Gurabopecten Waller, 2011
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. 71]
«Genus GURABOPECTEN n. gen.
Type species.— Gurabopecten uniplicatus n. sp., from the Gurabo Formation (late Miocene and early Pliocene age), northern Dominican Republic.
Diagnosis.— Aequipectininae of small size (maximum
known dimension 23 mm), slightly prosocline, Ht > L, valves of equal convexity or with LV slightly more convex than RV; hl much shorter than L; auricles small, lacking enlarged posterior dorsal costae, with shallow byssal notch and short active ctenolium; ribbing highly uneven, central sector of RV consisting of single wide plica with slightly rounded crest, steep sides, and secondary costae on crest beginning in midontogeny, bordered on each side by deep, wide interspace that becomes secondarily costate in late ontogeny; central sector of LV consisting of central deep, wide interspace flanked on each side by single wide plica, with secondary costae as on RV; ribs on anterior and posterior sectors of both valves much narrower than central plicae. Etymology.— Prefix referring to the Gurabo Formation of the northern Dominican Republic combined with -pecten, a common suffix used for members of the family Pectinidae.
Remarks.— The new genus Gurabopecten is clearly a member of the Aequipectininae, as evidenced by its pitted left preradial stage, well-developed carinae on the distal edges of internal plicae, commarginal lamellae that have normal rather than very dense spacing, and a right hinge consisting of dorsal and very strong resilial teeth. The new genus is probably derived from Argopecten, most likely from a form similar to the co-occurring species, A. thetidis. This is based on the presence in Gurabopecten n. gen. of steep-sided plicae, flattened crests on the enlarged central plicae, steep disk fl anks that are without costae early in ontogeny, and extensive foliated-calcite re-entry on the valve interiors that completely penetrates the separation between the striate and nonstriate adductor scars of the right valve. However, there is as yet no observable transition between the normal even-ribbed pattern of A. thetidis and the highly uneven pattern of Gurabopecten n. gen. There is only a hint of this transition provided by one individual among the 1,645 examined specimens of A. thetidis from the Gurabo Formation. This specimen, a right valve (USNM 540969, locality TU 1211; Pl. 7, Fig. 17), has an unusually low rib count (15) and has somewhat broader ribs and interspaces in the central sector than in the anterior and posterior sectors, the central rib crests becoming secondarily costate in late ontogeny.
The only other aequipectinine species that is known to develop enlarged, secondarily costate plicae, short auricles, and height greater than length is the extant species Pecten fasciculatus Hinds, 1845, of the tropical eastern Pacific (type locality: western coast of Panama off of Veragua, depth 31 m). It is now known to be a highly modified Cryptopecten that still retains the enlarged pair of dorsal costae on its posterior auricles, hinge structure, early microsculpture, and vesiculate sculpture that are typical of Cryptopecten (Waller, unpubl. data). Geographic range.— Known only from the northern Dominican Republic.
Stratigraphic range.—Upper Miocene to Lower Pliocene.»
THOMAS RICHARD WALLER, 2011
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Gurabopecten uniplicatus n. gen., n. sp.; T. R. Waller, 2011, Neogene Paleontology of the Northern Dominican Republic. 24. Propeamussiidae and Pectinidae (Mollusca: Bivalvia: Pectinoidea) of the Cibao Valley, plate 9, figures 6-16.
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