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ASSIMINEIDAE

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Cryptassiminea tasmanica (Tenison-Woods, 1876)

Description: Shell small, solid, spire convex in outline. Protoconch of 1.9 - 2.0 weakly convex whorls, usually eroded. Teleoconch of 3.5 - 5.5 weakly convex whorls, suture impressed, last whorl angled or rounded at periphery. Whorls sculptured with weak spiral threads, disappearing on two last whorls, usually eroded away. Aperture with peristome entire, outer lip prosocline. Umbilicus closed or narrowly open. Colour pale to dark brown with three obscure white spiral bands; the upper one separated from suture by a weak brown band, the others on periphery and base.

Size: Up to 4.9 mm in length.

Distribution: Endemic to Australia: Bundaberg, Queensland, southwards to Western Port, Victoria and to southern Tasmania.

Habitat: "Lives in estuaries from high to low salinity in mangroves and salt marsh. Found under wood, leaves, etc. and on the surface of sediment" (Fukuda & Ponder, 2005)

Comparison: This is often sympatric with C. buccinoides, but differs in the following characters:

• The shell is more ovate

• Periphery of last whorl more rounded than in C. buccinoides

• The uppermost white band is separated from the suture by a weak brown band.

Synonymy: In the literature this has usually not been separated from Cryptassiminea buccinoides, as discussed under that species.

Remarks: This species is usually eroded, but less so than C. buccinoides. Fig. 1 shows a typical eroded adult specimen, and Fig. 2 shows a less eroded specimen with a clear colour pattern.

Fig. 1: Currambene Creek, Jervis Bay, NSW (C.415204)

Fig. 2: Currambene Creek, Jervis Bay, NSW (C.415204)