Excellichlamys sowerbyi Dijkstra, 1998

Dijkstra, Henk H. & Maestrati, Philippe, 2013, Pectinoidea (Bivalvia: Propeamussiidae, Entoliidae and Pectinidae) from the Tarava Seamounts, Society Islands and the Tuamotu Archipelago (French Polynesia), Zoosystema 35 (3), pp. 361-375 : 372

Excellichlamys sowerbyi Dijkstra, 1998

Pecten parvus G. B. Sowerby I, 1835: 110 (preoccupied by Pecten parvus Da Costa, 1778 ). — Waller 1972: 248, pl. 6, figs 97-102 (holotype).

Excellichlamys spectabilis parva – Dijkstra 1989a: 14, fig.

Excellichlamys sowerbyi Dijkstra, 1998b: 247 (nom. nov.).

MATERIAL EXAMINED. — Tuamotu Archipelago. Marutea, holotype spm ( BMNH 197011), refigured by Waller (1972: pl. 6, figs 97-102).

Society Islands. Tarasoc, stn DW 3416, 16˚35’S, 151˚44’W, 914 m, 1 lv; stn DW 3422, 16˚43’S, 151˚04’W, 430-620 m, 1 rv; stn DW 3482, 17˚29’S, 149˚45’W, 440 m, 1 lv.

DISTRIBUTION. — Tuamotu Archipelago ( Waller, 1972: 250). Now also from the Society Islands (new record), post-mortem single valves washed down to 430-914 m depth.

DESCRIPTION

Shell up to c. 25 mm in height, solid, right valve more inflated than left valve, inequivalve, almost equilateral, auricles strongly unequal in size,umbonal angle c. 85˚, colour creamy whitish with brown and/or red maculations.

Left valve sculptured with 8-10 dissimilar, strongly developed radial plicae, weakly developed laterally. Primary radial plicae with one or two narrow grooves, covered with prominent commarginal lamellae. Secondary intercostal riblets scabrous. Anterior auricle large, strongly noduliferous, posterior auricle almost rudimentary.

Right valve with broader and more regularly developed radial costae. Auricles of similar sculpture to left valve. Hinge line straight. Byssal notch moderately deep, byssal fasciole narrow. Functional ctenolium with c. four weak teeth. Internal rib carinae present near ventral margin.

REMARKS The present single valves are morphologically similar to the holotype from the Tuamotu Archipelago.

For comparison with Excellichlamys spectabilis ( Reeve, 1853) see Waller (1972: 248).