Sistematic revision of Pseudobeaconia Bordas, 1944, and Mendocinichthys Whitley, 1953 (Actinopterigii: ?Perleidiformes?) from the Triassic of Argentina

LÓPEZ-ARBARELLO, A. & ZAVATTIERI, A.M.

PALAEONTOLOGY

The Palaeontological Association

Lugar: Londres; Año: 2008 p. 1025 - 1052

0031-0239

The perleidiform Mendocinichthys and Pseudobeaconia from the Potrerillos andSanta Clara Abajo formations (Upper Triassic; Argentina) are reviewed. Mendocinichthys has been known from a review of this species that is not based on the type material, but on referred specimens in the American Museum of Natural History. However, these latter specimens are here found to represent a different taxon, for instance a new species of Pseudobeaconia, P. celestae sp. nov. Consequently Mendocinichthys is here restricted to the type material and, within it, to the only specimen that clearly represents a distinct taxon and is thus designated lectotype. We further performed a cladistic analysis and propose a new family group, Pseudobeaconiidae for these two South American Triassic genera, which is mainly characterized by the presence of an incomplete dorsal ridge of spine-like scales between the skull and the dorsal fin, and scales with straight posterior border, an elevated central region and marginal concentric ridges of ganoine. The cladistic analysis further indicates the existence of some lineages endemic to either certain areas of Gondwana, or the actual Europe. Pseudobeaconia celestae sp. nov. represents the first record of Pseudobeaconia in the Cacheuta sub-basin of the Cuyana Basin. The genus was previously known from the Santa Clara depocenter of the Cuyana Basin only, and the new record agrees with previous hypothesis of correlation between those geological units.