A new pseudopimelodid catfish, Microglanis malabarbai, is described from the rio Ijuí drainage, tributary of the middle rio Uruguay, Rio Grande do Sul, Brazil. The new species is distinguished from all other Microglanis species by the caudal fin color pattern, almost completely black, with a narrow vertical white band across central portions of the caudal-fin rays. Furthermore, it is distinguished from M. cottoides and M. eurystoma, both from rio Uruguay drainage, by head length, maxillary barbel length, internareal distance, and number of lateral-line pores, and from M. cibelae from the coastal drainages of northern Rio Grande do Sul and southern Santa Catarina states, by head length, maxillary barbel length, and body width. A key is presented for the species of Microglanis occurring in southern Brazil.
Neotropical; taxonomy; M. eurystoma; M. cibelae; M. cottoides; rio Ijuí; Southern Brazil
