Produced by Chris Curnow, Tom Cosmas, Joseph Cooper and the Online Distributed Proofreading Team at http://www.pgdp.net _OCCASIONAL PAPERS_ of the MUSEUM OF NATURAL HISTORY The University of Kansas Lawrence, Kansas --------------------------------------------------------------- NUMBER 1 APRIL 29, 1971 --------------------------------------------------------------- A SYNOPSIS OF NEOTROPICAL HYLID FROGS, GENUS _OSTEOCEPHALUS_ By LINDA TRUEB[1] AND WILLIAM E. DUELLMAN[2] [1] Research Associate, Division of Herpetology, Museum of Natural History, University of Kansas. [2] Curator, Division of Herpetology, Museum of Natural History, University of Kansas. When we initiated a study of the herpetofauna at Santa Cecilia in Amazonian Ecuador in 1966, we were immediately confronted with many kinds of animals that we could not identify with the existing literature. Comparisons of our specimens with those preserved in other museums resolved some of the problems, but many identifications could be made only after study of type specimens; even then some determinations remained questionable. We now find that in order to prepare a meaningful account of the herpetofauna of Santa Cecilia, we must complete several taxonomic studies, the limits of which extend far beyond eastern Ecuador. Because of our interests in hylids we have begun our studies on these frogs. One of us (Trueb, 1970a) studied the cranial osteology of casque-headed hylid frogs and redefined the genus Osteocephalus but did not determine the number of species in the genus. Our work in Amazonian Ecuador resulted in the discovery of the sympatric occurrence of three species at each of two localities; one of these species was found with a fourth species at another locality. Study of museum specimens confirmed the recognition of these four species in the Amazon Basin and lower Amazonian slopes of the Andes. A fifth species from Bolivia and Peru also is included in the genus. Examination of museum specimens has provided data on the geographic variation in, and distribution of, the five species. However, our conclusions pertaining to some populations need substantiation, because we have been hampered by inadequate material from areas beyond Ecuador. More than half of the 905 specimens of _Osteocephalus_ are from Ecuador, a relatively small part of the total range of the genus.