Lepidopecten proterus 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. 593, pl. 97, figs. 1-3, 6]
1982 Lepidopecten proterus Woodring, 1982
W. P. Woodring, 1982, plate 97.
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«Small, right valve about twice as convex as left. Right valve sculptured with 16 to 19 ribs (with few exceptions 18), slightly narrower to slightly wider than interribs. Fine concentric lamellae conspicuous in interribs on some valves, generally more or less effaced, exceptionally extending across ribs, but crest of ribs generally bearing more widely spaced, irregularly developed low nodes. Narrow shallow groove, containing closely spaced curved microscopic pustules, exceptionally appearing on both edges of ribs at height of 10 mm, or appearing at height of 4 mm and near ventral margin of mature valve, microscopic pustular grooves appearing on flanks of ribs. Left valve sculptured with 17 to 19 ribs (generally 17 or 18), noded like those on right valve. Ribs flanked on both sides by a very thin radial lamella appearing at height about 10 mm. Space between rib and lamella containing microscopic pustules (probably base of minute scales), generally partly or completely effaced. Fine concentric lamellae in interribs. Radial sculpture of auricles moderate, slightly stronger on right auricles than on left. Byssal notch very shallow, very narrow. Ctenolium very short. Cardinal crura poorly developed, replaced on some valves by irregular swellings. Vertically striated dorsal area high for size of shell. Pair of auricular tubercles generally present.
Length 22.6 mm, height 22.5 mm, convexity 2.8 mm (type). Length (practically complete) 18.5 mm, height 18.5 mm, convexity 5 mm (paratype). Length 25 mm, height 23, convexity about 6 mm (largest specimen, right valve). Type (left valve): USNM 647122; paratype (right valve) USNM 647123. Type and paratype locality: 101h (USGS 23652, Panama Canal, west side of Las Cascadas Reach, Canal stations 1774 to 1778 plus 23 m, near top of canal cliff, Canal Zone), La Boca formation. Lepidopecten proterus is widespread and locally abundant in the La Boca formation: a total of 150 valves, left valves outnumbering right, but none is articulated. They range in length from 7.6 to 25 mm. Species is especially abundant at the type locality (91 valves, 83 percent of which are left). It occurs also doubtfully in the Culebra formation. This species is smaller than L. scissuratus; the difference in convexity of the two valves is greater, and a byssal notch and ctenolium are discernible. Two exceptional right valves, one of which is illustrated (pl. 97, fig. 3), have some of the sculptural features of left valves. Occurrence: Culebra formation (early Miocene), locality 112a (identification doubtful). La Boca formation (early Miocene), Gaillard Cut area, localities 99b, 99c, 99f, 99g, 101h, 114, 116a, 119; Las Cruces area, locality 94.» WENDELL PHILLIPS WOODRING, 1982
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