A new family of perleiliform fishes from the Late Triassic of Argentina.

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

Trelew, Chubut

Jornada; XXIII Jornadas Argentinas de Paleontología de Vertebrados; 2007

Museo Egidio Feruglio

We reviewed the perleiform genera Mendocinichthys and Pseudobeaconia from the Potrerillos and Santa Clara Abajo formations (Upper Triassic; Argentina). Both taxa has been almost exclively known from taxonomic reviews that are not based on the type specimens, but on referred material stored in North America museums. In the case of Mendocinichthys, its previous review is based on referred specimens in the American Museum of Natural History. However we found out that these latter specimens represent a different taxon, for instance a new species of Pseudobeaconia. Consequently, we restrict Mendocinichthys to the type material and, within it, to the only specimen that clearly represents a distinct taxon and its thus designed lectotype. We further performed a cladistic analysis and propose a new family group for these two South American Triassic genera. The new family differs from other perleidiforms in 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. Our cladistic analysis futher indicates the existence of some lineages endemic to either certain areas of Gondwana, or the actual Europe. Pseudobeaconia was previously known from the San Clara depocenter of the Cuyana Basin only, and the new record of this genus in the Cacheuta sub-basin agrees with previous hypothesis of correlation between those geological units.