A new species of Osteocephalus from Ecuador and a redescription of O-leprieurii (Dumeril & Bibron, 1841) (Anura : Hylidae)

The South American spiny-backed treefrog, Osteocephalus leprieurii, as previously understood, is a composite of several species. We redescribe it morphologically on the basis of specimens from French Guiana and add other data on the biology of the species. We describe O. mutabor n. sp., previously confused with O. leprieurii, from the Amazon Basin of Ecuador. The two species differ in coloration, vocalizations and ontogenetic colour change. Osteocephalus leprieurii is remarkable for bearing nuptial excrescences not only on the thumb, but also under the fingers and on the chin. The vocal sac is semicircular expanding posterolaterally. Osteocephalus mutabor n. sp. is characterized by numerous dark transversal bars on the dorsum and a semicircular vocal sac. The amount of keratinized tips on the dorsal granules in males of both species is dependent on sexual activity.