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Sphaerocylichna incommoda (E.A. Smith, 1893)

Description: Shell ovate, involute. Sides strongly convex. Smooth apart from weak spiral grooves at top and 2 or 3 stronger grooves at base. Aperture wide over top half, twice the width anteriorly; outer lip sharp. Parietal wall without callus. Columella smooth, narrow umbilicus behind, sometimes concealed by expanded columellar callus. Colour white.

Size: Up to 5 mm in length.

Distribution: Holotype from 410 fathoms (750 m) off Sydney. Other lots from 750 m off Sydney; 1000 m off Broken Bay, NSW; 79-295 m off Sydney; 238 m off Cape Jaffa, SA.

Habitat: Subtidal, down to 1000. Rare.

Remarks: This is one of the species from Challenger station 164B, from 410 fathoms off Sydney. When they were collected they appeared so foreign that Hedley (1901) and later Iredale (1962, p. 4) rejected them as not occurring in NSW, suggesting that a mix-up of samples had occurred, and the specimens must have been from an Atlantic station. However, subsequent collecting has established the species legitimately in the NSW fauna.

Fig. 1: Off Sydney, NSW, in 79-295 m (C.476116).

 

Copyright Des Beechey 2018