Delectopecten fosterianus (Powell, 1933)
POWELL, A. W. B. 1933. Two new moluscs of the Pectinidae from 600 to 700 fathoms, four hundred miles west of New Plymouth. Transactions of the Royal Society of New Zealand, 63: 370–372, pl. 40. [p. 370, pl. 40, figs. 6, 7]
1933 Palliolum fosterianum Powell, 1933
A. W. B. Powell, 1933, plate 40.
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«Shell of moderate size for the genus, subcircular, convex, very thin, translucent white, having faint "Camptonectes" divaricating striations, and minute rather distant hollow granule-like scales, which occur on the concentric lines of growth. These scales are usually worn off in the middle of the valves, but remain intact at the sides, where they appear as several radial series. In the holotype, which is 20 mm. in height, the striations are about 8 per mm., and the concentric growth-lines 3 per 2 mm., at the middle of the shell. Hingeline straight, ears unequal, produced a little longer anteriorly. Sculpture of anterior ear in right valve consists of six rows of imbricating radial ribs which are crossed by the concentric growth-lines. The posterior ear of the right valve and both ears of the left valve are without radial sculpture except for the growth-lines and "Camptonectes" striations. Byssal notch deep and wide, with a broad fasciole, and a ctenolium with four free teeth. Apart from the byssal notch the margins are entire, close fitting, thin, and not bevelled. The beaks are small, sharply pointed, and approximate.
Interior glassy, polished, muscle-scar indistinct. Ligamentary pit very small and shallow. Height 20 mm.; width of valves 19.75 mm.; width of hinge-plate 12 mm.; thickness (two valves) 6 mm. (holotype, fig. 6). Holotype and several paratypes in Auckland Museum. This new species appears very like the deep-water Atlantic Chlamys (Palliolum) chaperi Dautzenberg & Fischer.* The New Zealand species differs from the Atlantic one in being more circular, in having a proportionately longer hinge-plate, and in being without a constriction between the hinge-line and the disc; that is apart from the byssal sinus in the right valve. Unlike the colourless, translucent fosterianum the Mediterranean genotype is brightly coloured, but on shell characters it is very similar to the New Zealand species. The species is named after Mr W. Foster, of the cable steamer "Recorder," who, by collecting material from cables at every opportunity, has done much to further our knowledge of deep-sea life in Australasian waters. Another related species is the deep-water Pecten kermadecensis E. A. Smith, which was dredged by the "Challenger " at Station 171, north of the Kermadec Islands, in 600 fathoms.†» * Chlamys (Palliolum) chaperi Dautz. & Fischer. Station 584, 38º 31' N., 26º 49' 15" W. in 845 metres. Dautzenbergh, Ph. 1927. Resultats des Campagnes Scientifiques du Prince de Monaco. Mollusques. Provenant des Campagnes Scientifiques du Prince Albert 1er de Monaco dans l'ocean Atlantique et dans Le Golfe de Gascogne. † Challenger Reports, Zoology, voI. 13, 1885, p. 302, pI. 21, figs. 7 and 7a. ARTHUR WILLIAM BADEN POWELL, 1933
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«Distribution
Eastern and southern Australia (Dijkstra, unpubl. data), Pacific-Antarctic Ridge (Dell 1990), West Norfolk Ridge, Kermadec Ridge, and New Zealand, 376–1568 m; taken alive at 376–1568 m from hard substrata. Locally common (Fig. 41). Remarks
The present specimens are indistinguishable from the type material. Commarginal and radial sculpture in D. fosterianus ranges from prominent to very weak, or may even be absent. The minimum in Dell’s (1956) stated bathymetric range “25–700 fathoms” (repeated in metres by Dell 1990) is based on a misidentified juvenile Pecten novaezelandiae from Queen Charlotte Sound (M.6592) (Dell 1951: 16).» DIJKSTRA, H. H. & B. A. MARSHALL. 2008. The recent Pectinoidea of the New Zealand region (Mollusca: Bivalvia: Propeamusiidae, Pectinidae and Spondylidae). Molluscan Research, 28 (1): 1-88, figs. 1-70. [p. 49, 50]
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Delectopecten fosterianus (Powell, 1933); H. H. Dijkstra & B. A. Mashall, 2008, The recent Pectinoidea of the New Zealand region, figures 40A, 40B, 40D-40F.
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