Small land snails from Northern Australia, II: Species of Westracystis Iredale, 1939 (Mollusca: Pulmonata, Helicarionidae)

Summary

Dissection of two small helicarionid land snail species from the Kimberley and near Katherine, Northern Territory show that the genus Westracyst is lredale, 1939 belongs to the subfamily Helicarioninae. One species, Westracystis lissus (E. A. Smith 1894) and its subjective synonym Westracystis tentus Iredale, 1939, is widely distributed in the Kimberley, with records from the Harding and Napier Ranges, north and east of Derby, respectively, to Kalumburu and then west to the Lawford and Laidlaw Ranges on th south-east fringes, finally across the border of the Northern Territory to the Sorby Hills and Keep River in the north with a single record along the Victoria Highway, 25 km east of Timber Creek Police Station. The second species, Westracystis fredaslini, new species, is known from the vicinity of Katherine south to Elsie Station on the Roper River, Northern Territory. Discussion of anatomical differences, aestivation strategies, annual growth differences, and ecology help to explain the wide distribution of W. lissus.