A new Moenkhausia (Characiformes: Characidae) from rio Brao Norte, rio Tapajs basin, with comments on the fish endemism of Serra do Cachimbo plateau.

A new species of Moenkhausia is described from the rio Brao Norte, a tributary of Rio Teles Pires draining the Serra do Cachimbo, rio Tapajs basin, Par, Brazil. The new species is diagnosed from all congeners, except M. moisae and M. pirauba, by having a high number of scales in the longitudinal series (4346 vs. 2341 in other Moenkhausia species). It can also be distinguished from the aforementioned species based on the combination of the following characters: a single humeral blotch, 2125 branched anal-fin rays, and a round and symmetrical caudal blotch not continuous anteriorly with the dark midlateral stripe. The new tetra herein described represents an additional, possibly endemic, taxon from the headwaters draining from Serra do Cachimbo, in the Brazilian Shield.