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"Streptocionella pluralis n.sp. (Figs 446, 447, 448, 449)


MATERIAL EXAMINED: NZOI Stn A470; Eltanin Stn 1885.


DISTRIBUTION: Known only from the Ross Sea in 311-377 m.


DESCRIPTION: Shell small, white, helicoid, with a narrow umbilical chink. Whorls three, not including the protoconch, rapidly expanding. Protoconch of the submerged heterostrophic type. Whorl outline broadly convex, spire low, suture impressed. Sculptured by broadly curving growth lines, occasionally well marked, crossed by microscopic, ill-defined striae. Shell surface dull. Body whorl extremely inflated. Aperture ovate, considerably extended anteriorly. Outer lip thin, sweeping broadly forward from suture, becoming continuous with columellar lip which originates from the parietal wall of the last whorl deep inside the aperture and forming a widely shallow concave curve. Columella formed by the reflexed lip, which in some specimens bends over to coalesce with the last whorl to cover the narrow umbilical chink. The columella thus forms an elongate S-curve as it does in the type species of Streptocionella.


MEASUREMENTS: height 3.7 mm, diameter 3.0 mm (holotype); height 2.8 mm, diameter 2.3 mm (paratype).


HOLOTYPE: from NZOI Stn 470 in NZ Oceanographic Institute (H.551).


PARATYPES: from NZOI Stn 470 in NZ Oceanographic Institute (2, P.758) and the National Museum of New Zealand (2, MF.56632); from Eltanin Stn 1885 in National Museum of Natural History.


REMARKS: This unexpected addition to the Ross Sea fauna has a similar expanded last whorl, and style of aperture and columella to S. singularis Martens and Pfeffer, but has an extremely depressed spire."


(Dell, 1990: 247)


Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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