| NUMBER 1 | APRIL 29, 1971 |
When we initiated a study of the herpetofauna at Santa Ceciliain Amazonian Ecuador in 1966, we were immediately confrontedwith many kinds of animals that we could not identify with the existingliterature. Comparisons of our specimens with those preservedin other museums resolved some of the problems, but manyidentifications could be made only after study of type specimens;even then some determinations remained questionable. We nowfind that in order to prepare a meaningful account of the herpetofaunaof Santa Cecilia, we must complete several taxonomic studies,the limits of which extend far beyond eastern Ecuador. Because ofour interests in hylids we have begun our studies on these frogs.
One of us (Trueb, 1970a) studied the cranial osteology ofcasque-headed hylid frogs and redefined the genus Osteocephalusbut did not determine the number of species in the genus. Our workin Amazonian Ecuador resulted in the discovery of the sympatricoccurrence of three species at each of two localities; one of thesespecies was found with a fourth species at another locality. Studyof museum specimens confirmed the recognition of these four speciesin the Amazon Basin and lower Amazonian slopes of the Andes.A fifth species from Bolivia and Perú also is included in the genus.Examination of museum specimens has provided data on the geographic[Pg 2]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 areasbeyond Ecuador. More than half of the 905 specimens of Osteocephalusare from Ecuador, a relatively small part of the total rangeof the genus.
In this paper we are presenting a taxonomic review of the genusOsteocephalus; of necessity our study has been at the alpha level.We have utilized all of the usual external characters, as well asosteological features in our definitions of the species. Tadpoles andmating calls are available for only one species, O. verrucigerus(Trueb and Duellman, 1970); these and other important systematiccharacters, such as karyotypes, are not available for the group atthis time. Our tendency has been to take a conservative view ofspecies; thus it is doubtful that any subsequent worker will recognizefewer species in the genus. Our observations on these frogs inAmazonian Ecuador are presented in a final section of this paper.