A new subspecies of ithomiine butterfly, Oleria gunilla lourdes n. ssp., is described from northern Mato Grosso in central Brazil. The new taxon is confidently assigned to Oleria gunilla on the basis of both morphological and molecular evidence. Its wing pattern, with a broad expanse of orange on the dorsal forewing, is typical of the mimetic color patterns found in Ithomiini in the upper Amazon and Andean foothills of Peru, Colombia and Ecuador, very far from the type locality in northern Mato Grosso, where this taxon has no known co-mimics. Future studies are needed to investigate the mimetic relationships of this taxon with other sympatric butterflies.