Mirapecten moluccensis Dijkstra, 1988

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 : 202

Mirapecten moluccensis Dijkstra, 1988

Figs 43G,J, 44, 45E –F

Mirapecten moluccensis Dijkstra, 1988: 12 , figs; Pearson, 1991: 4, figs; Raines & Poppe, 2006: 130–131, lower figs; pl. 80, figs 1–8; Huber, 2010: 199; Raines, 2010: 612, pl. 997, figs 1–3; Dijkstra, 2013: 47, pl. 12, figs 2a–d, pl. 13, figs 5a–b.

Type data. Holotype (pr) ZMA Moll.3.88.034, 10 paratypes (8 pr & 2 v), 1 (pr) MNHN Moll 21159, 9 ZMA Moll.3.88.035-36, 3.88.062-65. Type locality: Indonesia, Moluccas [Maluku].

Additional material examined. — AUSTRALIA: WESTERN AUSTRALIA: Scott Reef, SE corner, 14°03'55.9"S 121°58' 17"E, dead, 10 m (1 pr, WAM S43978 ); Scott Reef, NE corner of northern reef, 13°53'S 121°53'E, dead, 18 m (1 v, HM colln) . — PHILIPPINE ISLANDS : Cebu, Olanga Island , alive, 25 m (3 pr, ZMA Moll. 146355) ; Bohol, Calituban Island ,alive, 30–35 m (1 pr, ZMA Moll. 146357) . — VIETNAM: Hon Tam Island , alive, 10 m (4 pr, ZMA Moll. 146539) .

Description. Shell up to c. 35 mm high, subcircular, radially undulated, almost equivalve and equilateral, right valve somewhat more inflated than left, auricles unequal in shape and size, umbonal angle c. 90°; internal costae with weak rib carinae, paticularly near ventral margin; hinge teeth weak; left valve cream or whitish with red, black or white spots, or uniform whitish; right valve cream or whitish without maculations; interior ventral margin reddish on most specimens.

Left valve sculptured with 8–9 prominent, nodulous radial plicae, with evenly and closely spaced secondary radial riblets on plicae and in interspaces. Very closely spaced, fine commarginal microsculpture throughout. Anterior auricle with 7–9 radial riblets, each bearing small nodules, more prominent dorsally.

Right valve with similar sculpture to left, but nodules on radial plicae weaker and costae on disc ends more spinose than on left valve. Auricles somewhat declined laterally, with scaly dorsal margins. Byssal notch moderately deep, byssal fasciole rather broad. Functional ctenolium with about 5 prominent teeth.

Dimensions. Illustrated specimen: WA, SE side Scott Reef, 10 m ( WAM S43978 ): H 15.5, L 15.5 mm .

Figure 44. Distribution of Mirapecten moluccensis Dijkstra (circle) and M. rastellum (Lamarck) (stars).

Habitat. Living in the littoral to sublittoral zones, byssally attached on the undersides of coral boulders or amongst coral rubble on sandy bottoms.

Distribution. Western and southwestern Pacific from the Philippines southwards to northern Australia, and eastwards to the Marshall Islands , Solomon Islands and Loyalty Islands (unpublished data, HHD; Raines & Poppe, 2006: 132); Philippines, 4–80 m (Dijkstra, 2013: 49). Maximum depth range of live-taken specimens is 4– 80 m. Present specimens from Australia dead at 10– 18 m.

Remarks. The few valves dredged from Australia are indistinguishable from the type material. Mirapecten moluccensis is a new record for Australia. For comparison with congeneric species see Dijkstra & Kilburn (2001: 285).