Juxtamusium Iredale, 1939
IREDALE, T. 1939. Mollusca. Part 1. In: Great Barrier Reef Expedition 1928-29, B.M.(N.H.), Scientific Reports, 5 (6): 209-425, pls. 1-7. [p. 368]
«Genus Juxtamusium nov.
Type: J. oblectatum sp. nov. (Plate V, figs. 27, 27a.)
Smith ('Fauna Maldive and Laccadive Arch.' II, p. 622, pl. xxvi, figs. 19, 20, 1904) described a Pecten maldivensis which Hedley added to the Queensland list. Hedley's species is here described as new, and the characters are much nearer those of Amusium than of Pecten, and therefore a new generic name is proposed.
Shell subcircular, thin, compressed, equivalve, almost equilateral, gaping a little at sides, ears large, unequal. The surface is finely striate radially on the right va1ve, which is coloured, but completely overridden by very flne, closely-set, concentric striae; the left valve is uniformly pale and the radials are practically obsolete, while the concentric striae are microscopic. Internally the edge is closely ribbed, but the ribs do not extend far into the valve. Hinge folded, but striae missing, the ligamental groove triangular, but the ligament itself linear. The type from Station XVI measures 22.5 mm. in height and 22 mm. in breadth, the depth of the conjoined valves being only 6 mm.» TOM IREDALE, 1939
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Juxtamusium oblectatum sp. nov.; T. Iredale, 1939, Mollusca, Great Barrier Reef Expedition 1928-29, plate 5, figures 27, 27a.
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Juxtamusium coudeini (Bavay); H. H. Dijkstra & A. G. Beu, 2018, Living scallops of Australia and adjacent waters, figures 40B, 40D, 40F, 40H, 40K.
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«Juxtamusium Iredale, 1939
Juxtamusium Iredale, 1939: 368. Type species (by original designation): Juxtamusium oblectatum Iredale, 1939 (= Pecten (Chlamys) coudeini Bavay, 1903); Recent, 0.5 miles W of North Direction Isle, QLD, in 20 fathoms [37 m].
Diagnosis. Small, thin-shelled, subcircular to circular Decatopectinini with depressed, unevenly to evenly spaced, low radial costae; narrowly spaced, delicate commarginal microsculpture throughout ontogeny; resilifer oblique, strongly erect on one side, strong internal hinge ligament, hinge plate very flat, lacking crura or denticles; ctenolium on both valves (see Waller, 1984: 211), byssal notch shallow.
Distribution. Early Miocene–Recent [Juxtamusium pseudojamviniensis (Eames & Cox, 1956: 41), early Miocene, Zanzibar; Waller (2006a) agreed that this belongs in Juxtamusium]. Tropical Indo-West Pacific, living in the littoral to sublittoral zones amongst coral rubble on soft sediment.
Discussion. Hertlein (1969: N357) treated Juxtamusium as a subgenus of Chlamys Röding, 1798 in the Chlamys group. Waller (1986: 40) raised Juxtamusium to a genus in Decatopectinini.»
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. 197]
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