Colomesus tocantinensis Leal do Amaral, Brito, da Silva & de Carvalho 2013

This species is distinguished from its congeners (asellus, psittacus) by the following characters: basal pterygiophores 6-7 and anal-fin rays 9 (vs. 10-11 for both its congeners); basal pterygiophores and dorsal-fin rays 10 (vs. 11); an opercle with a posterior ventral border subdivided in a ventral and a posterior region, the herein called ‘‘inverted V’’ shape (vs. triangular opercle); differs from C. asellus by the absence of dermal flaps across the chin (vs. uniquely present in C. asellus); caudal peduncle with 8 vertebrae (Ref. 122317).

Colomesus tocantinensis is a species of pufferfish in the family Tetraodontidae. It is endemic to Brazil, where it inhabits the Tocantins River basin. It reaches a length of 3.5 cm (1.4 inches) SL. The species was described in 2013 by Cesar R. L. Amaral, Paulo M. Brito, Dayse A. Silva, and Elizeu F. Carvalho based on morphology and genetic evidence, both of which separate it from its congeners Colomesus asellus and C. psittacus.