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Natica subcostata Tenison-Woods, 1878

Description: Shell moderately solid, spire low. Whorls rounded, sutures weakly impressed. Sculptured with weak axial folds below the suture and obliquely axial growth lines. Aperture entire; inner lip straight, smooth, with callus forming a small semicircular lobe at centre of umbilicus. Umbilicus widely open with strong funicle. Outer lip of aperture smooth. Colour fawn or pale purple, interior and callus white. Operculum calcareous, with about eight strong concentric ribs around a smooth nucleus.

Size: Up to 14 mm in length, but most specimens seen are less than 5 mm.

Distribution: Endemic to Australia; Moreton Bay, Qld, to south-western WA.

Habitat: Occurs subtidally, down to 183 m. Uncommon.

Comparison: The three small subtidal species of Natica can be separated by the structure of the callus in the umbilicus. In N. shorehami it is a circular lobe, completely filling the umbilicus; in N. subcostata it is a small semicircular lobe in the centre of the umbilicus creating a strong funicle, while in T. schoutanica it half closes the umbilicus from the top, and the funicle is broad and low.
Figs. 1,2,3: Twofold Bay, NSW (C.050078)


Copyright Des Beechey 2000