Colpospira cordismei (Watson, 1881)
Description: Protoconch 1½ whorls, teleoconch 13 whorls in mature shells. Whorls weakly rounded or straight-sided in outline, suture impressed. Whorls spirally ribbed; latter whorls with a strong primary spiral rib near bottom of whorls, with 1 or 2 riblets below, and 3-8 riblets of varying size above. Axial sculpture of growth lines conforming to shape of outer lip sinus. Base with up to 12 spiral threads. Inner lip flared outwards at base, outer lip thin with deep sinus, lip usually broken. Background colour fawn, with alternating brown and white on spiral ribs. Operculum circular, corneous.
Size: Up to 22 mm in length.
Distribution: Endemic to Australia; Moreton Bay, Queensland, southwards to Twofold Bay, NSW.
Habitat: Known from 18-404 m, usually shallower than 100 m. Moderately common.
Comparison: This species has alternating brown and white on the spiral ribs, making it similar in colouration to C. decoramen, but it is separated from that by being smaller and having more rounded whorls.
Synonymy: Colpospira aquamarina Garrard, 1972 is a weakly sculptured form of this species.
Remarks: There is always a strong primary rib near the bottom of whorls, but the number and strength of the other ribs is variable. In some specimens all spirals are patterned alternating brown and white, in others the pattern is restricted to the primary rib and top of whorls, and in worn shells the pattern is absent.
Fig. 1: Off Cronulla, NSW, in 64 m (C.358132).
Fig. 2: Off Eden, NSW, in 101 m (C.358072).
Copyright Des Beechey 2004