Delectopecten alcocki (E. A. Smith, 1904)
SMITH, E. A. 1904. Natural History from H.M. Indian Marine Survey Steamer "Investigator", commander T.H. Heming. R.N. - Series III, No. I . On Mollusca from the Bay of Bengal and the Arabian Sea. The Annals and Magazine of Natural History, 14: 1-14. [p. 13]
1904 Pecten alcocki E. A. Smith, 1904
Delectopecten alcocki (E. A. Smith, 1904); H. H. Dijkstra, 1995, Bathyal Pectinoidea from New Caledonia and adjacent areas, figs. 111-114.
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«Testa aequivalvis, aequilateralis, tenuissima, subpellucida, rotundata, seriebus radiantibus et concentricis, numerosis squamarum minutarum ornata, mediocriter convexa, radiatim tenuiter striata; auriculae inaequales, antica valvae dextrae infra profunde sinuata, liris quaternis granosis radiata.
Longit. 18 mm., alt. 19, diam. 7. Hab. Station 232, off South India, 430 fath. The radiating striae have the appearance of short scratches and are closer together down the sides of the valves. The scales which roughen the surface are generally more or less worn off, their position being indicated by the crenulated concentric lines of growth.» EDGAR ALBERT SMITH, 1904
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«Description. — Shell up to c. 15 mm high, 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. Disc also smooth. Auricles identically sculptured, posterior auricle continuous with disc. Hinge line straight. Right valve sculptured as on left valve, although 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 are described by Knudsen (1967: 282). 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: 150-750 m (Knudsen, 1967; Raines, 2010: 594), Japan: 274-1010 m (Higo, Callomon & Goto, 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). Present specimens from the Philippines alive at 80-810 m (minimum depth range). The bathymetric range of live-taken specimens is now extented to 80-1079 m. Living on soft bottom assemblages of sediments (mud and/or sand). Remarks. — The present specimens from the Philippines are identical in all morphological characters to the type material. Specimens are strongly variable in sculpture from nearly smooth to prominent sculptured.» DIJKSTRA, H. H. 2013. Pectinoidea (Bivalvia: Propeamussiidae and Pectinidae) from the Panglao region, Philippine Islands. Vita Malacologica, 10: 1-108, pls. 1-32. [p. 25]
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Delectopecten alcocki (E. A. Smith, 1904); H. H. Dijkstra, 2013, Pectinoidea from the Panglao region, Philippine Islands, plate 2, figures 1a-1d.
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«Distribution and ecology.— Throughout the (south)western Pacific and the Indian Ocean. Living on muddy or sandy sand bottoms and often byssally attached to silicious sponges. Bathymétrie range from sublittoral to bathyal depth.
Remarks.— The present specimen corresponds very well with the type material of D. alcocki from off South India, although no radial scratches are observed on the external surface of the valves (mentioned by Smith, 1904) (ZSI M669/1, holotype; M667-668,670-698/1, paratypes).» DIJKSTRA, H. H. 1991. A contribution to the knowledge of the pectinacean Mollusca (Bivalvia: Propeamussiidae, Entoliidae, Pectinidae) from the Indonesian Archipelago. Zoologische Verhandelingen, 271: 1-57, figs. 1-91. [p. 26]
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Delectopecten alcocki (E. A. Smith, 1904); H. H. Dijkstra, 1991, A contribution to the knowledge of the pectinacean Mollusca from the Indonesian Archipelago, figure 87.
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