A new species of Trichogenes from the rio Itapemirim drainage, southeastern Brazil, with comments on the monophyly of the genus (Siluriformes: Trichomycteridae)

Abstract

A new species of the formerly monotypic genus Trichogenes is described from a high-altitude stream of the rio Itapemirim system, an isolated Atlantic drainage in the State of Espírito Santo, southeastern Brazil. Trichogenes claviger, new species, differs from all other trichomycterids by the sexually dimorphic posterior process of the opercle, much elongated in males; the terminal mouth; the deeply bifurcated anterior neural spines and the presence of a large anterodorsal claw-like process on the neural arches of the anterior four free vertebrae. The new species also differs from its only congener, T. longipinnis, by a number of additional traits, including the the lack of branched anal-fin rays in specimens of any size; the broader than long posterior nostril; the deeper head (head depth 72.9-86.6% HL); the presence of a fine dark line along the base of the anal fin; the lack of dark spots on cheeks; the shape of the interopercle; the presence of odontodes on a bony expansion on the posterodorsal margin of the interopercle; the fewer vertebrae (35); the absence of an antorbital; and the fewer pleural ribs (eight). Small juveniles of the new species are also strikingly different from those of all other Trichomycteridae, including T. longipinnis, having a very large lateral eye, an upturned mouth, and compressed head. Trichogenes claviger occurs in shaded sectors of a blackwater sluggish stream with sandy substrate and patchy accumulations of vegetable debris, a habitat markedly different from the rocky torrential environment known for T. longipinnis. A comparison of the internal anatomy of the two species provides the basis for a hypothesis of a monophyletic Trichogenes. Data from the new species further support a sister-group relationship between Trichogeninae and Copionodontinae, as well as the position of that clade as sister group to all remaining Trichomycteridae.Uma espécie nova do gênero previamente monotípico Trichogenes é descrita de um riacho de altitude pertencente à drenagem do rio Itapemirim, uma bacia Atlântica isolada do Estado do Espírito Santo, sudeste do Brasil. Trichogenes claviger, espécie nova, difere de todos os outros Trichomycteridae pela presença sexualmente dimórfica de um processo posterior do opérculo muito alongado nos machos; a boca terminal; os espinhos neurais das vértebras anteriores profundamente bifurcados; e a presença de um grande processo em forma de garra ântero-dorsalmente nos arcos neurais das quatro primeiras vértebras livres. A espécie nova também se diferencia de seu único congenérico, T. longipinnis, por várias outras características, incluindo: a ausência de raios ramificados na nadadeira anal em exemplares de todos os tamanhos; a narina posterior mais larga que longa; a cabeça mais alta (altura da cabeça 72,9-86,6% do seu comprimento); a presença de uma fina linha negra ao longo da base da nadadeira anal; a ausência de manchas negras na face lateral da cabeça; o formato distinto do interopérculo; a presença de odontódeos em uma expansão óssea na margem posterodorsal...

A new catfish species of the genus Trichomycterus (Siluriformes: Trichomycteridae) from the río Orinoco versant of Páramo de Cruz Verde, Eastern Cordillera of Colombia

“…;Arratia, 1998;Schaefer & Fernández, 2009). A long rectangular fontanel has been verified also in Copionodontinae and Trichogenes Britski & Ortega, 1983, both taxa being the sister group of remaining trichomycterids (Bichuette et al, 2008;de Pinna, 1992bde Pinna, , 1998de Pinna et al, 2010), as well as in the sister group of Trichomycteridae, Nematogenys Girard, 1855 (pers. obs., Arratia Fuentes & Chang Garrido, 1975;Baskin, 1973).…”

Position of enigmatic miniature trichomycterid catfishes inferred from molecular data (Siluriformes)

“…Both Sarcoglanidinae and Glanapteryginae are psammophilic. In contrast with the typical habit shared by most catfishes of burying themselves into the substrate (Baskin, ), the Trichogeninae are mid‐water swimmers, usually exploring the water column (de Pinna, Helmer, Britski, & Nunes, ). The Copionodontinae are mainly algivorous (Zanata & Primitivo, ), whereas most species of the Trichomycterinae are insectivorous (de Pinna, ).…”

The dawn of phylogenetic research on Neotropical fishes: a commentary and introduction to Baskin (1973), with an overview of past progress on trichomycterid phylogenetics

“…Initially hypothesized as successive sister groups to all other trichomycterids (de Pinna, 1992), copionodontines and Trichogenes are in fact sister groups, forming a clade which is itself the sister group to the rest of the family (de Pinna, 1998;Datovo & Bockmann, 2010). This was further corroborated with the recent discovery of a second species of Trichogenes, T. claviger, which displays conditions resembling some of the supposed synapomorphies for Copionodontinae (de Pinna et al, 2010). A separate subfamilial rank for Trichogenes and copionodontines was initially deemed necessary in face of the original hypothesis about their relationships (de Pinna, 1992).…”