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 Río 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 Río 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 Río 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.Abstract
Drawings of ventral surface of head and anterior portion of body of (A) Tetranematichthys wallacei, MZUSP 30590, 142 mm SL; and (B) T. quadrifilis, MZUSP 37517, 141 mm SL, showing the differing alignments of the postorbital portions of the head. Only basal portions of mandibular barbels illustrated
Tetranematichthys wallacei, MZUSP 31096, 171 mm SL, holotype
Map of central and northern South America showing distribution of Tetranematichthys wallacei (dots, 1 = holotype locality) and T. quadrifilis (square, 2 = Rio Guaporé, inexact type locality of Ageneiosus quadrifilis). Some symbols represent more that one lot and/or locality
SEM photograph of the distal portion of the mandibular barbel of Tetranematichthys wallacei showing the fleshy digitiform processes of that region
Tetranematichthys quadrifilis, MZUSP 37517, 141 mm SL, Brazil, Matto Grosso, Rio Guaporé basin