New Pimelodus

[Silurus]

Lucinda, PHF, FRV Ribeiro & CAS Lucena, 2016. Pimelodus quadratus, a new long-whiskered catfish from the rio Tocantins drainage, Brazil (Siluriformes: Pimelodidae). Ichthyological Exploration of Freshwaters 27: 337–345.

Abstract

Pimelodus quadratus, new species, is described from rio Tocantins drainage, Brazil. It differs from its congeners by the possession of three horizontal rows of light brown square-shaped blotches along the flanks in juvenile specimens, which merge in adults giving rise to a gray-brownish background pattern interspersed by light vermiculations. Furthermore, P. quadratus can be distinguished from the species of Pimelodus with stripes along body sides in the following manner: adult specimens of P. quadratus are distinguished from adult specimens of P. albofasciatus and P. tetramerus by the possession of a narrow and sinuous whitish stripe extending longitudinally along the dorsolateral region (i. e. between the lateral line and the dorsal region profile) from the vertical through the posterior border of the predorsal plate to the end of the adipose-fin base (or just anteriorly to it). Pimelodus quadratus can be further distinguished from P. albofasciatus and P. tetramerus by having a pointed snout projecting well beyond the margin of the lower lip in juveniles and from P. albicans by the larger horizontal diameter of the orbit. Pimelodus quadratus apparently is an additional example of exclusive species reinforcing the hypothesis of the rio Tocantins drainage as an area of endemism within South America.