Argopecten ventricosus (G. B. Sowerby II, 1842)
SOWERBY II, G. B. 1842. Monograph of the genus Pecten. In: G. B. Sowerby II (Ed.), 1842-1847, Thesaurus conchyliorum; or, monographs of genera of shells, 1 (2): 45-78, pls. 12-20. London. [p. 51, pl. 12, figs. 18-19, 26].
1835 Pecten tumidus G. B. Sowerby I, 1835
1842 Pecten ventricosus G. B. Sowerby II, 1842 [nomen novum pro Pecten tumidus G. B. Sowerby I, 1935]
1846 Pecten pomatia Valenciennes in Petit-Thouars, 1846
1835 Pecten inca Orbigny, 1846 [nomen novum pro Pecten tumidus G. B. Sowerby I, 1835]
1853 Pecten solidulus Reeve, 1853
1864 Pecten aequisulcatus Carpenter, 1864
1898 Pecten (Pecten) compactus Dall, 1898
1903 Pecten (Plagioctenium) newsomi Arnold, 1903
1930 Pecten fililextus C. C. Li, 1930
1842 Pecten ventricosus G. B. Sowerby II, 1842 [nomen novum pro Pecten tumidus G. B. Sowerby I, 1935]
1846 Pecten pomatia Valenciennes in Petit-Thouars, 1846
1835 Pecten inca Orbigny, 1846 [nomen novum pro Pecten tumidus G. B. Sowerby I, 1835]
1853 Pecten solidulus Reeve, 1853
1864 Pecten aequisulcatus Carpenter, 1864
1898 Pecten (Pecten) compactus Dall, 1898
1903 Pecten (Plagioctenium) newsomi Arnold, 1903
1930 Pecten fililextus C. C. Li, 1930
G. B. Sowerby II, 1842, plate 12.
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«19. P. VENTRICOSUS. (pl. xii. f. 18, 19, 26.) nob. P. tumidus, Sow. Zool. Proc. 1835. p. 109.
"T. sub-inaequivalvi, aequilaterali; auriculis magnis, subaequalibus; valvâ alterâ turgidâ, fusco-rufescente albidoque variegatâ, radiatim octodecim costatâ, costis supernè planulatis, interstitiis transversim striatis, alterâ turgidiore, albicante, radiatim sulcatâ; costis interstitialibus latioribus, planulatis, lateralibus fusco-variis; marginibus ventralibus acutè dentatis: long. 1.75.; lat. 1.; alt. 1.75.; poll." "Found in sandy mud at from 6 to 10 fathoms." The above name is given on account of the name "tumidus" having been previously applied to a small lenticular species. It differs from P. Nucleus in having one valve much more ventricose near the apex than the other, in the more trigonal shape, and in the greater flatness of the ribs: it is also generally a much larger shell. St. Elena; and young specimens brought from Calapan, Philippines, by Mr. Cuming». GEORGE BRETTINGHAM SOWERBY II, 1842
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«Because the type of Pecten circularis Sowerby I (1835) was incorrectly named a new species by Sowerby and is in fact a specimen of Argopecten irradians concentricus (Say, 1822), Sowerby's name is a junior subjective synonym of the latter. The next available name in the synonymy list (Grau, 1959: 97) of Pecten circularis is Pecten ventricosus Sowerby II, 1842, a name that was introduced to replace the junior homonym, Pecten tumidus Sowerby I , 1835.
The locality of Pecten tumidus given by Sowerby I (1835: 110) is "Sanctam Elenam et ad Salango, Columbiae Occidentalis", referring to Santa Elena and Salango, both on the coast of Ecuador. Sowerby II (1842: 52) repeated the Santa Elena locality and added "and young specimens brought from Calapan, Philippines, by Mr. Cuming." The statement that the species occurs in the Philippines, which was repeated by Reeve (1852, Species 31), is erroneous. Six specimens labeled Pecten ventricosus are present in the type collection of The Natural History Museum, London, and one of these specimens must be designated a lectotype if the name is to be fixed firmly . All of these type specimens consist of paired valves, and all conform to the established concept of Eastern Pacific " Argopecten circularis", Three of the specimens are associated with an old label, possibly in the hand of Sowerby II, which gives the locality as "St. Elena, Philippines" ; the remaining three are associated with a similar old label that indicates the locality as "Philippine Is ." The locality "Philippines" is clearly erroneous. The three specimens in the first lot (BMNH 1994116-1994118) are all brightly colored (orange, reddish , or lavender) and conform to the present day concept of "Argopecten circularis," sensu stricto, rather than to the northern subspecies Argopecten "circularis" aequisulcatus (Carpenter, 1864) (see Waller, 1969). The three specimens in the second lot (BMNH 1994119-1994121), on the other hand, are mottled with very dark brown or maroon pigment and resemble specimens from more northerly localities, particularly those from La Paz, Mexico, but still within the range of variation of A. " circularis," s.s.. All six specimens are greater than 2 inches in length and thus exceed the value of "long. 1.75 poll." given by Sowerby I (1835, p. 110) in his original description of Pecten tumidus. Sowerby II (1842: pl. 12, figs. 18, 19, 26) illustrated three specimens of Pecten ventricosus, only one of which (his pI. 12, fig. 18, BMNH 1994117) is possibly but not definitely among the specimens in the type collection on the basis of its bright orange color and color pattern. (The figure shows a posterior view, but the commissure of the posterior auricles is curiously reversed with respect to actual pectinid morphology.) The new and improved illustrations that Sowerby II prepared for Reeve (1852-1853: figs. 31a, 31b) represent two additional specimens, both of which are probably represented by specimens in the type collection. Fig. 31a corresponds exactly in size, dark brown mottling separated by pinkish to white areas, and the approximate pattern of these colors to one of the specimens in the second lot of three specimens referred to above (BMNH 1994119, Figures 12-15 herein). Fig. 31b corresponds exactly in size and bright lavender hue to one of the specimens in the first lot (BMNH 1994116, Figures 12-15 herein). The second specimen (Reeve's fig. 31b) is selected herein as the lectotype, because it is the specimen with the color pattern that corresponds most closely to specimens known from Ecuador. Selection of the lavender specimen as the lectotype (fig. 32b in Reeve, 1852-1853) rather than the dark brownmottled specimen represented by Reeve's fig. 32a also avoids another potential problem. There is still no universal agreement on whether a northern geographic subspecies, Argopecten "circularis" aequisulcatus (Carpenter, 1864), should be recognized, and, if it is recognized, what its southern limit should be. As reviewed by Grau (1959: 101), the concept of a northern subspecies was originally based on populations in bays along the California coast from Santa Barbara southward. Grau himself continued to recognize the subspecies while acknowledging that it is only weakly differentiated from A. "circularis circularis." Others have considered it unnecessry to use a subspecies name because of the high degree of morphological intergradation (Waller, 1969; Bernard, 1983), while still others (McLean, 1978; Haderlie & Abbott, 1980) have considered the northern form to be a full species. Argopecten aequisulcatus. There has also been lack of agreement on the southern limit of the northern form. Grau (1959) gave the southern limit as Bahia San Quentin, northwestern Baja California, Mexico. Others, however, have considered the southern limit to be Cabo San Lucas (Dall, 1921; Fitch, 1953) or La Paz, Mexico (Keen, 1971), near the southern end of the Baja California peninsula. The southern form, A. "circularis," sensu stricto, extends from Isla Cedros, Mexico, and the Gulf of California southward to Paita, Peru, and westward to the Galapagos Islands (Grau, 1959). In order to avoid the issue of whether northern populations can be distinguished at the level of subspecies or species, a lectotype of Argopecten ventricosus preferably should be designated from a population where all specimens are clearly of the southern form. The logical choice would be a specimen from well south of Baja California. The lectotype chosen here, which is presumably from the Santa Elena, Ecuador, meets this requirement». WALLER, T. R. 1995. The misidentified holotype of Argopecten circularis. The Veliger, 38 (4): 298-303, figs. 1-14. [p. 301, 302]
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Argopecten ventricosus (G. B. Sowerby II, 1842 ); T. R. Waller, 1995, The misidentified holotype of Argopecten circularis, figures 5-8, 11-14.
Pecten ventricosus Sowerby; Reeve, L. A., 1852-1853, Conchologia Iconica, Monograph of the genus Pecten, plate 7, figures 31a, 31b.
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«Additional descriprive notes: This subspecies is the northern form of the typical and can be distinguished primarily by its thinner shell, flatter left valve and more subdued coloring. In adult specimens the ribs are more angulate than those of the typical and the concentric lamellae of the disk more prominent. The size of mature specimens is greater, the average height being 80 mm and the length 88. The author's collection contains a specimen from San Pedro measuring 98 mm in height and 106 in length, the largest for which any record could be found. Adult specimens are dark brown or red-brown, mottled with white or yellow; occasional juveniles are almost completely white, others red-orange or yellow and with white or brown mottling.
Remarks: The validity of this subspecies has been questioned by various authors. The criteria for separating the shell from that of the typical would seem to be weaker than is usually required for the recognition of subspecific rank, and gross anatomy studies by Dr. N. T. Mattox and graduate student R. Kleinknecht of the Hancock Foundation showed no apparent distinctions from the typical. However constant differences in shell structure cannot be ignored and the subspecies is geographically restricted, therefore the author feels that no change in its status is advisable. Only one specimen of Chlamys circularis aquisulcata has been found on the California coast during the past seven years, according to Mr. John E. Fitch, research Director of the California State Fisheries Laboratory at Terminal Island, San Pedro. In a recent conversation with the author, Mr. Fitch said that he has been unable to find any others in the course of his many field trips, and that marine laboratories, fishermen and divers have also been unsuccessful. Although water pollution is suspected of being a factor, no definite reason is known for the near disappearance of this subspecies. Geographical range: Elkhorn Slough, Monterey Bay, California to Bahia San Quintin, western Lower California. Geochronological range: Pleistocene, Recent. Bathymetric range: From several inches below surface at low tide to about 25 fathoms, possibly deeper. Ecological data: Found on sand or mud bottoms, often in eel grass beds: usually in bays or lagoons, also in quiet water just offshore. Hancock Expeditions Collecting Stations: SOUTHERN CALIFORNIA AND SANTA BARBARA ISLANDS: 32 stations; from just below surface at low tide to 15 fathoms, sand or mud.» GRAU, G. 1959. Pectinidae of the eastern Pacific. Allan Hancock Pacific Expeditions, 23: i-viii, 1-308, 57 pls. University of Southern California Press. Los Angeles, California. [p. 102, 103]
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Chlamys (Argopecten) circularis aequisulcata (Carpenter) 1864; G. Grau, 1959, Pectinidae of the eastern Pacific, plate 33.
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