society of Western Australia 65: 119-129.
Type locality: Cosy Corner, Hamelin Bay, near Augusta, Western Australia.
South-western Australia. Restricted to a few isolated localities between Cape Leeuwin and Cape Naturaliste
Each of the three known living populations is small and in danger of destruction from agricultural or other human activity. These threats include weed invasion, sedimentation, erosion, salinity, and loss of riparian vegetation. Due to their reliance on rain-fed springs and limited aestivation ability, these snails are also severely impacted by recent and predicted reduced rainfall in southwestern Australia.
Beesley, P. L., Ross, G. J. B. & Wells, A., Eds. (1998). Mollusca: The Southern Synthesis. Parts A & B. Melbourne, CSIRO Publishing.
Fukuda, H. & Ponder, W. F. (2003). Australian freshwater assimineids, with a synopsis of the Recent genus-group taxa of the Assimineidae (Mollusca: Caenogastropoda: Rissooidea). Journal of Natural History 37: 1977-2032.
Solem, A., Girardi, E.-L., Slack-Smith, S. & Kendrick, G. W. (1982). Austroassiminea letha, gen. nov., sp. nov., a rare and endangered prosobranch snail from south-western Australia (Mollusca: Prosobranchia: Assimineidae). Journal of the Royal Society of Western Australia 65: 119-129.