Epitonium tenellum (Hutton, 1885)
Description: Shell average width for genus, variable in height to width ratio; whorls connected. Whorls rounded, with 15-25 axial ribs per whorl. Ribs mainly thin and low, some greatly thickened, not peaked; not continuous from whorl to whorl. Interspaces smooth. Aperture oval; outer lip with normal rib externally. Umbilicus slightly open, almost concealed by inner lip of aperture. Colour fawn or light brown, with brown spiral band immediately below upper suture and another at base of last whorl. Operculum corneous.
Size: Up to 18 mm in length.
Distribution: Australia and New Zealand. In Australia, Port Douglas, Queensland, southwards to Western Port, Victoria.
Habitat: Known from empty shells from beach washup, plus a few dredged down to 27 m in Sydney Harbour.
Comparison: See "Identification of the NSW species of Epitonium" in the introduction to this family.
Synonymy: Shells of this species from Sydney Harbour were named Limiscala helicornua Iredale, 1936 (Fig. 2), on the basis that "the Neozelanic shell [ie E. tenellum] is smaller, with fewer ribs and also narrower", but none of these characters are consistently different between Australian and New Zealand shells (Kerslake, 1969).
Fig. 1: Bundeena, Port Hacking, NSW (C.169513)
Fig. 2: HOLOTYPE of Limiscala helicornua. Sydney Harbour (C.060649)
Copyright Des Beechey 2008