Serratovola pallula Dijkstra, 1998
DIJKSTRA, H. H. 1998. Pectinoidea (Mollusca: Bivalvia: Pectinidae: Propeamussiidae) from Hansa Bay, Papua New Guinea. Molluscan Research, 19 (1): 11-52, pls. 1-9. [p. 28, pl. 4, figs. 1-6]
1998 Serratovola pallula Dijkstra, 1998
H. H. Dijkstra, 1998, plate 4.
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«Description: Shell moderately small, up to 17 mrn high, inequivalve, equilateral, left valve somewhat concave, right valve convex, auricles nearly equal.
Left valve sculptured with 19 broad angulate radial costae with close interstices near the ventral margin. In early dissoconch stage exterior smooth apart from a few concentric growth lines. Radial ribs with fine interstitial concentric lamellae start ca. 1.5 mm beneath umbonal top. On central dissoconch hollow sections formed on both sides of radial costae, and interstices narrow grooves. Approximately 5 mm above the ventral margin in adults small interstices are exposed, diverging near margin, with concentric lamllae. Anterior auricle somewhat longer (7.8 mm) than posterior one (6.4 mm). Both auricles with fine concentric lamellae and few weak radial riblets, the latter more prominent anteriorly, near disc boundary. Hinge line straight. Outer ligament dark brown. Right valve sculptured with 20, somewhat rounded, radial costae, which are more angulate near periphery. Ribs are similar to left valve. Interstices wider than on left valve, with addition of concentric lamellae. Auricles with weak radial riblets with overrunning closely arranged concentric irregular lamellae. Hinge line straight with fine spines. Byssal notch rather small. Only one active tooth visible on suture (ctenolium). Resilial insertion triangular. Left valve dotted creamy-brown on brown, right valve uniform creamywhite. Type material: Holotype (H 16.8, L 18.0, D 5.9 mm) KBIN 25.955. 471. Type locality: PAPUA NEW GUINEA: Hansa Bay, S of Duangit, dredged, 60 m, leg. B. Tursch. Distribution: Papua New Guinea and northern Australia (AMS, QM, WAM) (material under study). Etymology: The radial costae of the shell are strongly angulate [Lat. pallula (substantivum: femininum) - small curtain]. Remarks: S. pallula differs from S. gardineri (E. A. Smith, 1903), known from the Maldive Islands, by a more concave left valve. The radial costae of the left valve are angular, that of the latter species more acute. The interstices of the left valve are very small, of S. gardineri broad. Interstitial concentric lamellae are not produced in the latter species and the radial ribs near the ventral margin are more rounded rather than angulate. The right valve in S. pallula is more convex and the ribs more closely arranged than in S. gardineri, and the hollow sections of the radial costae are somewhat larger. S. pallula differs from S. rubicunda by more angulate radial costae and smaller interstices of the left valve. The left valve of S. rubicunda is slightly convex, that of S. pallula concave. Concentric lamellae of S. rubicunda are more prominent. Hollow sections of the radial costae of the right valve are absent or much weaker in S. rubicunda and the ribs are more rounded near the ventral margin. The left valve of S. rubicunda is maculated red rather than spotted. Material from northwestern and northem Australia (AMS, QM, WAM) is very similar to the type material, although the radial costae are somewhat smaller and the interstices somewhat broader (under study).» HENK H. DIJKSTRA, 1998
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