Parvamussium vesiculatum Dijkstra, 1995

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 : 146

Parvamussium vesiculatum Dijkstra, 1995

Figs 14C,F–I

Parvamussium vesiculatum Dijkstra, 1995b: 37 , figs 59–62, 93–96; Dijkstra & Kastoro, 1997: 265, figs 95–98; Dijkstra & Marshall, 1997: 83, pl. 4, figs 11–16; Dijkstra, 2001: 87; Dijkstra & Marshall, 2008: 12, figs 10F–I, 11; Dijkstra & Maestrati, 2008: 96; Dijkstra & Maestrati, 2009: 43, pl. 3, figs 22–24; Spencer et al., 2009: 198; Dijkstra, 2011: 44, pl. 1017, figs 1a–b; Dijkstra & Maestrati, 2015: 613, figs 5G–I.

Type data. Holotype (pr) MNHN Moll 21167; paratypes (36 pr + 27 v): 2 AM C.201715, 12 ZMA Moll.395030, 43 MNHN Moll 21168, 2 NMNZ M.268538, 2 NSMT-Mo70542, 2 USNM890874. Type locality: SE New Caledonia, 22°47'S 167°14'E, alive, 440–450 m (BIOCAL stn DW 44).

Extralimital material examined. — NEW CALEDONIA: 4 ml S of Isle des Pins , 22°50'S 167°34'E, alive, 275 m (1 pr, C.165236; 1 pr, C.165442 [in part]). CORAL SEA: Gifford Guyot, 26°45.27'S 159°30.59'E, alive, 315–360 m (2 pr, C.165414; 1 pr, C.165415). TASMAN SEA: Derwent Hunter Seamount, 30°48.18'S 156°13.27'E, alive, 288 m (1 pr,C.165244);Taupo Seamount, 33°16.85'S 156°09.15'E, alive, 244 m (1 pr, C.165242) .

Description. Shell up to c. 8.6 mm high, fragile, semitranslucent white, almost circular, inequivalve, inequilateral, left valve slightly more convex than right, auricles unequal in size, umbonal angle c. 95°. Inner surface with rudimentary riblets anteriorly and posteriorly, also weak on auricles.

Left valve sculptured with widely spaced commarginal lirae with strongly developed, radially arranged nodules or hollow scales. Unevenly spaced radial riblets between commarginal lirae. Auricles with commarginal lamellae, prominent on anterior, slightly closer on posterior. Dorsal margin straight.

Right valve with evenly spaced commarginal lirae, weak near umbonal region. Prodissoconch pellucid. Anterior auricle with 4 delicate radial riblets with commarginal lamellae continuing over them uninterrupted, developed into scales on dorsal margin. Byssal notch shallow, byssal fasciole narrow.

Habitat. Living in the upper bathyal zone, free on soft sediment (sand and mud).

Distribution. Taiwan, 442 m (Dijkstra & Maestrati, 2009: 43); Philippines, 280 m (Dijkstra, 2011); Eastern Indonesia, 205–212 m (Dijkstra & Kastoro, 1997); New Caledonia, 260–650 m; Norfolk Ridge, 470 m; Loyalty Islands , 310 m, dead; Wallis and Futuna Islands , 400–600 m; and Vanuatu, 291–300 m (Dijkstra, 1995b; 2001); Norfolk Ridge, 470 m (Dijkstra & Marshall, 1997); New Zealand: 5 lots from Wanganella Bank, W Norfolk Ridge (32°10.5'S 167°21.2'E, 442–449 m, 12 v, NIWA P13) to Kermadec Ridge, W of Cape Reinga and Three Kings Trough, NW of Three Kings Islands (34°0'S 171°55'E, 805 m, 1 v, NMNZ M.107605), 205–650 m (Dijkstra & Marshall, 2008: 12, fig. 11); Fiji, 327–420 m (dead); Tonga, 327–418 m (dead); Solomon Islands , 396–411 m, dead) (Dijkstra & Maestrati, 2008). Now also extended westwards into the Indian Ocean from northwestern and southern Madagascar, 200–220 m (Dijkstra & Maestrati, 2015). The maximum depth range of live-taken specimens is 205– 650 m. Now also from the Coral Sea (315–360 m) and Tasman Sea (244–288 m).

Remarks. Parvamussium vesiculatum is not recorded from the continental shelf of Australia, but lives in the Coral Sea and Tasman Sea.