Chlamydella favus (Hedley, 1902)
HEDLEY, C. 1902. Scientific results of the trawling expedition of H.M.C.S. Thetis off the coast of New South Wales in Febr./March 1898. Part I. Brachiopoda and Pelecypoda. Australian Museum Memoir, 4: 287-324 [p. 305, fig. 50]
1902 Cyclopecten favus Hedley, 1902
1902 Cyclopecten obliquus Hedley, 1902
1902 Cyclopecten obliquus Hedley, 1902
Cyclochlamys favus (Hedley, 2002) comb. nov.; H. H. Dijkstra, 1995, Bathyal Pectinoidea (Bivalvia: Propeamussiidae, Entoliidae, Pectinidae) from New Caledonia and adjacent areas, figures 87-90.
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«Valves dissimilar in shape, size and sculpture. The left larger and more convex, thin, opaque white in the centre, transparent at the periphery, smooth except for a few delicate concentric growth lines. Hinge line straight, about two-thirds of the length of the valve; auricles nearly equal, latticed by radiating and concentric threads. Umbo projecting, with a callus crest. Ventral margin rounded, produced posteriorly. Hinge plate narrow, finely wrinkled. Chondrophore small, projecting into the cavity of the valve.
Right valve smaller, overlapped ventrally by its fellow, less oblique, pale yellow, opaque. Umbo not projecting, auricles unequal, the anterior narrow and produced. Beneath it a byssal notch, but no pectinated teeth. Sculptured by concentric growth lines and superficially by numerous fine, irregular, radiating threads, connected by close-set transverse bars which include narrow hexagonal spaces. This structure is seen to peel off in places, and is, therefore, probably epidermial, and perhaps corresponds to the pustules of the Atlantic species. Left valve, length, 3.2 mm.; height, 2.7 mm.
Right valve, length, 2.6 mm.; height, 2.5 mm. The species is referred to Verrill's genus Cyclopecten,* one member of which, C. murrayi, Smith,+ has already been reported from Australia. This and the next are readily distinguishable from co-generic forms by their obliquity and the honeycomb structure of the right valve. A couple of perfect shells and numerous separate valves were taken off Port Kembla in 63-75 fathoms, and off Cape Three Points in 41-50 fathoms. The Museum contains specimens which Mrs. Helena Forde collected on the beach at Pambula, N.S.W.» * Verrill — Trans. Connect. Acad., x., 1899, p. 70.
+ Smith — Chall. Rep., Zool., xiii., 1885, p. 303, pl. xxii., f. 1. CHARLES HEDLEY, 1902
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«Description. Shell small, fragile, up to c. 3 mm high, hyaline or opaque, valves dissimilar in shape, size and sculpture; prodissoconch of both valves similar, c. 245 μm in width, 135 μm in height (Dijkstra, 1995b: figs 87–88; Figs 21C, 23A), evenly and weakly convex, sculptured with many low, narrow, weakly defined radial ridgelets; contrasting strongly with that of Cyclochlamys nepeanensis in sculpture and in lack of central projection on left valve.
Left valve slightly larger and more convex than right valve, smooth except for a few minute commarginal growth lines (typical var.) or with more prominent commarginal lirae (var. obliqua); auricles almost equal, with some commarginal lines. Outer ligament insertion with small holes near resilifer (Dijkstra, 1995b: fig. 89). Right valve smooth apart from faint hexagonal microsculpture (Dijkstra, 1995b: fig. 90). Anterior auricle with closely spaced commarginal lamellae. Byssal notch well developed. Habitat. Living in the littoral zone (amongst algae) and in the bathyal zone amongst rubble on soft sediment (sand and mud).
Distribution. New Caledonia, 305–610 m (Dijkstra, 1995b); Fiji, 135–151 m (Dijkstra & Maestrati, 2008). Present material from Papua New Guinea (beached, dead) and Australia (northeastern Queensland southwards to New South Wales, Victoria and Tasmania, and westwards to South Australia and Western Australia up to Broome) (3–1000 m, alive).
Remarks. Chlamydella favus is variable in shape (almost circular to posteriorly oblique) and extremely variable in sculpture on the left valve (almost smooth to prominent commarginal, weak radial or reticulate sculpture, or intermediate variations). The specific epithet “favus” is an indeclinable noun (Latin, honeycomb), selected by Hedley (1902: 306) because of the hexagonal structure of the surface of the right valve.»
DIJKSTRA, H. H. & A. G. BEU. 2018. Living scallops of Australia and adjacent waters (Mollusca: Bivalvia: Pectinoidea: Propeamussiidae, Cyclochlamydidae and Pectinidae). Records of the Australian Museum, 70 (2): 113-330, figs. 1-102. [p. 161]
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Chlamydella favus (Hedley); H. H. Dijkstra & A. G. Beu, 2018, Living scallops of australia and adjacent waters, figures 21C, 21F–21L, 23A, 23D.
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