Euvola colpota (Woodring, 1982)
WOODRING, W. P. 1982. Geology and paleontology of Canal Zone and adjoining parts of Panama. United States Geological Survey Profesional Paper, 306-F: 1-759, pls. 83-124. [p. 579, pl. 110, figs. 12, 14]
1982 Pecten (Oppenheimopecten) colpotus Woodring, 1982
W. P. Woodring, 1982, plate 110.
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«Of medium size, right valve strongly convex, at least central dorsal area of left valve practically flat. Umbonal area of right valve narrow, flush with hinge line. Right valve sculptured with 21 or 22 high ribs, wider than interribs; sides steeply sloping, crest arched. Fine concentric lamellae scalloped. For most part, lamellae worn off on crest of ribs and obscure in many interribs. Anterior auricle set off by deep narrow groove; wide swelling adjoining groove and lower narrower undulations between swelling and dorsal margin. Byssal notch shallow. Posterior auricle not as strongly set off as anterior, not ribbed. Left valve represented only by thin umbonal fragment. Sculptured with 21 ribs, narrower than interribs on ventral part of fragment. On ventral part, fine concentric lamellae extending across ribs and interribs. Auricles depressed, not ribbed.
Length (almost complete) 48.5 mm, height (almost complete) 49 mm, convexity about 20 mm (type) . Type (right valve): USNM 646978; paratype (right valve) USNM 646979. Type locality: 82 (USGS 16929, Transisthmian Highway, 650 m south-southeast of Rio Chilibrillo bridge, Canal Zone), lower member of Alhajuela formation; paratype locality: 83 (USGS 16930, Transisthmian Highway, 400 m north of Rio Chagres bridge, Panama), lower member of Alhajuela formation. Pecten colpotus, represented by three right valves and an umbonal fragment of a left valve, was found in the lower member of the Alhajuela formation. The ventral margin of the right valves is defective. The scalloped concentric lamellae, especially those in interribs, are shown to best advantage on the posterior ventral part of the paratype (pI. 110, fig. 14). The late Miocene Venezuelan P. urumaconis (G. D. Harris, in Hodson, Hodson, and Harris, 1927, p. 22, pI. 13, fig. 1, pI. 14, figs. 3, 4, as Pecten soror urumaconis) reaches a larger size (length and height as much as 60 mm) and the right umbonal area is wider than that of P. colpotus. Though the scalloped rib growth lines are apparent on the ventral part of the type of the Venezuelan species, the interrib scalloping is visible only on the posterior ventral part, as for the most part the interribs are filled with matrix. The eastern Pacific P. vogdesi also is larger, and according to the scalloping of growth lines on the right valve, the left valve is more deeply recessed. Occurrence: Lower member of Alhajuela formation (early Miocene), localities 82, 83.» WENDELL PHILLIPS WOODRING, 1982
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