Propeamussium investigatoris (E. A. Smith, 1906 )

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 : 125

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-F815-3648-FF6B-2DE3FC1EF82F
treatment provided by	Felipe
scientific name	Propeamussium investigatoris (E. A. Smith, 1906 )
status

Treatment

Propeamussium investigatoris (E. A. Smith, 1906) View in CoL

Figs 1E,K–M, 3

Amussium investigatoris Smith, 1906: 255 .

Amussium margaritiferum Dautzenberg & Bavay, 1912: 36 , pl. 27, figs 15–18.

Propeamussium maorium (Dell, 1956) View in CoL .–Dijkstra, 1995b: 18, figs 11–14; Dijkstra & Marshall, 1997: 77, pl. 2, figs 1–5 (see also Dijkstra, 2001: 76) (misidentification).

Propeamussium investigatoris (Smith) .–Dijkstra & Kastoro, 1997: 248, figs 11–15; Dijkstra, 2001: 75, figs 1–4; Dijkstra & Marshall, 2008: 2, figs 1, 2A–E; Dijkstra & Maestrati, 2008: 82; Spencer et al., 2009: 198.

Type data. Amussium investigatoris : lectotype (pr) ZSI M835 /1, designated by Dijkstra & Kastoro (1997: 250), 2 paralectotypes (pr) NHMUK 1906.10.12.99–100. Type locality: India, W of Travancore , 08°37'N 75°37'E, alive, 410–519 m ( Investigator stn 248). For comments on type material see Dijkstra & Kastoro (1997: 250) GoogleMaps .

Amussium margaritiferum : holotype (pr) ZMA Moll.3.12. 021. Type locality: Indonesia, Moluccas, channel between Makjan and Halmaheira, 0°23.8'N 127°29'E, alive, 472 m ( Siboga stn 137) GoogleMaps .

Additional material examined. — AUSTRALIA: QUEENSLAND: E of GBR, 17°35'S 146°53' E, alive, 458–500 m (3 pr + 1 v, QM MO18021 ; 1 pr, QM MO17763 [in part]). WESTERN AUSTRALIA: off Barrow Island , 375–400 m, alive in sponges on rubble and mud (1 pr, HM) GoogleMaps [smooth var.];W of Lacepede Islands , approx. 16°55'S 119°52'E, 400–450 m, dredged alive on fine mud (1 pr, HM) GoogleMaps .

Description. Shell up to 25 mm high, fragile, semitranslucent, oval to circular, inequivalve, equilateral, weakly inflated, left valve more convex than right, umbonal angle 100–110°. Prodissoconch c. 220 µm high. Left valve orangetinted, right valve whitish.

Left valve sculptured with many unevenly spaced

Figure 3. Distribution of Propeamussium investigatoris (Smith) (circles), P. sibogai (Dautzenberg & Bavay) (star) and P.watsoni (Smith) (triangles).

radial riblets, squamous in late growth stage. Latticed microsculpture only in early growth stage (up to c. 10 mm in height).Anterior and posterior auricles with 7–10 delicate squamous radial riblets, weaker on right valve.

Right valve with fine, evenly spaced commarginal lamellae. Internal riblets 10 on most specimens, some with 2–4 intercostal rudimentary riblets near the margin and 2 auricular riblets. Dorsal margin straight. Resilifer triangular. Byssal notch and fasciole lacking.

Dimensions. Illustrated specimen, Qld, E of GBR, 17°35'S 146°53'E, alive, 458–500 m (QM MO18021), 2 separate valves: rv: H 16.7, L 16.2; lv: H 18.7, L 16.4 mm; largest lv (incomplete ventral skirt; not illustrated): H 18.9, L 20.1 mm GoogleMaps .

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

Distribution. Northern Indian Ocean, 410–519 m ( Smith, 1906); Indonesian Archipelago, 176–466 m (Dijkstra & Kastoro, 1997); Coral Sea, New Caledonia and Loyalty Islands , 600–960 m [as Propeamussium maorium ] (Dijkstra, 1995b, 2001); Norfolk Island and Kermadec Islands , 512–549 m [as Propeamussium maorium ] (Dijkstra & Marshall, 1997); Vanuatu, 602–650 m (Dijkstra, 2001); New Zealand, as far south as the Bay of Plenty (off Plate I., 37°30'S 176°48'E), 292–621 m, living at 337–585 m (Dijkstra & Marshall, 2008: 2, fig. 1); Solomon Islands , 367–500 m; Fiji, 395–699 m and Tonga: 395–710 m (Dijkstra & Maestrati, 2008). Present material from Australia living at 458– 500 m.

Remarks. The present specimens from Australia differ slightly from the type material in having somewhat finer radial sculpture on the left valve, in lacking the latticed microsculpture in early ontogeny, and by the more whitish colour of the left valve (type material orange-tinted). We are grateful to Gary Rosenberg for pointing out that the name investigatoris is the genetive form of the noun “investigator” and is not declinable.

For comparison with Propeamussium jeffreysii ( Smith, 1885) see Dijkstra & Kastoro (1997: 250).

Propeamussium investigatoris is a new record for Australia.