Osteocephalus festae is an Amazonian species recently resurrected from a synonymy withO. buckleyi. Because few specimens are known, its morphological variation, diagnostic characters, and distribution are poorly understood. Herein we determine its phylogenetic relationships and provide a complete taxonomic account based on recently collected specimens (adults and larvae) from nine localities in Ecuador and Peru. Osteocephalus festae is most similar to O. verruciger from which it differs in having less tuberculate dorsal skin on males, smaller tympanum, and more toothrows in the oral disk of larvae. A phylogeny based on mitochondrial DNA sequences, genes 12S and ND1, shows that O. festae is closely related to O. buckleyi, O. mutabor and O. verruciger. A clade consisting of O. festae, O. verruciger, and O. buckleyi is characterized by stream dwelling tadpoles. Surprisingly, we found paraphyly among Ecuadorian populations of O. buckleyi and O. verruciger. The causes for paraphyly are unknown but in O. buckleyi may result from the existence of cryptic species. © S.R. Ron, E. Toral, P.J. Venegas, C.W. Barnes.