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Tricolia rosea (Angas, 1867)

Description: Shell light to heavy in weight, transparent or opaque, moderately squat to moderately tall, whorls rounded (females) or relatively slender and somewhat angled (males). Protoconch with about 8 spiral threads, teleoconch smooth. Aperture oval, outer lip thin to thick. Umbilicus a chink, variable in size. Operculum corneous internally, calcareous externally, white, convex. Background colour white, pink, orange or amber, marked with 2 to 10 white flames descending from suture, and one or more spiral rows of dots or triangles. NSW specimens uniformly pink, or pink with 2 to 5 axial white flames.

Size: Up to 4.6 mm in length.

Distribution: Endemic to Australia; Sydney, NSW, to Shark Bay, WA.

Habitat: Lives on algae in the intertidal and shallow subtidal, down to about 6 m. Most specimens collected as empty beach shells. Uncommon in NSW

Comparison: Distinguished from T. variabilis by its uniformly pink colour, absence of zigzag axial lines, taller shell and more elongate aperture.

Remarks: There are two shell forms, which Robertson (1985) suggested are male and female. The female has rounded or only slightly shouldered whorls, while the male is smaller, thicker shelled, with more angled whorls. Burn (pers. comm.) observed female shells brooding eggs at Port Phillip, Victoria.

Fig. 1:  Gerringong, NSW. Male shell (C.115370).

Fig. 2:  South coast of NSW. Female shell. (C.unregistered)

Copyright Des Beechey 2004