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RISSOIDAE


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Rissoina (Rissoina) vincentiana Cotton, 1952

Description: Shell moderately large for genus, spire straight-sided or weakly convex. Protoconch usually eroded. Teleoconch of 6-8 weakly convex to straight-sided whorls. Sculpture of axial ribs, becoming weaker and more closely spaced on second-last whorl and usually absent from last whorl; spiral sculpture of fine threads between axials (usually eroded away). Aperture lens or D-shaped, with broad anterior canal and narrow posterior canal; outer lip greatly thickened externally; inner lip callused, thickened at top and bottom. Colour white or fawn.

Size: Up to 12.3 mm in length.

Distribution: Endemic to Australia; Tathra, NSW, southwards and around southern Australia, to south-western WA.

Habitat: In Victoria and South Australia, common under stones intertidally, with a few records down to 75 m. In NSW, known from only one record, from 170 m off Tathra.

Comparison: This is very similar to narrow specimens of Rissoina fasciata, but is larger and the spire is less convex.

Synonymy: This species has been incorrectly identified in some Australian literature as Rissoina dorbignyi (A. Adams, 1851), which is a tropical species.

Fig. 1: Western Port, Victoria (C.463911)

 

Copyright Des Beechey 2010