Laevichlamys mollita (Reeve, 1853)

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 : 244

Laevichlamys mollita (Reeve, 1853)

Figs 66, 69D,I, 71B,D

Pecten mollitus Reeve, 1853 : sp. 100, pl. 25, fig. 100; Küster & Kobelt, 1888: 202, pl. 54, figs 3–6.

Chlamys mollita (Reeve) .– Kira, 1959: 121 pl. 18, fig. 8; Masuda, 1962: 179, pl. 21, fig. 7, pl. 23, figs 6–8; Dijkstra, (1983–1989) 1983: 5, figs; Matsukuma et al., 1991: 137, pl. 135, fig. 5.

Chlamys (Chlamys) mollita (Reeve) .– Rombouts, 1991: 16, pl. 6, fig. 8; Lamprell & Whitehead, 1992: [20], no 40, pl. 8, fig. 40; Higo et al., 1999: 442.

Laevichlamys mollita (Reeve) .– Waller, 1993: 204; Dijkstra, 1997: 321, figs 9–12; Dijkstra, 1998a: 28, pl. 5, figs 5–8; Raines & Poppe, 2006: 204–205, lower figs; pl. 146, figs 2–6; Huber, 2010: 208; Raines, 2010: 620, pl. 1001, figs 6–8; Dijkstra, 2013: 68, pl. 18, figs 2a–d, pl. 20, figs 3a–b, pl. 29, figs 2a–b.

Type data. Two syntypes (pr) NHMUK1995081 . Type locality: Japan .

Comments on type data. The largest specimen in the type lot does not belong to the type series. Reeve (1853) described Laevichlamys mollita from Japan. However, the type lot has three labels, on two of which is written “ Celebes ” (Sulawesi, Indonesia). This again suggests confusion by Cuming over the true locality for these shells. The smallest syntype of L. mollita was refigured by Higo et al. (2001: 156, fig. B438).

Additional material examined. — AUSTRALIA: QUEENSLAND: Lizard Island, Granite Bluff , 14°39'S 145°27'E, dead, 15 m (4 v, C.128031); No Name Reef,SW end, 14°40'S 145°39'E,dead, 15–20 m (3 v,C.153124);Opal Reef, N of Cairns, 16°15'S 145°50'E,dead, 29 m (1 v,C.336872);Wheeler Reef, NE of Townsville, 18°46'S 147°31'E, dead, subtidal (1 pr, C.132031); Wheeler Reef, W side, NE of Townsville, 18°46'S 147°31'E, dead, 18 m (1 pr, C.336871); Broadhurst Reef, E of Townsville, 18°57'S 147°44'E, dead,subtidal (1 pr, C.132027;1 pr, C.132028;1 pr, C.132029;1 pr, C.132030) . — PAPUA NEW GUINEA: off Port Moresby, outer reef,alive, 20 m (1 pr, ZMA Moll.141099); Milne Bay,Waga Waga, alive, 18–26 m (3 pr, ZMA Moll.141328); Duke of York Island ,alive, 34 m (1 pr, ZMA Moll.142577) .— SOLOMON ISLANDS : Russell Group, Mbanika Island, Linggatu Cove , alive, 6 m (1 pr, ZMA Moll.142578); Russell Group, Pavuvu Island ,Samata,alive, 6 m (1 pr, ZMA Moll.142580); Guadalcanal, W of Honiara, between Bonegi I and II wrecks, alive, 39 m (1 pr, ZMA Moll.142581); Guadalcanal, W of Honiara,alive, 20–30 m (1 pr, 1 v, ZMA Moll.142583) .

Description. Shell up to 61 mm high ( Raines, 2010), thin, circular, weakly inflated, almost equally convex, somewhat inequivalve, equilateral, auricles unequal in shape and size, umbonal angle c. 100°; colour highly variable, yellow, orange, red, pink, purple or brown, mottled, with c. 8 paler radial streaks.

Both valves sculptured with numerous, evenly spaced, weak, delicate, squamous, round-crested radial riblets (c. 10 per cm in adult stage near ventral margin). Antimarginal microsculpture in radial interspaces in early radial stage and on postero-lateral area of disc. Anterior auricles much larger than posterior ones, with squamous radial riblets (c. 12 on lv, 6–8 on rv); c. 4–6 weaker riblets on posterior auricles. Byssal notch relatively deep, byssal fasciole broad. Functional ctenolium well-developed, with 6–9 teeth.

Dimensions. Illustrated specimen: Qld, GBR, Broadhurst Reef, E of Townsville, sublittoral (AM C.132030): rv: H 50.4, L 47.1 mm; lv: H 50.9, L 46.8 mm; D 11.8 mm.

Habitat. Living byssally attached under coral boulders or amongst coral rubble on soft sediment (sand) in shallow water.

Distribution. Indo-West Pacific, from southern Japan, Philippines, Indonesia, Papua New Guinea, Solomon Islands to northeastern Australia (Raines & Poppe, 2006: 204); Philippines to Australia, 2–60 m (Huber, 2010: 208); Philippines, 150–200 m (?) and 4–28 m ( Raines, 2010: 620; Dijkstra, 2013: 68); Papua New Guinea (Dijkstra, 1998a: 33). Maximum depth range of live-taken specimens is 2– 60 m. The bathyal records in Raines (2010: 620) are incorrect. The present material from Australia so far has been collected only dead from the subtidal zone to 29 m.

Remarks. The present specimens of Laevichlamys mollita from Australia are indistinguishable from the type material. Juveniles could easily be confused with other small specimens of congeneric multiradial species such as Laevichlamys andamanica , L. cuneata , and L. squamosa .