Cyclopecten powelli Dell, 1956

Dijkstra, Henk H. & Beu, Alan G., 2018, Living Scallops of Australia and Adjacent Waters (Mollusca: Bivalvia: Pectinoidea: Propeamussiidae, Cyclochlamydidae and Pectinidae), Records of the Australian Museum (Rec. Aust. Mus.) 70 (2), pp. 113-330 : 151-152

Cyclopecten powelli Dell, 1956

Figs 16, 17D,F–G,I

Cyclopecten powelli Dell, 1956: 23 , pl. 4, figs 34–35; Powell, 1979: 380, figs 93.5–6; Dijkstra & Marshall, 2008: 19, figs 17A–B, D–F, 18; Spencer et al., 2009: 198; Huber, 2010: 225.

Type data. Holotype (lv) ZMUC BIV-443, 4 paratypes (1 rv, ZMUC BIV-444; 1 lv + 2 rv, NMNZ M.5698). Type locality: New Zealand, SW of Cape Foulwind , 42°10'S 170°10'E, dead, 610 m, 20 Jan 1952 (RRS Galathea stn 626).

Additional material examined. — AUSTRALIA: WESTERN AUSTRALIA: off Albany, 35°23'33"– 35°24'04"S 118°18'32"– 118°18'22"E, dead, 748–776 m, hard substrate,leg. Whisson & Fromont, 23 Nov 2005 (CSIRO RV Southern Surveyor stn SS 1005/023) (3 v, WAM S77670 ); off Albany, 35°25'03"– 35°25'58"S 118°22'26"– 118°21' 58"E, dead, 1019–1031 m, soft substrate,leg. Whisson & Fromont, 26 Nov 2005 (CSIRO RV Southern Surveyor stn SS 1005/043) (5 v, WAM S77658 ) .

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.