Colpospira guillaumei (Iredale, 1924)
Description: Protoconch of 1½ whorls , teleoconch up to 11 whorls in adult shells. Whorls straight-sided or concave in outline, separated by a deep suture. Whorls spirally ribbed; latter whorls with a broad, low rib at top and a stronger rib at bottom, with a smooth concave area between ribs. Axial sculpture of growth lines conforming to shape of outer lip sinus. Inner lip of aperture reflected outwards at base; outer lip thin, with a deep sinus, lip usually broken. Body whorl angled, base smooth. Colour fawn and white; spiral ribs alternately but irregularly marked with brown and white. Operculum circular, corneous.
Size: Up to 17.5 mm in length.
Distribution: Endemic to Australia; Tweed Heads, NSW, southwards to Bass Strait.
Habitat: Taken as dead beach shells, and alive down to 100 m. Moderately common.
Comparison: Three species in the NSW fauna are of similar size with brown and white markings - C. sinuata, C. guillaumei, C. quadrara. C. sinuata has only fine spiral threads and the whorls are weakly convex or straight. C. guillaumei has broad, low ribs at top and bottom of whorls but is smooth between. C. quadrata also has ribs at top and bottom of whorls but there are spiral threads between.
Remarks: This species lives in relatively shallow water. It has been dredged from Sydney Harbour at depths down to 20 m, and is found occasionally as beach shells in the harbour and on the ocean beaches.
Fig. 1: East of Malabar, NSW, in 66 m (C.357307).
Copyright Des Beechey 2006