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Cycloscala hyalina (Sowerby, 1844)

Description: Protoconch tall, of 5 moderately rounded whorls with fine axial striae. Teleoconch whorls completely separated, rounded, with high, thin axial ribs. Ribs 6 or 7 on last whorl, weakly crenulate, sometimes weakly peaked, not aligned from whorl to whorl. Interspaces smooth. Aperture oval, with normal rib externally. Colour translucent white.

Size: Up to 14 mm in length, usually much smaller, less than 5 mm.

Distribution: Indo-West Pacific. Full extent of Australian range unknown, but it definitely occurs in Northern Territory, Queensland and NSW, as far south as Twofold Bay.

Habitat: Known mainly from beach washup; also Sydney Harbour dredgings, and a few lots down to 64 m. Uncommon in NSW.

Synonymy: Solvaclathrus jacobiscala Iredale, 1936 (NEW SYNONYM) falls within the range of variation and is a synonym.

Remarks: The degree of separation of the whorls varies widely, from a distance equal to the rib height to about 4 times the rib height (Fig. 3). The angle between the protoconch axis and the teleoconch axis is also variable, depending on the degree of uncoiling of the first teleoconch whorl.

Fig. 1: Gunnamatta Bay, Port Hacking, NSW (C.460971)

Fig. 2: HOLOTYPE of Solvaclathrus jacobiscala. Sydney Harbour, Triton dredge (C.060652)

Fig. 3: Gunnamatta Bay, Port Hacking, NSW (All C.460971)


Copyright Des Beechey 2008