Paraleptopecten olgensis (Mansfield, 1939)
MANSFIELD, W. C. 1939. Notes on the upper Tertiary and Pleistocene mollusks of Peninsular Florida. Florida Geological Survey Bulletin, 18: 5-75, pls. 1-4. [p. 51, pl. 2, figs. 1, 2, 4]
1939 Pecten (Pecten?) wendelli olgensis Mansfield, 1939
1953 Chlamys (Plagioctenium) irremotis Olsson & Harbison, 1953
1953 Chlamys (Plagioctenium) irremotis Olsson & Harbison, 1953
W. C. Mansfield, 1939, plate 2.
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«Shell small, low, nearly equivalve and equilateral. Ears large, the right being deeply sinuate. Right valve with 15 rounded, roughened ribs of nearly uniform size; left valve slightly higher in the umbonal area than right valve, with 14 rounded ribs; two weaker ribs alternate with a single stronger rib.
Holotype with attached valves (U. S. Nat. Mus. No 497970) measures: length, 22 millimeters; height, 22 millimeters; diameter, 7.4 millimeters. Type locality.— Station 14077, dredged from the Caloosahatchee River, 2 miles above Olga. Horizon and occurrence.— Pliocene ?; station 14076, dredged one mile above Olga and station 14194 a quarter of mile above Olga. The new species is closely allied to Pecten wendelli Tucker from the Pliocene Caloosahatchee marl at Fort Denaud and at Shell Creek, but is larger than the latter species and has more rounded ribs. The right valve of P. wendelli has sharper primary ribs, which are usually intercalated with a finer rib, whereas the left valve usually has three instead of two weaker ribs between a stronger rib on either side. Both Pecten wendelli and the new subspecies differ from P. leonensis Mansfield, a known Miocene species, in having a less inflated right valve and a higher left valve and in the character of the radials. The new subspecies appears to intergrade the known Miocene and Pliocene species. The original of figure 8, plate 4 of Tucker probably should be referrred to Pecten wendelli and not to Pecten leonensis, and her figure 9, plate 4 appears to be incorrectly identified. The illustration of this form indicates than it may be closely related to the new subspecies P. wendelli olgensis. One small right valve collected at Walkers Bluff, Cape Fear River (station 13156) appears also to be more closely related to the new subspecies olgensis than to Pecten leonensis. The matrix adhering to the new subspecies consists of a limey clay and phosphatic grains. This group may be nearer the subgenus Chlamys than the subgenus Pecten.» WENDELL CLAY MANSFIELD, 1939
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«The species-level taxonomy of Paraleptopecten n. gen. of the Late Miocene to Early Pleistocene is confused and in need of revision, in part because past authors have not fully appreciated the degree to which rib patterns vary. Using the method of encoding rib patterns explained in the Materials and Methods section, I have identifi ed 17 rib patterns on the disks of LVs of extant P. bavayi in the Smithsonian (USNM) collection of Recent mollusks (Table 18). Specimens of P. olgensis (Mansfield, 1939) from the middle Pliocene of Florida, raised herein to species rank, falls within the range of variation of P. bavayi in terms of the rib pattern of the LV but differs from all living P. bavayi in lacking single medial costae in the interspaces of the RV. Paraleptopecten olgensis also has a narrower umbonal angle in early ontogeny and only one minor plica between the outermost major rib and shoulder of the disk flank on the anterior and posterior of the LV. Paraleptopecten leonensis (Mansfield, 1932) of the Pliocene Jackson Bluff Formation of Florida resembles P. olgensis in umbonal angle and lack of single medial costae, but differs in having only 11 ribs on the LV in the pattern /r R r R r Rc r R r R r\. Paraleptopecten wendelli (Tucker, 1934), from the upper Pliocene to lower Pleistocene Caloosahatchee Formation of Florida and the Waccamaw Formation of South Carolina, differs from P. olgensis mainly in having a single medial costae in each interspace originating in mid-ontogeny.»
WALLER, T. R. 2011. Neogene Paleontology of the Northern Dominican Republic. 24. Propeamussiidae and Pectinidae (Mollusca: Bivalvia: Pectinoidea) of the Cibao Valley. Bulletins of American Paleontology, 381: 1-197, pls. 1-18. [p. 92]
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