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Description

Astarte antarctica Thiele, 1912 (Figs 103, 104)

 

 

Astarte antarctica Thiele, 1912: 229, pl.18, fig. 8; Thiele and Jaeckel, 1931: 212; Soot-Ryen, 1951: 24; Powell, 1958: 177; Egorova, 1982: 69, figs 302, 303.

 

 

MATERIAL EXAMINED: NZOI Stns A463, A464, A521; Eltanin Stns 1870, 1997, 2005, 2007, 2020, 2073.

 

 

DISTRIBUTION: Astarte antarctica has been recorded from 49°E, 89°E, 158°W around the continent and from the Ross Sea. It has been recorded from only three stations outside the Ross Sea and from nine stations within the Ross Sea in 256-870 m.

 

 

REMARKS: Nicol (1966: 47) listed antarctica Thiele as a synonym of longirostris Orbigny and identified two specimens from the eastern extremity of the Ross Sea as longirostris. He gave no reasons for not retaining antarctica as separable. Most specimens from the Ross Sea have numerous closely spaced raised commarginal ridges (21-25) as in Thiele's figure of antarctica. Magellanic specimens of longirostris have from 15-17 commarginal ridges in specimens of comparable size. Nicol's single adult figured valve has widely spaced commarginal ridges and the writer has seen one other specimen from the Ross Sea with similar sculpture. The general pattern, however, is closely spaced commarginal ridges as in Thiele's specimen of antarctica. Examination under SEM shows the presence of shell pits arranged in broad radial rows separated by much smaller pits in longirostris (Fig. 102). The shell of antarctica shows similar shell pits which are, however, of subequal size and not arranged in any definite pattern (Fig. 104). The differing arrangement of shell pits in the two forms supplies additional evidence for retaining the name antarctica for the truly antarctic form. Specimens examined by the writer from the Magellanic region, Falkland Islands and South Georgia all have the characters of longirostris. The material from Prince Edward Island, Marion Island and Kerguelen recorded as longirostris should be re-examined to determine its relationships.”

 

 

(Dell, 1990: 58)

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© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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