Laevichlamys wilhelminae (Bavay, 1904)

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 : 246-248

Laevichlamys wilhelminae (Bavay, 1904)

Figs 70, 71A,C, 72B–C

Chlamys wilhelminae Bavay, 1904a: 200 , pl. 6, figs 13–14; Dautzenberg & Bouge, 1933: 428; Dijkstra, (1983–1994) 1987: 3, figs; Dijkstra, 1989: 14, 18, figs.

Chlamys wilhelminae var. maculata Bavay, 1904a: 201 , pl. 6, figs 3–4.

Pecten (Chlamys) wilhelminae (Bavay) .–Dautzenberg & Bavay, 1912: 17.

Chlamys marshallensis Waller, 1972a: 236 , pl. 2, figs 26–33, 36–37, text figs 3, 16, table 4.

Chlamys (Chlamys) wilhelminae Bavay. –Dijkstra et al., 1989: 24; Dijkstra, 1990: 6–7, figs; Dijkstra, 1990a: 9; Rombouts, 1991: 21, pl. 24, fig. 9; Lamprell & Healy, 1998: 238, fig. 709.

Laevichlamys wilhelminae (Bavay) .– Waller, 1993: 204; Dijkstra, 1997: 323; Raines & Poppe, 2006: 212–213, lower figs; pl. 154, figs 1–7; Dijkstra & Moolenbeek, 2008: 20; Huber, 2010: 208; Raines, 2010: 622, pl. 1002, figs 4–6; Dijkstra, 2013: 72, pl. 19, figs 2a–d, pl. 20, figs 5a–b.

Comments on synonymy. Chlamys wilhelminae var. maculata is only a colour variant of L. wilhelminae (see description).

Waller (1972a: 237) compared Chlamys marshallensis with the closely related congeneric species Laevichlamys squamosa (Gmelin, 1791) and Laevichlamys irregularis (G. B. Sowerby II, 1842) , but overlooked L. wilhelminae , which is morphologically identical to C. marshallensis (see also Waller 1993: 202).

Type data. Chlamys wilhelminae Bavay : holotype (pr) ZMA Moll.3.04.003, 7 paratypes (pr): 2 MNHN Moll 21204–5, 2 NMW 1955.158.01309, 3 ZMA Moll.3.04.004. Type locality: “Moluques” [Maluku, Indonesia].

Figure 72. A, E–G, Notochlamys hexactes (Lamarck) , 2 pairs; (A, F) AM C.119739, large tasmanica form, Tasmania, ex J. C. Cox collection; rv interior (A), lv exterior (F); (E, G) AM C.375079, anguinea form, King George Sound, WA; lv exterior (E), rv interior (G). B, C, Laevichlamys wilhelminae (Bavay) , specimen in Fig. 71A, C; rv interior (B), lv exterior (C). D, Pedum spondyloideum (Gmelin) , lv of pair, AM C.041556, beach, Lizard Island, QLD; lv exterior. H, I, Pascahinnites coruscans coruscans (Hinds) , pair, AM C.332575, Wistari Reef, Capricorn group, GBR, QLD; rv interior (H), lv exterior (I). Scale bars represent 20 mm (A, E–G), 10 mm (B, C, H, I), 30 mm (D).

Chlamys wilhelminae var. maculata Bavay : lectotype NMW 1955.158.596, herein designated, 1 paralectotype ZMA Moll.3.04.005. Type locality: not mentioned explicitely, herein designated as Loyalty Islands (see Bavay, 1904a: 201).

Chlamys marshallensis Waller : holotype (pr) USNM 701200, 5 paratypes (pr): 1+1 v USNM701196 (stn EMBL 6), 1 v USNM701197 (stn EMBL 20), 1 USNM701198 (stn EMBL 21), 1 USNM701199 (stn EMBL 12). Type locality: Marshall Islands , Eniwetok Atoll, lagoon, 11°24'12"N 162°22'E, stn EMBL 21, 65 ft [20 m], living deep within a crevice in a head of Porites , scuba, leg. T. Waller, 27 Sep 1969.

Comments on type data. The original description of Chlamys wilhelminae and C. wilhelminae var. maculata by Bavay (1904a: 201) was based on material of different sources:

(a) Material in Bavay’s private collection, donated by M. Bouge from the Loyalty Islands . Bavay’s Pectinidae collection was auctioned by P. Géret at Paris (original list in NMW) and most material was purchased by Tomlin (now in Melvill-Tomlin collection in NMW) and Dautzenberg (now in KBIN). The figured specimen of Chlamys wilhelminae var. maculata (Bavay, 1904a: pl. 6, figs 3–4), not mentioned by Oliver (1982: 9), was found in the Melvill-Tomlin collection (NMW1955.158.596). During a visit to the NMW (August 1987) the senior author also examined two specimens of C. wilhelminae , formerly belonging in Bavay’s private collection, which also belong to the type series, with two handwritten labels by Bavay glued on the back of a small pillbox and one handwritten label by Tomlin. A yellow variety of Chlamys wilhelminae from Lifou (Loyalty Islands ), identified as “ Pecten wilhelminae var. lutea ” [manuscript name] by Bavay, is also preserved in the Dautzenberg collection (KBIN). However, Bavay did not indicate this colour variation in his original description. This specimen is not part of the type series.

(b) Material of Chlamys wilhelminae in MNHN from New Caledonia (2 specimens) with one handwritten label by Bavay also belongs to the type series (card file by B. Métivier in MNHN) .

(c) Material of Chlamys wilhelminae in the ZMA [ex Heukelom collection, leg. Van der Hucht] from “ Molukken ” [= Maluku] (4 specimens), of which one is the figured specimen ( Bavay , 1904a: pl. 6, figs 13–14) ( ZMA Moll.3.004.003), and one specimen of C. wilhelminae var. maculata from the same sample ( ZMA Moll. 3.004.005). All material was examined and determined by Bavay and also belongs to the type series .

Additional material examined. — AUSTRALIA: QUEENSLAND: Torres Strait, 9°44'S 142°21'E,alive (1 pr, ZMA Moll.147090);Reef N of Single Rock Entrance, inside of reef, 12°01'S 143°55'E, dead, 4–13 m (1 v, C.160959); Ham Cay, 13°02'S 145°52'E,alive, 10–12 m (1 pr,C.157604);Lizard Island,Rocky Point, 14°40' S 145°26'E, dead, 7.5 m (1 v, C.161011); Lizard Island, 14°40'S 145°28' E, alive (1 pr, C.125133); Lizard Island, Yonge Reef, 14°60'S 145°61.7' E, alive (1 pr, C.125134); Lizard Island, between South Island & Bird Island, 14°41'S 145°28' E, alive, 4.5 m (1 pr, C.344008); Reef 14-151, 14°55'S 145°41'E, dead, 8–13 m (1 v, C.157656); No. 9 Ribbon Reef, 14°57'S 145°42.5' E,alive, 11 m (1 pr,C.165226);No.10 Ribbon Reef, 14°57'S 145°42' E, alive, 8–10 m (2 pr,C.165227);No. 7 Ribbon Reef, NW end, 15°08'S 145°44'E, dead (1 v, C.157598); Ruby Reef, NW side, 15°44'S 145°47'E, dead (1 v, C.157614); Orpheus Reef, Pioneer Bay, 18°35' S 146°29'E, alive, 3–4 m (2 pr, ZMA Moll.146237); Swain Reefs, Big Sandy Cay, 21°80'S 151°86.7'E, alive, 9 m (1 pr, C.161007); Swain Reefs, No. 1 Herald Prong Reef, 21°16.7' S 151°40'E,alive, 20 m (1 pr + 1 v,C.119507);Swain Reefs, Mystery Reef, 21°22' S 152°01'E, dead, 6–10 m (1 pr, C.332600); Swain Reefs, Finger Reef, 21°22'S 152°01'E,alive, 30 m (4 pr,ZMA Moll.143861);Swain Reefs,Reef 21-184, 21°23'S 151°42'E,alive, 10–11 m (1 pr, C.165569); Swain Reefs, Reef 21-189, 21°27' S 151°41'E, alive, 9–10 m (1 pr, C.165570); Swain Reefs, 3 km NE of W side of Gillett Cay, 21°42'S 152°26' E, dead, 64–73 m (1 v, C.161010); Swain Reefs, 22°12'S 152°37'E,dead (1 pr,C.157609);Capricorn Group,Heron Island, 23°26'S 151°57'E,alive (1 pr,C.344007).— PHILIPPINE ISLANDS : Bohol,Balicasag Island,alive, 130 m (1 pr, ZMA Moll.139563). — MARSHALL ISLANDS : Kwajalein Atoll, Shell Island, inside lagoon, alive, 6 m (1 pr, ZMA Moll.143070); Majuro Atoll, alive, 2–5 m (2 pr, ZMA Moll.139737). CORAL SEA: Chesterfield Islands , 19°34'S 158°15'E, alive, 32 m (1 pr, ZMA Moll.143075);Saumarez Reef,off North East Cay, 21°38'S 153°46'E,dead, 12–18 m (1 pr,C.157594).— NEW CALEDONIA:Koumac, 20°41.4'S 164°14.8'E,alive, 20–30 m (1 pr, ZMA Moll.139678). LOYALTY ISLANDS :Lifu, 20°53'S 167°13'E,dead (1 v, C.332601).— FIJI ISLANDS :Viti Levu, 16°57' S 178°47' E,dead, 9–35 m (2 v,C.067849); Viti Levu, Beqa Island, alive, 9 m (4 pr, ZMA Moll.143069);Viti Levu, Mbenga Island (Beqa Island), alive, 36 m (1 pr, ZMA Moll.143969). TONGA:Nukua-lofa, Makaha’a, 21°07'S 175°10' W, alive, 0.5–1 m (3 pr, ZMA Moll.143072).

Description. Shell small, up to 35 mm high, most specimens 20–25 mm; thin, semi-translucent to opaque, oblong, somewhat prosocline, moderately inflated, right valve slightly more convex than left to equally convex, almost equivalve, inequilateral, auricles highly unequal, umbonal angle c. 85–90°; colour variable, whitish or cream with pink radial streaks or radially arranged maculations (visible on the interior); some specimens uniform yellow, orange or pink; interior white, glossy.

Both valves sculptured with numerous (c. 60–70) weak, low, rounded, squamous radial riblets, uneven in spacing and prominence. Antimarginal microsculpture commences in radial interspaces in early radial stage and spreads laterally; lacking on central disc. Anterior auricles much larger and differing in shape from posterior ones, bearing 6–8 radial riblets on left valve and 5 more prominent ones on right valve. Posterior auricles strongly declined dorsally, bearing 2–3 weak radial riblets. Byssal notch relatively deep, byssal fasciole rather broad. Functional ctenolium well-developed, with 4–6 teeth. Resilifer narrowly triangular.

Dimensions. Illustrated specimen: QLD, GBR, Ham Cay (AM C.157604): rv: H 15.1, L 13.7 mm; lv: H 15.1, L 13.1 mm; D 4.2 mm.

Habitat. Living in shallow water (subtidal to c. 40 m), byssally attached to rocks or Acropora corals, or amongst coral rubble on soft sediment (mainly sand) (see also Waller 1972a: 238).

Distribution. Tropical Indo-West Pacific, from the Philippines to northern Australia, Coral Sea, Marshall Islands , New Caledonia, and eastwards to the Society Islands ( French Polynesia) (Raines & Poppe, 2006: 121); Indonesia to Polynesia, 5–140 m (Huber, 2010: 208); Philippines, 4–100 m ( Raines, 2010: 622; Dijkstra, 2013: 73); Marshall Islands , intertidal zone to 54 m (as Chlamys marshallensis Waller, 1972 ; Waller, 1972: 239); Indonesia, 10–25 m, dead (Dijkstra & Moolenbeek, 2008: 20); Vanuatu, 5–45 m (Dijkstra & Maestrati, 2012: 399). Maximum depth range of live-taken specimens is from the intertidal zone to 140 m. Present specimens from Australia alive at 3– 30 m.

Remarks. The present specimens from Australia are morphologically indistinguishable from the type material.

Juveniles of Laevichlamys wilhelminae could easily be confused with small specimens of L. cuneata . The two species have almost identical sculpture, but differ in shape and colour ( Laevichlamys wilhelminae is wider and more inflated with more strongly declined posterior auricles, slightly weaker in sculpture, and more translucent and more brightly coloured than L. cuneata ).