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Colpospira australis (Lamarck, 1822)

Description: Protoconch one and a half whorls, teleoconch up to 13 whorls. Whorls spirally ribbed; latter whorls with a strong spiral rib near or at bottom of whorl and a weaker rib at top of whorl, with area between smooth or weakly grooved or ribbed; ribs coarsely and irregularly beaded, beading varying from weak to strong. Axial sculpture of growth lines conforming to shape of outer lip sinus. Base convex with about seven flat indefinite ribs. Inner lip of aperture reflected outwards at base; outer lip thin with moderately deep sinus, lip usually broken. Colour yellowish-brown, with brown band around centre of base and sometimes at top of whorls. Operculum circular, corneous.

Size: Up to 20 mm in length.

Distribution: Endemic to Australia; central NSW, southwards to SA, including Tasmania.

Habitat: Known from beach specimens, and down to 140 m. Moderately common in Tasmania, rare in NSW.

Comparison: This species is separated in the NSW fauna by its relatively shallow habitat, beaded ribs and the dark brown colour band. The only other beaded species in the NSW fauna is C. curialis, which is a pure white, very deep water species.

Synonymy: Turritella australis diffidens Iredale, 1925 is based on a specimen with weak beading. Other synonyms are Turritella granulifera Tenison-Woods, 1876 and Turritella terebellata Tate, 1893, a fossil.

Remarks: The position of the major beaded rib is variable, with Tasmanian specimens showing it two-thirds of the way down the whorls, but in NSW shells it is more commonly placed at the bottom of the whorls.

The extension of the range from Bass Strait to include South Australia appears to be based on the fossil Turritella terebellata Tate, 1893

Fig. 1: Off Merimbula, NSW, in 27-37 m. (C.358266)


Copyright Des Beechey 2006