Similipecten oskarssoni Dijkstra, Warén & Gudmundsson, 2009
DIJKSTRA, H. H., A. WARÉN & G. GUDMUNDSSON. 2009. Pectinoidea (Mollusca: Bivalvia) from Iceland. Marine Biology Research, 5: 207-243, figs. 1-20. [p. 220, figs. 2B, 7B-7F, 9E, 9F, 10E, 10F]
1898 Pecten groenlandicus var. minor Locard, 1898
2009 Similipecten oskarssoni Dijkstra, Warén & Gudmundsson, 2009
2009 Similipecten oskarssoni Dijkstra, Warén & Gudmundsson, 2009
H. H. Dijkstra, A. Warén &
G. Gudmundsson, 2009, figures 2, 7, 9, 10. |
«Pecten groenlandicus; Jeffreys (1879: 560 [not P. greenlandicus Sowerby]).
Pecten groenlandicus var. minor Locard (1898: 399 [original description]). Propeamussium sp. b Ockelmann (1959:72). Similipecten similis (Laskey); Schein (1989:96 [pro parte]). Type material
Lectotype of Pecten groenlandicus var. minor (spm: H 6.2, L 6.5, C 1.6 mm), 5 paralectotypes (3 spm + 2 v) in MNHN [no register number], here designated. Type locality
Bay of Biscay, 647–1190 m depth. Etymology
Named after Ingimar Óskarsson (1892–1981), honorary doctor at the Icelandic University, and an initiator of high level amateur natural history in Iceland. Distribution
Western and south-western Iceland to the Bay of Biscay, probably also off West Africa but the paralectotypes supposed to originate from such localities, have unclear locality data or are lost. BIOICE material alive at 33 stations in 291–1408 m, on fine sediments (Map 5). Description
Shell (Figures 7B–F) up to ca. 10 mm high, fragile, transparent, weakly convex, equivalve, nearly circular (somewhat longer than high), equivalve and equilateral, anterior auricles slightly longer than posterior ones and somewhat more demarcated from disc, umbonal angle ca. 120°, internal ribs lacking. Prodissoconch (Figure 2B), length 175 μm, colour white. Both valves smooth (Figures 9E,F, 10E,F), except the umbonal area of the left valve, which has a sculpture similar to S. greenlandicus, but more delicate (Figure 10E). Posterior auricle more continuous with disc than anterior one. Anterior auricle of right valve larger and more curved laterally than anterior one of left valve. Byssal notch moderately small, byssal fasciole very weak, ctenolium lacking. Remarks
The type material of Pecten groenlandicus var. minor consists of two lots, one labelled ‘Talisman 1883, dragage 34’, from 112 m depth off northwestern Morocco. A second lot consists of 3 spm and 4 v from ‘Travailleur 1880, dragages 2, 7, 90, 12, 14, 16 and 20’, from the Bay of Biscay, in 697–1190 m. A third lot with a single specimen and the same station numbers has obviously been separated later from this and glued to a piece of cardboard. Two lots listed by Locard (1898) are missing. The specimen from dragage 34 seems to be mislabelled, already by or before Locard, since the depth is much smaller than expected. We have therefore selected a specimen from the mixed lot as lectotype. A restriction of the type locality, more detailed than Bay of Biscay, does not seem necessary. All specimens in identifiable condition belong to S. oskarssoni and the characteristic, irregular lines can be seen on the umbo of the left valve. Similipecten oskarssoni can be confused with S. greenlandicus of similar size. Both species occur in Iceland and live in similar habitats, but with no overlap in distribution (Map 5). Similipecten oskarssoni has only a few irregular radial lines on the umbo of the left valve, visible at 50 with a good stereomicroscope, whereas S. greenlandicus has a similar but much coarser micro-sculpture and S. similis is smooth (Figures 7G,H, 9I). For further differences see Table I. Schein (1989:96) regarded this species as a ‘forme incolore’ of Similipecten similis. According to the IZCN (1999: 50, art. 45.6.4) the name Pecten groenlandicus var. minor Locard, 1898 may be considered subspecific, but the subspecies name is preoccupied by Pecten maximus var. minor Locard, 1888. Therefore the epithet is replaced with Similipecten oskarssoni nom. nov. (ICZN, 1999: 63, art. 60.3).»
HENK H. DIJKSTRA, ANDERS WARÉN & GUDMUNDUR GUDMUNDSSON, 2009
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