A new species of Hyphessobrycon from the upper Rio Tapajós basin, in the Tapajós-Juruena ecoregion, is described. Hyphessobrycon pinnistriatus n. sp. is distinguished from its congeners by having a black, oblique stripe extending from the origin of the second branched ray to the distal end of the third branched anal-fin ray, lacking a conspicuous black midlateral stripe on the body, inner premaxillary teeth with up to seven cusps, and fins normally hyaline or with scattered chromatophores. The description of a new species that is restricted to the Tapajós-Juruena ecoregion is consistent with this region being an area of high endemism of freshwater fishes.
Keywords: Hemigrammus unilineatus; Hyphessobrycon s.s; Moenkhausia hemigrammoides; Parque Estadual Cristalino.
© 2017 The Fisheries Society of the British Isles.