Cryptopecten nux (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 : 300-303

Cryptopecten nux (Reeve, 1853)

Figs 99, 100B, 101B–C

Pecten coruscans Hinds. –Reeve, 1853: sp. 143, pl. 32, fig. 143 (misidentification).

Pecten nux Reeve, 1853 : errata; Küster & Kobelt, 1888: 163, pl. 45, figs 5–8; Paetel, 1890: 232; Smith, 1903: 621; Smith, 1904: 13; Lynge, 1909: 155; Melvill, 1909: 127.

Pecten hastingsii Melvill, 1888: 279 , pl. 2, fig. 7; Trew, 1987: 44.

Pecten guendolenae Melvill, 1888: 279 , pl. 2, fig. 6; Trew, 1987: 43.

Chlamys smithi G. B. Sowerby III, 1908: 18 , pl. 1, figs 6–7; Viader, 1937: 62.

Chlamys corymbiatus Hedley, 1909: 423 , pl. 36, figs 1–4.

Pecten (Aequipecten) vesiculosus Dunker. –Dautzenberg & Bavay, 1912: 148 (misidentification).

Chlamys (Aequipecten) nux (Reeve) .–Cox, 1930: 124, pl. 14, fig. 11; Eames & Cox, 1956: 43.

Chlamys nux (Reeve) .–Dautzenberg & Bouge, 1933: 427; Viader, 1937: 62.

Pecten (Aequipecten) nux Reeve. – Nomura, 1933: 55; Nomura & Zinbo, 1934: 117 [in part].

Pecten (Aequipecten) kikaiensis Nomura & Zinbo, 1934: 153 , pl. 5, figs 9a–b.

Aequipecten nux (Reeve) .– Lamy, 1935: 315.

Cryptopecten nux (Reeve) .–Habe, 1951: 77; Habe, 1961: 118, pl. 53, fig. 9; Habe, 1964b: 174, pl. 53, fig. 9; Habe, 1977: 84; Kira, 1962: 174, pl. 53, fig. 9; Hayami, 1982: 235; Wang, 1983a: 403, figs 1(8–13); Hayami, 1984: 99, pl. 2, fig. 4, pl. 3, figs 1–2, pl. 9, figs 2–5, pl. 12, figs 1–2; Dijkstra, 1991: 36; Lamprell & Whitehead, 1992: [26], pl. 11, fig. 66; Bernard et al., 1993: 50; Dijkstra & Marshall, 1997: 107; Dijkstra, 1998a: 42; Dijkstra, Drivas & Jay, 1998: 6, fig. 6; Dijkstra & Knudsen, 1998: 86, pl. 3, figs 12–13; Hayami, 2000: 905, pl. 450, fig. 40; Dijkstra, 2001: 92; Dijkstra & Kilburn, 2001: 310, figs 50–51; Wang, 2002: 211, fig. 91, text fig. 15; Taylor & Glover, 2004: 262; Raines & Poppe, 2006: 314–315, lower fig; pl. 276, figs 1–8; Dijkstra & Moolenbeek, 2008: 22; Dijkstra & Maestrati, 2008: 109; Xu & Zhang, 2008: 87, fig. 244; Dijkstra & Maestrati, 2010: 350; Huber, 2010: 203; Raines, 2010: 646, pl. 1014, figs 1–6; Dijkstra, 2013: 99, pl. 25, figs 1a–d, 3a–b; Dijkstra & Janssen, 2013: 204, figs 32–33; Dijkstra & Maestrati, 2013a: 371.

Chlamys (Cryptopecten) nux (Reeve) .– Shikama, 1964: 50, fig. 93.

Cryptopecten kikaiensis (Nomura & Zinbo) .–Habe, 1977: 84.

Cryptopecten hastingsii (Melvill) .–Habe, 1977: 85.

Cryptopecten bernardi corymbiatus (Hedley) .–Dijkstra, (1983–1994) 1988: 7, figs.

Cryptopecten bernardi nux (Reeve) .–Dijkstra et al., 1990: 9–10, fig.

Chlamys (Cryptopecten) bernardi (Philippi) .– Rombouts, 1991: 23, pl. 23, figs 3–3a; Oliver, 1992: 72, text-figs 21a–b, 76, pl. 14, figs 3a–b (misidentification).

Cryptopecten guendolenae (Melvill) .–Huber, 2010: 203.

Figure 99. Distribution of Cryptopecten nux (Reeve) .

Type data. Pecten nux Reeve : lectotype (pr) NHMUK 1950. 11.14.52, 2 paralectotypes (pr) NHMUK 1950.11.14.50–51, designated by Wagner (1989a: 58). Type locality: Philippine Islands , Bohol, Panglao, designated by Wagner (1989a: 58).

Pecten hastingsii Melvill : holotype (pr) NMW1955.158 . 10. Type locality: Japan.

Pecten guendolenae Melvill : holotype (pr) NMW1955 . 158.02. Type locality: Mauritius.

Chlamys smithi Sowerby : holotype (pr) NHMUK1908.5 . 30.63. Type locality: Mauritius.

Chlamys corymbiatus Hedley : two syntypes (lv + rv) AM C.027532 (lv in Fig. 101C). Type locality: Australia, N QLD, Hope Islands , 5–10 fathoms [9–18 m].

Pecten (Aequipecten) kikaiensis Nomura & Zinbo : holotype (rv) IGPS50357. Type locality: Japan, Amami Islands , Kikai Island , Kamikatetsu , Wan Formation, late Pleistocene (Marine Isotope Stage 5e, 125 000 yrs).

Additional material examined. — AUSTRALIA: QUEENSLAND: N Gulf of Carpentaria, 9°34'S 139°26' E,dead, 38 m (1 v, C.343744);Torres Strait,Darnley Island, 9°35'S 143°46'E,dead, 46–55 m (4 v,C.061519);Torres Strait,off Murray Island, 9°56'S 144°04'E,dead, 9–15 m (1 v,C.030274);N Gulf of Carpentaria, 10°01'S 139°29'E, dead, 57 m (1 v, C.343741); Cape York Peninsula, Albany Passage, 10°45'S 142°37'E, dead, 7–26 m (16 v, C.036127); Gulf of Carpentaria, 10 mls SW of Mapoon, 12°05'S 141°40'E, dead, 18 m (3 v, C.014076); N Gulf of Carpentaria, 12°58'S 139°30'E, dead, 64 m (1 v,C.343743);GBR,off Bow Reef, near Cape Sidmouth, 13°20'S 143°40'E,dead, 19 m (2 v,C.002557); 10 mls SE of Cape Sidmouth, 13°25'S 143°36'E, dead, 24 m (1 v, C.047346);E Gulf of Carpentaria, 14°20'S 140°34'E, dead, 59 m (1 v,C.165184); GBR, Howick Group, Coquet Island, 14°32'S 144°59'E, dead (2 v, C.049388); 0.5 ml SE of Lizard Island, 14°41'S 145°29' E, dead, 35 m (1 v, C.343789); E Gulf of Carpentaria, 14°50'S 140°42' E,dead, 44 m (1 v,C.343736);off Cape Flattery,Decapolis Reef, 14°50' S 145°17'E,dead, 12–14 m (1 v,C.343748);0.5ml W of Two Isles, 15°01'S 145°26'E,dead, 30 m (10 v, C.343749); S Gulf of Carpentaria, 15°29'S 139°31'E, dead, 49 m (1 v, C.343737);Cairns Reef lagoon& between Cairns Reef& Hope Island, 15°42'S 145°30'E, dead, 9–18 m (5 v, C.027532; many v, C.170684); between Cairns Reef & Endeavour Reef, 15°45'S 145°35'E, dead, 37 m (many v, C.044614); Endeavour Reef, 15°47' S 145°35'E, dead (6 v, C.343750); SE Gulf of Carpentaria, 15°51'S 140°27'E, dead, 38 m (1 v, C.343738); E Gulf of Carpentaria, W of Nassau River, 15°51'S 140°54'E, dead, 22 m (1 v,C.343734);GBR,Undine Reef, 16°08'S 145°40'E, alive (3 pr,C.343751);1.5 ml NW of Low Isles, 16°22' S 145°33'E, dead, 20 m (1 v, C.343752; 1 v, C.161020); Low Isles, 16°23'S 145°34'E, dead (1 v, C.161019 [in part]); Low Isles, near Port Douglas, 16°23'S 145°34'E, dead, 16–22 m (many v, C.343754); NE of Cairns, 16°33'S 146°09'– 146°09.6'E, dead, 55 m (5 v, C.343760); off Cairns, 16°34'S 146°15'– 146°13.6'E, dead, 192 m (1 v,C.343749);Michaelmas Cay, 16°36'S 145°59'E,dead, 20 m (10 v,C.343761); off Cairns, 16°36'– 16°35'S 146°14' – 146°13.8'E, dead, 172–197 m (3 v, C.343755); off Cairns, 16°51'S 146°01' – 146°04' E, dead, 33–35 m (5 v, C.343756); off Cairns, 16°52' – 16°53'S 146°06'E, dead, 37–38 m (4 v, C.343758); off Cairns, 16°55'S 146°07'E, dead, 37–40 m (4 v, C.343757); Kurramine Beach,S of Innisfail, 17°47' S 146°06'E, dead (1 v, C.343762);Palm Islands , 18°40'S 146°33'E,dead, 27 m (many v,C.010359);Palm Islands , Fantome Island, 18°43'S 146°31'E,dead, 18.3 m (2 v,C.343765);off Townsville,6–7mls E of Keeper Reef, 18°45'S 147°23'E,dead, 43 m (1 v,C.343766);Palm Islands ,off Eclipse Island, 18°46'S 146°33'E,dead, 13 m (1 v, C.343764);off Townsville, 18°48'S 146°55'E, dead, 32.5–34 m (5 v, C.343768); off Townsville, 18°49'S 146°58'E, dead, 34–35 m (15 Figure 100. A, C, Cryptopecten bullatus (Dautzenberg & Bavay) , rv only, AM C. 160969, 171 km N of Melville Island, Arafura Sea, NT, 148 m; rv exterior (A), rv interior (C). B, Cryptopecten nux (Reeve) , rv of pair, AM C.303782, Turkey Beach, Rodds Bay, QLD; rv interior. D, F–I, K, Haumea rehderi (Grau) , separate valves, AM C.161025, Chevert Exped., Darnley Island, Torres Strait, QLD, 9°35'S 143°46'E, 55 m; rv exterior (D), lv exterior (F), rv interior (G), rv anterior auricle interior (H), lv anterior auricle exterior (I), rv anterior auricle exterior (K). E, Mimachlamys spinicostata sp. nov., paratype, lv of specimen in Figs 95E, 96F,G; lv exterior. J, L, Volachlamys singaporina (G. B. Sowerby II) , pair, AM C.019176, Moreton Bay, QLD; lv exterior (J), rv interior (L). Scale bars represent 10 mm (A–C), 3 mm (D, F, G), 30 mm (E, J, L), 0.5 mm (H, I, K).

v, C.343767);Townsville,off Horseshoe Bay, Magnetic Island, 19°07' S 146°51'E, dead, 5.5–9 m (4 v, C.343763); off Townsville, northern coast of Magnetic Island, N end of Horseshoe Bay, 19°08'S 146°50'E, dead (4 v, NTM P011948); S of Townsville, 19°17'S 147°32'E,dead, 24 m (many v, C.343769);off Cape Upstart, 19°42'S 147°45'E, dead, 36 m (1 pr, C.343770); E of Bowen, 19°45'S 148°19'E, dead, 46 m (7 v, C.343772); off Bowen, 19°48'S 148°53'E, dead, 62 m (8 v, C.343773); off Bowen, 20°0'S 148°22'E, alive, 27–45 m (7 pr, C.343771); W of Hayman Island, 20°03'S 148°50'E, dead, 33 m (many v, C.120135); off Hayman Island,Whitsunday Islands , 20°03'S 148°53'E,alive, 9 m (1 pr,C.343775);Whitsunday Passage, 20°13'S 148°47'E,dead, 24 m (10 v,C.343777); Kennedy Sound, between Lindeman Island & Shaw Island, 20°25' – 20°30'S 149°01' – 149°04'E,dead (2 v,C.343774);Whitsunday Islands ,Lindeman Island, 20°27'S 149°02'E, dead (many v, C.058933); off Shaw Island, N of Mackay, 20°29' S 149°05' E, dead, 37 m (many v, C.061525); Whitsunday Passage, 20°32'S 149°01'E, dead, 27 m (many v, C.343776);E of Mackay, 20°52'E 149°29'E,dead, 35 m (many v,C.116552);E of Sarina, 21°27'S 150°08'E,dead, 42 m (many v, C.343778); E of Sarina, 21°28'S 150°08'E,dead, 40 m (many v, C.120874); Swain Reefs, 3 km NE of W side of Bylund (Gillett) Cay, 21°42'S 152°26'E, dead, 64–73 m (19 v, C.343781); SE of Sarina, 21°47'S 150°34' E, dead, 59 m (many v,C.116490);E of Broad Sound, 21°58'S 150°45'E,dead, 57 m (many v, C.343780); off Broad Sound, 22°06'S 150°49'E, alive, 53 m (1 pr + 20 v, C.343779); off Yeppoon, 22°30'S 151°26' E, dead, 55 m (4 v, C.343787); off Yeppoon, 22°40'S 151°16'E,dead, 58 m (12 v, C.343783);off Yeppoon, 22°42'S 151°37'E,dead, 68 m (6 v, C.343788); NE of Rockhampton, 22°50'S 151°39'E, dead, 64 m (12 v, C.343782); E of Keppel Islands , 23°0'– 23°12'S 151°10' – 151°20' E, dead, 46–49 m (1 v, C.101115); Capricorn Channel,4 mls E of North Reef, 23°09'S 151°58' E,alive, 64 m (1 pr,C.344006); Capricorn Group, North West Island, 23°18'S 151°42'E, dead (3 v, C.343784; 5 v, C.343785); Gladstone Harbour, 23°51'S 151°16' E, alive, 18–24 m (1 pr, C.343790); Bunker Group,off Lady Musgrave Island, 23°54'S 152°25' E,dead, 47 m (3 v,C.343786); Turkey Beach, Rodds Bay, 24°0' S 151°33'E, alive (1 pr, C.303782); off Maryborough, 25°47' S 153°33'E,dead, 64 m (5 v,C.343791);Frazer Island,off S end, 25°48'S 153°46'E, dead, 73 m (14 v,C.343793); Frazer Island, off S end, 25°57'S 153°34'E, dead, 58–60 m (2 v,C.343792);E of Moreton Bay, 26°91.7'S 153°55'E,dead, 115–175 m (1 v,C.160955); off Dunwich, Stradbroke Island, Moreton Bay, 27°30'S 153°24'E, dead, 5–7 m (1 v, C.343795); off Moreton Bay, 27°31'S 153°40' E, dead, 75–80 m (1 v, C.343794). NEW SOUTH WALES: off Tweed Heads, 28°17'S 153°44' E,dead, 73 m (1 v, C.343796); SE of Ballina,29°06'– 28°57'S 153°34'– 153°38'E,dead, 44–53 m (1 pr,C.343797);off Iluka, 29°25' S 153°24' E, alive, 45–65 m (1 pr, C.344004); SE of Yamba, 29°28'– 29°33' S 153°30'– 153°25'E, alive, 51–55 m (1 pr, C.343798). WESTERN AUSTRALIA: W of Dongara, 29°49'S 114°24'E, dead, 128–132 m (1 v, WAM); 92 km W of Dongara, 29°07.05'S 113°57.04' E,dead, 110 m (1 v, WAM);SW of Point Cloates, 23°25'S 113°29' E, dead, 150 m (1 v, WAM);W of Point Cloates, 22°52'S 113°29'E,dead, 134 m (1 v, WAM); W of North West Cape, 21°50'S 113°46' E, dead, 137 m (2 v, WAM); North West Cape, 21°42'S 114°13' E, dead, 36 m (8 v, C.343692); North West Shelf, 26 n. mls NNE of DampierArchipelago, 20°14'S 116°50' – 116°50.6'E,alive, 40–41 m (1 pr + 3 v,C.343690); North West Shelf, 95 km NE of Dampier, 19°59'S 117°16'E, dead, 50 m (1 v,C.343694); North West Shelf, 44 n. mls NW of Port Hedland, 19°56'S 117°53'– 117°53.4'E,alive, 40 m (3 pr, C.344005); 45 n. ml NW of Port Hedland, 19°55.2'– 19°55.6' S 117°56.0'– 117°55.6'E, dead, 40 m (2 v, C.165174 [in part]); North West Shelf, 19°55'S 117°55'E, alive, 40–45 m (1 pr, WAM 521); North West Shelf, 52 n. mls NNE of Port Hedland, 19°30' – 19°28'S 118°49' – 118°55.4' E, alive, 36–37 m (4 pr + 2 v, C.148706); North West Shelf, 19°28.9' – 19°29.0'S 116°29.4'– 116°29.0'E, alive, 110 m (2 pr, C.165231); North West Shelf, 72 n. mls NNW of Dampier, 19°28'– 19°29'S 116°29'E, dead, 110 m (6 v, C.343689; 10 v, C.165181); North West Shelf, c. 90 mls N of Port Hedland, 19°07'S 118°15'E, dead, 88 m (1 v,C.343705); North West Shelf, 78 n. mls NNE of Port Hedland, 19°04' – 19°04.2'S 119°04'– 119°0.7'E, dead, 82 m (5 v, C.149935); North West Shelf, 80 n. mls NNE of Port Hedland, 19°03'– 19°03.4' S 119°03' – 119°03.5' E, dead, 82 m (many v, C.343687);North West Shelf, 85 n. mls NNW of Port Hedland, 19°00.8'S 118°01.3' E,dead, 112 m (4 v, C.343691;8 v, C.165177 [in part]); 85 n. ml NNW of Port Hedland,19°00.4'– 19°00.3'S 118°01.0'– 118°01.1' E, dead, 116–120 m (1 v, C.165175 [in part]); North West Shelf, 94 n. mls NNE of Port Hedland, 18°48' S 119°0'E,dead, 92–94 m (many v, C.343693; 17 v,C.165190 [in part]);North West Shelf,110 mls N of Port Hedland, 18°46' S 119°17' E, dead, 106 m (1 v, C.343704); North West Shelf, c. 120 mls N of Port Hedland, 18°40'S 119°23'E, dead, 117 m (1 v, C.343706); North West Shelf, c. 100 mls NW of Broome, 16°58'S 120°47'E,dead, 194 m (3 v,C.343697); North West Shelf, c. 100 mls W of Cape Leveque, 16°18'S 121°40'E, dead, 69 m (1 v,C.343701); W of Broome, dead, 90 m (1 v, WAM 475); North West Shelf, c. 240 mls NE of Broome, 14°37'S 123°40'E, dead, 80 m (3 v,C.343702);North West Shelf,c. 224 km N of Cape Leveque, 14°29'S 123°03'E,dead, 124 m (2 v,C.343699);Cassini Island,S side, 13°56'S 125°38'E,dead, 45–48 m (many v, WAM);Arafura Sea,Flat Top Bank, 12°16' S 129°15'E,dead, 27 m (1 v,C.343711);Timor Sea, Sahul Banks, 10°30'– 12°10'S 123°30'– 126°30' E, dead, 27 m (3 v, C.343712). NORTHERN TERRITORY: Darwin, 36 km off Point Charles, 12°10'S 130°22'E,dead, 27–37 m (3 v,C.060755);W of Gunn Point,N of Darwin Harbour, 12°10.02'S 130°49.86'E, dead, 27 m (1 v, NTM P005396 [in part]);Arafura Sea, c. 100 mls N of Croker Island, 9°30'S 132°34'E,dead, 124 m (1 v,C.343717);Arafura Sea, 91 km NE of Croker Island, 10°15'S 132°54' E,dead, 70 m (1 v,C.343719);Arafura Sea, 295 km N of Goulburn Island, 8°41'S 133°12'E,dead, 196 m (1 v,C.343718);Arafura Sea, 125 km N of Goulburn Island, 10°23' S 133°36'E, dead, 62 m (3 v, C.343720); Arafura Sea, c. 210 mls NE of Croker Island, 8°18'S 133°58' E,dead, 132 m (4 v, C.343715);Arafura Sea, c. 250 mls NE Croker Island, 8°09'S 134°50'E, dead, 115 m (5 v, C.343714);Arafura Sea, N of Wessel Islands , 8°36'S 135°08' E, dead, 82 m (1 v, C.343716); Arafura Sea, c. 200 mls NW of Wessel Islands ,Arnhem Land, 8°15'S 135°20'E, dead, 81 m (2 v,C.343722);Gulf of Carpentaria, Groote Eylandt, 14°0'S 136°25'E, dead (1 v, C.343723); N of Arnhem Land, 10°48'S 136°30'E, dead, 50 m (1 v, C.343729); Gove Peninsula,Nhulunbuy town beach, 12°11'S Figure 101. A, Cryptopecten bullatus (Dautzenberg & Bavay) , specimen in Fig. 100A, C; rv exterior. B, C, Cryptopecten nux (Reeve) ; (B) specimen in Fig. 100B; rv exterior; (C) lv only, AM C.027532, syntype of Chlamys corymbiata Hedley, Hope Islands, N QLD , 5–10 fathoms [9–18 m]; lv exterior. D, E, Volachlamys singaporina (G. B. Sowerby II) , specimen in Fig.100J,L; lv exterior (D), rv exterior (E). Scale bars represent 10 mm (A–C), 30 mm (D, E). 136°47'E, dead (1 v, C.343731); N of Arnhem Land, 10°02' S 137°10'E, dead (2 v, C.343726);N ofArnhem Land, 9°49'S 137°12'E,dead(1 v,C.343725);Gulf of Carpentaria, 12°06'S 137°26'E, dead, 55 m (1 v, C.165189). —RED SEA: Gulf of Aqaba, off Wadi Murach,alive, 73–82 m (5 pr, ZMA Moll.142644). TANZANIA: Zanzibar Channel,alive, 55 m (1 pr, ZMA Moll.145578).— MAURITIUS:off Port Louis,alive, 238 m (2 pr, ZMA Moll.142641). SRI LANKA: N of Sri Lanka,Palk Strait, 10°02.5'N 80°02'E, dead, 22 m (4 v, C.160963). — THAILAND: S of Phuket Island, Koh Raya Yai, alive, 42 m (1 pr, ZMA Moll.143693). — JAPAN: Tanega-shima Island, dead, 80–100 m (10 v, ZMA Moll.144696). — CHINA: S China Sea, alive, 40 m (1 pr, ZMA Moll.142634). — PHILIPPINE ISLANDS : Davao, Samal Island, Matanos, alive, 165 m (9 pr, ZMA Moll.145093). SINGAPORE: 1°12'N 103°44'E, sand from Selat Sulong & vicinity, dead (1 v,C.343806).— INDONESIA:Kai Islands ,alive, 124–850 m (2 pr, ZMA Moll.145666). — PAPUA NEW GUINEA: New Britain, 4°12'S 152°11'E, dead (2 v, C.045589); New Britain,Rabaul Harbour,Matupi Island, 4°14'S 152°12'E, dead (7 v,C.343799);Trobiand Group, Kiriwina Island, Between Magulata & Kabulina Points, 8°27'S 151°0'E, just off outer reef,dead,c. 73 m (1 v,C.160962);SW Port Moresby,Lolorua Island, 9°30'S 147°06' E, dead, 13–18 m (1 v,C.343805); Port Moresby,Manubada(Local) Island,off W end, 9°31'S 147°10'E,dead, 18–22 m (2 v,C.343804).— NEW CALEDONIA:Koumac,alive, 82–120 m (2 pr + 18 v, ZMA Moll.139672). VANUATU:off Aneityum Island, 20°16'S 169°51'E, dead, 85–100 m (2 v, C.343803); off Aneityum Island, 20°17'S 169°48'E, dead, 55–75 m (1 v, C.343802).TASMAN SEA:Lord Howe Rise, 31°34' S 159°0'E, alive, 73 m (2 pr + 2 v,C.300121); Lord Howe Rise, 31°38'S 159°03' E,dead, 44 m (2 v, C.300122).

Description. Shell up to c. 20 mm high, most specimens to 10–15 mm; solid, moderately to strongly inflated, right valve more convex than left, circular to subcircular, almost equivalve, equilateral to inequilateral, anterior auricles larger and longer than posterior ones, umbonal angle c. 90°; colour polychromatic, left valve more strongly pigmented; a few specimens monochrome yellow or purple.

Both valves with 18–22 evenly spaced, vesicularsculptured radial plicae, when worn appearing more tripartite; interplical spaces bearing obvious commarginal lamellae. Auricles with 4–6 spinous radial riblets, most prominent on anterior auricle of right valve. Dorsal margin straight. Byssal notch deep, byssal fasciole moderately wide. Functional ctenolium well-developed, with 4–6 teeth. Resilifer triangular, slightly oblique. Interior weakly furrowed, internal rib carinae prominent in relatively wide zone around ventral margin. Resilial and dorsal teeth prominent.

Dimensions. Illustrated specimen: QLD, Turkey Beach, Rodds Bay ( AM C.303782), single rv: H 18.5, L 19.0 mm. Hedley (1909: 423) stated the dimensions of a syntype of Chlamys corymbiatus as “Height 20; length 20; depth of single valve 7 mm ” .

Habitat. Living in the littoral to upper bathyal zones, amongst shell rubble on sandy and/or muddy bottoms.

Distribution. Throughout the tropical and subtropical Indo-West Pacific, from southern Japan southwards to northern Australia, westwards into the Indian Ocean to South Africa and into the Red Sea, and eastwards across the Pacific to French Polynesia (absent from the Hawaiian Islands ) (Raines & Poppe, 2006: 314); Red Sea and Gulf of Aden, 40–73 m, alive, 71–447 m, dead (Dijkstra & Knudsen, 1998: 87; Dijkstra & Janssen, 2013: 204); South Africa, 49–64 m (Dijkstra & Kilburn, 2001: 311–312); Philippines to Australia, 13–150 m (Huber, 2010: 203); Philippines, 5–230 m ( Raines, 2010: 646; Dijkstra, 2013: 100); Indonesia, 124–850 m, dead (Dijkstra & Kastoro, 1997: 275); Vanuatu, 45–153 m (Dijkstra & Maestrati, 2012: 403); Norfolk Ridge, Loyalty Islands , Solomon Islands , Fiji and Tonga, 97–120 m (Dijkstra & Maestrati, 2008: 109–110); Society Islands and Tuamotu, 96–1060 m, dead (Dijkstra & Maestrati, 2013a: 371); Austral Islands , 110–390 m, 783–1000 m (Dijkstra & Maestrati, 2010: 350–351). Maximum depth range of live-taken specimens is 5–1000 m. Present material from Australia alive at 9– 110 m.

Remarks. Cryptopecten nux is highly variable in outline,

convexity, sculpture and colour (Hayami, 1984: 100; Dijkstra, 1991: 37). For further discussion see Dijkstra & Kilburn (2001: 312).