The Catfish Genus Tetranematichthys (Auchenipteridae)

The neotropical auchenipterid catfish genus Tetranematichthys is reviewed. Tetranematichthys was previously thought to be monotypic with its single species, T. quadrifilis, reported to have a broad range encompassing major portions of the Amazon basin and southern tributaries of the Rı́o Orinoco. Tetranematichthys quadrifilis was rather found to be endemic to the Rio Guaporé in the southwestern portions of the Amazon basin and a new species of the genus is described from material originating in the upper Rio Negro system in Brazil and Venezuela and the upper Rı́o Orinoco basin in southern Venezuela. The new species is also apparently widespread within the Amazon basin and the southern and north-central portions of the Rı́o Orinoco system. The species of Tetranematichthys have distinctive modifications of the mandibular barbel and associated systems, which are proposed as synapomorphic for the species of the genus and that potentially function as a fishing lure.