Revisão Taxonômica De Caiapobrycon Malabarba & Vari (2000) Characiformes: Characidae

Abstract

The subfamily Stevardiinae is one of the most diverse within Characidae, containing 371 valid species. One of them is Caiapobrycon tucurui, a small-sized species that inhabits clear, flowing waters with sandy and rocky substrates. It is distinguished from other characids by its ventral mouth, expanded maxillary bone, and strongly articulated infraorbitals 1 and 2. Caiapobrycon was described in a monotypic genus as Caiapobrycon tucurui, but based on the revisionary study conducted herein, this genus has at least three additional undescribed species: Caiapobrycon sp. n. 1, from the Xingu River basin which is distinguished from its congeners by the absence of a humeral spot,; Caiapobrycon sp. n. 2, from the Juruena River basin, distinguished by a relatively longer papillae on the lips and maxillary region; and Caiapobrycon sp. n. 3, also from the Xingu River basin, which differs from all other taxa by having a vertical spot at the insertion of the median caudal-fin rays. Until now Caiapobrycon was only distributed in the Tocantins River basin, but based on the results provided by us, its geographic distribution is expanded to other two more basins draining from the Brazilian crystalline shield: the Xingu and the Juruena rivers basins.