Propeamussium jeffreysii (E. A. Smith, 1885)
SMITH, E. A. 1885. Report on the Lamellibranchiata collected by H.M.S. Challenger during the years 1873-76. In C. W. Thomson & J. Murray: Report on the Scientific Results of the Voyage of H.M.S. Challenger during the years 1873-1876. Zoology, 13: 1-341, pls. 1-25. [p. 310, pl. 23, figs. 2, 2a-2c]
1885 Amussium [sic] jeffreysii E. A. Smith, 1885
E. A. Smith, 1885, plate 23.
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«Testa tenuissima, paulo inaequivalvis, oblique rotunde ovata, utrinque conspicue hians, subnitida, valvis dissimiliter sculptis, diverseque coloratis dextra superne in medioque aurantiaca, marginem versus pallida diaphana, radiatim tenuiter lirata, incrementique lineis ornata, valva sinistra superne in medioque quam dextra pallidiore, inferne pellucida, concentrice tenuiter lirata. Auriculae parvae, subaequales, ad latera obliquae, postica valvae sinistrae caeteris leviter dissimile. Pagina interna nitens, liris radiantibus inaequalibus albis abrupte terminatis circiter 15 instructa.
This very beautiful species is higher than long, compressed, gapes considerably at the sides, is slightly oblique, roundly ovate, and a little inequivalve. The valves are very thin, somewhat differently coloured, and ornamented with different sculpture. The deeper valve (regarded as the right) is more brightly coloured, having the upper and central portion tinted bright orange, and the outer border very much paler and transparent. It is sculptured with numerous fine rounded lirae which radiate from the beak and extend almost to the circuniference all round. In addition it is marked with fine concentric lines of growth, producing, chiefly towards the umbo, a distinctly cancellated surface. The other valve is much paler than the right, and adorned throughout with numerous fine concentric lirae. The beaks are acute, converging with slightly concave sides to an angle of about 114°. The ears are small, about equal on both sides, feebly sculptured with striae of growth and oblique at the sides. The posterior of the left valve diflfers from the rest in having a very small sinus where it joins the dorsal slope of the valves. The interior is coloured like the outside very glossy, and strengthened with about fifteen white radiating lirae which terminate abruptly and extend over the tinted portion of the valves. Some of them in certain specimens are very short, and are not produced towards the beaks like the rest, which gradually attenuate upwards.
Length 19½ mm., height 21½, diameter 5. Habitat.— Station 210, Philippine Islands, in 375 fathoms; blue mud. This species is remarkable for the orange colour of the right valve and the fleshy tint of the left, also for the strongish and abruptly terminating internal lirae. I name it with much pleasure after my late friend Dr. Gwyn Jeffreys, of "British Conchology" renown.» EDGAR ALBERT SMITH, 1885
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«Description. — Shell relatively small, fragile and semitransparent, up to 28 mm high, commonly 20-23 mm, slightly higher than wide, equilateral, inequivalve, weakly inflated, left valve somewhat more than right, auricles equal, umbonal angle c. 100-110˚. Prodissoconch c. 210 μm. Colour of left valve orangebrown-tinted, of right whitish. Left valve has a delicate regular latticed sculpture in early growth stage, distinct near the umbo, but tends to be obsolete near the ventral margin. Anterior and posterior auricles are relatively small, equal in size, with fine radial riblets, weaker on right valve. Right valve sculptured with fine regularly spaced concentric lirae. Internal riblets 10 with 2 auricular riblets, and a few (2-4) intercostal rudimentary riblets near the periphery. Hinge line straight. Resilifer triangular. No byssal fasciole, or byssal
notch, no ctenolium. Soft parts, reproduction and food described by Knudsen (1967: 277). Distribution. — SE Africa: 430 m (alive), Gulf of Aden: 655-732 m (alive), Maldive Islands: 400-797 m (alive) (Knudsen 1967: 276); Japan, Taiwan, East and South China Sea, Philippines: 100-1000 m (Bernard, Cai & Morton, 1993: 53; Hayami, 2000: 913; Xu & Zhang, 2008: 77); Wallis and Futuna, and Vanuatu: 470-775 m (Dijkstra 2001: 78); Fiji: 596-729 m (Dijkstra & Maestrati, 2008: 83). Present material from the Philippines alive in 120-784 m (minimum depth range). The bathymetric range of live-taken specimens is now 80-797 m. Remarks. — All morphological characters of the present material are identical to the type specimens. The internal ribs are generally 10-11 in number. The interstitial rudimentary riblets vary strongly (1-4) or are sometimes lacking. The sculpture on the left valve is also variable in prominence (very weak to more prominent) and development (varying from the early ontogeny to the central part of the disc).» DIJKSTRA, H. H. 2013. Pectinoidea (Bivalvia: Propeamussiidae and Pectinidae) from the Panglao region, Philippine Islands. Vita Malacologica, 10: 1-108, pls. 1-32, 2 tabs. [p. 13]
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Propeamussium jeffreysii (E.A. Smith, 1885); H. H. Dijkstra, 2013, Pectinoidea from the Panglao region, Philippine Islands, plate 1, figures 2a-2d.
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