Argopecten irradians irradians (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. 173]
Pecten irradians; B. Delessert, 1841, Recueil de coquilles décrites par Lamarck, plate 15, figures 4a, 4b.
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«P. testa rotundata, subaequivalvi, albida , fulvo fuscoque variegata; radiis 18 ad 32 convexis: striis transversis exilissimis.
Habite..... Mon cabinet. Coquille rare, exotique, ayant l'aspect d'un p. operculaire très-rembruni. Largeur, 74 millimètres». JEAN-BAPTISTE LAMARCK, 1819
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«REMARKS :
Rosalie's marginal annotation mentions one specimen, but there are two specimens isolated from the Delessert collection. The larger specimen, figured by DELESSERT (1841) matches Lamarck's measurement, and is here selected as lectotype. The smaller specimen, figured by CHENU (1845), corresponds neither with Lamarck's measurement nor with Rosalie's annotation, and is not considered a type specimen. According to ICZN art. 74 a(v), the designation of the smaller specimen as lectotype by CLARKE (1965 : 176) is invalid. CURRENT TAXONOMIC POSITION AND DISTRIBUTION: P. irradians is placed in Argopecten Monterosato, 1889. For further information on synonymy and distribution, see CLARKE (1965).» 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, 30 pls. [p.485, 486]
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Pecten irradians Lamarck; J. C. Chenu, 1842-1854, Illustrations conchyliologiques, plate 30, figures 10, 11.
Pecten irradians Lamarck, 1819; H. H. Dijkstra, 1994, Type specimens of recent species of Pectinidae described by Lamarck, plate 21, figures 88-92.
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«Description. Shell outline.— Mature individuals rather large, commonly attaining heights of 50 to 70 mm, ancl moderatey right-convex (text-fig. 9). Outline of disk roughly equilateral; disk flanks shallow and curved in plane perpendicular to commissure and to disk flank. Disk gapes of narrow to moderate width.
Outer ligament and auricles.—Right auricles with dorsal margins parallel to and only slightly dorsal to outer ligament; free margins forming 90º or obtuse angles at junctures with outer ligament. Free margins of posterior auricles very shallowly sigmoidal, with most of sigmoidal curve forming about a 90º angle with dorsal margin in plane of commissure. Right anterior auricle with rounded anterior margin; byssal notch of mature individuals moderately deep, with apex rounded or truncated; ctenolium weakly developed or absent on large individuals; byssal fasciole generally strongly arched. Ornament.— Plicae of right valve 15 to 20 in number (text-fig.8), with external surfaces low and evenly rounded and with width somewhat greater than that of interspaces. Concentric lamellae on disk generally somewhat projecting only in interspaces of right valve, commonly projecting both in interspaces and on plicae of left valve, and moderately to rather broadly spaced in central region of mature shells; trend of lamellae across central region of either valve at heights greater than 20 mm distally convex across interspaces and distally concave over plicae. Disk flanks distinctly costate, with costae about equal in amplitude to auricular costae. Color very variable, that of left valve ranging from pastel orange, brown, yellorw, or almost white to very dark brown or black; right valve commonly as darkly pigmented as left. Internal features.— Resilial insertions longer than high (mean values of ad/ce of right-valve samples, .66, .67, and .79). Auricular denticles weakly to moderately developed. Cardinal crura weak. Comparison. A. irradians irradians differs from A. irradians concentricus in having thinner and flatter valves, lower marginal amplitude, and resilial insertions smaller relative to height of valve and longer relative to resilial height. Stratigraphic range. Pleistocene?, Holocene, and living.» WALLER, T. R. 1969. The evolution of Argopecten gibbus stock (Mollusca: Bivalvia), with Emphasis on the Tertiary and Quaternary Species of Eastern North America. The Paleontological Society. Memoir 3 [Journal of Paleontology, 43 (5, supplement)]: 125 pp. [p. 40]
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Argopecten irradians irradians (Lamarck); T. R. Waller, 1969, The evolution of Argopecten gibbus stock, plate 8, figure 12.
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«Types. According to Dr. Eugène Binder, 2 of Lamarck's original specimens of P. irradians are in the Museum d'Histoire Naturelle, Geneva, Switzerland, along with the bulk of Lamarck's collection. Photographs of these specimens are reproduced in Plate 1 and Plate 2. One of these, an obese and apparently somewhat malformed individual, was figured by Delessert and Chenu (Fig. 11) and the other, an apparently normal specimen, was also figured by Chenu (Fig. 10) but not by Delessert. The latter specimen is here designated as lectotype.
Although both specimens are accompanied by a label bearing the locality "Méditerranée", this is clearly erroneous. See "Remarks" below. Remarks. Lamarck's brief description (loc. cit.) of this species is as follows: "Peigne rayonnant. Pecten irradians. P. testa rotundata, subaequivalvi, albida, fulvo fuscoque variegata; radiis 18 ad 20 convexis: striis transversis exilissimis . Habite . . . mon cabinet. Coquille rare, éxotique, ayant l 'aspect d'un p. operculaire très-rembruni. Largeur, 74 millimètres." Measurements of Lamarck's specimens, partly supplied by Dr. Binder and partly deduced from examining the photographs, are given in Table 6. Much information regarding the original locality of these specimens can be deduced from the specimens themselves. Their prominent growth rests indicate an origin north of North Carolina. Growth rests in specimeris from south of that region are either not well marked or are entirely absent. With respect to rib count and W/L and H/L indices, Lamarck's specimens do not fall entirely within the observed range of any single population sample seen. They do, however, fall within the overall range of Group II (see p 15), i.e . population samples B to F, and they are outside the overall range for either Group I (sablensis), Group III (concentricus) or Group IV (amplicostatus). The rich brown color illustrated by Chenu is much like that of specimens from the United States National Museum labelled "New Jersey", but in this species group color, other than white, and within broad limits, appears to be a non-conservative character and the appearance of similarly colored individuals elsewhere would not be surprising. In addition, New Jersey is within the zone of intergradation of groups II and III. Since no characters preclude a more northern origin, and since the designation irradians is widely accepted as applying to the taxon represented by Group II, in the interests of precision and stability it is advisable to restrict the type locality to a region inhabited by specimens which belong unequivocally to Group II. Such a locality is Waquoit Bay, 7 mi. NE of Falmouth, Massachusetts, and the type locality of A. irradians s .s. is hereby restricted thereto. See Tabl e 3, Sample D, for a description of the variation of A. irradians from the new type locality. Range. North Shore of Cape Cod at Barnstable and Provincetown, Massachusetts to New Jersey. Disjunct populations also exist at Cohasset and at Scituate, Massachusetts. The precise southern limit of A. i. irradians is unknown but evidence (populations G and H) indicates that it intergrades with A. i. concentricus in the region of New Jersey and Maryland. Geologic range: Pleistocene to Recent (Dall, 1898).» CLARKE JR., A. H. 1965. The scallop superspecies Aequipecten irradians (Lamarck). Malacologia, 2 (2): 161-188. [p. 176, 177]
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Aequipecten irradians irradians
(Lamarck); A. H. Clarke Jr., 1965, The scallop superspecies Aequipecten irradians, plate 1, figures 7-9; plate 2, figures 1-7; plate 3, figures 1-4. |