Dalton Tavares Bressane Nielsen and Christian Silva Pinto: Melanorivulus imperatrizensis, a new species of killifish (Cyprinodontiformes: Rivulidae) from the rio Tocantins basin, Brazil, pp. 136-143
Melanorivulus imperatrizensis, new species, collected in a small spring, at the middle rio Tocantins basin, northeast Brazil, is described. Melanorivulus imperatrizensis differs from all other species of the genus Melanorivulus by possessing all fins orange (vs. orange fins absent in other species of Melanorivulus or orange distal stripe on M. dapazi). The hypothesized close relationship between M. imperatrizensis and M. parnaibensis suggests a historical biogeographic relationship between Southern Amazonian tributaries and Rio Parnaíba.