Catillopecten graui (Knudsen, 1970)
KNUDSEN, J. 1970. The systematics and biology of abyssal and hadal Bivalvia. Galathea Report, 11: 1-241, pls. 1-20, text-figs. 1-132. [p. 97, pl. 13, fig. 1, text-figs. 59, 60]
1970 Cyclopecten (Hyalopecten) graui Knudsen, 1970
J. Knudsen, 1970, plate 13.
|
«Material:
St.726, E.Pacific, Gulf of Panama (5°49'N, 78°52'W), 3670-3270 m, 13 May 1952. Gear: HOT. Bottom: clay. Bottom temp.: 2.0°C. – 1 specimen. Diagnosis:
A Cyclopecten having a circular shell with well-demarcated anterior auricles. The left valve is slightly convex with a distinct concentric sculpture. The right valve is flat with a peripheral concentric sculpture only. The ventral mantle edge has long and slender tentacles; velum is very well developed and without tentacles. The foot is small, the byssus well developed, the byssus retractor stout and bipartite. Description:
The valves are hyaline and rather delicate, almost circular, equilateral and inequivalve; the right valve is flat, while the left one is slightly convex. Both valves have concentric undulations, which become gradually more pronounced towards the periphery. The anterior auricle is well demarcated, being separated from the disc by a deep furrow. The posterior auricles are only indistinctly demarcated. The left valve has a distinct concentric sculpture consisting of regular, sharp ribs, covering the whole surface. A similar sculpture is found in the peripheral part of the right valve only. In addition both valves have a delicate radiating striation. The dorsal edge is straight. The right auricle has a distinct concentric sculpture which becomes foliaceous dorsally, turning into distinct serrations on the dorsal edge. The byssal notch is moderately deep. The posteriormost part of the posterior auricle of the right valve has a few serrations, corresponding to the peripheral concentric ribs already referred to. The dorsal edge of the left valve is completely without any serrations. The ligament is small and rounded-triangular. The soft parts: There appears to be no difference in the development of the mantle of the two sides. The mantle edge has numerous close-set tentacles, which are very long and slender at the ventral part, diminishing gradually towards both ends. At the ventral edge some of the long tentacles are interspaced by 6-8 shorter ones of different lengths. The individual tentacle appears to have a dark central part and a hyaline outer layer. Eyes are absent. The velum is very broad ventrally, diminishing towards both ends; the radiating muscles are distinct and no velar tentacles are present. The foot is very small and has a rounded sole. The byssus is very well developed, consisting of numerous threads. The byssal retractor is strong and bipartite inserted anterior to the "catch" part of the adductor on the left side. The "quick" part of the adductor is very large and extremely oblique. The areas of insertion of the two sides are nearly equal, and about three times the area of the "catch" part. The latter is only slightly oblique. The gills are large, reaching ventrally the edge of the velum. Measurements:
L H L. of dorsal edge 18.0 17.0¹ 10.3 ¹ Approximately, edge of shell somewhat damaged. Remarks:
The present species is close to C. (H.) undatus (Verrill & Smith, 1885) (see p. 101). It differs, however, in having a circular shell, that of C. (H.) undatus being somewhat higher than long and by having a distinct concentric sculpture of the left shell, while no such sculpture is found in C. (H.) undatus. There are also marked differences in the shape of the auricles and the byssal notch. C. (H.) neoceanicus (Dall, 1908) differs by having a cancellate sculpture, a nearly straight antero-dorsal edge and pointed auricles. The species is named for the late Mr. GILBERT GRAU, California, an outstanding authority on the Pectinidae. Biology: The present species appears to be carnivorous.
Distribution: Known only from the Gulf of Panama, 3270-3670 m, 2.0°C.
Type: ZMUC.
Type locality: "Galathea" St.726.» JØRGEN KNUDSEN, 1970
|