Mirapecten rastellum ( Lamarck, 1819 )

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 : 202-204

Mirapecten rastellum ( Lamarck, 1819)

Figs 43I,K, 44, 45A

Pecten rastellum Lamarck, 1819: 166 ; Delessert, 1841: pl. 16, figs 2a–b [holotype]; Chenu, 1845: pl. 15, figs 2–2b [holotype]; Dijkstra, 1994: 474, pl. 6, figs 17–20 [holotype].

Pecten amaliae Kobelt, 1887: 84 , 198, pl. 53, figs 5–6.

Pecten (Chlamys) squamatus (Gmelin) .–Dautzenberg & Bavay, 1912: 9 (misidentification).

Chlamys (Mirapecten) rastellum (Lamarck) .–Springsteen & Leobrera, 1986: 329, pl. 93, fig. 20; Rombouts, 1991: 31, pl. 12, figs 4–4b.

Mirapecten rastellum (Lamarck) .–Dijkstra, (1983-94) 1991: 22, figs; Dijkstra, 1991: 48; Lamprell & Whitehead, 1992: [32], pl. 14, fig. 82; Dijkstra, 1998a: 24, pl. 3, figs 7–8; Raines & Poppe, 2006: 132–133, upper figs; pl. 81, figs 1–6; pl. 82, figs 1–6; Dijkstra & Moolenbeek, 2008: 23; Huber, 2010: 199; Raines, 2010: 612, pl. 997, figs 4–8; Dijkstra, 2013: 49, pl. 12, figs 3a–d, pl. 13, figs 4a–b.

Type data. Pecten rastellum Lamarck : holotype (pr) MHNG1088/24. Type locality: “Habite les mers du Nord” [error].A new type locality was designated by Dijkstra (1994: 474): off Punta Engaño, Mactan Island , Cebu, Philippine Islands .

Pecten amaliae Kobelt : lectotype (lv) LMAD [not registered], herein designated. Type locality: “Amboyna?”. It is likely that the type specimen was found in the Moluccas. Similar material from eastern Indonesia has been examined ( RMNH).

Comments on type data. For nomenclatural notes on Pecten rastellum var. “beta” see Dijkstra (1994: 474).

The first author traced only the left valve (Kobelt’s fig. 5) of an articulated specimen (see Kobelt, 1887: pl. 53, figs 5–6) of Pecten amaliae in the LMAD collection.

Additional material examined. — AUSTRALIA: QUEENSLAND: GBR, No Name Reef,SW end, 14°40'S 145°39'E,dead, 15–20 m (1 v,C.153123);North East Herald Cay, 16°56'S 149°11'E,dead (14 v,C.331909;3 v,C.331910);Flinders Reef, 17°44'S 148°27'E,dead,beach (1 v,C.147354). WESTERNAUSTRALIA: Scott Reef, SW side, 14°05'S 121°50' E,dead, 10 m (1 pr, ZMA Moll.146193);Scott Reef,SE corner, approx. 14°0'S 121°45'E, dead, 34 m (1 v, WAM); Scott Reef, N of North Entrance, approx. 14°0'S 121°45'E, dead, 42 m (1 pr + 1 v, WAM); Seringapatam Reef, 13°40' S 122°05' E, NE corner, dead, 20 m (1 pr + 3 v, WAM); Cartier Island, N side, 12°31'S 123°29'E, dead, 10–20 m (3 v, WAM); Ashmore Reef, NE corner, 12°17' S 123°02'E, dead, 24 m (6 v, WAM); Ashmore Reef, 12°17'S 123°02'E, dead, 20 m (7 v, WAM); Ashmore Reef, NE corner, 12°17'S 123°02'E,dead, 5–24 m (1 v, WAM524;1 v,WAM); Ashmore Reef, NW corner, 12°17'S 123°02'E, dead, 8 m (1 v, WAM); Hibernia Reef, 11°58' S 123°19'E, dead (3 v, WAM); Hibernia Reef, 11°58'S 123°19'E, dead, 5–8 m (1 v,WAM);Hibernia Reef, 11°58'S 123°19'E, dead (2 pr + 1 v,WAM); Hibernia Reef, N side, 11°58'S 123°19' E,dead, 25 m (1 pr, ZMA Moll.146194).— JAPAN: Okinawa,Bolo Point, alive, 27 m (1 pr, ZMA Moll.140198). — PHILIPPINE ISLANDS : Cebu, Punta Figure 45. A, Mirapecten rastellum (Lamarck) , specimen in Fig. 43I, K; rv exterior. B–D, Amusium pleuronectes (Linnaeus) , pair, AM C.121126, W of Nassau River, E Gulf of Carpentaria, QLD, 11 m; lv exterior (B), rv exterior (C), lv interior (D). E, F, Mirapecten moluccensis Dijkstra , specimen in Fig. 43G, J; lv exterior (E), rv exterior (F). Scale bars represent 20 mm (A), 30 mm (B–D), 10 mm (E, F).

Engano, 10°19'N 124°01'E, dead, 90–145 m (9 v, C.331911); Bohol, Panglao, alive, 110–150 m (7 pr, ZMA Moll.142772); Mindanao,Samal Island, Matanos, alive, 165 m (19 pr, ZMA Moll.145091). GUAM:Oroto Point,alive, 23 m (2 pr, ZMA Moll.139641). — MARSHALL ISLANDS :KwajaleinAtoll,Carlson Island,outside lagoon,alive, 12 m (1 pr, ZMA Moll.142753); Johnston Atoll, outside lagoon, alive, 30 m (2 pr, 1 v, ZMA Moll.142782).— INDONESIA:Malacca Strait,off Balikpapan,alive, 51 m (3 pr, ZMA Moll.142789). — PAPUA NEW GUINEA: Port Moresby, Quayles Reef, alive, 20 m (1 pr, ZMA Moll.142792). — SOLOMON ISLANDS : Uepi Island, Morovo Lagoon, 8°25'S 157°56'E, alive, 15–45 m (2 pr, C.303795); Guadalcanal, Bonegi, alive, 28–32 m (5 pr, ZMA Moll.142830); Guadalcanal, W of Honiara, alive, 30–35 m (3 pr, ZMA Moll.144009). CORAL SEA: Chesterfield Islands , 19°41' S 158°22'E, alive, 45 m (1 pr, ZMA Moll.142787).— NEW CALEDONIA: 21°0'S 165°0'E,dead (1 v, C.047356); 21°0'S 165°0'E, dead (3 v, C.119742). — FIJI ISLANDS :Viti Levu, Nadi Bay, 16°57'S 178°47'E,dead, 9–35 m (1 v,C.067851);Viti Levu, Mbenga Island (Beqa Island),alive, 36 m (3 pr, ZMA Moll.142777).

Description. Shell up to 53 mm high (Huber, 2010), most specimens to c. 25 mm; subcircular, left valve flattened, right valve more inflated, slightly inequivalve and equilateral, auricles somewhat unequal in shape and size, umbonal angle about 85–90°; internal plicae with weak, moderately long rib carinae around ventral margin in most specimens (lacking in a few); hinge teeth weak; colour highly variable, white, cream, yellow, red, purple, brownish, uniform or mottled.

Both valves sculptured with 7–9 evenly spaced radial plicae, with widely spaced curved scales (larger on left valve than on right), more prominent marginally. Plicae and interstices equal in width. Auricles with very closely spaced commarginal microsculpture (almost lacking on disc), macrosculpture lacking except for 2–3 radial riblets on anterior auricle of right valve; dorsal margin spinose. Byssal notch moderately deep, byssal fasciole rather broad. Functional ctenolium with 5–8 prominent teeth.

Dimensions. Illustrated specimen: QLD, GBR, No Name Reef, 15–20 m, single rv (AM C.153123): H 37.4, L 37.8 mm.

Habitat. Living in the littoral zone and on the continental shelf, amongst coral rubble on sandy bottoms. In Western Australia on offshore islands and reefs with clean conditions.

Distribution. Tropical Indo-West and central Pacific from southern Japan to northern Australia, eastwards to the Line Islands (not recorded from the Hawaiian Islands or French Polynesia) (Raines & Poppe, 2006: 132); Philippines, 27–120 m (Dijkstra, 2013: 50); Indonesia, 34 m and 285–305 m, dead (Dijkstra, 1991: 48); Papua New Guinea, 10–58 m (Dijkstra, 1998a: 24); Vanuatu, 13–80 m (Dijkstra & Maestrati, 2012: 406). Maximum depth range of live-taken specimens is 12– 165 m. This species is not found along Australian shores, but recorded only from offshore reefs.

Remarks. The present specimens are indistinguishable from the type material. For comparison with congeneric species see Dijkstra & Kilburn (2001: 285).