A comprehensive phylogeny of species relationships of the Auchenipteridae is reconstructed here with a large-scale taxon sampling based on combined morphological and molecular datasets. The hypothesized phylogeny includes most species of Auchenipteridae (97 of 124 valid species) and multiple members of siluriform families as an outgroup (32 species) to embrace the diversity of forms among related catfishes. As the first large-scale phylogeny of the Auchenipteridae, comparison between taxa included information from both morphology (264 characters) and mitochondrial and nuclear molecular markers (3490 nucleotides) from five genes: coI, 16S, rag2, myh6 and SH3PX3. Trees were generated under two different optimality criteria (Maximum Parsimony and Bayesian Inference). A new classification for the family is presented herein to bring the taxonomy more in line with the new phylogenetic hypothesis. The strict consensus tree corroborates the monophyly of superfamily Doradoidea, family Auchenipteridae and its two subfamilies, Centromochlinae and Auchenipterinae. The new classification scheme proposes nine tribes in Auchenipteridae, based on the monophyly of major groups in both subfamilies. Centromochlus, Glanidium and Tatia are each recovered as paraphyletic. To maintain a monophyletic classification, some species treated as Tatia and Centromochlus are assigned to genera not previously recognized as valid.

Otothyropsis piribebuy, new species, is described from the río Piribebuy, a tributary to the río Paraguay basin, Cordillera, Paraguay. The new species is distinguished from O. marapoama mainly by having a continuous mid-dorsal series of 17-18 lateral plates, a robust levator crest in the hyomandibula, naked areas in the abdomen, an unpigmented circular blotch on the median portion of the lower lobe, and by several features related to sexual dimorphism. In addition, Otothyropsis is rediagnosed and its phylogenetic relationships are discussed based on its present diversity.Otothyropsis piribebuy, espécie nueva, es descrita del río Piribebuy, cuenca del río Paraguay, Departamento de Cordillera, en Paraguay. La espécie nueva es diferenciada de O. marapoama principalmente por presentar una serie continua de 17 a 18 placas laterales médio-dorsales, cresta levator robusta en la hiomandíbula, abdomen con áreas desnudas, ausencia de pigmentación en la región media del lóbulo inferior con formato circular, y por la presencia de diversas características de dimorfismo sexual. Adicionalmente, es presentada una rediagnosis para Otothyropsis, discutida sus relaciones filogenéticas y su actual diversidad.

Analysis of specimens of the auchenipterid catfish genus Tatia collected in the rio Teles Pires, a tributary of the rio Tapajós, along the border between the states of Pará and Mato Grosso, Brazil, revealed it to be an undescribed species. This new species is distinguished from all congeners with the exception of T. carolae and T. musaica by the intense, clearly demarcated, dark coloration on the dorsal and to varying degrees lateral and sometimes ventrolateral portions of the body versus the very lightly colored regions which are translucent in life on the remainder of the body. Various details of head, body and dorsal and caudal-fin pigmentation along with meristic and morphometric features distinguish the new species from T. carolae and T. musaica. The new species provides further evidence that the upper and middle rio Tapajós is a region of ichthyofaunal endemism.A análise de espécimes do bagre auquenipterídeo do gênero Tatia, provenientes do rio Teles Pires, um tributário do rio Tapajós, na divisa entre os estados do Pará e Mato Grosso, Brasil, revelou se tratar de uma espécie ainda não descrita. Esta espécie nova distingue-se de seus congêneres, com exceção de T. carolae e T. musaica, por sua intensa e distintamente demarcada, coloração escura sobre o dorso a variados graus na porção lateral e algumas vezes ventro-lateral do corpo em contraste com regiões de coloração muito clara, a qual é translúcida em vida, no restante do corpo. Vários detalhes da pigmentação da cabeça, corpo, e nadadeira caudal e dorsal juntamente com características merísticas e morfométricas distinguem a espécie nova de T. carolae e T. musaica. A espécie nova fornece evidência adicional de que a porção alta e média da bacia do rio Tapajós é uma região de endemismo da ictiofauna.