Similipecten greenlandicus (G. B. Sowerby II, 1842)
SOWERBY II, G. B. 1842. Monograph of the genus Pecten. In G. B. Sowerby II (Ed.): Thesaurus conchyliorum, or monographs of genera of shells, 1 (2): 45-78, pls. 12-20. Sowerby. London [p. 57, pl. 13, fig. 40]
1824 Pecten vitreus Gray, 1824
1842 Pecten greenlandicus G. B. Sowerby II, 1842
1919 Pseudamusium [sic] andersoni Dall, 1919
1924 Pecten binominatus Hanna, 1924
1842 Pecten greenlandicus G. B. Sowerby II, 1842
1919 Pseudamusium [sic] andersoni Dall, 1919
1924 Pecten binominatus Hanna, 1924
G. B. Sowerby II, 1842, plate 13.
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«T. aequivalvi, orbiculari, sub-compressâ, sub-aequilaterali, pellucidâ, tenuissimâ, laevi; auriculis parvis, obtusangulatis, anticis minoribus; valvâ dextrâ laminâ tenuissimâ, opacâ, indutâ. Long. 1; lat 0, 25; alt. 1; poll.
This white transparent shell is brought from Greenland. We are indebted to Albany Hancock, Esq., of Newcastle, for the loan of the specimen figured.» GEORGE BRETTINGHAM SOWERBY II, 1842
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Type material
Not found; not in The Hancock Museum at Newcastle upon Tyne (UK) (L. Jessop, personal communication) or in BMNH. Type locality
Greenland. Distribution
Arctic region except the Chukchi Sea (north of Bering Sea); in the North Atlantic southwest to the Gulf of St. Lawrence (Clarke 1974; Lubinsky 1980) southeast to northern Norway (Lofoten), south-eastern Iceland and the Faeroes (Madsen 1949; Petersen 1968). Living in 4 to ca. 600 m, on fine sediments. Some very deep records (2000 m in Knudsen 1985; Richling 2000) probably originate from ice drift. BIOICE material alive at 55 stations in 107–1048 m, only two records below 600 m (Map 5). Description
Shell (Figures 6A,B,D–F) up to ca. 30 mm high, fragile, almost circular (adult specimens slightly longer than high), weakly convex, left valve somewhat more convex than right valve, equilateral, anterior auricles larger than posterior ones, both nearly equal in length, umbonal angle ca. 120, Greyish semitransparent, internal ribs lacking. Prodissoconch (Figure 2D), length 160–170 μm, colour white. Left valve (Figures 9G, 10G) with delicate antimarginal, micro-sculpture of irregularly branching and anastomosing raised lines and commarginal growth lines near ventral margin. Auricles with growth lines and slightly raised laterally, anterior auricle more demarcated from disc than posterior one. Right (Figures 9H, 10H) valve smooth with commarginal growth lines. Anterior auricle with closely spaced growth lines and strongly demarcated from disc, anterior margin curved, posterior auricle continuous with disc. Byssal notch small, byssal fasciole narrow, ctenolium lacking. Remarks
High arctic specimens are much larger, up to 32.5 mm in height in Svalbard (Knipowitsch 1901) and 35 mm in East Greenland (Ockelmann 1959), than specimens from Iceland and northern Norway (up to 12 mm in height), but they cannot otherwise be separated. Jeffreys (1879: 560) considered certain small, smooth specimens from off western Europe to be young S. greenlandicus; Locard (1898:399) introduced a varietal name (var. minor); and Jensen (1912: 32) considered such specimens as a ‘dwarfform’. Ockelmann (1959: 72) had the opinion that the arctic and more southern specimens differed anatomically. Moreover, arctic and West European specimens differ in sculpture of the left valve, which in S. greenlandicus has an antimarginal micro-sculpture of irregular raised lines, while southern specimens have a much weaker sculpture, restricted to the umbo and visible mainly in well preserved specimens. The almost smooth specimens are here considered a distinct species and renamed Similipecten oskarssoni.» DIJKSTRA, H. H., A. WARÉN & G. GUDMUNDSSON. 2009. Pectinoidea (Mollusca: Bivalvia) from Iceland. Marine Biology Research, 5: 207-243, figs. 1-20. [p. 219, 220]
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Similipecten greenlandicus (Sowerby II, 1842); H. H. Dijkstra, A. Warén & G. Gudmundsson, 2009, Pectinoidea (Mollusca: Bivalvia) from Iceland, figures 6A, 6B, 6D, 6E, 6F.
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