Parvamussium pauciliratum (E.A. Smith , 1903 )

Parvamussium pauciliratum (E.A. Smith, 1903) View in CoL

Figs 8G,J, 9

Amussium paucilirata [sic] Smith, 1903: 622, pl. 36, figs 23–24.

Parvamussium pauciliratum ( Smith) View in CoL .–Dijkstra, 1991: 14, figs 33–34; Dijkstra, 1995b: 26, figs 107–110, 151–152; Dijkstra & Kastoro, 1997: 261, figs 73–74; Dijkstra, 1998a: 12, pl. 1, figs 1–2; Dijkstra & Maestrati, 2008: 92; Dijkstra & Moolenbeek, 2008: 16; Xu & Zhang, 2008: 78, fig. 215; Huber, 2010: 224; Dijkstra, 2011: 42, pl. 1016, figs 2, 3a–b, 4; Dijkstra, 2013: 19, pl. 3, figs 1–1d, pl. 4, fig. 9.

Type data. Lectotype (pr) designated by Dijkstra (1995b: 28) NHMUK 1903.9.17.17, 2 paralectotypes (pr) NHMUK 1903.9.17.18/1–2. Type locality: Maldive Islands , S Nilandu Atoll, alive, 2–66 m.

Comments on type data. Although the original registration number indicated 4 specimens, only 3 types are now present in NHMUK .

Figure 9. Distribution of Parvamussium multiliratum Dijkstra (circles), P. pauciliratum ( Smith) (stars), P.retiolum Dijkstra (triangles) and P.scitulum ( Smith) (squares).

Additional material examined. — AUSTRALIA: QUEENSLAND: NE of Cairns ,16°33'54"– 16°33' 48"S 146°09'42"– 146°09'36"E GoogleMaps , dead, 55 m (3 v, C.157659; 2 v, C.157660, in part); SE of Swain Reefs , 22°31.4'S 152°32.6'E GoogleMaps , dead, 100 m (3 v, C.157661,in part).— INDONESIA: Ceram, Piru Bay , 3°10'S 128°08'E,(2 v,C.338458) GoogleMaps . — PAPUA NEW GUINEA: Port Moresby, Fairfax Harbour, 0.5 ml off Wharf , 9°26'S 147°06'E GoogleMaps ,dead, 15–18 m (1 v,C.165515);off Port Moresby,W end of Manubada Island , 9°31'S 147°10'E GoogleMaps , alive, 18–22 m (many v, C.165513); off Port Moresby, on sheltered NW side of Manubada Island , 9°31'S 147°10'E GoogleMaps , dead, 23 m (many v,C.165514); Rabaul Harbour, Matupi Island , 4°14'S 152°12' E GoogleMaps , dead, beach grit (1 v, C.338459).

Description. Shell fragile, small, up to c. 8 mm high, hyaline or opaque, sub-orbircular, inequivalve, right valve more convex than left, slightly inequilateral, auricles almost equal, umbonal angle c. 105°, prodissoconch c. 200 µm in height. Left valve creamy-white stained with white dots, right valve uniform white.

Left valve glossy, with a few minute growth lines, covered with microscopic granules. Auricles smooth on most specimens; a few have delicate commarginal lirae near anterior margin.

Right valve also glossy, smooth apart from microscopic granules. Anterior auricle with minute commarginal lirae. Dorsal margin straight. Internal riblets rudimentary, 1 or 2, with a small auricular lira on each side in most specimens. Resilifer triangular. Byssal notch very narrow.

Habitat. Living as shallow as 2 m in the littoral zone and on the continental shelf, free on soft sediment (sand and coral rubble, muddy sand or mud).

Distribution. Maldive Islands , 2–66 m ( Smith, 1903); Indonesia, 34–467 m (dead) (Dijkstra, 1991; Dijkstra & Kastoro, 1997); Philippines, 32–82 m (Dijkstra, 2011, 2013); Papua New Guinea, 48–125 m (Dijkstra, 1998a); Chesterfield Islands , Coral Sea, 150–225 m (dead); New Caledonia, 27–45 m (Dijkstra, 1995b); Solomon Islands , 509–522 m (Dijkstra & Maestrati, 2008). Present material taken alive from southern Papua New Guinea at 18– 22 m. Maximum depth range of live-taken specimens is 2– 522 m. Present material from Australia ( Queensland) taken only dead at 55– 100 m.

Remarks. The present specimens are identical to the type specimens from the Maldive Islands (Indian Ocean).

Parvamussium pauciliratum is a new record forAustralia.