Pedum spondyloideum (Gmelin, 1791)

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 : 253-255

Pedum spondyloideum (Gmelin, 1791)

Figs 72D, 74G–I, 75, 76A,C–D

Pedum Bruguière, 1792 : pl. 178, figs 1–4 (no included species).

Ostrea spondyloidea Gmelin, 1791: 3335 , no. 109; Dillwyn, 1817: 280.

Ostrea pedum Röding, 1798: 170 .

Pedum spondyloidea [sic] (Gmelin).– Lamarck, 1799: 88.

Pedum spondyloides [sic] (Gmelin).– Lamarck, 1801: 136; Bosc, 1802: 250; Bosc, 1824: 245, pl. 10, figs 3–4; Defrance, 1825: 248.

Pedum spondyloideum (Gmelin) .– Lamarck, 1819: 154; Reeve, 1841: 154, pl. 111, figs 1–5; Reeve, 1860: 61, pl.

Figure 75. Distribution of Pedum spondyloideum (Gmelin) .

28, fig. 164, pl. N, fig. 3; G. B. Sowerby II, 1842: 438, pl. 91, figs 1–4; Chenu, 1843: 1, pl. 1, figs 1–3; Sganzin, 1843: 11; Mörch, 1853: 61; Chenu, 1862: 189, fig. 961; Issel, 1869: 105; McAndrew, 1870: 450; Martens, 1880: 313; Cooke, 1886: 136; Shopland, 1896: 235; Shopland, 1902: 179; Sturany, 1905: 141; Lamy, 1928: 220; Cox, 1929: 207; Kuroda, 1931: 82; Lamy, 1935: 306; Viader, 1937: 62; Yonge, 1967: 311, figs 1–8; Hertlein, 1969: N364, figs C.86.1a–b; Habe, 1964b: 174, pl. 53, fig. 15; Waller, 1972a: 226, 230, 254, pl. 8, figs 136–143, figs 21B–22; Habe, 1977: 92; Mastaller, 1978: 138; Mastaller, 1979: 142; Mergner, 1979: 481, 500; Oliver, 1982: 14; Abbott & Dance, 1982: 315, fig; Nielsen, 1986: 8, figs 3A–B [holotype]; Wells & Slack-Smith, 1986: 54; Dijkstra, (1983–1994) 1987: 9, figs; Dijkstra et al., 1989: 24; Dijkstra et al., 1990: 4; Dijkstra, 1991: 40; Lamprell & Whitehead, 1992: [34], pl. 15, fig. 86; Oliver, 1992: 69, 78, text-fig. 1, pl. 14, figs 5a–c; Bernard et al., 1993: 53; Dijkstra, 1997: 332, fig. 41; Dijkstra, 1998a: 34; Dijkstra & Knudsen, 1998: 79, pl. 5, figs 23–24; Savazzi, 1998: 413–421, figs 1–5; Hayami, 2000: 911, pl. 453, fig. 64; Dijkstra & Kilburn, 2001: 293, figs 29–30, Wang, 2002: 247, text-fig. 103; Dharma, 2005: 250, pl. 100, figs 15a–b; Raines & Poppe, 2006: 224–225, pl. 171, figs 1–5; pl. 296, fig. 1; Xu & Zhang, 2008: 93, fig. 263; Huber, 2010: 204; Raines, 2010: 626, pl. 1004, figs 1–2; Dijkstra, 2013: 74, pl. 19, figs 6a–d, pl. 20, figs 6a–b, pl. 32, figs 2a–b.

Pedum spondiloideum [sic] (Gmelin).–Quoy & Gaimard, 1835: 447, pl. 76, figs 15–21.

Pedum spondyloideum (Gmelin) var.–P. Fischer, 1858: 340.

Pedum pedum intensum Iredale, 1939: 340 .

Pedum sp. Mastaller, 1978: 127 , 138.

Pedum pedum (Röding) .– Roberts et al., 1982: 116, pl. 34, figs 7–7a.

Type data. Ostrea spondyloidea Gmelin : holotype (pr) ZMUC BIV-57. Type locality: India.

Ostrea pedum Röding : type material lost. Type locality: not indicated. We designate the holotype of Ostrea spondyloideum Gmelin, 1791 , ZMUC BIV-57, as the neotype of Ostrea pedum Röding, 1798 .

Pedum pedum intensum Iredale : holotype (pr?) AM C.090353. Type locality: Australia, N QLD, GBR, Low Isles, anchorage, in Porites . Iredale (1939: 341) stated that “a nice specimen [presumably the holotype of Pedum pedum intensum ] … taken in Porites in the Anchorage [at Low

Figure 76. A, C, D, Pedum spondyloideum (Gmelin) ,pair, specimen in Figs 72D, 74H; lv interior (A), rv interior (C), rv exterior (D).B, E, G, I, Scaeochlamys livida (Lamarck) , 2 pairs; (B, E) one of three syntypes of Pecten foliaceus Quoy & Gaimard, MNHN Moll 21186, King George Harbour, Albany, WA; rv exterior (B), lv exterior (E) (MNHN photos by Barbara Buge); (G, I) AM C.097513, off Peel Island, Moreton Bay, QLD, 9 m; lv exterior (G), rv exterior (I). F, H, Scaeochlamys squamea Dijkstra & Maestrati , pair, HM, south passage, Shark Bay, WA, 12–15 m; lv exterior (F), rv exterior (H). Scale bars represent 30 mm (A, C, D, G, I), 20 mm (B, E, F, H).

Isles], measures” H 55, L 44 mm. However, the two valves in C.090353 are different sizes and shapes, the rv being taller and considerably wider than the lv rather than the other way around, as is usual; they apparently represent two specimens.

Additional material examined. — AUSTRALIA: QUEENSLAND: Lizard Island, 14°40'S 145°28'E, dead (1 pr + 1 v, C.041556); Lizard Island, S side of South Island, 14°42' S 145°27'E, dead, 3–18 m (1 pr, C.375133); Low Isles anchorage, 16°23'S 145°33.8' E, alive (pr [holotype of Pedum pedum intensum Iredale, 1939 ], C.090353); Palm Islands , Orpheus Island, Pioneer Bay, 18°36'S 146°29'E, alive, 3 m (1 pr, C.099281); GBR, Whitsunday Islands , Hayman Island, 20°03.6' S 148°53.5' E, alive (1 pr, C.132393). WESTERN AUSTRALIA: Hugh Morrison (pers. comm., Aug.2000) has observed live specimens in situ in Porites at Rowley Shoals,Scott Reef, Seringapatam Reef,Ashmore Reef,Hibernia Reef,and Cartier Reef.—RED SEA:Gulf of Aqaba,Elat, alive, 10–15 m (2 pr, ZMA Moll.142936).— DJIBOUTI:Gulf of Aden, alive, 10–18 m (7 pr, ZMA Moll.143582).— MAURITIUS: 20°11'S 57°32'E, dead (1 pr, C.004966; 2 pr, C.110093; 2 pr, C.132394).—CHAGOS ARCHIPELAGO:Diego Garcia, 6°34'S 72°24'E,dead(3 pr,C.132395).— THAILAND: Phuket Island,Kho Kao Yao, alive, 15–25 m (3 pr, ZMA Moll.145486). — CHINA: Hainan, alive, 0–20 m (1 pr, ZMA Moll.145739). — PHILIPPINE ISLANDS : Cebu Island, 10°17'N 123°56'E, alive (2 pr, C.084282); Mactan, Tambuli, alive, 8–25 m (2 pr, ZMA Moll.146158). — INDONESIA:Moluccas,Ceram,alive, 8 m (1 pr, ZMA Moll.142937).— PAPUA NEW GUINEA: off Madang, N end of Kranket Island, 5°11'S 145°51'E, alive, intertidal (4 pr, C.375348); Madang Harbour, E side of Beliau Island, 5°12' S 145°50'E, alive (1 pr, C.375349).— NEW CALEDONIA:Nouméa,Ile St.Marie, 22°18'S 166°29' E, dead (1 pr, C.375134); idem, NW & W side, dead, 0–2 m (1 pr, C.375135).

Description. Shell up to 110 mm high, most specimens 50–70 mm; shape rendered extremely variable by mode of life, transversely oblong in juvenile stage, dorsoventrally elongate in mature stage, left valve flattened, right valve weakly inflated, laterally curved; strongly inequivalve and inequilateral, auricles of left valve not clearly differentiated, of right valve more distinct and unequal than in left valve; whitish or cream, with lateral and umbonal purple spots on right valve, left valve with purple or brown patches or streaks.

Left valve sculptured with numerous delicate, unevenly spaced, scabrous radial riblets, very weak or lacking near ventral margin in mature stage. Right valve with microscopic, closely spaced scabrous radial riblets in early growth stage and closely spaced commarginal lamellae laterally, more prominent near antero-marginal area. Dorsal margin of anterior auricle strongly declined. Byssal notch deep, byssal fasciole rather broad. Functional ctenolium lacking. Outer ligament strongly developed in ventral direction. Resilial insertion elongate, narrow and deflecting. Hinge teeth lacking.

Dimensions. Illustrated specimens: QLD, Lizard Island, beach (AM C.041556): tall, narrow pr, rv: H 108.5, L 62.7 mm; lv: H 105.2, L 57.2 mm; D 14.3 mm, D (including curvature of entire specimen) 16.5 mm; smaller single rv: H 66.0, L 55.5 mm.

Habitat. Living in tropical shallow waters, embedded in massive heads of scleractinian corals.

Distribution. Throughout the tropical Indo-West Pacific, from southern Japan to northern Australia, westwards into the Indian Ocean, into the Red Sea and southwards to South Africa, eastwards into the central Pacific to French Polynesia (not recorded from the Hawaiian Islands ) (Waller, 1972: 258; Raines & Poppe, 2006: 224); Red Sea to Japan, 1–24 m (Huber, 2010: 204); Philippines, 3–10 m ( Raines, 2010: 626; Dijkstra, 2013: 76); Vanuatu, intertidal zone to 55 m (Dijkstra & Maestrati, 2012: 400). Maximum depth range of live-taken specimens is from the intertidal zone to 55 m. Present specimens from Australia alive at 3–25 m (unpublished data, HHD).

Remarks. The present specimens from Australia are morphologically identical to the type material of Pedum spondyloideum . This coral-dwelling species is highly variable in shape, due to xenomorphic development in fissures of massive heads of the coral Porites .

For information on the functional morphology and ecology of Pedum see Yonge (1967), Waller (1972a), Nielsen (1986), Kleemann (1990, 2001), and Savazzi (1998).