Amussiopecten woodringi Masuda, 1971
MASUDA, K. 1971. Amussiopecten from North America and Nothern South America. Transactions and Proceedings of the Palaeontological Society of Japan [N. S.], 84: 205-224, pls. 25-26. [p. 214, pl. 26, figs. 2a-b, 3a-b]
«Amussiopecten woodringi
MASUDA, n. sp. Pl. 26, figs. 2a-b, 3a-b 1926. Pecten antiguensis BROWN, HARRIS, Johns Hopkins Univ., Stud. Geol., No. 7, p. 107, pl. 19, fig. 4 (non BROWN, 1913).
Holotype:— U.S. Natl. Mus .. Coll. No. 646474.
Description:— Shell medium in size, rather thin, compressed, orbicular in outline, equilateral, subequivalve; right valve a little more inflated than left valve; valves radiately ribbed and forming an angle of about 115º at apex. Right valve slightly inflated, with about 21 very low, roundly flat-topped radial ribs and fine incremental lines; radial ribs somewhat broader than their interspaces in younger stage but tend to become broader and obsolete towards ventral and lateral margins; auricles rather large, angulate, subequal to each other, with somewhat raised, rugose, fine concentric lines; anterior auricle with shallow and wide byssal notch. Left valve slightly inflated, with very low, rounded radial ribs tending to become obsolete towards ventral and lateral margins with growth and rather distinct, regularly spaced, fine incremental lines; radial ribs narrower than their interspaces in younger stage but tending to become nearly equal to or a little broader than their interspaces with growth; auricles straight, with rugose, fine concentric lines and faint, fine radial threads. Hinge with simple cardinal crura provided with fine provinculum and wide and shallow resilial pit; auricular crura distinct, terminate distally in a distinct denticle at each extremity. Interior surface with distinct paired internal ribs near ventral margin. Dimensions (in mm): --
* — holotype, ** — thickness
Remarks:— This species is named in honor of Dr. Wendell P. WOODRING of the Smithsonian Institution, who has greatly contributed to the stratigraphical and paleontological studies in the Central America and South America.
Comparison:— Pecten antiguensis illustrated by HARRIS (1926) from the Ste. Croix Formation in Trinidad can be referred to the present new species, because the type specimen (Paleont. Res. Inst., Coll. No. 25058) has radial ribs showing characteristics similar to those of the present species but it differs from antiguensis in several particulars. Although HARRIS (1926) described this specimen as an Oligocene species, the locality of this specimen at present is considered to belong to the Early Miocene Ste. Croix Formation. This new species can be distinguished from A. antiguensis (BROWN) by its smaller apical angle at the apex and the larger number of very low radial ribs. Also A. harrisi MASUDA differs from the present one in having a smaller number of perpendicular sided radial ribs in the right valve and distinctly broader radial ribs in the left valve. Type locality:— U.S. Geol. Surv., Loc. No. 19775. Central La Plata quadrangle, northeast of Central La Plata, Puerto Rico. Lares Limestone. Late Oligocene. Distribution:— Lares Limestone. Puerto Rico; Ste. Croix Formation, Trinidad: Late Oligocene to Early Miocene.» KÔICHIRÔ MASUDA, 1971
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K. Masuda, 1971, plate 26.
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