Laevichlamys andamanica ( Preston, 1908 )

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 : 238-239

Laevichlamys andamanica ( Preston, 1908)

Figs 66, 67B, 69K–L

Chlamys andamanica Preston, 1908: 204 , pl. 14, fig. 19; Dijkstra, 1991: 29, fig. 90; Subba Rao & Dey, 2000: 222.

Pecten perfectus Melvill, 1909: 127 , pl. 5, fig. 15; Trew, 1987: 56.

Chlamys perfecta (Melvill) .– Viader, 1937: 62; Oliver, 1982: 7; Dijkstra, (1983–1994) 1986: 9, figs.

Mimachlamys andamanica (Preston) .–Dijkstra & Knudsen, 1998: 81, pl. 4, figs 14–15.

Laevichlamys andamanica (Preston) –Dijkstra, 1998a: 30; Raines & Poppe, 2006: 196–197, upper figs; pl. 140, figs 1, 2, 4, 6, 8–9; pl. 144, fig. 5; Dijkstra & Moolenbeek, 2008: 19; Huber, 2010: 207 [in part]; Raines, 2010: 622, pl. 1002, fig. 1.

Type data. Chlamys andamanica Preston : holotype (pr) ZSI M4042/1. Type locality: Bay of Bengal, Andaman Islands . Pecten perfectus Melvill : holotype (pr) NHMUK.1910.3. 17.22. Type locality: Indian Ocean, Chagos Archipelago, Peros Banhos, Diamant, 16 fathoms [29 m].

Additional material examined. — AUSTRALIA: QUEENSLAND: No. 10 Ribbon Reef,SW end, 14°56'S 145°42' E,dead, 8–10 m (1 v, C.157602);E of Swain Reefs, 21°43'S 152°51'E,dead, 113 m (2 v,C.153558).—RED SEA:Elat,alive, 12–15 m (3 pr, ZMA Moll.142022).— YEMEN:off Hadibo,alive, 18 m (2 pr, ZMA Moll.142031). — KENYA:off Watamu,alive, 27 m (1 pr, ZMA Moll.139616).— SEYCHELLES:Mahé, N-point,alive, 13 m (1 pr, ZMA Moll.143608).—MASCARENE ISLANDS :Cargados Island, 16°0'S 60°0'E, dead (13 v, C.119508). — MALDIVE ISLANDS : Helengeli Hansreef, alive, 5–25 m (2 pr, ZMA Moll.142029).—ANDAMAN ISLANDS :Snake Island, alive, 8 m (2 pr, 1 v, ZMA Moll.142032). — VIETNAM: off Nha Trang, Hon Mieu, alive, 15 m (1 pr, ZMA Moll.146126). — SOLOMON ISLANDS : Kira Kira, San Cristobal, 10°27'S 161°53'E, dead, 15–24 m (1 pr + 1 v, WAM 515).CORAL SEA: Osprey Reef, SE end, 13°59'S 146°40' E, dead, 20–30 m (1 v, C.332557); North East Herald Cay, 16°56'S 149°11'E, dead (4 v, C.153559); North East Herald Cay, 16°56' S 149°11' E, dead,beach (33 v, C.332556);Wreck Reef,Porpoise Cay, 22°13'S 155°18'E, dead, 1–2 m (1 v,C.157595).— NEW CALEDONIA: 20°16'S 169°51' E, dead, 85–100 m (3 v,C.154684);Nouméa,alive, 2–5 m (1 pr, ZMA Moll.141975). TUVALU: Funafuti Atoll, 8°31'S 179°13'E, dead (1 v, C.006148).

Description. Shell small, up to c. 30 mm high, thin, oblong, weakly inflated, right valve slighly more convex than left, almost equivalve and equilateral, auricles unequal in shape and size, umbonal angle c. 85°; colour variable, red, orange, yellow, purple or brown, with paler or darker maculations and striations or mottled, a few specimens uniformly coloured.

Both valves sculptured with numerous, closely spaced, squamous radial costae (c. 60 in adult stage), granulous microsculpture in interspaces in early growth stage, developed into divaricate scratches near anterior and posterior margins in late growth stage. Anterior auricles with prominent squamose radial riblets crossed by commarginal lamellae. Byssal notch deep, byssal fasciole broad. Functional ctenolium well-developed, with c. 6–8 teeth.

Figure 66. Distribution of Laevichlamys andamanica (Preston) (circles), L. deliciosa (Iredale) (stars), L. limatula (Reeve) (triangles) and L. mollita (Reeve) (squares).

Dimensions. Illustrated specimen: QLD, GBR, E of Swain Reefs, 113 m (AM C.153558), lv only: H 15.9, L 13.9 mm.

Habitat. Living in tropical shallow waters, byssally attached to rocks or coral, or amongst coral rubble on sandy substrates.

Distribution. Tropical Indo-West Pacific from Vietnam to northeastern Australia, westwards into the Indian Ocean to eastern Africa and the Red Sea, and eastwards across the Pacific to Tuvalu (Raines & Poppe, 2006: 196); Red Sea, 1.5–20 m, Gulf of Aden, 18 m (as Mimachlamys andamanica ; Dijkstra & Knudsen, 1998: 82). Maximum depth range of live-taken specimens is 2– 27 m. Present specimens from Australia dead at 8–10 m and 113 m.

Remarks. Laevichlamys andamanica is a new record for Australia. Only dead shells have been found from the offshore reefs of Queensland. They are similar to the type material. Juveniles could easily be confused with small specimens of Laevichlamys deliciosa ( Iredale, 1939) , also known from Queensland, but occurring in deeper water. Laevichlamys andamanica differs from L. deliciosa by its more subcircular and flatter shape ( L. deliciosa more inflated and dorso-ventrally elongate), by its coarser radial riblets that are more widely spaced than those of L. deliciosa , and by its variable and darker coloration ( L. deliciosa is bright orange, red, yellow or cream).

For synonymy see Dijkstra & Knudsen (1998: 82).

Figure 67. A, C, Hemipecten forbesianus A. Adams & Reeve , specimen in Fig. 65D, E; lv exterior (A), rv exterior (C). B, Laevichlamys andamanica (Preston) , lv only,AM C.153558, E of Swain Reefs, E QLD, 21°43'S 152°51'E, 113 m; lv exterior.D, F, Laevichlamys cuneata (Reeve) , pair,AM C.303770, off Great Palm Island, GBR, QLD; lv exterior (D), rv exterior (F). E, K, L, Laevichlamys limatula (Reeve) , pair, WAM S30731 , Beacon Island, E side of Goss Passage, Wallabi Group, Abrolhos Islands , WA, 28°28'S 113°45'E; lv exterior (E), rv exterior (K), lv interior (L). G–J, Laevichlamys deliciosa (Iredale) , 2 pairs; (G, H) lectotype of Mimachlamys deliciosa, AM C. 089669, Great Barrier Reef Exped. stn 14, 0.5 miles SE of Lizard Island, Low Isles, N QLD, 14°41'S 145°29'E, 35 m; lv exterior (G), rv exterior (H); (I, J) AM C.119510, 0.25 miles N of North Direction Isle, GBR, QLD, 34.5 m; lv exterior (I), rv exterior (J). Scale bars represent 10 mm.