The South American catfish genus Auchenipterus Valenciennes, 1840 (Ostariophysi : Siluriformes : Auchenipteridae): monophyly and relationships, with a revisionary study

The Neotropical catfishes of the genus Auchenipterus Valenciennes (1840) ar e reviewed, The genus is hypothesized to be a monophyletic assemblage on th e basis of rile shared presence of grooves in the ventral surface of the he ad that accommodate adducted mental barbels. A possible second synapomorphy , the presence of papillae on the dorsal and medial surface of the ossified maxillary barbel of mature males: is tentatively advanced pending discover y of adult males of three species. Contrary to previous hypotheses which co nsidered Auchenipterus to consist of a maximum of five species, we recogniz e 11 species, including two previously undescribed forms, A. britskii and A . menezesi: Auchenipterus is broadly distributed through the Rio Orinoco, R io Amazonas, and Rio de La Plata basins, and the coastal drainages of the G uianas, with one species in the Rio Pindare-Mirim and Rio Parnaiba basins o f northeastern Brazil. Auchenipterus nuchalis, previously thought to be bro adly distributed across the range of the genus, is found to rather have a r estricted distribution in the eastern portions of the Amazon basin, the low er portions of the Rio Tocantins, and lower courses of some rivers in Surin ame and French Guiana. Citations of A. nuchalis from elsewhere: in the rang e of the genus are of other species. Euanemus Muller & Troschel (1842) and Ceratocheilus Miranda Ribeiro (1918) are considered synonyms of Auchenipter us. Euanemus colymbetes Muller & Troschel (1842) is considered a synonym of Auchenipterus dentatus Valenciennes (1840), and A. paysanduanus Devincenzi (1933) is placed into the synonyms of A. nigripinnis Boulenger (1895). A n eotype is designated for Hypopthalmus nuchalis Spix & Agassiz (1829). Lecto types are designated for Euanemus colymbetes and Auchenipterus nigripinnis. (C) 1999 The Linnean Society of London.