Amusium pleuronectes ( Linnaeus, 1758 )

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 : 205-207

Amusium pleuronectes ( Linnaeus, 1758)

Figs 45B–D, 46, 47F

Ostrea pleuronectes Linnaeus, 1758: 696 , no. 159; Linnaeus, 1764: 524, no. 103; Linnaeus, 1767: 1144, no. 189; Born, 1778: 82, no. 4; Born, 1780: 99; Gmelin, 1791: 3317, no. 6; Bruguière, 1797: pl. 208, fig. 3; Cuvier, 1798: 420, no. 3; Dillwyn, 1817: 250, no. 6; Dijkstra, 1999: 399, figs 1C–F [lectotype]; Dijkstra, 2016: 114, fig. 5.

Pecten pleuronectes (Linnaeus) .–Bosc, 1802: 260; Lamarck, 1819: 164, no. 7; Bosc, 1824: 255; Defrance, 1825: 239; Deshayes, 1832a: 717, no. 6; Deshayes, 1836: 132, no. 7; G. B. Sowerby II, 1842: 55, no. 30, pl. 16, figs 127–128, 135–136; Chenu, 1843: 4, pl. 11, figs 1–3; Reeve, 1853: sp. 48, pl. 13, fig. 48; Küster & Kobelt, 1888: 49, no. 15, pl. 13, fig. 4.

Amusium pleuronectes (Linnaeus) .–Röding, 1798: 165, no. 124; Oyama, 1951: 84, text-fig. 4; Kira, 1962: 138, pl. 49, fig. 16; Morton, 1980: 375–404; Abbott & Dance, 1982: 303, fig.; Grecchi, 1983: 7–9, figs; Dijkstra, 1990a: 9–10; Rombouts, 1991: 4, pl. 3, fig. 3; Dharma, 1992: 84, pl. 20, fig. 1; Bernard et al., 1993: 52; Dijkstra, 1997: 319; Taylor & Glover, 2004: 262; Raines & Poppe, 2006: 138–139, lower figs; pl. 87, figs 1–5; Huber, 2010: 197; Raines, 2010: 614, pl. 998, figs 1–2; Dijkstra, 2013: 50, pl. 11, figs 4a–b, pl. 13, figs 1a–d; Mynhardt et al., 2014: 406, figs 1A–C.

Amusium magneticum Röding, 1798: 165 .

Pectinium pleuronectes (Linnaeus) .– Link, 1807: 156.

Pleuronectia laevigata Swainson, 1840: 388 .

Amussium [sic] pleuronectes (Linnaeus) .– Smith, 1884: 116, no. 75; Smith, 1885: 308; Lynge, 1909: 158.

Pecten (Amussium) milneedwardsi Gregorio, 1898: 6 , pl. 1, figs 1, 6.

Amusium pleuronectes pleuronectes (Linnaeus) .–Habe, 1964a: 2, pl. 1, figs 3–4; Matsukuma et al., 1991: pl. 133, fig. 11; Dharma, 2005: 250, 364, pl. 100, fig. 18; pl. 147, figs 12a–b; Xu & Zhang, 2008: 78, fig. 218.

Amusium pleuronectes australiae Habe, 1964a: 2 , pl. 1, figs 1–2; Dharma, 2005: 250, pl. 100, fig. 17.

Amusium (Amusium) pleuronectes (Linnaeus) .–Dijkstra, 1990b: 52–53, figs; Dijkstra, 1997: 315, 319; Dijkstra, 1999: 400.

Amusium pleuronectes nanshaensis Wang & Chen, 1991: 152 , 160, fig. 3.

Comments on synonymy. Röding (1798) introduced a new species name “species 126 Amusium Magneticum ” for Gmelin’s “ Ostrea pleuronectes ” [after Linnaeus], which he also reported higher up the same page as “species 124 Amusium Pleuronectes ”. Amusium magneticum is an objective junior synonym of A. pleuronectes ( Linnaeus, 1758) .

Pleuronectia laevigata Swainson, 1840 , the type species of Pleuronectia Swainson, 1840 , is based on a reference to Lamarck (1816: pl. 208, fig. 3), which clearly shows the present species.

Gregorio (1898) extensively described and figured a new species Pecten (Amussium) milneedwardsi from New Caledonia, which closely resembles the present species. This is a subjective junior synonym of A. pleuronectes ( Linnaeus, 1758) .

Habe (1964) described a new subspecies from the Arafura Sea, which differs in his opinion from Amusium pleuronectes by having fewer internal rib carinae (22–24, A. pleuronectes 26–34) and a somewhat different colour of the left valve. However, the number of internal carinae varies strongly and intermediates are also observed. Also the bluish radial lines and interstitial small pale dots are highly variable. In our opinion this subspecies falls within the range of variation of the present species.

Recently Wang & Chen (1991) introduced a new subspecies from China, which in their opinion can be distinguished from Amusium pleuronectes by “the shell (almost rounded), the radial lines (reddish) and by the white and brown spots”. These characters are also observed in other material of the present species from the Southwest Pacific.

Type data. Ostrea pleuronectes Linnaeus : lectotype (pr) LSL [not registered] designated by Dijkstra (1999: 400), paralectotype (lv) MSNP [not registered]. Type locality: “ Habitat in Indiis ” [= Indonesia].

Amusium magneticum Röding : type material lost. Type locality not indicated.

Pleuronectia laevigata Swainson : type material unknown, not in the Manchester Museum or in the Natural History Museum, London. Type locality not indicated.

Pecten (Amussium) milneedwardsi Gregorio : type material lost. Type locality: New Caledonia. We designate the lectotype of Ostrea pleuronectes Linnaeus as the neotype of Amusium magneticum Röding, 1798 , the neotype of Pleuronectia laevigata Swainson, 1840 and the neotype of Pecten (Amussium) milneedwardsi Gregorio, 1898 .

Amusium pleuronectes australiae Habe : holotype (pr) NSMT-Mo54544. Type locality: Arafura Sea.

Amusium pleuronectes nanshaensis Wang & Chen : holotype (pr) IOAS M11600. Type locality: China, Nansha Islands , 4°08'N 112°53'E, 62 m, muddy sand.

Additional material examined. — AUSTRALIA: QUEENSLAND: Torres Strait,Nagir [Mt Ernest] Island, 10°15'S 142°29' E, alive (1 pr,C.097691); Cape York Peninsula,Albany Passage, 10°43'– 10°45'S 142°34'– 142°37'E,dead, 16–22 m (1 pr, C.093043);Cape York Peninsula,Albany Passage, 10°45'S 142°37'E,dead, 7–26 m (2 v, C.036126); 2 mls NE of Hannibal Island, 11°33'S 142°57'E, alive, 22–23 m (4 pr, C.338849); GBR, Raine Island, 11°35'S 144°01'E, alive (1 pr, C.093044); NE Gulf of Carpentaria, W of Weipa, 12°42' S 141°31'E, dead, 18 m (1 v, C.107106); GBR, near Cape Sidmouth, off Bow Reef, 13°20' S 143°40'E, dead, 19 m (2 v, C.002577); Gulf of Carpentaria, W of Holroyd River, 14°10'S 141°13'E, alive, 24 m (3 pr, C.109331); Gulf of Carpentaria, NW of Edward River, 14°31'S 141°19'E, dead, 18 m (1 pr, C.114116);GBR, 0.5 ml W of North Direction Isle, 14°45'S 145°30'E,dead, 36.5 m (1 v, C.093039); Gulf of Carpentaria, W of Edward River, 14°46'S 141°20'E, dead, 18 m (1 v, C.338471); off Cape Flattery, Decapolis Reef, 14°50'S 145°17'E, dead, 12–14 m (1 v, C.133561); Gulf of Carpentaria, W of Mitchell River, 15°09'S 141°09'E, dead, 22 m (1 v, C.111583); Gulf of Carpentaria, W of Mitchell River, 15°10'S 141°06'E, dead, 24 m (1 v, C.109308); between Cairns & Endeavour Reefs, 15°45'S 145°35'E, dead, 37 m (5 v, C.044613); E Gulf of Carpentaria, W of Nassau River, 15°89.2' S 141°23'E, alive, 11 m (1 pr,C.121126);Weary Bay, 15°54'S 145°23'E,dead, 15 m (1 v,C.029722); GBR, S of Cooktown, 16°01'S 145°29'E, alive, 20 m (4 pr + 1 v, C.130394); Gove Peninsula,Nhulunbuy town beach (1 v,C.133266);E Gulf of Carpentaria,SW of Nassau River, 16°06'S 140°44' E, alive, 22 m (1 pr, C.110629); SW of Nassau River, 16°08'S 140°52' E, alive, 18 m (1 pr, C.338851); GBR, Penguin Channel, 16°15'S 145°31'E, dead, 18–28.5 m (1 v, C.089680); 1.5 ml NW of Low Isles, 16°22'S 145°33'E, dead, 20 m (1 v, C.093041); Low Isles, 16°23'S 145°34'E, dead, 16–22 m (12 v, C.100703; 1 v, C.161019 [in part]; 1 v, C.338463); SE Gulf of Carpentaria, W of Staaten River, 16°25'S 140°17'E, alive, 25.6 m (5 pr, C.108355); inside Wentworth Reef, 16°31'S 145°31'E, alive, 13 m (1 pr, C.093040); Michaelmas Cay, 16°36'S 145°59'E, alive (1 pr, C.338474); SE Gulf of Carpentaria, W of Gilbert River, 16°41'S 140°09'E, alive, 18.3 m (2 pr, C.110625); off Cairns, 16°51'– 16°51'S 146°01'– 146°04'E, dead, 33–35 m (1 v, C.338464); Cairns Harbour, 16°53'S 145°48'E, dead (1 v, C.338486); Gulf of Carpentaria, 28 mls S of Sweers Island, 17°06'S 139°37'E, dead (2 v, C.338479); Figure 47. A, C, Annachlamys kuhnholtzi (Bernardi) , pair, AM C.064359, off Burnett Heads, QLD, 46 m; lv exterior (A), rv interior (C). B, Ylistrum balloti (Bernardi) , rv of pair, AM C.303800, trawled off North West Island, Capricorn Group, GBR, QLD; rv interior. D, E, Annachlamys flabellata (Lamarck) , pair, AM C.069985, Rodds Harbour, Port Curtis, QLD; rv interior (D), lv exterior (E). F, Amusium pleuronectes (Linnaeus) , specimen in Fig. 45B–D; rv interior. Scale bars represent 30 mm (A, C–F), 50 mm (B).

SE Gulf of Carpentaria, W of Fitzmaurice Point, 17°12'S 140°15' E, alive, 11 m (1 pr, C.107439); Gulf of Carpentaria, Karumba, 17°29'S 140°50'E, dead (18 v, C.338468); GBR, off Cardwell, 18°30'S 146°54'E, alive, 59 m (1 pr, C.337124); off Cardwell, 18°30'S 147°12'E, alive, 45 m (1 pr,C.337125); Palm Islands , 18°40'S 146°33'E, dead, 27 m (9 v, C.010260; 8 v, C.010261); off Palm Islands , 18°44'S 146°31'E, alive, 20 m (3 pr, C.338853); Great Palm Island, Challenger Bay, 18°44'S 146°34'E, dead, 12 m (1 v, C.338487); off Ingham, 19°03'S 148°07'E,alive, 65 m (1 pr,C.337123);Townsville, Magnetic Island, 19°08'S 146°50'E, alive (1 pr, C.097586); S of Townsville, 19°17'S 147°32'E, alive, 24 m (7 pr,C.123886); off Bowen, 19°44'S 148°14'E, dead, 40 m (4 v, C.119573);E of Bowen, 19°45'S 148°19'E,dead, 46 m (many,C.120872);N of Bowen, off Abbot Point, 19°53'S 148°05'E, alive, 7–23.5 m (1 pr, C.308869; 1 pr, C.308870; 1 pr, C.308871; 1 pr, C.308872; 1 pr, C.308873; 1 pr, C.308874; 1 pr, C.308875; 1 pr, C.308876; 1 pr, C.308877; 1 pr, C.308878; 4 pr, C.308879; 1 pr, C.308880; 1 pr, C.308881; 2 pr, C.308882; 3 pr, C.308883; 1 pr, C.308884; 1 pr, C.308885; 2 pr, C.308886; 4 pr, C.308887; 3 pr, C.308888; 1 pr, C.308889; 2 pr, C.338871; 2 pr, C.338872; 4 pr,C.338873);W of Hayman Island, 20°03'S 148°50'E, dead, 33 m (many v,C.120137);Bowen Harbour (Port Denison), 20°04' S 148°22'E,alive (2 pr,C.080051); Gloucester Passage, 20°04'S 148°28'E, dead (1 pr, C.012174); Whitsunday Passage, 20°13'S 148°47'E, dead, 24 m (9 v, C.119601); Whitsunday Islands , Lindeman Island, 20°45'S 149°03.3'E, dead (2 v, C.058935); Whitsunday Passage, off Lindeman Island, 20°27'S 149°02'E, dead (1 pr, C.133264); N of Mackay, off Shaw Island, 20°29'S 149°05'E, alive, 37 m (4 pr, C.338833);Whitsunday Passage, 20°32'S 149°01'E, dead, 27 m (15 v,C.338485);Repulse Bay, off The Brothers Islands , 20°47'S 148°53'E,alive, 15 m (1 pr, C.093042); E of Mackay, 20°52'S 149°29'E, dead, 35 m (1 v, C.338481); N of Mackay, Seaforth, 20°54'S 148°58'E, dead (1 v, C.133265); E of Sarina, 21°27' S 150°08'E, alive, 42 m (1 pr, C.119589); E of Sarina, 21°28'S 150°08'E, dead, 40 m (15 v,C.338480); Swain Reefs, 3 km NE of W side of Gillett Cay, 21°42'S 152°26'E,dead, 64–73 m (2 v, C.338483); SE of Sarina, 21°47'S 150°34'E, alive, 59 m (3 pr + 1 v, C.116483);W of Swain Reefs, 22°0'S 151°30'E,alive, 73 m (3 pr,C.097584);Capricorn Channel, 22°30'– 24°0'S 152°0' – 153°0'E, dead (5 v, C.303799); 30 mls NE of Yeppon, 22°50' S 151°11'E,dead, 46–55 m (21 v,C.073927);E of Keppel Islands , 23°0'S – 23°12'S 151°10' E – 151°20'E,alive, 46–49 m (5 pr,C.338870);Keppel Bay, North Keppel Island, 23°04'S 150°54'E, alive, 7 m (1 pr, C.338869); Capricorn Channel, E of North West Island, 23°15'S 152°24'E, dead, 284 m (1 v, C.119622). NEW SOUTH WALES: off Newcastle, 32°56'S 151°57' E, alive, 73–82 m (3 pr + 1 v, C.093038). NORTHERN TERRITORY: SE of Darwin, Tree Point, 14°01'S 129°36'E, dead (7 v, C.108739; pr, C.338475); Port Darwin, 12°28' S 130°50'E, dead (8 v, C.011349); Port Darwin, off Rail Pier, 12°28'S 130°50'E, dead (1 v, C.057350); Port Darwin, 12°28'S 130°50' E, alive, 10 m (1 pr, C.097587); Darwin, Casuarina Beach , 12°21'S 130°52' E, dead (3 v, C.060728);Arafura Sea, c. 110 mls N of Melville Island, 9°34'S 131°22'E, dead, 135 m (1 v, C.338489); Arafura Sea, 11°01'S 132°03'E, alive, 32–33 m (7 pr, C.338836); Cobourg Peninsula,off Port Essington, 11°02'S 132°04'E,alive, 31 m (many,C.077848); off Cobourg Peninsula, 11°16'S 132°09'E,alive(4 pr,C.084729);Arafura Sea,c. 45 mls N Croker Island, 10°17' S 132°38'E,dead, 65 m (many v,C.078866);Arafura Sea, 160 km N of Goulburn Island, 10°08'S 133°05'E,dead, 73 m (2 v,C.338484);Arafura Sea, 91 km N of Goulburn Island, 10°42'S 133°36'E,dead, 58 m (1 v,C.096291);Arafura Sea, 11°24'S 134°54'E,dead, 38–40 m (1 pr,C.126514);Gulf of Carpentaria,Groote Eylandt, 14°0'S 136°25'E, (1 v, dead, C.092402; 1 pr, alive, C.338476); N of Arnhem Land, 10°50'S 137°10'E, dead, 59 m (1 v, C.338488); N of Arnhem Land, 9°49' S 137°12' E, dead (1 v, C.338482).— INDIA:off Kilakarai, Tamilnadu, alive, 35 m (2 pr, ZMA Moll.143647). — THAILAND:S of Phuket,alive, 30–50 m (7 pr, ZMA Moll.143677).— JAPAN:Tosa Bay,Shikoku,alive, 73 m (2 pr, ZMA Moll.144272).— CHINA:Beibu Gulf,alive, 10–80 m (2 pr, ZMA Moll.145735). — VIETNAM: off Nha Trang, Hon Noi Island, alive, 65 m (3 pr, ZMA Moll.145833).— INDONESIA:Makassar Strait, 1°11'S 107°06'E,alive, 21 m (1 pr, ZMA Moll.141780); S Sumatera, Kuala Mesudji, Lampung, alive, 15 m (2 pr, ZMA Moll.143728).— PAPUA NEW GUINEA: Gulf of Papua, 1.5 ml SW of Yule Island, 8°51'S 146°30'E, dead, 22–23 m (10 v,C.338466); Gulf of Papua, Caution Bay, 9°20'S 146°57' E, alive (2 pr, C.093035); off Port Moresby, Manubada [Local] Island, 9°31'S 147°10'E, dead, 23 m (3 v, C.096418); off Port Moresby, Manubada [Local] Island, 9°31'S 147°10'E, dead, 18–22 m (1 v, C.338465). — SOLOMON ISLANDS : Russell Island, alive, 35 m (1 pr, ZMA Moll.141111).

Description. Shell (sub)circular, up to c. 100 mm high, most specimens smaller; rather thin, weakly inflated, right valve slightly more convex than left, gaping at anterior and posterior margins, somewhat higher (dorso-ventrally) than wide in adult stage, inequivalve, equilateral; auricles small, equal in size, umbonal angle c. 120°. Left valve variable in colour, cream, pinkish or brownish with variable bluish or reddish radial lines and intermediate minute paler and darker dots; right valve and interior of most specimens white. Outer surface of both valves smooth and glossy, inner surface with 20–34 rib carinae, clearly arranged in pairs. Dorsal margin straight, byssal notch shallow, ctenolium lacking in adult stage.

Dimensions. Illustrated specimen: QLD, W of Nassau River, E Gulf of Carpentaria , trawled 11 m ( AM C.121126): rv: H 60.2, L 59.8 mm; lv: H 59.9, L 59.2 mm; D 12.6 mm .

Habitat. Living free in shallow water on clean sand with silt and shell rubble, partially buried.

Distribution. Recorded throughout the western and southwestern Pacific, from southern Japan southwards to northern and northeastern Australia (as far south as northern New South Wales), westwards to southern India and eastwards to the Solomon Islands (Raines & Poppe, 2006: 138); Philippines, 26–160 m (Dijkstra, 2013: 51). Maximum depth range of live-taken specimens is 7– 160 m. Present specimens from Australia alive at 7– 82 m.

Remarks. Morton (1980) observed that specimens of Amusium pleuronectes swim with an average speed of 37–45 cm s-1. He suggested that swimming is not a response to predation, but apparently related to a seasonal migration, possibly linked to reproduction. However, Brand (2016: 502) stated that “Scallops swim primarily to escape predators”, and it is likely that both predator avoidance and seasonal migrations occur in A. pleuronectes . Swimming in scallops was described in detail by Guderley & Tremblay (2016), summarising a huge amount of research in this field. This phenomenon was also observed in A. pleuronectes by Rumphius (1705). Del Norte (1988) reported that the major spawning season for the Lingayen Gulf (northern Philippine Islands ) is in February and another minor one takes place from July to September.