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RETUSIDAE


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Retusa atkinsoni (Tenison-Woods, 1877)

Description: Shell elongate, involute, width of shell length. Apex umbilicate (Fig. 2), protoconch visible at bottom of umbilicus. Last whorl with sides parallel or weakly constricted over middle part of shell. Aperture narrow over top half, wide at bottom; outer edge sharp. Columella smooth, parietal wall with thin callus. Whole surface smooth or with coarse axial growth lines, glossy with extremely fine spiral grooves when not abraded. Shell translucent when fresh under an orange periostracum, becoming opaque white when long dead.

Size: Up to 6 mm in length.

Distribution: Endemic to Australia; NSW southwards to SA (Burn, 2006, 2015).

Habitat: Occurs in estuaries and on the open coast. In estuaries, found in sediment associated with seagrasses intertidally and in the shallow subtidal (Ponder, Clark & Dallwitz, 2000) Common, sometimes abundant.

Figs. 1, 2: Shelly Beach, Clarence River, NSW. (C.474287).

 

Copyright Des Beechey 2018