William Edward Duellman

“ It is contrary to evolutionary theory that a specialized group would evolve into a generalized form and then evolve new kinds of specializations to meet the needs imposed by the same environmental conditions affecting the earlier specialized group. A more reasonable hypothesis is that the evolution of opposable digits took place in a phyletic line that had as its ancestral stock a frog with generalized hands and feet. If this assumption is correct, Phyllomedusa and Agalychnis represent different phyletic lines ”

“ With few exceptions the species of Agalychnis are more arboreal in their habits than are other hylids. The species of Phyllomedusa live in the same kinds of habitats as do those of Agalychnis, but throughout the ranges of most of the species of Phyllomedusa the diversity of arboreal hylids is much greater than in Central America. In the upper Amazon Basin as many as 35 hylids occur sympatrically. Many groups of Hyla in this area (for example, the Hyla boans and Hyla marmorata groups) are equally as arboreal in their habits as are the species of Agalychnis in Central America. ”

“ According to Savage's (1966) interpretation of the origins and history of the American herpetofauna, Agalychnis and Pachymedusa are members of the Mesoamerican fauna, and Phyllomedusa is part of the Neotropical fauna. Perhaps the phyllomedusines arose in South America; from there a primitive stock spread northward and survived as Pachymedusa in México, whereas the stock in Central America and South America evolved into Agalychnis and Phyllomedusa, respectively. ”