Pseudohinnites levii Dijkstra, 1989
DIJKSTRA, H. H. 1989. Pseudohinnites levii gen. et spec.nov. (Mollusca, Bivalvia: Pectinidae) from New Caledonia. Basteria, 53 (1-3): 29-33, figs. 1-3. [p. 31, figs. 1-3]
1989 Pseudohinnites levii Dijkstra, 1989
H. H. Dijkstra, 1989, figures 1-3
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«Description. — Shell medium-sized, up to 46 mm high, higher than wide, thin, fragile and somewhat translucent, inequivalve, left valve convex, right valve flat. Exterior of left valve with very irregular small and close-set concentric lamellae, crossed by irregular radial costae, giving the surface a cancellate appearance. In the dissoconch stage only concentric lamellae are visible, the radial costae start only at about 4-8 mm from the beaks. Concentric lamellae more pronounced near the sides and the ventral margin. Sculpture continued on the auricles, no interruption between the shell disc and the auricles. Anterior auricle slightly longer than posterior auricle.
Internal sculpture of left valve composed of irregular radial plicae reproducing the external irregular radial sculpture. Exterior of right valve somewhat smooth with irregular growth lines, becoming coarser towards the ventral margin. In addition, on both valves irregular concentric low waves or irregular depressions; surface strongly deformed with a “Hinnites”- like appearance. Auricles ofright valve with radial ribs directly under the hinge line, bearing tiny scales where growth lines are crossed. No byssal notch; inactive and active ctenolium present. Interior reproducing the exterior deformed disc. Hinge line straight with a rather broad triangular resilium pit and a very small outer ligament. Exterior surface milky white, interior more or less polished and silvery. Derivatio nominis. — The new species is dedicated to Prof. C. Levi, principal investigator of the BIOCAL-Expedition.
Locus typicus. — Southeast of New Caledonia, 23°25'5, 167 C53'E, 965 m, "Jean Charcot", BIOCAL sta. DW 70, coll. Bouchet, Metivier & Richer de Forges, 4.1X. 1985.
Type material. — Holotype: 34 mm (h), 30.5 mm (l), left valve. Paratypes: 22°40'S, 166°27'E, 1618-1740 m, BIOCAL sta. CP 26, 28.VIII. 1985, 2 fragments of left valve, 3 fragments of right valve; 23°09'S, 166°41'E, 1140 m, BIOCAL sta. CP 30, 29.VIII. 1985, 4 fragments of left valve, 1 fragment of right valve; 20°32'S, 166°48'E, 900-980 m, BIOCAL sta. DW 80, 5.IX. 1985, right valve; 21°00'S, 166°58'E, 1820-1980 m, BIOGEOCAL sta. CP 260, 17.IV. 1987, 3 left valves and 2 right valves; 21°02'S, 166°57'E, 1920-2040 m, BIOGEOCAL sta. CP 273, 20.IV. 1987, 4 left valves and 3 right valves. Holotype and paratypes are deposited in the collection of the Muséum National d'Histoire Naturelle, Paris (MNHN).
Habitat. — The material was collected on a fine muddy and sandy bottom with gravel, from 900 to 2040 m deep. No live specimens were dredged. The specimen from the Siboga Expedition has a fresh appearance, but no soft parts are preserved.
Distribution. — Philippines, Indonesian Archipelago and off New Caledonia.
Other material examined. — Philippines: 12°53'N, 122°27'E, 1650-1660 m, MUSORSTOM 2, a right valve, MNHN; Indonesia: 10°48'S, 123°23.1'E, 918 m, SIBOGA sta. 300, 30.1.1900, one complete juvenile specimen, Zoological Museum, Amsterdam.
Remarks. — The only other species in the genus Pseudohinnites is Pseudohinnites adamsi (Dall, 1886) from off St. Vincent (West Indies) at 1031 m (573 fms.), represented by one left valve only and described as Hinnites adamsi (Dall, 1886: 223, pl. 5 fig. 6). It is very close to Pseudohinnites levii. Another left valve was dredged by the Dana Expedition, south of the Virgin Islands (Dana sta. 1275, 17°41.5'N, 64°55'W, 550 m, 28.V. 1922), and is housed in the Zoological Museum, Copenhagen (ZMK). No right valves have yet been taken.
Pseudohinnites levii is slightly larger than P. adamsi, the sculpture on the external surface of the left valve is less pronounced, and the auricles have more irregular radial costae than in P. adamsi. A possible third representative of Pseudohinnites is Pecten (Chlamys) fluctuatus Bavay, 1904, from the Andaman Islands of unknown depth; the type is possibly preserved at the Zoological Survey of India in Calcutta. Unfortunately the author has not been able to examine this species.» HENK H. DIJKSTRA, 1989
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«Description. — The delicate shell is almost circular, slightly higher than long. It is strongly inequivalve; the right valve is either flat or slightly concave; the margin of the right valve is reflected against that of the left. The posterior auricles are continuous with the disc margins. The dorsal margin is shallowly V-shaped in cross-section. The umbonal angle is between 105º and 110º. The resilial insertions are acline, rather small and restricted to the dorsal half of the hinge plate. The interior of the valves is nacreous.
Measurements of right valves (mm): The right valve (fig. 1a) is thin and transparent. It has close-setz irregular and shallow radiating ribs most of which emerge some 100 mm from the umbo. About 45 ribs are present at the periphery, including those of the posterior auricle. Three irregular, shallow, commarginal undulations are present; a fine irregular commarginal striation is also present and the valve is irregularly battered. The anterior auricle (fig. 2a) is separated from the disc by a distinct suture. The ctenolium (fig. 2b) has 4-7 active teeth and numerous inactive ones. The byssal fasciole forms an angle of 22".It has closeset irregular ribs which continue across the auricle to the dorsal edge, forming a crest of ribs which become more prominent distally. The dorsal section of the auricle has 5-7 radiating irregular ridges. The dorsal edge of the right valve is curved, overlapping that of the left. The posterior auricle is smaller, continuous with the disc and has an identical sculpture. Two indistinct resilial teeth are present; dorsal teeth (crura) are lacking.
The left valve (fig. 1b) is thicker, opaque and convex (convexity: about 6 mm); it is slightly larger than the right valve, overlapping it by about 1 mm along the whole periphery of the disc. The umbo is more prominent than that of the right valve. The sculpture of the disc and the auricles consists of irregular, close-set, radiating ribs; they emerge gradually 6-8 mm from the umbo. Towards the periphery, secondary ribs are intercalated; 56 ribs are present at the shell margin. Near the umbo the commarginal sculpture consists of regular fine ridges. At the point at which the radiating ribs emerge, they are transformed into close-set lamellae in the interstices between the ribs (fig. 3). On the ribs they develop into hollow vesicles, which are often broken, forming curved scales. The auricles are continuous with the disc and have the same sculpture. The valve has three shallow, irregular, commarginal undulations. No hinge teeth are present.
In terms of microstructure (fig. 4), the right valve comprises an irregular prismatic layer. The left valve has irregular, close-set, radiating folds crossed by more distant concentric folds, together forming an irregular reticulate sculpture. This sculpture appears to be unique in the Pectinoidea.» DIJKSTRA, H. H. & J. KNUDSEN. 1997. The morphology and assignment of Pseudohinnites levii Dijkstra, 1989 (Bivalvia: Pectinoidea). Basteria, 61:1-15, figs. 1-11. [p. 1, 2]
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Pseudohinnites levii; H. H. Dijkstra & J. Knudsen, 1997, The morphology and assignment of Pseudohinnites levii Dijkstra, 1989 (Bivalvia: Pectinoidea), figures 2-4.
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