Mactra rugata Sowerby 1846 from: Griffin, M..Nielsen, S.N.. (2008): A revision of the type specimens of Tertiary molluscs from Chile and Argentina described by d’Orbigny (1842), Sowerby (1846), and Hupé (1854) . Journal of Systematic Palaeontology
|Notice: This catalogue page may contain unedited data.
To find validated information on this taxon please visit the following project pages:
Species Mactra rugata Sowerby 1846
|Discussion / Comments:
Griffin & Nielsen (2008):
TYPE MATERIAL. The only original specimen, the holotype, was not located in the Darwin Collection at the NHM, and is presumably lost (see below).
REMARKS. The identity of this species has been in doubt over the years, as the holotype seems to have been lost early in the history of the Darwin Collection. However, it can be clearly identified with the specimen that Ihering (1907, p. 326-327, pl. 12, figs 85a-85b) illustrated as Panopea nucleus (non Panopea nucleus Ihering, 1899, p. 23, pl. 1, fig. 7). This specimen shows a very thin shell with a delicate ornamentation of radial rows of minute pustules. The exact nature of the shell in the very few specimens in which it is preserved is not known, but the possibility of this species being an anomalodesmatan cannot be ruled out. It certainly does not belong in Panopea nucleus, a species that presumably had a typical thick Panopea-like shell with a smooth interior (as this is all that can be seen in the holotype). The name Panopea nucleus has been used over the years for specimens from various localities and ages from southern South America, but many of these, as is the case of the specimen in the Ihering Collection assigned to Panopea nucleus fit better in Sowerby’s species. The generic position must remain uncertain and, while certainly not belonging in Panopea, further study of good interiors is needed to confirm an anomalodesmatan relationship. In the meantime, we provisionally place them in Mya, because of their overall similarity with species such as Mya nucleoides (Wilckens, 1911) from the Antarctic Eocene (Stillwell & Zinsmeister 1992). A neotype for “Mya” rugata is needed in order to stabilize the name and avoid continued confusion with other taxonomic units in the future. However, we prefer to wait until better material is collected and the generic position is clarified before such an action is taken.
Philippi (1887, p. 143, pl. 32, fig. 6) described a specimen from Levu (i.e., Lebu, Chile) that he identified with Sowerby’s material. He mentioned the presence on the outer shell surface of small microscopic pustules on the median area of the shell, a feature also observable on Ihering’s illustrated specimen (Ihering 1907, pl. 12, figs 85a-b).
|Griffin & Nielsen (2008):
? 1995 Panopea ibari Philippi. - Chiesa et al.
: p.46 pl. 4; fig. 4a-4b
1999 Panopea nucleus Ihering. - Frassinetti & Covacevich
: p.41 pl. 8; fig. 2-4
2008 "Mya" rugata Sowerby. - Griffin & Nielsen
: pl. 15; fig. 12
Descriptions of Tertiary fossil shells from South America..
In: Geological observations on South America. Eds: Darwin, C.. p. 249-264
Die tertiären und quartären Versteinerungen Chiles.. p. 266
Conchylien der patagonischen Formation . Neues Jahrbuch für Mineralogie, Geologie und Palaontologie p. 1-46
Les mollusques fossiles du Tertiaire et du Crétacé Supérieur de l’Argentine . Anales del Museo Nacional de Buenos Aires 3/7 p. 611
Chiesa,J.O..; Parma,S.G.. and Camacho,H.H.. (1995):
Invertebrados marinos de la Formación El Chacay (Eoceno), provincia de Santa Cruz, Argentina. Sistemática y Bioestratigrafia . Monografias de la Academia Nacional de Ciencias Exactas, Físicas y Naturales Vol. 11 p. 17-68
Frassinetti,D.. and Covacevich,V.. (1999):
Invertebrados fosiles marinos de la Formacion Guadal (Oligoceno superior-Mioceneo inferior) en Pampa Castillo, region de Aisen, Chile Translated Title: Invertebrate marine fossils from the Guadal Formation (upper Oligocene-lower Miocene) at Pampa Castillo, Aisen region, Chile.. Vol. 51 p. 96
Griffin,M.. and Nielsen,S.N.. (2008):
A revision of the type specimens of Tertiary molluscs from Chile and Argentina described by d’Orbigny (1842), Sowerby (1846), and Hupé (1854) . Journal of Systematic Palaeontology
This work is licensed under a Creative Commons Attribution 2.5 License.