Nodipecten colinensis colinensis (F. & H. Hodson, 1927)
HODSON, F., H. K. HODSON & G. D. HARRIS. 1927. Some Venezuelan and Caribbean mollusks. Bulletins of American Paleontology, 13 (49): 1-80, pls. 1-40. [p. 33, pl. 18, figs. 3 & 6; pl. 19, fig. 4]
1927 Pecten (aff. Nodipecten) colinensis F. & H. Hodson in Hodson et al., 1927
1968 Chlamys (Nodipecten) colinensis guadeloupensis Mongin, 1968 [partim]
1982 Nodipecten clydonus Woodring, 1982
1968 Chlamys (Nodipecten) colinensis guadeloupensis Mongin, 1968 [partim]
1982 Nodipecten clydonus Woodring, 1982
F. Hodson, H. K. Hodson & D. Harris, 1927, plates 18, 19.
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«Shell averages 90-100 mm. in altitude, and is nearly equivalve, suborbicular and moderately convex. The right valve is ornamented with about 11 rather flat-topped, prominent, radially striate ribs, in addition to less well developed ribs and radial striae on the submargins; the tops of the ribs carry 3 or 4 about equally spaced, coarse, radial striae; the sides of the main ribs are steep; the interspaces are about as wide or slightly wider than the ribs and carry 1-3 strong, radial threads; the radial ornamentation is crossed by the concentric lines of growth which swing up over the top of the ribs; at the points of intersection of the two sets of ornamentation, small beads or prominences are formed on the radial striae, but no large nodes or large imbricating scales are to be found on this valve, which easily distinguishes it from the left valve. The hinge line is straight and about one-half as long as the disc of the shell. The anterior ears are slightly longer than the posterior; both are radially striate with 5-6 or more, strong, radial threads which are slightly noded by the imbricate growth lines. The left valve is ornamented with about 12 main ribs in addition to the incipient ribs and striae on and near the submargins. The tops of the ribs are slightly rounded and carry 3-5 slightly scaly, radial striae; the interspaces are about as wide, or slightly narrower than, the ribs, and carry 1-3 strong radial threads of the same general character as those on the ribs; at periodic intervals, usually about 10-15 mm. apart, there occur concentric rows of prominences, which are noticeable on all the ribs and interspaces of the left valve; the characteristic feature of this species is that every third rib on this valve bears larger nodes or very prominent scales at points of intersections with the rows of concentric prominences.
The left valve of P. nodosus Linné usually has 9-10 ribs with every rib noded the left valve of P. pittieri Dall has about 10 ribs with every other rib noded more strongly; the left valve of the present species has 11-12 ribs with every third rib noded more strongly. Age: Miocene-Pliocene. Locality: District of Colina, State of Falcón, locality numbers 115, 125, 150, 151, 188, 205A, 207, 208, 209 (?), 292, 421 (?), 1011, 1252, 1353.» FLOYD HODSON & HELEN K. HODSON, 1927
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«Remarks.-- Nodipecten colinensis colinensis is apparently restricted to strata of Late Miocene age. The single specimen on hand from the Dominican Republic is stratigraphically the lowest of the three species of Nodipecten that occur there. Specimens from the vicinity of the type locality near La Vela, in the state of Falcón, Venezuela, are also of Late Miocene age (Caujarao Formation). Contrary to Smith (1991b: 51) and del Río (2006: 752), I am unable to confirm any occurrences of N. colinensis s. s. in the Cantaure Formation of Venezuela, which is now regarded as late Early Miocene in age (Hunter, 1978). Although the Aljahuela Formation of Panama has not been precisely dated, Nodipecten clydonus, regarded by Smith (1991b: 50) and the present author as a junior synonym of N. colinensis colinensis, occurs with Leopecten gatunensis, an indicator of the Late Miocene (see preceding section on L. gatunensis).
Comparison.—Nodipecten colinensis colinensis and N. c. vokesae differ from N. pittieri (Dall, 1912) of the Venezuelan Pliocene in the rib pattern of the central sector of the left valve, N2 r Nc 2r N in N. colinensis s. l. and N r Nc r N in N. pittieri. Nodipecten arnoldi (Aguerrevere, 1925) of the Pliocene and Pleistocene of Venezuela also has the N r Nc r N pattern. The two subspecies of N. colinensis differ only slightly from one another in the number of ribs, 12-14 in N. c. colinensis but commonly only 10 or 11 in N. c. vokesae. The difference in rib number shows up in the anterior and posterior sectors, particularly on the left valve, where an additional rib is distinguishable from the costate disk flank in N. c. colinensis but not in N. c. vokesae. Nodipecten colinensis guadeloupensis (Mongin, 1968) as represented by its holotype has a left central sector with the pattern N r Nc r N. Both Smith (1991b: 97) and the present author place it in the synonymy of N. pittieri. Two other specimens illustrated by Mongin (1968: pl. 43, figs 1-2), however, have a rib pattern of N 2n Nc 2n N and, as noted by Smith (1991b: 51) are N. c. colinensis. Their precise stratigraphic position, however, has not been determined. The reports of Smith (1991b: 51) of Nodipecten colinensis colinensis from Trinidad (Tamana Formation, Guaracara Limestone Member, late Early Miocene) and Carriacou (Carriacou Formation, late Early Miocene) have not been confirmed. A specimen of a Nodipecten in the Smithsonian collections from USGS 21790, Concord Quarry, Pointe-a-Pierre, Guaracara Limestone Member, Tamana Formation, is Lyropecten dumblei (Gardner, 1945), a species that would be expected in strata this old. Smith's (1991b) report from the Carriacou Formation of Carriacou was based on poorly preserved material not positively identified (Jung, 1971: 165, pl. 1, fig. 3). If the Carriacou specimens prove to be N. c. colinensis, then they are the oldest representatives of the species (Middle Miocene). Evolution.— Smith (1991b: 51) thought that the ribbing scheme of the left valve of Nodipecten colinensis s. l. allied the species with what she referred to as the "Lyropecten crassicardo-L. magnificus stock" of Miocene to Holocene age in the eastern Pacific. In contrast, Waller (2007: 933) regarded this rib pattern as plesiomorphic in Nodipecten but presented evidence that the extant N. magnificus of the Galápagos Islands, which has the same pattern, is a recently derived species convergent in this respect. According to the phylogeny by Waller (2007: fig. 3), N. colinensis s. l. is drived from the base of the Nodipecten clade and gave rise to a Tertiary Caribbean Nodipecten complex that includes all of the later species. The stratigraphic position of N. c. colinensis relative to other Nodipecten species is consistent with this pattern. Occurrence.— Nodipecten colinensis colinensis is reported for the first time from the Dominican Republic, where it occurs on the Río Yaque del Norte at a level equivalent to the lower Cercado Formation of the Río Gurabo. Distribution.—Outside of the Dominican Republic, Nodipecten colinensis colinensis is known from Upper Miocene strata in Venezuela (Caujarao Formation), and Panamá (lower member of Alhajuela Formation).» 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. 122]
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Nodipecten colinensis colinensis (F. & H. Hodson in Hodson et al., 1927); T. R. Waller, 2011, Neogene Paleontology of the Northern Dominican Republic, pl. 16, figs. 12, 13.
Phylogeny of Lyropecten Conrad, 1862 and Nodipecten Dall,
1898; T. R. Waller, 2007, The evolutionary and geographic origins on the endemic Pectinidae of the Galapagos Islands, fig. 3. |