On Frog Distribution Patterns East of the Andes

The frogs of the Tropical and Subtropical lowland forests east of the Andes comprise a diverse assemblage whose basic Zoogeographie patterns are just beginning to be understood. Part of the problem in understanding the basic distributions has been the unequal representation of frog collections on a geographical basis. Recently, authors have been proposing some general distribution patterns, especially for the frogs of the Amazonian and Atlantic Forest regions (e.g. Duellman, 1982; Lynch, (1979). One general pattern proposed is that the lowland frog fauna next to the Andes is much more diverse and contains many more endemics than the central Amazonian frog fauna (Duellman, 1982; Lynch, 1979). A second pattern proposed is that the Atlantic Forest frog fauna is characterized by a high local endemicity producing a latitudinal gradient of distribution patterns (e.g. i^ynch, 1979). Although almost everyone who discusses Neotropical frog distributions includes a caveat that there is still some question regarding the distributional data-base itself, no one has attempted to assess the adequacy of the data base. In this paper, an attempt is made to assess the adequacy of the distributional data base for the frogs that occur in the tropical forests east of the Andes, emphasizing the Amazonian and Atlantic Forest areas. The first portion of this paper comprises an assessment of whether collecting artifact is cause for concern. The second portion of this paper discusses general patterns, questions, and practical consequences arising from the first section.