Nodipecten colinensis vokesae (Smith, 1991)
SMITH, J. T. 1991. Cenozoic Giant Pectinids from California and the Tertiary Caribbean Province: Lyropecten, "Macrochlamis", Vertipecten, and Nodipecten species. United States Geological Survey Professional Paper, 1391: v, 155 p., figs. 1-18, pls. 1-38. [p. 51, pl. 16, figs. 1-3; pl. 17, fig. 3; pl. 18, figs. 2-4; pl. 19, figs. 2, 4]
J. T. Smith, 1991, plates 16-19.
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«Holotype.— USNM 334988, a double-valved individual 6.5 cm. high, 7.2 cm long.
Type locality.— Dominican Republic, 2.9 km west of Los Quemados in roadcut on the Los Quemados-Sabaneta road; 0.3 km west of bridge over Rio Gurabo (TU 1338). Gurabo Formation, late Miocene or early Pliocene. Description.— Valve outlines circular to slightly longer than high. Right valve slightly more convex than left valve. Beaks project slightly beyond hinge line. Auricles subequal, costate, and Iirate, anterior auricle having about three coarse radials. Byssal notch moderately deep. Hinge line slightly shorter than half shell length. Right valves with 10-11 ribs sculptured by moderately coarse to coarse costae crossed by lirae; wide central space flanked by uniformly arranged to slightly grouped ribs and 1-3 coarse riblets in interspaces. Left valves flatter than right valves, with 9 ribs arranged in the scheme N 2r Nc 2r N; individuals over 1 cm high have hollow, flanged nodes on the three key ribs, 1-2 radials in interspaces. Nodes correspond to slight ledges or constrictions in the shells. Anterior and posterior shell margins have incipient radial ridges that confuse rib counts. The largest individual seen measured 9 cm high, 8.5 cm long (incomplete) (TU loc. 1209). Whole specimens tend to be longer than high. Variability.— Juvenile parts of shells have one or two more ribs than adults, the earlier riblets becoming obsolete marginal ridges in later growth stages. Radial costae vary from coarse (four radials per rib) to very coarse (three radials per rib). Comparative morphology.— Lyropecten colinensis vokesae differs from L. colinensis, s.s. in having one or two fewer ribs. Its rib count overlaps that of L. modulatus, from which it differs in having coarser fine sculpture and the flanged nodes characteristic of Caribbean Nodipectens and L. colinensis, s.s. The left-valve node scheme N 2r Nc 2r N separates L. colinensis vokesae from Nodipecten collierensis and N. pittieri (N r Nc r N), which are present in the Miocene and Pliocene of the Greater Antilles. Phylogenetic affinities.— Juvenile rib counts and sculptural similarity indicate that L. colinensis vokesae evolved from L. colinensis, s.s. It is a Tertiary Caribbean taxon represented in Panama; its relation to Lyropecten tiburonensis, n. sp. from the northern Gulf of California and to L. modulatus of the Vizcaino Peninsula, Baja California Sur is uncertain. Geographic distribution and stratigraphic occurrences.— Isolated occurrences within the Tertiary Caribbean Province in the Dominican Republic and Panama. Dominican Republic, west of Los Quemados, near the Rio Gurabo. Gurabo Formation and in float from the Gurabo and Cercado Formations (TU 1209, 1210, 1231, 1338). W.H. Akers (oral commun., 1981) has identified early Pliocene N19 zone foraminifers from TU 1209, 1210; the Gurabo Formation is shown as late Miocene to early Pliocene by Saunders and others (1982). Panama. Colon Province, Madden Basin. Alhajuela Formation(?) of collector T. Thompson (LSJU loc. 2659, about 1 mi below the Madden Dam on north bank of Chagres River). Caimito Formation, upper part, and Albajuela Sandstone of Woodring (1957, pI. 1). Geologic age.— Late Miocene to early Pliocene.» JUDITH TERRY SMITH, 1991
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«Remarks.--Nodipecten colinensis vokesae is possibly a junior synonym of Chlamys (Nodipecten) nunezi Torre, 1971, the type locality of which is the roof of the Galería del Confesionario, Cueva de Bellamar, Matanzas Province, Cuba (Torre, 1971: 7). This is probably in the Bellamar Member of the Canímar Formation, Lower Pliocene, Globorotalia margaritae Zone, N18, as indicated in Torre & Kojumdgieva (1985: 2), and thus is of approximately the same age as the upper part of the Gurabo Formation in the Dominican Republic. The problem is that Torre (1971) based his original description on only two specimens, the holotype being the anterior half of a right valve (incorrectly said to be a left valve) and another very worn specimen. His only illustration, which is of poor quality, is of the holotype. Nevertheless, Torre's figure is good enough to show that the specimen compares closely to the specimen (USNM 167122, Pl. 17, Fig. 14) from the La Cruz Formation of Cuba incorrectly identified with N. pittieri by Cooke (1919: 135, pl. 13, fig. 5) as well as by Torre (1971). Their rib numbers and even rib spacing on the anterior half of the disk are identical with each other and very similar to these features on the holotype of Lyropecten colinensis vokesae. The left valves of the Cuban species, however, are unkown, and therefore the synonymy cannot be confirmed.
Torre (1971) regarded his new species to be morphologically intermediate between Nodipecten pittieri and N. nodosus. Twenty years later, however, Smith (1991b) demonstrated the importance of the patterns of major and minor ribs, particularly in the central sector of the left valve, for distinguishing various lineages of Lyropecten and Nodipecten. Both N. pittieri and N. nodosus have a clear pattern of N r Nc r N in their left central sector, whereas N. colinensis s. l. has N 2r Nc 2r N. The pectinids with which Nodipecten colinensis vokesae is most commonly associated, as well as its stratigraphic positions in the Río Gurabo section, indicate that it lived on the outer shelf platform. It is commonly associated with other outershelf pectinids such as Argopecten thetidis and Gurabopecten uniplicatus n. gen., n. sp., but not with very shallow-water species such as Argopecten eccentricus (Table 23). In the Río Gurabo section, N. colinensis vokesae disappears just at the point of rapid deepening at ca. 400 m above the base of the section (Saunders et al., 1986: 16). This is also close to the Miocene-Pliocene boundary, but in this case, Nodipecten seems to be eliminated from younger strata for ecological reasons, not because of extinction. Comparisons.— Nodipecten colinensis vokesae differs from N. c. colinensis in having one less rib and/or a less developed incipient rib in the anterior and posterior sectors adjacent to the disk flanks. Both subspecies have a left central-sector rib pattern of N 2r Nc 2r N, which distinguishes them from N. pittieri, which has N r Nc r N. See Smith (1991b: 51) for comparison with eastern Pacific Neogene species. Evolution.— Smith (1991b: 51) observed that the pattern and number of ribs in the early ontogeny of Nodipecten colinensis vokesae resembles that of mature members of the nominal subspecies and therefore inferred that the former is descended from the latter. The stratigraphic position of the single specimen of N. colinensis s. s. found in the northern Dominican Republic corroborates this conclusion in that it occurs in the lower Cercado Formation, whereas all of the specimens of N. c. vokesae occur stratigraphically higher, in the upper Cercado and Gurabo formations. Stratigraphic occurrences elsewhere in the Caribbean region are also consistent with this hypothesis. Nodipecten colinensis s. s. in its type area in northern Venezuela is Late Miocene in age (see N. colinensis s. s.); Cuban occurrences of N. nunezi are Pliocene. Occurrence.—In the Cibao Valley of the northern Dominican Republic, Nodipecten colinensis vokesae occurs only in the upper Cercado and lower Gurabo formations. Distribution.--Nodipecten colinensis vokesae is thus far known from the Dominican Republic, unless N. nunezi of Cuba should turn out to be this subspecies (see Remarks above). Specimens identified by Smith (1991b: 51) from the Alhajuela Formation of Panama were misidentified. One specimen is probably a Lindapecten of the L. buchivacoanus complex; the other is the left valve of N. c. colinensis.» 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. 123, 124]
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Nodipecten colinensis vokesae (Smith, 1991); T. R. Waller, 2011, Neogene Paleontology of the Northern Dominican Republic, pl. 17, fig. 14; pl. 18, figs 1-4.
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