Parvamussium dautzenbergi (Dijkstra, 1990)
DIJKSTRA, H. H. 1990. Three new pectinacean species from the Indonesian Archipelago collected during the Siboga Expedition (1899-1900), with additional information and corrections on the previous report (Mollusca: Propeamussiidae, Pectinidae). Beaufortia, 40 (1): 1-14, pls. 1, 2. [p. 2, pl. 1, figs. 5-8]
1990 Propeamussium (Parvamussium) dautzenbergi Dijkstra, 1990
H. H. Dijkstra, 1990, plate 1.
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«Type material. Holotype: one left valve. Measurements: Height 8.8 mm, length 9 mm (ZMA Moll. no. 3.89.005). Paratypes: SIBOGA stat. 90, one left valve (ZMA Moll. no. 3.89.006), and SIBOGA stat. 95, one left valve (ZMA Moll. no. 3.89.007).
Locus typicus. SIBOGA stat. 90. Indonesia, Makassar Strait, 1°17'.5 N, 118°53' E. Dredge. 281 m. Bottom coral sand and stones. 21.VI.1899.
Description. Shell small, approximately 9 mm in height and length, convex and circular. Anterior and posterior auricles unequal, umbonal angle about 90°. The surface of the left valve is cancellated, produced by irregular radial costae and small concentric lamellae. The radial costae are somewhat more pronounced than the concentric lamellae. Near the umbonal area only concentric lamellae are present, 1.5 mm from the umbonal top radial riblets start. Towards the sides the radial costae are squamose caused by overrunning concentric lamellae. Near the central part of the disc, and also near the ventral margin intermediate radial costae are present. On the anterior auricle the concentric lamellae are more pronounced than on the external surface, and near the dorsal edge undulated. Some radial riblets are very weak. The sculpture of the posterior auricle is more smoothish, and also produced by undulated concentric lamellae and smooth radial riblets.
On the internal surface 11 radial lirae are visible, almost running to the edge of the shell, and near the ventral margin the external sculpture is visible. Hinge line straight with crashed crurae and a triangular resilial pit. Above the resilial pit the top of prodissoconch, and dissoconch is also visible. Etymology. The new species is named after Philippe Dautzenberg (1849-1935), the famous Belgian malacologist, who published in 1912 with Arthur Bavay on the Propeamussiidae and Pectinidae of the SIBOGA Expedition.
Distribution and ecology. This species is only known from Indonesia, with a bathymetric range of 281 to 522 m. Dead specimens are dredged from a stony bottom, or a coral sand bottom with stones.
Discussion. A related species is P. cristatellum (Dautzenberg & Bavay, 1912), which lives sympatric with the new species. It has less but more pronounced radial costae, which do not suggest the character of a cancellated structure of the external surface of the left valve. The concentric lamellae are somewhat closer arranged. P. thetidis (Hedley, 1902) (= Ctenamusium salacon Iredale, 1929) from eastern Australia has the same conchological characters as P. cristatellum, but is less sculptured. P. scitulum (E. A. Smith, 1885) and P. torresi (E. A. Smith, 1885) are smaller and smoothly sculptured with fine radiations (P. scitulum) or concentric striae (P. torresi) without a cancellated structure.»
HENK H. DIJKSTRA, 1990
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