A new species of copionodon lacking a free orbital rim (Siluriformes: Trichomycteridae)

Abstract

A new species of the copionodontine genus Copionodon is described from the upper reaches of a tributary to the rio Paraguaçu in the Diamantina Plateau, Bahia State, northeastern Brazil. This species represents the northernmost occurrence of the subfamily yet known. The new species can be readily recognized by its large eye without a free orbital rim. Other characters such as the entirely cartilaginous second hypobranchial, and the uniformly broad irregular midlateral dark band further diagnose the new taxon. Its particular combination of characters is superficially intermediate between Copionodon and Glaphyropoma. Detailed analysis, however, indicates that it forms a monophyletic group with species of Copionodon and therefore it should be included in that genus.