Caribachlamys ornata (Lamarck, 1819)
LAMARCK,
J. B. 1819. Histoire naturelle des animaux sans vertèbres, présentant les
caractères généraux et particuliers de ces animaux, leur distribution, leurs
classes, leurs familles, leurs genres, et la citation des principales espèces
qui s'y rapportent. Tome sixième, Premier partie, 343 p. Chez l'Auteur, au
Jardin du Roi. De l'imprimerie de A. Belin. Paris, 1819. [p. 176]
1819 Pecten ornatus Lamarck, 1819
J. C. Chemnitz, 1784, Neues Systematisches Conchylien-Cabinet, Band 7, plate 66.
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«P. testa subaequivalvi, rubra, fusco zonata: umbone albo maculato; radiis 36: allernis minoribus.
An List. Conch. t. 175. fig. minor. Encyclop. pl. 214. f. 5. Chemn. Conch. 7. t. 66. f. 625. [b] var.? testa alba, undique spadiceo maculata. Chemn. Conch. 7. t. 66. f. 626, 627. Habite l'Océan atlantique austral. Mus. nº. Mon cabinet. Coquille de taille médiocre ou petite, un peu transparente, à oreillettes très-inegales. Ses rayons sont un peu rudes, subécailleux. Largeur, 28 millimètres. Notre espèce paraît être la même que l'ostrea pellucens de Gmelin , sans être celui de Linné.» JEAN BAPTISTE LAMARCK, 1819
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«Although Lamarck mentioned Pecten ornatus var. [b] with a question mark, there is no original label referring to that material. It is possible that the variety cited by Lamarck in his original text is included among the type specimens isolated from the Delessert collection. However, Rosalie made no annotation, and this would mean that Lamarck did not have or did not separate specimens of the variety [b] in his own collection. Among the material isolated (six specimens, though Rosalie mentioned only five ones) are also two other distinct species, i.e. Pecten rubromaculatus Sowerby II, 1842 (1088/73/1 and 1088/73/4), and Ostrea multistrata Poli, 1795 (1088/73/3), which are somewhat similar to P. ornatus Lamarck. Lamarck mentioned the resemblance between P. ornatus and Ostrea pellucens L. (Gmelin, 1791: n° 45 var. "beta" (non Lamarck)), and used the same reference as Gmelin, whose taxon is different from Ostrea pellucens Linnaeus, 1758. The latter is similar to Ostrea imbricata Gmelin, 1791 or Ostrea hyalina Poli, 1795 (under study). The specimen closest in size to that given by Lamarck is here selected as lectotype.»
DIJKSTRA, H. H. 1994. Type specimens of recent species of Pectinidae described by Lamarck (1819), preserved in the Muséum d'Histoire Naturelle of Geneva and the Muséum National d'Histoire Naturelle of Paris. Revue Suisse de Zoologie, 101 (2): 465-532, pls. 1-30. [p. 490]
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Pecten ornatus Lamarck, 1819, lectotype MHNG 1088/75; H. H. Dijkstra, 1994, Type specimens of recent species of Pectinidae described by Lamarck, plate 27, figures 115-118.
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«Types.— Specimens of Pecten ornatus in the Lamarck Collection in Geneva are in two lots. One of these, GNH 1088/75, which contains a single pair of matching valves of length 28.2 mm, is selected herein as the lectotype, because the specimen conforms to Lamarck's measurement and is the specimen illustrated by Chenu (1845, pl. 35, figs. 3 and 3a). The second lot, GNH 1088/73, contains five pairs of matching valves some of which clearly belong to species other than P. ornatus.
Type locality.— Lamarck's reference to the locality of this: species as "l'Océan atlantique austral" is overly generalized. Caribachlamys omata extends south of the Equator for only a short distance to islands offshore from Brazil. The type locality is herein emended to the Antillean region of the western Atlantic, Diagnosis.— Caribachlamys with valves about equal in convexity or with left valve slightly less convex than right but not markedly flattened; closely spaced, fine ribs with early non-scaly phase followed by scaly phase; ribs introduced continuously throughout ontogeny, with more than 70 ribs at distal margin of disk on mature shells; ribs of right valve commonly in clusters of three, those of nonscaly phase of left valve high and I-beam shaped in cross section, with deeply undercut rib flanks; scales fine, closely spaced, erect, distally concave, and open; commarginal lirae well developed in rib interspaces in early ontogeny and fairly uniform in trend and spacing across rib interspaces; antimarginal striae prominent between commarginal lirae and well developed on rib crests. Morphological variation.— Caribachlamys ornata, like its congeners, is of small size, seldom exceeding a height of 40 mm; no geographic trends in maximum size were observed. The degree to which the ribs of C. ornata are non-scaly, smooth crested, and I-beam shaped is highly variable both within and among population samples. Furthermore, these features q e less well developed on the right valve than on the left valve. Among 30 measured valves from Florida and the Bahamas, the non-scaly phase of ribs in the central sector of the disk was found to disappear at shell heights ranging from 7 to 10 mm on the right valve and from 9 mm to 25 mm on the left valve. There is much less variation in shell color and color pattern than in ribbing. Most C. ornata have dark red, maroon, or purple maculations on a light-colored, generally white, background. Distinct orange coloration in this background is relatively rare, occurring in the collections examined from eastern Puerto Rico through the Virgin Islands to Dominica. Specimens from the northern Bahamas, represented by a good suite of specimens in the Delaware Museum of Natural History, are lightly pigmented, and the extent of the I-beam phase of their ribbing is highly variable. Comparison.— Caribachlamys ornata resembles C. sentis in both the ribbing-introduction pattern and the microsculpture of the early commarginal stage. C. ornata differs, however, from C. sentis and all other Caribachlamys in having a distinct non-scaly I-beam-shaped ribbing phase in early ontogeny, persisting on the left valve at least to a shell height of 9 mm (refer to preceding section on C. sentis). Living habits.— Caribachlamys ornata lives byssally attached beneath rocks and coral heads in shallow water on the more turbulent parts of coral reefs, on hard, rocky bottoms, or in channels with strong currents. The only documented depth records for live specimens are all shallower than 20 m. Dead shells, apparently dislodged from reef fronts, have been dredged from as deep as 165 to 180 m (USNM 501824, off Lazaretto, Barbados). Geographic range.— Caribachlamys ornata occurs throughout the Antilles and in the northern Bahamas, southeastern Florida, and the Florida Keys. I have not been able to substantiate its presence in Bermuda, an occurrence which Abbott (1974, p. 443) also questioned. In the southern and western Caribbean, the species occurs on or near reefs adjacent to islands off Venezuela, Belize, and Quintana Roo, Mexico. In the Gulf of Mexico (other than along the Florida Keys), the species is apparently either very rare or absent. The USNM collections have one poorly documented lot from Veracruz, Mexico (USNM 57655). Rios (1985: 222) reported the presence of this species in the Brazilian islands of Fernando de Noronha and Atol das Rocas. Stratigraphic range.— Lower? Pleistocene to present. The oldest fossil occurrences of Caribachlamys ornata thus far known are specimens reported by Trechmann (1933: 33) from both high (300 m) and low levels of the Coral Rock of Barbados. Two specimens collected by Trechmann and deposited in The Natural History Museum, London (Palaeontology Section) were examined by me in 1979. Although both clearly belong to C. ornata, nothing further can be said about their relationship to modern forms without reexamining the specimens. It was noted at the time that one of the specimens, a left valve from "below the Garrison, west side of Barbados," still retains a remnant of a typical C. ornata color pattern. Trechmann (1933) argued that the Coral Rock of Barbados, now tilted and variously displaced by tectonic sliding, may be of fairly uniform age, mainly early Pleistocene. More recent studies (Mesolella, 1967; Ladd et al., 1990) have emphasized that Barbados emerged throughout the Pleistocene. Specimens of Caribachlamys ornata of Pleistocene age have also been collected on San Salvador Island, Bahamas, from a fossil coral reef northwest of the center of Cockburn Town [USNM(P) 474636]. This reef is Sangamonian in age, based on 234U-230Th dates that range from 130.75 ± 1.5 ky to 119.2 ± 1.5 ky (Curran and White, 1989). Dall (1898) reported that this species occurs in the Pleistocene of the Florida Keys and the Antilles. Discussion.— There remains some doubt as to whether Caribachlamys ornata is distinct from C. sentis at the species level or whether the two are merely subspecies. Along the southeastern Florida coast and in the Florida; Keys, where both forms occur, there is little doubt that they are well separated morphologically. In the Bahamas, however, particularly at Abaco Island, specimens identified herein as C. ornata have only a very short early growth stage with I-beam shaped, non-scaly ribs, and after this phase even shell color can become uniform and similar to that of C. sentis. The specimen of Lamarck chosen here as the lectotype in fact is close to these specimens in having a short I-beam phase and an abrupt shift to a more uniform color pattern. A possible interpretation is suggested by the fact that C. ornata appears to have a very recent origin in the later Pleistocene. It could well be that the species is still in the process of change and that selection pressures have operated more strongly in reef-front situations in the Lesser Antilles and Florida than on the carbonate banks and patch reefs of the Bahamas.» WALLER, T. R. 1993. The evolution of Chlamys (Mollusca: Bivalvia: Pectinidae) in the tropical western Atlantic and eastern Pacific. American Malacological Bulletin, 10 (2): 195-249. [p. 221, 223]
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Caribachlamys ornata; T. R. Waller, 1993, The evolution of Chlamys, figures 6q, r.
Caribachlamys ornata, micrographs of prodissoconchs pre-radial microsculpture and early radial stage sculpture; T. R. Waller, 1993, The evolution of Chlamys, figures 7b, e, h, k.
Caribachlamys ornata planar and oblique views of I-beam shaped rib; T. R. Waller, 1993, The evolution of Chlamys, figures 9a, b.
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