Cyclopecten fluctuosus 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. 14, figs. 12A-12D]
2008 Cyclopecten fluctuosus Dijkstra & Marshall, 2008
H. H. Dijkstra & B. A. Marshall, 2008, figure 12.
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«Cyclopecten sp. Spencer et al. in press.
Type material
Holotype (pr) NIWA and 3 paratypes (2 pr, M.173003; 1 pr, ZMA Mol. 4.02.012); Tasman Basin, 41º20.4’S, 166º54.8’E, alive, 1760–1799 m, 22 Apr. 1980, RV Tangaroa (NIWA P939). Paratypes: Bounty Trough, 45º21.2’S, 173º35.8’E, alive, 1386 m (2 pr, NIWA S153); 45º24.2’S, 173º59.8’E, alive, 1373 m (2 pr, NIWA S154). Material examined
The type material (see above). Tasman Basin, 41º22.7’S, 166º44.4’E, 2092–2154 m (1 fragment, NIWA P940). Description
Shell up to 6.55 mm high, subcircular, equivalve (relatively narrow, thin ventral margin of right valve disintegrating post mortem: thickened inner part 84% height of left valve), almost equilateral, left valve slightly more convex than right valve, auricles similar in size, umbonal angle about 120º, no internal riblets; colourless, strongly transparent. Prodissoconch c. 150 μm long, D-shaped, smooth, sharply separated from dissoconch. Dissoconch left valve sculptured throughout with regularly spaced commarginal lamellae (c. 10 per mm), more closely spaced on auricles. Microsculpture of minute, crisp granules throughout. Right valve disc sculptured throughout with regularly spaced commarginal lamellae. Auricles sculptured with fine, closely spaced, commarginal lirae. Anterior auricle and byssal fasciole separated from disc by a rather deep groove, posterior auricle continuous with disc. Byssal fasciole narrow. Distribution
Tasman Basin and Bounty Trough, New Zealand, 1373–2154 m, alive at 1373–1799 m (Fig. 13). Remarks
Cyclopecten fluctuosus resemble Cp. kapalae (see below) in gross facies, but differs in having more closely spaced commarginal sculpture in early ontogeny, in lacking radial sculpture on the left valve, and in having a deeper groove beside the byssal fasciole on the right valve. It is also similar to Cp. pellucidulus Dijkstra, 1995 (northern Norfolk Ridge, 680–700 m), but differs in being narrower and in having finer, more closely spaced commarginal lamellae. Specimens from the Bounty Trough have slightly and distinctly more widely spaced commarginal lamellae on both valves than specimens from the Tasman Basin, but are otherwise indistinguishable. Etymology
With waves (Latin), alluding to the commarginal sculpture on both valves.» HENK H. DIJKSTRA & BRUCE A. MARSHALL, 2008
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