Catillopecten tasmani Dijkstra & Marshall, 2008
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. 39, figs. 32A-32F]
2008 Catillopecten tasmani Dijkstra & Marshall, 2008
H. H. Dijkstra & B. A. Marshall, 2008, plate 32
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«Catillopecten sp. Spencer et al. in press.
Type material
Holotype (left v) NIWA S151, and paratypes (6 v, M.158279; 1 pr, 28 v NIWA; 1 pr, 4v, ZMA Moll. 4.02.013); Bounty Trough, southern New Zealand, 45º48.8’S, 174º30.5’E, alive, 1586 m, 26 Oct.1979, RV Tangaroa. Paratypes: Challenger Plateau, 41º15.2’S, 167º07.2’E, alive, 1457–1463 m (3 pr, NIWA P941). Bounty Trough: 45º21.2’S, 173º35.8’E, 1386 m (1 v, NIWA S153); 45º24.2’S, 173º59.8’E, alive, 1373 m (1 pr, 2 v, NIWA S154); 45º52.3’S, 174º04.9’E, alive, 1676 m (1 pr, 13 v, NIWA S152). Material examined
The type material (see above). Description
Shell up to c. 10 mm high, extremely thin and fragile, nearly circular, equivalve, compressed, left valve more convex than right valve, inequilateral, auricles unequal, umbonal angle c. 90º, resilifer triangular, translucent, colourless, both valves matt due to exceedingly finely granular surface texture. Prodissoconch c. 150 μm long, convex, smooth. Dissoconch left valve smooth apart from low, broadly rounded, commarginal undulations that commence almost immediately. Posteromarginal area of disc somewhat elevated. Auricles poorly demarcated from disc. Fine commarginal growth lines on anterior auricle, weaker growth lines on posterior auricle. Right valve disc with weak, irregular, commarginal undulations, fine commarginal growth lines, and obscure radial lines. Posterior auricle not demarcated from disc, with fine commarginal growth lines. Anterior auricle sharply demarcated from shell disc, with fine crowded commarginal threads. Byssal gape rather deep, no byssal fasciole or ctenolium. Distribution
Eastern Tasman Sea and Bounty Trough, New Zealand, taken alive at 1373–1676 m from foraminiferal ooze (Fig. 33). Remarks
Catillopecten tasmani most closely resembles C. eucymatus (Dall, 1898) (Atlantic, 1057–4829 m: see Schein 1989: 101), but differs in that the right valve is more strongly undulated and lacks commarginal striae. It differs from C. murrayi and C. graui (Knudsen, 1970) (tropical eastern Pacific, 3270–3670 m), principally in attaining smaller size (height up to 10 mm, versus c. 15 mm and 17 mm respectively), in having a weakly commarginally undulating rather than smooth disc, and in lacking commarginal lamellae. It differs from C. translucens (Dautzenberg & Bavay, 1912) (Indonesia, 1301 m), primarily in that the auricles are finely sculptured rather than smooth; from C. knudseni (Bernard, 1978) (north-eastern Pacific, 220–2900 m), in being smaller (C. knudseni up to ca. 18 mm high) and in lacking radial microsculpture; from C. squamiformis (Bernard, 1978) (NE Pacific, 2030–2884 m), in having more regular undulations, with the left valve having fewer, more widely spaced commarginal lamellae; and from C. vulcani (Schein-Fatton, 1985) (tropical eastern Pacific, 2620 m), in attaining smaller size (C. vulcani up to 14 mm high), in being subcircular rather than elongate, and in that the left valve is more weakly undulated, and the right valve is more inflated. Etymology
After Abel Janszoon Tasman (1602–1659), a Frisian mariner and explorer, who served the Dutch East India Company, and in 1642–43 made the first European discovery of Tasmania and western New Zealand.» HENK H. DIJKSTRA & BRUCE A. MARSHALL, 2008
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