BY WILLIAM E. DUELLMAN University of Kansas Lawrence 1960 University of Kansas Publications Museum of Natural History Volume 13, No. 2, pp. 19-72, pls. 1-8, 3 figs. August 16, 1960 University of Kansas Publications, Museum of Natural History Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Robert W. Wilson Volume 13, No. 2, pp. 19-72, pls. 1-8, 3 figs. Published August 16, 1960 University of Kansas Lawrence, Kansas PRINTED IN THE STATE PRINTING PLANT TOPEKA, KANSAS 1960 28-3859...

Few regions in Middle America are so important zoogeographically as is the Isthmus of Tehuantepec, that neck of land connecting North America with Central America, separating the Pacific Ocean from the Gulf of Mexico by a distance of only about 220 kilometers (airline), and forming a low break between the highlands of México and those of Central America. Before World War II the isthmus could be reached readily only by railroad or by ocean vessel to Salina Cruz or Coatzacoalcos. With the advent o

The Isthmus of Tehuantepec is a strip of land forming a low pass, which separates the mountain masses of México proper from those of Central America, and at the same time provides a continuum of lowlands from the Gulf of Mexico to the Pacific Ocean. This topography combines with the climatic conditions to create extremely diverse environments, the distribution of which can be adequately understood only after an acquaintance with the topography and climate of the region. In east-central Oaxaca th

The following localities are those referred to in the text. The name of the locality (listed alphabetically by states) is followed by latitude, longitude, elevation, general description (town, ranch, etc.), and general type of habitat. Unless otherwise noted, distances are straight-line (airline) distances in kilometers. The localities have been plotted from the American Geographical Society's "Map of Hispanic America on the Scale of 1:1,000,000" (Millionth Map). Numbers in brackets identify the

In presenting an account of the amphibian fauna of the lowlands of the Isthmus of Tehuantepec three items must be considered: 1. The composition of the fauna. 2. The ecology of the fauna. 3. The distribution of the fauna. These items, together with similar data concerning the amphibians of the adjacent highlands, will form the basis for the subsequent discussion of the establishment of present patterns of distribution in the isthmian region. The amphibian fauna of the lowlands of the Isthmus of

To amphibians inhabiting the foothills and mountains of southern México and northern Central America, the isthmus presents a great barrier to dispersal. For example, salamanders of the genus Thorius , the mexicanus and augusti groups of the genus Eleutherodactylus , the bistincta group of the genus Hyla , and the genus Tomodactylus occur on the Mexican Plateau and southward into the mountains of Oaxaca. Nevertheless, no members of these groups are present in the Guatemalan-Chiapan Highlands. The

From the foregoing analysis of geographical and ecological distribution in the Isthmus of Tehuantepec we may strive for an interpretation of the events that led to the establishment of patterns of distribution displayed not only by the amphibians, but other terrestrial vertebrates as well. The thesis that I am proposing below is based on the premise that in southern México and northern Central America climatic fluctuation during the Pleistocene was of sufficient magnitude to cause vegetational s

For each species of amphibian known to occur in the lowlands of the Isthmus of Tehuantepec, localities where one or more specimens were collected are listed, and variation, ecology, and life histories are discussed. A total of 2833 specimens has been examined for the purposes of this study. Individual specimens cited in the text are listed with catalogue numbers and abbreviations of the name of the museum, as follows: AMNH  American Museum of Natural History KU    University of Kansas Museum of

Investigations of the amphibians and their environments in the Isthmus of Tehuantepec have been presented with the aim of gaining an understanding of the present biological and of the historical events responsible for the present patterns of distribution of amphibians in this region. The Isthmus of Tehuantepec embraces three major environments—savanna, semi-arid scrub forest, and quasi-rainforest. The rainforest presents an environment noticeably different from the other two and has a different

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. 1931. A study of the teiid lizards of the genus Cnemidophorus with special reference to their phylogenetic relationships. Bull. U. S. Nat. Mus., No. 154, pp. viii + 286. Contreras A., A. 1942. Mapa de las provincias

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