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RISSOIDAE


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Rissoina (Rissoina) nielseni (Laseron, 1950)

Description: Shell large for genus, tall and slender, spire straight. Protoconch of about 2 whorls, with indistinct junction to teleoconch. Teleoconch up to about 8 whorls, weakly angled at top and bottom, weakly convex between angles. Axial sculpture of very weak, irregularly spaced riblets or growth lines, persisting onto base of last whorl. Spiral sculpture of microscopic grooves, more prominent on latter whorls. Aperture lens or D-shaped, with broad anterior canal and narrow posterior canal; outer lip expanded, with weak varix externally; inner lip callused, thickened at top and bottom. Colour white with large orange patches.

Size: Up to 12.9 mm in length.

Distribution: Endemic to Australia; Coffs Harbour, NSW, southwards to Eden, NSW.

Habitat: On the continental shelf, 26-150 m. Uncommon.

Comparison: See R. ferruginea.

Synonymy: None.

Fig. 1: SYNTYPE Off Crookhaven, NSW, in 55-64 m (C.102383)

 

Copyright Des Beechey 2010