Lyropecten denaius (Woodring, 1982)
WOODRING, W. P. 1982. Geology and paleontology of Canal Zone and adjoining parts of Panama. United States Geological Survey Professional Paper, 306-F: 1-759, pls. 83-124. [p. 598, pl. 92, fig. 11; pl. 98, figs. 7, 9]
1982 Nodipecten denaius Woodring, 1982
W. P. Woodring, 1982, plate 92.
W. P. Woodring, 1982, plate 98.
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«Small, height little less than length, right valve more convex than left on only articulated specimen. Both valves marked by a "resting stage." Ribs inverted U-shaped, slightly undercut, except near ventral margin, wider than interribs. Fifteen nonnoded, subequal ribs on right valve; interribs subequal. Twelve ribs remaining on incomplete left valve. Leftvalve ribbing of Nodipecten magnificus type, but on posterior side, median rib flanked by three, instead of two, weakly noded ribs. Ribs and interribs of both valves bearing radial threads, crimped by more or less distant concentric threads or growth lines. Flanks very narrow, radially sculptured. Auricles not well preserved or missing, radially sculptured where preserved. Interior not preserved or inaccessible.
Length (almost complete) 47.5 mm, height 49 mm, convexity (both valves) 16.5 mm (type). Type (articulated) : USNM 647126. Type locality: 101g (USGS 23654, Panama Canal, west side of Las Cascadas Reach, Canal station 1767 plus 15 m, Canal Zone), upper limestone in upper part of La Boca formation. The type (pI. 98, figs. 7, 9), from the La Boca formation, is the only unequivocally identified specimen of Nodipecten denaius. Though it is articulated, the valves are rotated about 15º. Two valves are doubtfully identified: one from the Caimito formation, the other from the Emperador limestone member of the La Boca in Madden basin. Both evidently are right valves. They are doubtfully identified, as the left valve is unknown. The valve from the Caimito (pI. 92, fig. 11; length 47 mm, height 44 mm) is of special interest as the oldest known reasonably preserved Nodipecten. Though it is not well preserved, it has 15 ribs at the ventral margin, like the right valve of the type of N. denaius. Only traces of radial threads and concentric sculpture are discernible on a few ribs and interribs. At the ventral margin, an interrib near the median line is slightly wider than the others. The valve is marked by two "resting stages." Only the lower posterior part of the valve from the Emperador is exposed, showing eight ribs. N. denaius probably is a small predecessor of N. colinensis (F. and H. Hodson, in Hodson, Hodson, and Harris, 1927, p. 33, pI. 18, figs. 3, 6, pI. 19, fig. 4; length 97 mm), a late Miocene Venezuelan species. The Hodsons' illustration of a left-valve paratype (their pI. 19, fig. 4) shows to good advantage the sculpture of a species of the group of N. magnificus. A small laterally crushed valve from the Panama formation, also of late Oligocene age, is listed as Nodipecten sp. (height 29.5 mm). Occurrence: Caimito formation (late Oligocene), locality 52a (identification doubtful). La Boca formation (early Miocene), Gaillard Cut area, locality 101g. Emperador limestone member of La Boca formation (early Miocene), Madden basin, locality 72 (identification doubtful).» WENDELL PHILLIPS WOODRING, 1982
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