Cyclopecten powelli Dell, 1956
DELL, R. K. 1956. The archibenthal Mollusca of New Zealand. Dominion Museum Bulletin, 18: 1-235, pls. 1-25, text-figs. 1-6. [p. 23, pl. 4, figs. 34, 35]
1956 Cyclopecten powelli Dell, 1956
R. K. Dell, 1956, plate 4.
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«Shell minute, inequilateral and inequivalve, white, fragile, the two valves with discrepant sculpture. Left valve sculptured with weak concentric raised threads, crossed by distant weak radials, both becoming obsolete over outer third of shell surface; concentric threads about 5 per mm. Ears subequal, not clearly defined from disc, anterior ear with fine concentrics, posterior ear with very fine radials. Right valve with closely spaced concentric lines about 14 to 15 per mm., interspaces with very fine interstitial radials. Both ears with fine concentrics, anterior ear clearly marked off from disc by a groove, a well-defined byssal notch.
Length, 4.0 mm.; height, 4.3 mm.; inflation, 0.73 mm. (right valve); length, 4.5 mm.; height, 4.5 mm.; inflation, 0.82 mm. (left valve). Holotype: Type right and left valves (disconnected) in Zoological Museum, Copenhagen. To avoid any confusion should the two valves prove to belong to different species, the left valve, which shows the chief diagnostic features is designated the holotype. Several paratypes in Copenhagen, and in Dominion Museum. Locality: Galathea Station 626, Tasman Sea, in 610 metres. C. powelli is closest to aupouria Powell which has comparable sculpture. Fro aupouria it differs in the finer (though less closely spaced) concentric ridges in the left valve and obsolete radial sculpture over the latter half of the shell. In addition the radial sculpture in this valve consists of threads which cross the concentrics rather than the small, dense interstitial radials of aupouria.» RICHARD KENNETH DELL, 1956
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«Description. Shell up to c. 7.5 mm high, almost circular, left valve more convex than right valve, equivalve, almost equilateral, auricles dissimilar in shape, anterior auricle larger than posterior one, umbonal angle c. 105°, translucent or opaque white. Prodissoconch c. 180 μm long, smooth and convex. Pre-radial dissoconch of left valve up to c. 2 mm height with granular microsculpture.
Left valve sculptured with weak radial threads and commarginal lamellae in early growth stage or completely smooth, other parts of disc smooth. Auricular sculpture similar to that of disc, with more closely spaced commarginal lamellae on posterior auricle. Right valve with crisp, widely and regularly spaced commarginal lamellae, transformed into low, rounded, regularly spaced ridges. Posterior auricle continuous with disc, sculptured with closely spaced commarginal lamellae and finer radial threads and granules, anterior auricle and byssal fasciole separated from disc by sharply incized groove, sulptured with commarginal lamellae, and 3–5 radial threads on ventral half. Byssal notch shallow, byssal fasciole narrow. Interior riblets lacking. Habitat. Living in the bathyal zone on soft sediment.
Distribution. Tasman Sea, 750–1463 m, alive (Dijkstra & Marshall, 2008, p. 19). Now also from Australia (Western Australia). Maximum depth range of present material is 748–1031 m (single valves only).
Remarks. The present material from Australia is similar to the type specimens from New Zealand, although the sculpture on the left valve is somewhat weaker, and some specimens have only traces of radial threads or are smooth.
Cyclopecten powelli is a new record for Australia.» DIJKSTRA, H. H. & A. G. BEU. 2018. Living scallops of Australia and adjacent waters (Mollusca: Bivalvia: Pectinoidea: Propeamussiidae, Cyclochlamydidae and Pectinidae). Records of the Australian Museum, 70 (2): 113-330, figs. 1-102. [p. 151, 152]
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Cyclopecten powelli Dell; H. H. Dijkstra & A. G. Beu, 2018, Living scallops of australia and adjacent waters, figures 17D, 17F, 17G, 17I.
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