Cyclopecten barbarensis Grau, 1959
GRAU, G. 1959. Pectinidae of the eastern Pacific. Allan Hancock Pacific Expeditions, 23: viii, 308 p., pls. 1-57. University of Southern California Press. Los Angeles, California. [p. 37, pl. 14, figs. 1, 2]
1959 Cyclopecten barbarensis Grau, 1959
G. Grau, 1959, plate 14.
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«Shell extremely small, quite thin, translucent, inequivalve and equilateral, largest specimen found (a left valve) measuring 4.5 mm in height; hinge line about ¾ as long as disk, with beaks protruding slightly above. Right valve shallowly convex and reflexed at ventral margin; disk covered with numerous very fine concentric ridges, stronger near ventral margin; 4-6 faint radial ridges adjoining anterior submargin. Anterior auricle longer than posterior and with 9 lamellose radial riblets; byssal notch rather shallow and no ctenolium present. Posterior auricle with 6 lamellose radial riblets. Left valve rather deeply convex; concentric sculpture consisting of 10 prominent rows of lamellae in juvenile stage, increasing to 18-20 later; radial sculpture of low narrow ridges, starting with 10-12 at the umbo and increasing by intercalation to 24-32 (of varying strength) at the ventral margin. Anterior auricle rather large and with shallow byssal sinus; rows of concentric lamellae present as on disk, starting with 8-10 in juvenile stage and increasing to 12-15; 7 or 8 fine radial ridges in juvenile stage, increasing to 10-12. Posterior auricle with 5-7 rows of concentric lamellae in juvenile stage, increasing to 8 or 9; 6 or 7 radial ridges, increasing to 8-10. External sculpture clearly visible from interior of valve.
Holotype: Juvenile specimen: height and length 3 mm; diameter 1 mm; hinge line 2.3 mm. Largest valve found (left): height and length 4 mm; diameter 1.5 mm; hinge line 3 mm. Allan Hancock Foundation. Type locality: Off Santa Barbara Island, southern California, in 27 fathoms. Hancock expeditions bottom sample 1064; 33° 30' 01" N; 119° 02' 20" W; May 29, 1939. This species also occurred in bottom sample 1086, taken off the east side of San Nicolas Island, southern California, in 30 fathoms; 33° 18' 20" N; 119° 28' 45" W. Remarks: The sculpture of the left valve of this species separates it from any other eastern Pacific Cyclopecten. In fact, of all the species of this genus. the only one with similar concentric lamellae is the New Zealand Cyclopecten aupouria Powell (1937, p. 167, pI. 47, figs. 1-2). On the eastern Pacific C. incongruus (Dall) and the western Atlantic C. reticulus (Dall) the lamellae are much less prominent. (The latter species was described by Dall (1886, p. 221, pI. 5, figs. 8, 10) as Pecten (Pseudamusium) reticulus.) At the author's request Dr. Harald A. Rehder, of the U. S. National Museum, compared individuals of this species with the holotype of Dall's Pecten incongruum; his comments follow: "The specimens from off Santa Barbara island are not P. incongruum Dall, which is quite different, larger, flatter, and with the axial riblets not as strong, so that the sculpture is not as fenestrated as in your species. The concentric riblets of the latter are much more lamellate than in incongruum." Dall's species also differs from Cyclopecten barbarensis in being thicker and opaque, rather than thin and nearly translucent. The recorded depths are quite shallow, but this species undoubtedly also lives in considerably deeper water.» GILBERT GRAU, 1959
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