Propeamussium watsoni (E. A. Smith, 1885 )

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 : 128

publication ID	https://doi.org/ 10.3853/j.2201-4349.70.2018.1670
publication LSID	lsid:zoobank.org:pub:8084C----
persistent identifier	https://treatment.plazi.org/id/039A87AD-F816-364B-FF5D-2F95FA2CFCD1
treatment provided by	Felipe
scientific name	Propeamussium watsoni (E. A. Smith, 1885 )
status

Treatment

Propeamussium watsoni (E. A. Smith, 1885) View in CoL

Figs 3, 4A–C,F

Amussium watsoni Smith, 1885: 309 , pl. 22, figs 8–8c; Clarke, 1962: 61; Knudsen, 1967: 280, pl. 1, fig. 18.

Amussium alcocki Smith.– Thiele & Jaeckel, 1931: 8 (misidentification) .

Propeamussium watsoni bayonnaisense Okutani, 1962: 15 View in CoL , pl. 2, figs 1–2; Okutani, 1966: 8.

Propeamussium watsoni (Smith) View in CoL .– Kiseleva, 1971: 221;Abbott & Dance, 1982: 303, fig.; Hayami, 1988b: 476, figs 2–6; Dijkstra, 1995b: 24, figs 27–30, 123–124 [lectotype]; Hayami, 2000: 913, pl. 454, fig. 5; Dijkstra & Maestrati, 2010: 334; Dijkstra & Maestrati, 2013a: 362; Dijkstra & Maestrati, 2013b: 470; Dijkstra & Maestrati, 2015: 595, figs 1K–L.

Type data. Amussium watsoni Smith: lectotype (pr) NHMUK 1887.2.9.3307, designated by Dijkstra (1995b: 24), 2 paralectotypes (pr) NHMUK 1887.2.9.3308/1–2. Type locality: NE of New Guinea, 2°23'S 144°04'E, alive, 1957 m (Challenger stn 218) GoogleMaps .

Propeamussium watsoni bayonnaisense Okutani : holotype (pr) NSMT Mo.62759, 3 + 3 v + fragments, paratypes NSMT Mo.62760. Type locality: Japan, 24 miles off Bayonnaise Rocks GoogleMaps , 32°00.0'N 140°21.4'E, alive, 2140–2160 m.

Additional material examined. — AUSTRALIA: QUEENSLAND: ENE of Cape York Peninsula , 10°34.28'S 144°13.33' E,alive, 815–825 m (5 pr,C.165216); E of Cape York Peninsula, 10°37.17' S 144°21.99'E, alive, 990–1053 m (2 pr, C.165217) GoogleMaps . NEW SOUTH WALES: off Broken Bay , 33°30'– 33°34'S 152°08' – 152°11'E,alive, 875 m (1 pr [var.], C.165223). TASMAN SEA:Lord Howe Rise, 28°05.76'S 163°06.04' E, alive, 1051 m (1 pr, C.165411) GoogleMaps .

Description. Shell up to c. 60 mm high, inequivalve, almost circular, slightly higher than wide, somewhat inequilateral, umbonal angle c. 125°. Prodissoconch c. 240 µm high. Opaque, left valve milky-white, right valve cream.

Left valve more convex than right valve, with commarginal lamellae near ventral margin and delicate radial lirae that commence at c. 3 mm shell length and extend to central part of disc; lamellae and lirae variable. Auricles equal, commarginal lamellae prominent on anterior, finer and more closely arranged on posterior. Most specimens with 10 internal riblets and a small auricular riblet on each side, commencing just below resilifer and extending to pallial line.

Right valve with fine regular commarginal lirae and granulate interstitial microsculpture (prismatic calcite layer). Auricles with commarginal lirae, anterior auricle with a few radial lines near suture, absent from posterior auricle. Prominent scales on anterior and posterior dorsal margins of auricles. Resilifer triangular, erect. No byssal notch.

Dimensions. Illustrated specimen, AM C.165216, QLD, ENE of Cape York Peninsula, 815–825 m; rv, ventral skirt broken off: H 31.1, L 31.9 mm; lv: H 43.4, L 41.8 mm; D 6.3 mm .

Habitat. Living in the bathyal and abyssal zones, free on soft sediment (muddy sand or mud).

Distribution. Gulf of Aden, 1469 m (Thiele & Jaeckel, 1931); Arabian Sea, 1354 m; Zanzibar area, E Africa, 914 m ( Knudsen, 1967), now extended to northwestern and southern Madagascar, 780–821 m (Dijkstra & Maestrati, 2015); Laccadive Sea, 1337–1410; Bay of Bengal, 1026 m; and NE of Irian Jaya, Indonesia, 1958 m ( Smith, 1885); Strait of Malacca, 1140 m ( Knudsen, 1967: 281); Philippine Islands , 1800–1950 m (Dijkstra, 1995b); Japan, 2020–2160 m [as P. watsoni bayonnaisense ] ( Okutani, 1962, 1966); Chesterfield Islands , Coral Sea, 650–970 m; New Caledonia, 825–1500 m; Loyalty Islands , 780–800 m (Dijkstra, 1995b, 2001); Vanuatu, 980–990 m (Dijkstra, 2001); Austral Islands , 900–1300 m, dead (Dijkstra & Maestrati, 2010). The maximum depth range of live-taken specimens is 815–2160 m. Present material from Australia living at 815–1053 m.

Remarks. Knudsen (1967: 281) considered Propeamussium watsoni bayonnaisense to be part of the variation of P. watsoni . Examined material from Australia is morphologically similar to the type specimens from NE Indonesia, although the radial sculpture of the left valve is more delicate, but the sculpture is rather variable in development in this species.

Propeamussium watsoni is a new record for Australia.