A new species of the tridentine Rhinotridens from the Amazon basin (Siluriformes: Trichomycteridae)

Abstract

A new species of the recently discovered miniature tridentine catfish, Rhinotridens, is described from the Amazon basin in Brazil, Colombia, and Peru. It differs from Rhinotridens chromocaudatus, type-species of the genus, in having the caudal fin mostly hyaline, a rictal barbel vestigial or externally absent, a longer anal fin with 22–29 segmented rays, and numerous other features from the skeleton. An osteological account of the new species is provided based on cleared and stained specimens, and traits of its external morphology are revealed through scanning electron microscopy (SEM), which for the first time reveal details of the lip structure of tridentines. The seven morphological characters previously listed as synapomorphies for Rhinotridens are confirmed in the species described herein, corroborating its generic allocation. An additional characteristic from the morphology of the lateral process of the autopalatine is proposed as a novel synapomorphy for the genus.