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ABSTRACT
The Siluriformes constitutes an important monophyletic ostariophysan group of mainly freshwater fishes that occurs in almost all continents. They are extremely abundant and diverse in South America, where the oldest otophysans and siluriforms occur. We restudied two putative catfish species from the early Eocene lacustrine Tufolitas Laguna del Hunco of northwestern Patagonia, Argentina, concluding that Arius argentinus CitationDolgopol, 1941, is a junior synonym of Bachmannia chubutensis CitationDolgopol, 1941. Phylogenetic analyses were performed to show the relationships of B. chubutensis, which appears as the sister group of Diplomystes. Bachmannia chubutensis is one of the most primitive catfishes known and we based on it a new family. The family is clearly diagnosed by the presence of a anterior ventrolateral expansion of cleithrum, short maxilla with two rows of teeth, double-headed autopalatine, accessory tooth plates, very huge teeth, supraoccipital process long and acute, first and fifth vertebrae not joined to complex vertebra, neural arch of fifth and sixth vertebrae very well developed, enlarged supraneural 5, suture between ceratohyal and epihyal without interdigitations, suture between contralateral cleithra and coracoids without interdigitations, six hypurals. Individuals of B. chubutensis inhabited lakes and were preserved into fine-grained, laminated fall-out and reworked pyroclastic debris inside a caldera.
ACKNOWLEDGMENTS
We thank the Agencia Nacional de Promoción Científica y Tecnológica, Consejo Nacional de Investigaciones Científicas y Técnicas, National Science Foundation (DEB-0345750. 2004–2008), and Universidad Nacional de La Plata for financial support; M. Mirande for help in the phylogenetic analysis; A. Martínez for composition of the figures; Ø. Bratland and F. Goin for the photographs; A. M. Báez, N. Brugni, the late R. Casamiquela, N. Cúneo, C. Ferraris Jr., J. Fiori, L. Grande, J. Lundberg, J. Powell, E. Romero, E. Ruigómez, M. Sabaj, R. Vari, and P. Wilf for loan of material under their care; and P. Puerta, K. Johnson, and P. Wilf for help in the field work. Detailed comments and suggestions provided by two anonymous reviewers greatly improved the manuscript.
Handling editor: Terry Grande.