Spathochlamys benedicti (Verrill & Bush in Verrill, 1897)
VERRILL, A. E. 1897. A study of the family Pectinidae, with a revision of the genera and subgenera. Transactions of the Connecticut Academy of Arts and Sciences, 10: 41-95, pls. 16-21. [p. 74]
1853 Pecten mundus Reeve, 1853
1897 Chlamys benedicti Verrill & Bush in Verrill, 1897
1898 Chlamys verrilli Dollfus, 1898
1906 Pecten (Chlamys) nympha Bavay, 1906
1897 Chlamys benedicti Verrill & Bush in Verrill, 1897
1898 Chlamys verrilli Dollfus, 1898
1906 Pecten (Chlamys) nympha Bavay, 1906
Chlamys benedicti Verril & Bush; A. E. Verrill & K. J. Bush, 1898, Revision of the deep-water Mollusca of the Atlantic coast of North America, plate 84 figures 1, 2.
|
«Shell small, higher than long, with the posterior auricle much longer than the anterior, with a deep byssal notch in the right valve. The dorsal margin is straight and only slightly oblique; the anterior auricle, in the right valve, is decidedly angular, with its outer end slightly incurved and serrated by the terminations of the radial ribs. The posterior auricle is considerably prolonged and angulated at the upper corner, obtusely rounded at the end and deeply notched where it joins the main shell; it has four strongly marked radiating ribs, besides the dorso-marginal fold; below these there is a slightly concave space corresponding to the byssal notch. On the body of the shell there are six or seven shai'p serrations along the lower margin of the notch. In the upper valve the posterior auricle is broad and decidedly angular, the dorsal and outer margin forming less than a right angle; its surface is covered with about five or six radiating ribs decussated by more numerous and finer concentric raised lines, the anterior and posterior margins of the body of the shell slope about equally and form an acute angle; the ventral margin forms a regular semicircular curve; its entire surface on both valves is covered by strongly raised, rather close radiating ribs, separated by rather wider deep grooves. The interspaces are decussated by regular raised concentric lines; these are scarcely apparent on the ribs except on very young shells, but there are rather strong elevated spine-like points, especially near the margins, arranged along the ribs in pretty regular concentric lines. These become higher and more pointed anteriorly, and are frequently nearly obsolete in the middle portion of the lower valve; in that case the ribs appear nearly smooth and rounded. The ribs project at the margin as blunt points, or serrations. On the inner surface there are radial grooves corresponding to the external ribs. The hinge-margin is thin, with a slender submarginal ligamentary groove and a small triangular resilial pit in the center. The color is variable. The single valve from station 2571 is uniform lemon-color; those from the other locality are chestnut-brown and reddish, variegated with paler, and sometimes with white blotches.
Length of largest specimen, 5.5 mm; height, 6 mm; length of dorsal margin, 4 mm. Off Martha's Vineyard, in 1356 fath., dead; West Indies, in 25 to 72 fath., living. This species is allied to C. varia of Europe, but when compared with the young of that species, of the same size, the radial ribs are found to be fewer and coarser, and there are other differences which render it probable that they are distinct species. The ribs are stronger and fewer than in C. Islandica, and the auricles are different in shape. It is probable, however, that it grows to a much larger size than any of the specimens obtained. It may possibly prove to be the young of some known West Indian species, but does not agree with any known to us.» ADDISON EMERY VERRILL & KATHARINE JEANETTE BUSH, 1897
|
«Geographic Range.— Although dead specimens have been collected as far north as Latitude 40° 9' N, southeast of George's Bank (the locality referred to by Verrill and Bush in their original description), the distribution of this species is primarily from off Cape Hatteras southward throughout the Gulf of Mexico and Caribbean and as far south as Brazil. Rios (1985: 222) reported the species (as Chlamys munda) in Brazil from Amapá to Espirito Santo and in the Abrolhos and Trindade Islands. The species is also present in Bermuda (Waller, 1973).
Stratigraphic Range.— Upper? Pliocene to present. Fossils of Spathochlamys benedicti are reported herein for the first time from the James City Formation of North Carolina (Fig. 10i). There is now substantial agreement that the age of this formation is early Pleistocene (Cronin et al., 1984: 40; Ward and Blackwelder, 1987: 114; Miller III, 1989; Cronin, 1990). Weisbord (1964) reported the species from the Playa Grande Formation (Catia Member) of Venezuela. The age of the Playa Grande Formation is generally considered to be early Pleistocene (Bermúdez, 1980: 303), not early Pliocene as originally stated by Weisbord (1964), but the stratigraphic relationships of formations in the Cabo Blanco area of Venezuela are still controversial (e.g. see, for example, Gibson-Smith, 1976: 4). The fossil occurrences in Costa Rica are from beds now placed in the Moin Formation, which most workers have considered to be Pleistocene in age (e.g. Akers, 1972: 42; Cassell and Sen Gupta, 1989: 147; Robinson, 1990; Lyons, 1991: 159). Coates et al. (1992: 821), however, date what are apparently the same beds as late Pliocene-early Pleistocene. The Panamanian fossils (Figs. 10j,k) are all from Bocas del Toro area from beds that contain a fauna that is clearly younger than that of the Miocene Gatun Formation and is assumed herein to be of late Pliocene or early Pleistocene age. Coates et al. (1992: 819) have recently described a stratigraphic sequence in this general area that extends in age from the late Miocene through the Pliocene, but they do not specifically mention what is present on Bocas Island and Nancy Cay, the sites that yielded S. benedicti. The oldest known representative of S. benedicti could be a specimen [USNM(P) 4746491 from the Quebradillas Limestone of Puerto Rico. This limestone apparently forms the upper part of the Camuy Formation and may be early Pliocene in age but younger than the Gurabo Formation of the Dominican Republic and the Bowden shell beds of Jamaica (Bermúdez and Sieglie, 1970). Discussion.— The holotype of Pecten mundus Reeve, BMNH 1950.1 1.14.48, was examined. It is a pair of matching valves, both broken, the right valve (Fig. 10a) having a restored height of 12.7 mm. Reeve's species is clearly a senior synonym of Chlamys benedicti but is a junior primary homonym of P. mundus M'Coy, 1844, a fossil from the Carboniferous of Ireland. Dollfus (1898: 180) introduced the new name Chlamys verrilli to replace Chlamys benedicti Verrill and Bush on the erroneous assumption that Verrill and Bush's name is a junior homonym of Pecten benedictus Lamarck, 1819. The endings of the two names, however, differ in case, not in gender, and this is sufficient to prevent homonymy. Bavay (1902) applied the name Pecten (Chlamys) mundus Reeve to two small shells in a collection said to come from Corsica and concluded that the species is "European and even French" [translation]. Although the specimen that he illustrated appears to be what is here called Spathochlamys benedicti, there is no reason to believe that the locality data are correct. My own studies of European pectinid collections have not turned up any authentic records of the species in the eastern Atlantic. In a later publication, Bavay (1913: 26) identified shells from Salvador (Bahia), Brazil, as P. mundus Reeve, concluding that the species is present on both sides of the Atlantic. In support of this contention, he reported that P. commutatus Monterosato, a well-known Mediterranean species, also occurs in Bahia, Brazil. It seems more likely, however, that his "P. commutatus" was in fact Argopecten noronhensis (Smith, 1885), a species which is known only from the western Atlantic and which may co-occur with S. benedicti (Waller, 1973). Bavay (1906) described Pecten (Chlamys) nympha on the basis of a shell in the Paris museum collection. Because the shell was found glued to a board that also held a specimen of P. antillarum Récluz, 1853, a well-known Caribbean species, Bavay assumed that his new species also came from that region. The holotype, a pair of matching valves marked by Bavay as the figured type, is refigured herein (Figs. 10c, d). It is clearly a junior synonym of Spathochlamys benedicti. Weisbord (1964: 139), in his report of fossil Chlamys benedicti from the Pleistocene Playa Grande Formation of north central Venezuela, referred (p. 141) to "the type" of C. benedicti and to "illustrations of the type" but gave no references. He was apparently assuming that the specimen illustrated by Verrill and Bush (1898) is the holotype, although it was never specified as such. Fischer-Piette and Testud (1967) applied the name Chlamys munda Reeve to specimens from Brazil, apparently drawing support from Bavay's (1913) previous report of its occurrence there. Apparently neither Fischer-Piette and Testud (1967) nor Bavay (1902, 1913) were aware that the name C. benedicti was already in use for this same species in the western Atlantic.» 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, figs. 1-14. [p. 232, 233]
|
Spathochlamys benedicti (VerriIl and Bush, 1897); T. R. Waller, 1993, The evolution of Chlamys, figures 10a-k.
|