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Species Pecten centralis Sowerby 1846 | ||||||
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| Discussion / Comments: | ||||||
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Griffin & Nielsen (2008): TYPE MATERIAL. Specimen NHM-L27696 was designated lectotype (as “tipo”) by Morra and Erdmann (1989, p. 121), but as Sowerby’s original description clearly implies that there was more than one specimen, their lectotype designation by inference of holotype is invalid (ICZN 1999, Art. 74.5). This specimen is a highly incomplete left valve from “Port San Julian, Argentina”. Of the two other syntypes, NHM-L27697 (from Port Desire) is a fragment of the disc of a small specimen with very coarse scales on the costal crests, and NHM-L27698 (also from Port Desire) is a small, highly incomplete umbo from a large and flat specimen, i.e., a left valve, with weak surface sculpture and three prominent plicae. Del Río (2004a) has recently reviewed the large pectinids from the Patagonian Cenozoic and illustrated specimen NHM 27696, which she erroneously considered as the holotype (p. 696, fig. 6.10), probably following Morra & Erdmann (1989). Again, this type designation is invalid, as there are other syntypes, as explained above. As one of the other syntypes belongs in a different species, and in order to stabilize nomenclature and avoid further confusion with this species, we follow general usage and formally designate this specimen (NHM 27696) as lectotype. REMARKS. The illustration provided by Sowerby appears to be a composite of all three specimens he had available. The width of the main radial costae and the prominence of the scales are greatly overemphasized on the figured specimen, which is the lectotype NHM-L27696. Conversely, paralectotype NHM-L27697 has much coarser scales than the figure, while paralectotype NHM-L27698 accounts for the exaggerated width of the main costae of the figured specimen. This is one of the large pectinids found in the late Oligocene and early Miocene of Patagonia and, as stated by Beu & Darragh (2001, 52-53 ) fits reasonably well in Equichlamys Iredale, 1929 [type species Pecten bifrons Lamarck, 1819]. It shares with other members of the genus the large inequivalve shells with few strong ribs and shagreen microsculpture covering the entire shell surface. In her revision of this species, del Río (2004a) included it in the new genus Jorgechlamys del Río, 2004 [type species Myochlamys juliana Ihering, 1907], a view which is followed here. Most of the material she described comes from rocks exposed along the southern coast of the San Jorge Gulf and included by her in the San Julián Formation, although the exact relationship of these rocks with the San Julián Formation exposed further south remains yet to be fully understood. Likewise, the material referred to this species and described and illustrated by Morra & Erdmann (1989), comes also from rocks exposed along the San Jorge Gulf, i.e., Cañadón El Lobo and Bahía Mazarredo. They also included these sediments in the San Julián Formation of Bertels (1970), the type section of which lies about 400 kilometers to the south. These rocks are probably referable to other lithostratigraphic units (Bellosi, 1995). |
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| Synonym list: | ||||||
| Griffin & Nielsen (2008): 1846 Pecten centralis Sowerby. - Sowerby : p.253 pl. 3; fig. 31
1989 Mesopeplum centralis Sowerby. - Morra & Erdmann : 120-121 pl. 1; fig. 1-2
1999 "Chlamys" centralis Sowerby. - Frassinetti & Covacevich : p.24 pl. 4; fig. 5-7
2004 Jorgechlamys centralis Sowerby. - del Rio : p.695 fig. 6.1-6.10
2004 Jorgechlamys centralis Sowerby. - del Rio : fig. 13.5
2008 Jorgechlamys centralis Sowerby. - Griffin & Nielsen : pl. 3; fig. 4
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| References: | ||||||
Sowerby,G.B.. (1846): Morra,G.. and Erdmann,S.. (1989): Frassinetti,D.. and Covacevich,V.. (1999): del Rio,C.J.. (2004): del Rio,C.J.. (2004): Griffin,M.. and Nielsen,S.N.. (2008): |
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| Anonymous: Unedited TaxonConcept data | ||||||
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