Juxtamusium maldivense (E. A. Smith, 1903)
SMITH, E. A. 1903. Marine mollusca. In: Gardiner, J.S., ed. The fauna and geography of the Maldive and Laccadive archipelagoes, Volume II, Part II: 589-630, pls. 35, 36. [p. 622, pl. 36, figs. 19, 20]
1903 Pecten maldivense E. A. Smith, 1903
1908 Amussium [sic] scrobiculatum Schepman, 1908
1908 Amussium [sic] scrobiculatum Schepman, 1908
E. A. Smith, 1903, plate 36.
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«Testa compressissima, albida, plus minus roseo radiata et maculata, et maculis albis opacis interdum variegata, tenuissime radiatim striata, lineisque incrementi tenuibus sculpta; valvae subaequales, dextra vix convexiore; auriculae inaequales, posticis paulo majoribus, levibus, anticis costis tenuissimis paucis radiantibus ornatis.
Longit. 17 mm., alt. 19, diam. 3½. Very compressed and usually very finely radiately striated, but sometimes smoother, with less distinct striae. The colour is variable, some specimens are entirely white with only a few colour-spots on the dorsal slopes. Others are dirty whitish, with about seven rather obscure reddish rays and one example has the right valve rayed with red and the left blotched with opaque white and red. All exhibit the red-spotting at the sides of the dorsal slopes.» EDGAR ALBERT SMITH, 1903
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«Description. — Shell up to c. 25 mm high, most specimens c. 15 mm; flattened (left valve almost flat, right valve weakly inflated), thin, circular to ovate, slightly higher than
wide, inequivalve, almost equilateral, auricles unequal in shape and size, umbonal angle c. 85-90˚; cream to pink, with shades of red or brown, and paler and darker blotches, interior purple or reddish, right valve paler. Both valves sculptured with numerous fine, unevenly spaced radial riblets of angular section (with narrow crests), increasing by bifurcation and/or intercalation, and very closely spaced, microscopic commarginal lamellae. Posterior auricle larger than anterior, with c. 3-7 radial riblets, riblets very weak on some specimens. Byssal notch and fasciole weak to almost lacking. Functional left and right ctenolia with a few teeth, lacking from some specimens. Resilifer oblong, oblique. Internal rib carinae present. Hinge teeth weak. Distribution. — Throughout the tropical Indo-West Pacific, from southern Japan to northern Australia, westwards into the Indian Ocean to South Africa and in the Red Sea, eastwards into the Pacific to Wallis and Futuna Islands [MNHN, ZMA, unpublished data] (Raines & Poppe, 2006: 126; Raines, 2010: 608). Present specimens from the Philippines alive at 62-90 m (minimum depth range). Living byssally attached to coral branches, under rocks or amongst coral rubble on sandy bottoms. Remarks. — The present specimens from the Philippines are indistinguishable from the type material from the Maldive Islands.» DIJKSTRA, H. H. 2013. Pectinoidea (Bivalvia: Propeamussiidae and Pectinidae) from the Panglao region, Philippine Islands. Vita Malacologica, 10: 1-108, pls. 1-32. [p. 46]
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Juxtamusium maldivense (E. A. Smith, 1903); H. H. Dijkstra, 2013, Pectinoidea from the Panglao region, Philippine Islands, plate 11, figures 2a-2d; plate 13, figures 2a, 2b (juvenile).
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«Juxtamusium maldivense closely resembles its only known congener, J. oblectatum lredale, 1939, the type species of the genus (Figures 7, 128-133, 135; Table 12). The latter species differs from J. maldivense primarily in having radial costae that are low and broadly rounded rather than angular and that begin later in growth (generaly at a height of about 6 mm, with a range from 2 to 12 mm), resilifers that do not project into the internal umbonal areas, right anterior auricular costae that become obsolete early in growth (generally after anterior outer ligament lengths between 2 and 3 mm are reached), and right and left ctenolia that are weaker and less persistent throughout growth. In addition, J. oblectatum reaches a somewhat larger size, particularly in the area of New Caledonia. One specimen in the collections of the Academy of Natural Sciences of Philadelphia (ANSP 271682, Figure 135) measures 32 mm high.
Although the geographic ranges of Juxtamusium maldivense and J. oblectatum broadly overlap (Figure 7), there appears to be no intergradation of their distinctive characters even where both may occur at the same locality (as in a single dredge haul from Bikini Lagoon, USNM 582893 and 582903, 25 fathoms). A third species, Pecten natans Philippi, 1845, from the eastem Pacific off Terra del Fuego, was assigned to Juxtamusium by GRAU (1959, p. 125). This assignment is incorrect because the species lacks the peculiar resilium, twin ctenolia, and closely lamellate growth so characteristic of Iredale's genus.» WALLER,
T. R. 1972. The Pectinidae (Mollusca: Bivalvia) of Eniwetock Atoll,
Marshall Islands. The Veliger, 14 (3): 221-264, pls. 1-8. [p. 252]
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Juxtamusium maldivense (E. A. Smith, 1903); T. R. Waller, 1972, The Pectinidae of Eniwetock Atoll, plate 7, figures 111-127.
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