Three new species of Poptella (Characiformes: Acestrorhamphidae: Stethaprioninae) from the Tocantins-Araguaia river system, central-northern Brazil.

Examination of extensive comparative material currently identified as Poptella compressa has enabled us to verify the existence of three new species. These three species are characterized by nine branched dorsal-fin rays. Poptella magnuspina sp.n has the following diagnostic characteristics: a longer predorsal spine, larger hooks, and a smaller pelvic fin in sexually mature males, and it is widely distributed in the Rio Tocantins-Araguaia basin of Brazil. Poptella spinula sp.n, distributed in the upper Rio Tocantins and middle and upper Rio Araguaia, is distinguished from all its congeners, with the exception of P. longipinnis, by the long first rays of the dorsal fin, a spot present on the upper lobe of the caudal fin, and a shorter predorsal spine. Finally, Poptella abathes sp.n is distinguished from congeners by having a comparatively larger mouth and a shallower body. This species is currently found only in the upper Rio Araguaia.