Holotype-based validation, redescription and continental-scale range extension of the South American catfish species Hypophthalmus oremaculatus Nani and Fuster, 1947, with additional information on Hypophthalmus edentatus Spix and Agassiz, 1829 (Siluriformes, Pimelodidae)

ABSTRACT. The heretofore little-known pimelodid species Hypophthalmus oremaculatus Nani and Fuster, 1947, from the rio Parana, Argentina is redescribed and validated based on examination of its recently found holotype and extensive comparative study of specimens of all nominal species of the genus. Specimens of Hypophthalmus from the Parana Basin have often been mistakenly labelled as H. edentatus Spix and Agassiz, 1829, and H. oremaculatus has occasionally been considered a junior synonym of H. edentatus. Examination of the syntypes of H. edentatus reveals a long-mistaken concept of its diagnostic features in the original description based on Spix's inaccurate illustration. Hypophthalmus oremaculatus is common and widespread in the Parana Basin, including the Upper Parana system. This species is also widespread in the Amazon and Orinoco basins. Hypophthalmus oremaculatus is distinguished from other species of the genus by the following combination of characters: caudal fin shallowly-forked, head broad an...