Bractechlamys oweni (de Gregorio, 1884)

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 : 182-183

Bractechlamys oweni (de Gregorio, 1884)

Figs 32D–E, 33, 34B,D

Pecten pictus G. B. Sowerby II, 1842: 62 , 163, pl. 20, fig. 233; Reeve, 1853: sp. 116, pl. 28, fig. 116; Küster & Kobelt, 1888:165, pl. 46, fig.2 (junior primary homonym of Pecten pictus of Da Costa, 1778, of Röding, 1798, of Deshayes in Laborde & Linant, 1830, and of Goldfuss, 1833).

Pecten oweni de Gregorio, 1884: 133 (replacement name for P. pictus Sowerby, 1842 ).

Chlamys (Aequipecten) sp. cf. “picta (Sowerby)”.–Kuroda, 1932: 95, fig. 108.

Pecten (Chlamys) oweni de Gregorio. –Hertlein, 1936: 55.

Cryptopecten oweni (de Gregorio) .–Habe, 1951: 77; Habe, 1977: 84; Koyama et al., 1981: 67, pl. 5, fig. 2; Bernard et al., 1993: 50; Higo et al., 1999: B479.

Semipallium (Semipallium) oweni (de Gregorio) .–Dijkstra, 1990a: 8.

Chlamys (Cryptopecten) oweni (de Gregorio) .– Rombouts, 1991: 24, pl. 8, fig. 4.

Bractechlamys oweni (de Gregorio) .–Dijkstra, 1998a: 16; Wang, 2002: 193, fig. 81; Raines & Poppe, 2006: 102–103, lower figs; pl. 38, figs 1–6; pl. 51, fig. 4; Xu & Zhang, 2008: 85, fig. 237; Huber, 2010: 199; Raines, 2010: 600, pl. 991, figs 1–2; Dijkstra, 2013: 35, pl. 8, figs 1a–d, 4a–b.

Bractaechlamys [sic] oweni (de Gregorio) .–Hayami, 2000: 907, pl. 450, fig. 42.

Type data. Holotype (pr) NHMUK 1950.11.14.53. Type locality: “Isle of Baicus”. Herein more precisely: Philippine Islands , Negros Island, “Baicus Isle”, 13 m, in coarse sand. Description. Shell up to c. 30 mm high, solid, inflated, adults somewhat pyxoid, almost circular, adult shells slightly higher than wide, almost equivalve and equilateral, auricles unequal in shape and size, umbonal angle c. 90°; colour of left valve highly variable with cream, orange, red, pink or brown spots, many specimens with 3 uniformly coloured (cream or yellowish) radial costae, right valve paler and more uniform in colour (cream or whitish), laterally some blotches. Inner surface of left valve usually reddish, of right valve whitish, dorsally reddish or brownish.

Both valves sculptured with 11–13 radial costae and covered with closely spaced commarginal microsculpture; surfaces of costae bearing 2–3 narrow costellae near ventral margin, more numerous and obvious on right valve than left; a few secondary interstitial radial riblets near ventral margin on some specimens. Anterior auricle of right valve with 4 prominent noduliferous radial costae, other auricles weakly ribbed or almost smooth. Dorsal margin of right valve with prominent tubercles. Dorsal margin straight. Byssal fasciole small, byssal notch moderately deep, functional ctenolium with 3–4 teeth beneath suture ridge. Resilifer narrowly triangular. Intermediate and dorsal teeth well-developed. Internal rib carinae present near ventral margin.

Dimensions. Illustrated specimen: off Hibernia Reef, WA, 30–35 m (HM): H 26.6, L 25.7 mm.

Habitat. Living free in the intertidal zone and on the continental shelf, amongst coral rubble under coral slabs on sand.

Comments on type data. G. B. Sowerby II (1842: 163) mentioned a more accurate locality in Latin with data in a subsequent description of Pecten pictus : “Hab. Ins. Baiae, Ins. Negros, Philippinarum. H. Cuming legit. Found in coarse sand at a depth of seven fathoms” [13 m]. “Isle of Baicus” or “Ins. Baiae” is possibly a small island near Bais, southeastern Negros. However, as many of Hugh Cuming’s localities have proved to be incorrect, the accuracy of the supposed type locality is questionable.

Additional material examined. — AUSTRALIA: QUEENSLAND: GBR, Flinders Reefs, c. 170 n. ml off Townsville,17°61' S 148°52'E,alive, c. 18 m (1 pr, photoAM); Moreton Island , NE of Cape Moreton,SW side of Hutchinson Shoal , 26°59'S 153°48'E, dead, 27 m (1 pr, R.C. Willan colln) . WESTERN AUSTRALIA: Onslow, Peak Island , W side, 21°36' S 114°30'E, dead, 18 m (1 v, WAM 520.91 ) ; Scott Reef, north reef, approx. 14°0'S 121°45'E, exposed reef flat, dead (1 pr, ZMA Moll. 143825); Cartier Island , 12°32'S 123°33'E, dead (1 v, WAM) ; Cartier Island, NE corner, dead, 20–25 m (2 v, ZMA Moll. 146223); Ashmore Reef , central N side, 12°17'S 123°02'E, dead, 3 m (1 v, WAM 525.91 ) ; Ashmore Reef , NE corner, 12°17'S 123°02'E, dead, 18 m (1 v, WAM) .— JAPAN: Okinawa, Manzamo , alive, 49 m (1 pr, ZMA Moll. 141181) . — PHILIPPINE ISLANDS : Davao, Samal Island , Matanos, alive, 165 m (4 pr, ZMA Moll. 145086) ; Davao, Talikud Island , alive, 120–180 m (3 pr, ZMA Moll. 146103) .— INDONESIA: Java,off Semarang ,alive, 46–48 m (1 pr, ZMA Moll. 139609) .— PAPUA NEW GUINEA: Madang, E of Worgat Island ,dead (1 pr, WAM) ; Port Moresby, Quayles Reef , alive, 20 m (1 pr, ZMA Moll. 142676) . — SOLOMON ISLANDS : W side of Malanpaina Island , 10°14.05'S 161°58'E, dead, 15 m (1 pr, WAM) ; Ontong Java , alive, 34–38 m (6 pr, ZMA Moll. 142679) .

Figure 33. Distribution of Bractechlamys oweni (Gregorio) (circles) and B. vexillum (Reeve) (stars).

Figure 34. A, C, Anguipecten superbus (G. B. Sowerby II) , specimen in Fig. 32A, C; rv exterior (A), lv interior (C).B, D, Bractechlamys oweni (Gregorio) , specimen in Fig. 32D, E; rv interior (B), lv exterior (D). E, F, Bractechlamys vexillum (Reeve) , specimen in Fig. 32F, H; rv interior (E), lv exterior (F). G, H, Decatopecten strangei (Reeve) , specimen in Fig. 32G, I; rv interior (G), lv exterior (H). Scale bars represent 20 mm (A, C, E–H), 10 mm (B, D).

Distribution. Amami Islands ( Japan) southwards to tropical West Pacific, 10–20 m (Hayami, 2000: 907); East China Sea, Taiwan, South China Sea, intertidal– 20 m (Bernard et al., 1993: 50); Philippines, 10–25 m (alive), 627-645 m (dead) ( Raines, 2010: 600; Dijkstra, 2013: 35); Tiur Island, Indonesia, 54 m (Dijkstra, 1990a: 8); Hansa Bay, Papua New Guinea, 3–25 m, live (Dijkstra, 1998a: 16); Japan to Indonesia, 5-86 m (Huber, 2010: 199). Maximum depth range intertidal to 180 m (HHD, unpublished data). Present material from Australia alive at c. 18 m.

Remarks. Bractechlamys oweni is a new record for Australia. The present specimens from Queensland and Western Australia differ slightly from the type specimen from the Philippine Islands in their greater convexity and the more prominent sculpture on the anterior auricle of the right valve. However, these characters are also observed on other material from the Philippine Islands and the Solomons.