Present patterns of distribution are attributed to bioclimatic fluctuation in the Pleistocene. In the course of these climatic shifts, tropical environments and their amphibian inhabitants seem to have survived in the isthmian region.
The amphibian fauna of the lowlands of the Isthmus of Tehuantepec consists of 16 genera and 36 species. Systematic studies of all available specimens from the region show that Eleutherodactylus conspicuus Taylor and Smith is a synonym of Eleutherodactylus alfredi Boulenger and that Hyla axillamembrana Shannon and Werler is a synonym of Hyla loquax Gaige and Stuart.
LITERATURE CITED
Beard, J. S.
1953. The savanna vegetation of northern tropical America. Ecol. Mono., vol. 23 (2):149-215.
Boulenger, G. A.
1898. Fourth report on additions to the batrachian collection in the Natural History Museum. Proc. Zool. Soc. London, 1898, pp. 473-482, pls. 38-39.
Burt, C. E.