Propeamussium investigatoris

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 10.3853/j.2201-4349.70.2018.1670

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Propeamussium investigatoris


Propeamussium investigatoris   (E. A. Smith, 1906)

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)   .–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.


Natural History Museum, London


Universiteit van Amsterdam, Zoologisch Museum


Queensland Museum


Hastings Museum














Propeamussium investigatoris

Dijkstra, Henk H. & Beu, Alan G. 2018

Amussium investigatoris

Smith, E 1906: 255