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4968-1.jpg (101272 bytes)

 

4970-1.jpg (117574 bytes)

Pisinna olivacea (Frauenfeld, 1867)

Description: Shell minute, solid, variable in shape, usually eroded, spire convex in outline. Protoconch of 1 whorls, sculptured with spiral rows of minute pits, with distinct junction to teleoconch. Teleoconch up to about 3 weakly to moderately rounded whorls; first teleoconch whorl smooth, latter whorls with oblique axial ribs, absent on final third of last whorl. Spiral groove below suture, forming nodules between groove and suture. Aperture circular to D-shaped, sharp edged; outer lip without varix. Colour red to orange-brown, often with sutural nodule band white.

Size: Up to 2.3 mm in length.

Distribution: Endemic to Australia: Noosa Heads, Queensland, southwards to eastern Victoria and Tasmania.

Habitat: "Lives in the middle to lower littoral and shallow subtidal on short algae and beneath stones etc." (Ponder & Yoo, 1976). Common in beach washup.

Comparison: See Comparison of Pisinna species

Synonymy: Rissoa diemenensis Petterd, 1884 is a synonym.

Remarks: The shape and sculpture of this species is variable. The number and strength of the axial ribs is variable, as is their point of commencement on the spire. The spiral groove below the suture varies in strength, as does the spiral row of nodules it defines.

Fig. 1: 4968-1 Little Manly Beach, Sydney, NSW (C.353046)

Fig. 2: 4970-1 Both specimens Ulladulla, NSW (C.302891)

 

Copyright Des Beechey 2010. Modified 2014