Delectopecten alcocki (E. A. Smith, 1904 )

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 : 167

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-F82F-3672-FF1F-2A15FA39F923
treatment provided by	Felipe
scientific name	Delectopecten alcocki (E. A. Smith, 1904 )
status

Treatment

Delectopecten alcocki (E. A. Smith, 1904) View in CoL

Figs 24, 25A,C–E

Pecten alcocki Smith, 1904: 13 View in CoL ; Alcock et al., 1907: pl. 18, fig. 4–4b; Knudsen, 1967: 282, pl. 2, figs 3–4, textfig. 19.

Pecten (Pseudamussium) alcocki View in CoL Smith.– Thiele & Jaeckel, 1931: 6 .

Propeamussium (Hyalopecten) alcocki (Smith) View in CoL .– Winckworth, 1940: 26.

Delectopecten alcocki (Smith) View in CoL .– Poutiers, 1981: 331, pl. 1, fig. 1; Dijkstra, 1991: 26, fig. 87; Dijkstra, 1995b: 50, figs 111–114, 147–150 [lectotype]; Dijkstra & Kastoro, 1997: 265, figs 101–108; Dijkstra, 2001: 91; Raines & Poppe, 2006: 56–57, upper figs; pl. 2, figs 3–4, 6, 9; Dijkstra & Maestrati, 2008: 105; Huber, 2010: 213; Raines, 2010: 594, pl. 988, figs 1–2; Dijkstra, 2013: 24, pl. 5, figs 1a–d; Dijkstra & Janssen, 2013: 201, figs 30–31, 54–55.

Type data. Lectotype (pr) ZSI M669 /1 designated by Dijkstra (1995b: 50), 29 paralectotypes (pr) ZSI M667-668 , M670-698 /1. Type locality: off southern India, 7°17'N 76°54'E, alive, 786 m ( Investigator stn 232). GoogleMaps

Comment on type data. Although Smith (1904: 13) indicated the measurements of a type specimen, this specimen was not segregated from the type lot and several other type specimens are of similar size. Therefore, during his visit to the ZSI, Dijkstra (1991: 26) designated a specimen from the type lot as the lectotype, which has identical measurements to those mentioned by Smith in his original description.

Additional material examined. — AUSTRALIA: QUEENSLAND: GBR, Swain Reefs , 23°15'S 153°18'E,alive, 424 m (6 pr, QM MO33657 ) GoogleMaps . WESTERN AUSTRALIA: 200 km NNW of Dampier, 18°53'S 116°10'E, alive, 450 m (1 pr, C.157677); off Lacepede Islands , 16°57'S 119°48'E, 450 m, alive in sponge (1 pr, HM) GoogleMaps [smooth var.]; SE of Cassini Island , 13°56' S 125°38'E, alive, 40–48 m (1 pr, WAM GoogleMaps

S12963 View Materials ); NW of York Sound, approx. 12°48'S 122°56' E, 500 m, dredged alive (1 pr, HM).— PHILIPPINE ISLANDS : Bohol,Balicasag Island, tangle nets, alive, 500–600 m (3 pr, ZMA Moll.146300), 150 m ( Raines,2010).— INDONESIA:Tanimbar Islands , 08°20' S 132°11'E, alive, 399–405 m (1 pr, ZMA Moll.139809). —INDIAN OCEAN: between Port Darwin and Java (Indonesia), byssally attached to submarine cable, alive (1 pr, SAM TD11329). — NEW CALEDONIA: S New Caledonia, 23°02' S 166°57'E, alive, 558–647 m (1 pr, ZMA Moll.146246).

Description. Shell up to c. 19 mm high ( Raines, 2010), circular, hyaline or opaque, whitish, auricles almost equal in size, umbonal angle c. 125°.

Left valve with delicate antimarginal striae over entire disc. Commarginal growth lines crenulated, with radially aligned scales. Auricles identically sculptured, posterior auricle continuous with disc. Dorsal margin straight.

Right valve sculptured as on left valve, athough sculpture somewhat weaker. Anterior auricle separated from disc by suture; bearing 2–4 antimarginal ridges. Byssal fasciole and notch strongly developed. Inactive and active ctenolium (with 3–5 teeth) present. Resilifer triangular. External sculpture barely visible from interior.

Soft parts described by Knudsen (1967: 282).

Habitat. Living on the continental shelf and in the bathyal zone on soft sediment (mud and/or sand).

Distribution. Eastern Africa, 1079 m (Thiele & Jaeckel, 1931); Gulf of Aden, 274–732 m ( Knudsen, 1967); S India, 786 m,?alive ( Smith, 1904); western Sumatra, 614–750 m (Thiele & Jaeckel, 1931); eastern Indonesia, 176–688 m, alive (Dijkstra & Kastoro, 1997); Philippine Islands , 150 m ( Raines, 2010), 710–750 m ( Knudsen, 1967); Japan, 274–1010 m (Higo et al., 1999); Chesterfield Islands , 650–660 m (Dijkstra, 1995b); New Caledonia, 464–647 m (Dijkstra, 2001) and the Solomon Islands , 509–564 m (Dijkstra & Maestrati, 2008). Now also from Australia (Queensland and Western Australia), in 40–450 m (alive). Maximum depth range of live-taken specimens is 40–1010 m.

Remarks. The present specimens from Queensland and Western Australia are identical in all morphological characters to the type material.

Delectopecten alcocki is a new record for Australia.