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diff --git a/38440-8.txt b/38440-8.txt new file mode 100644 index 0000000..f62c3f3 --- /dev/null +++ b/38440-8.txt @@ -0,0 +1,3641 @@ +The Project Gutenberg EBook of A Distributional Study of the Amphibians of +the Isthmus of Tehuantepec, Mexico, by William E. Duellman + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: A Distributional Study of the Amphibians of the Isthmus of Tehuantepec, Mexico + +Author: William E. Duellman + +Release Date: December 30, 2011 [EBook #38440] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK A DISTRIBUTIONAL STUDY OF *** + + + + +Produced by Chris Curnow, Joseph Cooper, Diane Monico, and +the Online Distributed Proofreading Team at +http://www.pgdp.net + + + + + + + + + + + +UNIVERSITY OF KANSAS PUBLICATIONS +MUSEUM OF NATURAL HISTORY + +Volume 13, No. 2, pp. 19-72, pls. 1-8, 3 figs. + +August 16, 1960 + +A Distributional Study of the Amphibians +of the Isthmus of Tehuantepec, México + +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 + +A Distributional Study of the Amphibians +of the Isthmus of Tehuantepec, México + +BY +WILLIAM E. DUELLMAN + +UNIVERSITY OF KANSAS +LAWRENCE +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 + + + + +A Distributional Study of the Amphibians of the Isthmus of Tehuantepec, +México + +BY + +WILLIAM E. DUELLMAN + + + + +CONTENTS + + + PAGE +INTRODUCTION 21 + Acknowledgments 23 + Field Studies in the Isthmus of Tehuantepec 23 + Sources of Material 24 + +DESCRIPTION OF THE ISTHMUS OF TEHUANTEPEC 25 + Physiography 25 + Climate 28 + Vegetation 29 + The Sierra de los Tuxtlas 32 + +GAZETTEER 33 + +THE AMPHIBIAN FAUNA OF THE LOWLANDS 37 + Composition of the Fauna 37 + Ecology of the Fauna 38 + Distribution of the Fauna 42 + +THE AMPHIBIAN FAUNA OF THE FOOTHILLS AND ADJACENT HIGHLANDS 44 + +ESTABLISHMENT OF PRESENT PATTERNS OF DISTRIBUTION 45 + +ACCOUNTS OF SPECIES 49 + +SUMMARY 68 + +LITERATURE CITED 69 + + + + +INTRODUCTION + + +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 of roads, principally the Trans-isthmian +Highway, vast areas of the interior of the isthmus became accessible to +biologists. Nevertheless, long before roads were built in the isthmian +region collectors and biologists visited it, especially the town of +Tehuantepec, from which collections date back to the 1870's. Therefore, +it is rather surprising that no attempt has been made to present a +faunal list of the amphibians or reptiles of the isthmus. Ruthven +(1912) summarized his collections from the vicinity of Cuatotolapam, +Veracruz, and Hartweg and Oliver (1940) presented an annotated list of +the species collected by them in the vicinity of Tehuantepec. In recent +years there have been only a few papers reporting species from the +isthmus (Fugler and Webb, 1957; Langebartel and Smith, 1959). The +zoogeographic significance of the Isthmus of Tehuantepec is exemplified +by the works of Burt (1931), Duellman (1958), Gloyd (1940), Oliver +(1948), and Stuart (1941), who in their discussions of evolution and +dispersal of various genera of reptiles, pointed out that the Isthmus +of Tehuantepec was a region of zoogeographic importance. + +Originally I intended to study the entire herpetofauna of the isthmus. +But I have not had opportunity to study all of the reptiles, and I have +not had the inclination to solve certain taxonomic problems concerning +them. The amphibians that I collected, together with all other known +specimens in museums, have been studied. Therefore, the present report +is concerned only with the amphibians. Only the amphibians of the +lowlands of the isthmus have been sampled adequately. Although I have +commented on the highland species in the discussion of distribution, +they are not included in the systematic section, which deals solely +with the 36 species definitely known to occur in the lowlands of the +isthmus. + +Among the species of amphibians that I would expect to occur in the +isthmus, the only one not yet found there is _Hyla phaeota_. Sufficient +specimens of most of the species are available to show their variation +in the isthmus. Consequently, the systematics of these amphibians is on +a fairly substantial basis. Probably certain species in the isthmian +region will be found to be conspecific with others to the south, for +example _Hyla ebraccata_ with _Hyla leucophyllata_ and _Hyla +robertmertensi_ with _Hyla underwoodi_. Nevertheless, such taxonomic +changes will not affect the distributional picture presented here. Our +greatest lack of knowledge concerning the amphibians is about their +life histories, as may be illustrated by the following questions, all +of which now are without definite answers. Where do many of the small +frogs conceal themselves during the dry season? What amount of, if any, +interspecific competition exists among several species of tree frogs, +all of which breed in the same ponds? What factors in the environment +permit certain amphibians, but not others, to live in the humid +rainforests, as well as in the arid tropical scrub forest? The answers +to these questions and many others must await additional field studies. + +The purpose of this paper is to make known the species of amphibians +living in the Isthmus of Tehuantepec, to describe the environments in +which they live, and to discuss their distribution in the isthmus. With +respect to the distribution of animals in the Isthmus of Tehuantepec I +will attempt to explain the present patterns of distribution with +special reference to climatic fluctuation in the Pleistocene. + + +_Acknowledgments_ + +My extensive field work in the Isthmus of Tehuantepec was made possible +by grants from the Penrose Fund of the American Philosophical Society +(1956) and the Bache Fund of the National Academy of Sciences (1958). +Furthermore, my field work received the hearty support of the Museum of +Zoology at the University of Michigan; for their cooperation I am +indebted to Norman Hartweg, T. H. Hubbell, and Henry van der Schalie. +In the course of my studies I received helpful suggestions from Norman +Hartweg, L. C. Stuart, and Charles F. Walker, to whom I am grateful. +For permission to examine specimens in their care I thank Doris M. +Cochran, Hobart M. Smith, and Richard G. Zweifel. I am deeply indebted +to Thomas MacDougall for many suggestions and for aid in preparing the +gazetteer. I am most grateful for the efforts of my field companions, +Richard E. Etheridge, Jerome B. Tulecke, John Wellman, and especially +my wife, Ann S. Duellman, who spent many long days and nights gathering +much of the data on which this report is based. Our work in the isthmus +was furthered by the generous help and hospitality of many residents, +especially the late Wilbur Barker of Tehuantepec, Fortunado Delgado of +Rancho Las Hojitas near Acayucan, César Fárjas of Donají, and Juan +Mayol of San Andrés Tuxtla. Profesor Jordi Juliá Z. of the Laboratorio +de Entomología, Comisión del Papaloapan, Ciudad Alemán, Veracruz, +helped make possible my field work in 1959; for this he has my sincere +thanks. In conclusion I express my gratitude to Ing. Juan Lozano +Franco, Secretaria de Agricultura y Ganadería, for providing me with +the necessary permits. + + +_Field Studies in the Isthmus of Tehuantepec_ + +I first visited the Isthmus of Tehuantepec and collected on the Pacific +lowlands of the isthmus in July, 1955. At that time heavy rains and +impassable roads restricted travelling. In February and March of 1956 +my wife and I concentrated our efforts in the central region between +the Río Jaltepec and Matías Romero, but also made several trips across +the isthmus to gather ecological data in the dry season. In July of the +same year, accompanied by Richard E. Etheridge, we again crossed the +isthmus several times in order to gather ecological data in the wet +season, and studied especially hylid frogs, most of which had not been +seen in the dry season. Accompanied by Jerome B. Tulecke and John +Wellman, I collected again in the isthmus in July, 1958, between Salina +Cruz and Tehuantepec, and between Coatzacoalcos and Cosoleacaque. In +March and April, 1959, I collected at Ciudad Alemán. Nearly 1200 +specimens of 30 species of amphibians were thus collected in the +Isthmus of Tehuantepec; all specimens are now in the Museum of Zoology +at the University of Michigan. Of other species known from the isthmus, +I have had field experience with all but one (_Bolitoglossa +veracrucis_) in other parts of México. + + +_Sources of Material_ + +There are in museum collections nearly 3000 specimens of amphibians +with reliable data from the Isthmus of Tehuantepec. Among the first +herpetological specimens collected in the isthmian region are those +assembled by Francis Sumichrast in the 1870's from the vicinity of +Santa Efigenia and Tapanatepec, Oaxaca. These specimens were sent to +the United States National Museum and the Museum National d'Histoire +Naturelle in Paris; many served as the types of new species: _Bufo +canaliferus_ Cope, _Eleutherodactylus rugulosus_ Cope, _Syrrhophus +leprus_ Cope, and _Hylella sumichrasti_ Brocchi. In 1911 Alexander G. +Ruthven collected in the savanna country near Cuatotolapam, Veracruz; +the report on his collections (1912) is the first dealing with the +herpetofauna of a part of the isthmus. His specimens are in the +collection of the University of Michigan Museum of Zoology. Norman +Hartweg and James A. Oliver collected for the University of Michigan +Museum of Zoology in the vicinity of Tehuantepec, Oaxaca, during the +summer of 1936. The results of their work were published as an +annotated list of species occurring on the Pacific slopes of the +isthmus (1940). Hobart M. Smith collected in the vicinity of +Tehuantepec in January, 1940; his specimens are in the United States +National Museum. Specimens collected by Smith served as the types of +_Eleutherodactylus avocalis_ Taylor and Smith and _Diaglena reticulata_ +Taylor. Walter W. Dalquest collected vertebrates for the University of +Kansas in southern Veracruz in the winters of 1947 and 1948; he spent +about six months on the Gulf lowlands of the isthmus, principally in +the vicinity of Jesús Carranza. For the past two decades Thomas +MacDougall, a resident of New York City, has spent his winters +collecting biological specimens in southern México. He makes his +headquarters at Tehuantepec, but his compulsion to see the "back +country" has taken him to many remote parts of southern Oaxaca. His +earlier collections are in the American Museum of Natural History; the +later ones are in the University of Illinois Museum of Natural History. + +Minor collections include those made by Matthew W. Stirling at San +Lorenzo, Veracruz, February-April, 1946 (United States National +Museum), by Fred G. Thompson on a trip across the isthmus in December, +1955 (University of Michigan Museum of Zoology), by the University of +Kansas Museum of Natural History field party under the direction of +Rollin H. Baker at Tolosita, Oaxaca, and by David A. Langebartel and +associates from southern Oaxaca in June, 1958 (University of Illinois +Museum of Natural History). + +In the collections of the United States National Museum are several +species of amphibians sent to the museum from Tehuantepec by Francis +Sumichrast. These include _Bolitoglossa platydactyla_ (USNM 30305, +30344-6, 30528), _Bolitoglossa rufescens_ (10042), _Chiropterotriton +chiropterus_ (30347), _Lineatriton lineola_ (30353), _Parvimolge +townsendi_ (30352), _Pseudoeurycea cephalica_ (30350), _Thorius +pennatulus_ (30348-9), _Hyla miotympanum_ (30302-3), and _Hyla picta_ +(30304). Because of the poor condition of the specimens, determinations +of those listed as _Bolitoglossa rufescens_ and _Pseudoeurycea +cephalica_ are uncertain. With the exception of the _Bolitoglossa +rufescens_, which is stated to have come from Santa Efigenia, all of +these specimens are catalogued as having come from Tehuantepec. None of +these species has since been recorded from the Pacific slopes of the +isthmus; however, they all occur in the vicinity of Orizaba, Veracruz. +Probably Sumichrast carried the specimens with him from Orizaba, his +home before moving to Santa Efigenia, and shipped them from Tehuantepec +to the United States National Museum. These species definitely should +not be considered as inhabitants of the Pacific slopes of the Isthmus +of Tehuantepec. + + + + +DESCRIPTION OF THE ISTHMUS OF TEHUANTEPEC + + +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. + + +_Physiography_ + +In east-central Oaxaca the mountain masses comprising the Sierra Madre +Oriental and the Sierra del Sur terminate in a series of ranges--Sierra +de Juárez, Sierra de los Míjes, and Sierra de Choapam. From lofty +peaks, such as Cerro de Zempoaltepetl (3400 meters), the highlands +diminish eastward to succeedingly lower ridges, until in the middle of +the Isthmus of Tehuantepec the continental divide is about 250 meters +above sea level. Eastward from this low divide the land rises to form +the Sierra Madre de Chiapas, which is continuous with the highland +masses of Guatemala. + +For the purposes of this description, the lowlands of the isthmus may +be divided into three parts--the Gulf Coastal Plain, the central +ridges, and the Pacific Coastal Plain, which in the isthmus is called +the Plains of Tehuantepec (Figs. 1 and 2). + +The Gulf Coastal Plain is broad and fairly level near the coast, but +rolling in the interior. The plain, throughout most of its length in +the isthmus, is at least 75 kilometers wide. The majority of the region +in the isthmus is drained by the Río Coatzacoalcos, which flows in a +northerly course to the Gulf of Mexico. The western part is drained by +the Río San Juan, the principal tributary of the Río Papaloapan. Behind +the coastal dunes are frequent, and sometimes large, lagoons. +Immediately inland from Coatzacoalcos and along the lower stretches of +the Río Papaloapan are extensive marshes. Essentially the entire +coastal plain, with the exception of the coastal dunes, consists of +rich alluvial deposits. + +[Illustration: FIG. 1. Map of the Isthmus of Tehuantepec based on the +American Geographical Society's "Map of Hispanic America on the Scale +of 1:1,000,000." + +The localities shown are numbered in the gazetteer; the numerical +sequence of localities is an arrangement whereby north takes precedence +over south and west over east. 1. Alvarado. 2. Lerdo de Tejada. 3. +Tlacotalpan. 4. Tula. 5. Tecolapan. 6. Amatitlán. 7. Cosamaloapan. 8. +Chacaltianguis. 9. Novillero. 10. Ciudad Alemán. 11. Papaloapan. 12. +Tuxtepec. 13. Cuatotolapam. 14. Hueyapan. 15. Berta. 16. Coatzacoalcos. +17. Ayentes. 18. Río de las Playas. 19. Cosoleacaque. 20. Minatitlán. +21. Acayucan. 22. Aquilera. 23. San Lorenzo. 24. Naranja. 25. Suchil. +26. Jesús Carranza. 27. La Oaxaqueña. 28. Ubero. 29. Donají. 30. +Tolosita. 31. El Modelo. 32. Sarabia, 33. Guichicovi. 34. La Princesa. +35. Santa María Chimalapa. 36. Matías Romero. 37. Santo Domingo Petapa. +38. El Barrio. 39. Palmar. 40. Chivela. 41. Santiago Chivela. 42. +Nizanda. 43. Agua Caliente. 44. Portillo Los Nanches. 45. Ixtepec. 46. +La Ventosa. 47. Zanatepec. 48. Unión Hidalgo. 49. Tres Cruces. 50. +Juchitán. 51. Escurano. 52. Salazar. 53. Santa Efigenia. 54. +Tequisistlán. 55. Cerro de Quiengola. 56. San Pablo. 57. Mixtequilla. +58. Tapanatepec. 59. Zarzamora. 60. Limón. 61. Tehuantepec. 62. +Bisilana. 63. Santa Lucía. 64. Cerro de Arenal. 65. Cerro de San Pedro. +66. La Concepción. 67. Tenango. 68. San Antonio. 69. Huilotepec. 70. +Salina Cruz.] + +[Illustration: FIG. 2. Topographic profile of the Isthmus of +Tehuantepec showing major localities along the Trans-isthmian Highway +and major types of vegetation. Vertical exaggeration approximately 165 +times.] + +The central ridges extend from the Río Jaltepec southward to within 40 +kilometers of the Pacific coast. It is in this area that the continuity +of the high ridges and volcanic peaks, which extend nearly the entire +length of the Americas, is interrupted at a point almost directly in +line with the shortest distance between the two oceans. The northern +part of this central region consists of hills dissected by tributaries +of the Río Coatzacoalcos; the principal ones from north to south +are--Río Jaltepec, Río Tortuguero, Río Sarabia, and Río Malatengo. The +plains of Chivela are south of these rivers and lie at an elevation of +about 200 meters; at the southern edge of these plains a range of hills +rises to 250 to 400 meters above sea level. These hills drop abruptly +to the Plains of Tehuantepec. In the northern and central parts of this +central region the rocks are granitic; the hills to the south of the +Plains of Chivela are limestone. + +The Pacific Coastal Plain or Plains of Tehuantepec have a maximum width +of about 30 kilometers. From the base of the hills at an elevation of +about 75 meters the plains slope gradually to the sea. To the west of +the Río Tehuantepec and to the east of the Plains of Tehuantepec at the +base of the Sierra Madre de Chiapas, the coastal plain becomes much +narrower; in these places the continuity of the plain is frequently +interrupted by low north-south ridges extending outward from the +mountains or by isolated hills. The soil is poor, varying from volcanic +rock to gravel and sand. + + +_Climate_ + +The prevailing winds are from the north across the Gulf of Mexico. +These moisture-laden winds precipitate most of their moisture north of +the central ridges. This results in high rainfall on the northern +slopes and Gulf Coastal Plain and relatively little rainfall on the +southern slopes and the Pacific Coastal Plain. Precipitation is cyclic; +there is a marked wet and a dry season throughout the region, but this +is most noticeable on the Pacific lowlands (Fig. 3). At Salina Cruz on +the Pacific Ocean the average annual rainfall is 1040 mm. (Contreras, +1942); of this amount, only 15 mm. falls from November through April. +On the Gulf Coastal Plain (Minatitlán station) the average annual +rainfall is 3085 mm. In this region the driest months are February +through May, during which time 236 mm. of rain falls. At Salina Cruz +the wettest month is June; at Minatitlán it is September. There is +little variation in temperature throughout the isthmus; the average +annual temperature at Salina Cruz is 26.6° C.; that at Minatitlán is +26.2° C. During the winter when masses of air from the arctic move +southward into the Great Plains of the United States, cool winds blow +across the isthmus. These are usually accompanied by overcast sky and +sometimes a slight amount of precipitation. These "nortes" may cause a +drop in temperature of about six to eight degrees in a few hours. + +[Illustration: FIG. 3. Climatographs for Minatitlán, Veracruz, and +Salina Cruz, Oaxaca, based on data given by Contreras (1942). Plotted +points are for mean monthly temperatures and rainfall; months are +indicated by numbers.] + + +_Vegetation_ + +The topography and climate combine to produce drastically different +types of climax vegetation on the northern and southern lowlands of the +isthmus. The picture is somewhat complicated by the savannas on the +Gulf Coastal Plain, which, as will be shown later, are dependent upon +edaphic features more than climatic conditions. The following brief +account of the vegetation in the Isthmus of Tehuantepec is based on +data provided by Williams (1939) and Goldman (1951), supplemented by +personal observations. The purpose of this description is not to +analyze the flora of the isthmus, but to give the reader a picture of +this aspect of the biota of the major environments with which I shall +be concerned in the ensuing discourse on the amphibians of the region. +The three divisions of the isthmus recognized in the account of the +physiography serve equally well in describing the vegetation. Those +divisions are as follows: + +Gulf Lowlands + +On the lowlands north of the continental divide and extending to the +Gulf of Mexico are three major types of vegetation--tropical +rainforest, arid tropical scrub forest, and savanna. Aside from these, +there are marshes and lagoons near the coast. + +On the coastal dunes there are thickets of sea grape, patches of +_Cenchrus_, and clumps or scattered _Opuntia_. The lagoons are bordered +by mangrove thickets made up primarily of _Lonchocarpus hondurensis_. +In the marshes along the lower Río Coatzacoalcos and Río Papaloapan the +tall tough grass, _Gynerium sagittatum_, is common. + +According to Beard (1953: 291) the development of savanna vegetation is +dependent upon soil, topography, and drainage. Level regions having +permeable soil horizons lying on top of an impermeable horizon provide +poor drainage. In most savanna regions in the Americas the grasslands +become waterlogged or even partly flooded during the rainy season and +desiccated in the dry season. Many ecologists and phytogeographers have +postulated that savannas are either man made or are examples of a fire +climax. Beard (_op. cit._: 203) provided multitudinous evidence that +the association of savanna vegetation and certain types of edaphic and +topographic conditions was so strongly marked that grassland is the +natural vegetation in these areas. + +Savannas are scattered through southern Veracruz eastward to British +Honduras. These usually are grasslands having scattered trees or clumps +of trees around depressions, which may contain water throughout the +year (Pl. 1, fig. 1). According to Williams (_op. cit._), the most +common trees in the savannas in southern Veracruz are _Ceiba +pentandra_, _Chlorophora tinctoria_, and _Byrsonima crassifolia_. + +Lying in a rain shadow cast by the Tuxtlas and on sandy and +well-drained soils is a dense xerophytic forest. The crown of this +deciduous forest usually is little more than ten to twelve meters above +the ground (Pl. 1, fig. 2). Conspicuous trees in this scrub forest are +_Acacia cornigera_, _Bauhinia latifolia_, _Calliandra bijuga_, _Cassia +laevigata_, _Guazuma ulmifolia_, and various species of _Bursera_. + +The most extensive type of vegetation on the Gulf Coastal Plain is a +tall evergreen forest resembling tropical rainforest. Although this +forest is made up of many species of trees that are characteristic of +true rainforest, the forest on the Gulf Coastal Plain cannot be +classified as true rainforest, neither by the climatic conditions, nor +the structure of the forest. The seasonal variation in rainfall +probably is the chief factor in hindering the development of a +rainforest climax vegetation. Usually a minimum of 65 mm. of rainfall +each month is considered essential for the development of true +rainforest. At Minatitlán the average rainfall for March (39 mm.) and +April (36 mm.) is far below this minimum. Structurally, this forest has +a crown about 30-35 meters above the ground but individual trees rising +five meters or more above the crown (Pl. 2, figs. 1-2). There is no +clear stratification within the forest; in many parts of it there are +dense growths of bushes, small trees, and palms. The forest on the Gulf +Coastal Plain, therefore, most properly might be referred to as a +quasi-rainforest, a term that has been applied to other such forests in +tropical America. + +Among the abundant and dominant trees in this forest are _Swietenia +macrophylla_, _Calophyllum brasiliense_, _Achras zapota_, _Ceiba +pentandra_, _Castilla elastica_, _Cedrela mexicana_, _Tabebuia +Donnell-Smithi_, _Calocarpum mammosum_, _Bombax ellipticum_, and a +variety of _Ficus_. Epiphytes and Ilianas are abundant. + +Central Ridges + +The vegetation of the central ridges of the isthmus is, for the most +part, transitional between the tall rainforest of the Gulf Coastal +Plain and the low xerophytic scrub forest of the semi-arid Pacific +Coastal Plain. On the northern slopes of the ridges the rainforest is +more poorly developed than on the plains to the north. Many of the same +species of trees are present, including _Ceiba pentandra_, _Cedrela +mexicana_, _Swietenia macrophylla_, and _Ficus_ sp.; nevertheless, +these seldom are as large as members of the same species in the forest +on the plains. Other species present on the forested slopes include +_Tabebuia Donnell-Smithi_, _Zanthoxylum melanostictum_, _Pithecolobium +arboreum_, and a species of _Pterocarpus_. The structure of this forest +differs from that on the Gulf Coastal Plain in that there is no +continuous upper canopy and there is a dense undergrowth (Pl. 3, fig. +1). This type of forest extends from Mogoñe southward to about Matías +Romero. + +In the vicinity of Matías Romero open pine-oak forest (_Pinus caribaea_ +and _Quercus_ sp.) is found on some ridges as low as 250 meters above +sea level. + +On the Plains of Chivela in the southern part of the central region +the vegetation takes on a semi-arid appearance, especially in a savanna +on the plains. Clumps of small trees and bushes, consisting of _Croton +nivea_, _Cordia cana_, _Jacquinia aurantiaca_, _Calycophyllum +candidissimum_, and _Cassia emarginata_, are scattered on a grassy +plain, from which rise widely-spaced palms of an unknown species (Pl. +3, fig. 2). + +Pacific Coastal Plain + +The vegetation of the Pacific lowlands definitely is semi-arid in +character. Most of the trees are deciduous, thorny, and short. During +the dry season the landscape presents a barren appearance, but shortly +after the first summer rains dense green foliage appears (Pl. 4, figs. +1 and 2). Between Juchitán and La Ventosa few trees are more than two +meters high (Pl. 5, fig. 1). In many areas the trees and bushes form an +almost impenetrable tangle, whereas on especially rocky soils or on +slopes those plants are more widely spaced. Abundant and widespread +species of trees on the Plains of Tehuantepec include _Acacia +cymbispina_, _Prosopis chilensis_, _Caesalpinia coriaria_, _Caesalpinia +eriostachys_, _Celtis iguanaea_, _Cordia brevispicata_, _Jatropha +aconitifolia_, and _Crescentia alata_. + +Montane Vegetation + +In order to illustrate the interruption of subtropical and temperate +types of vegetation by the lowlands of the Isthmus of Tehuantepec, it +is necessary to digress for a moment from the isthmus and consider the +types of vegetation present on the adjacent highlands. On the higher +peaks, such as Cerro de Zempoaltepetl, above about 2500 meters is fir +forest (_Abies religiosa_); lower on the slopes are extensive pine +forests, which on some slopes are mixed with oak or replaced entirely +by oaks. Subtropical cloud forest, characterized by relatively cool +temperatures and high humidity, is found at elevations usually between +1000 and 1800 meters on the windward slopes of the Sierra Madre +Oriental in Veracruz and northern Oaxaca and on the northern and +southern slopes of the Chiapan-Guatemalan Highlands. None of these +forest types is continuous across the Isthmus of Tehuantepec. + + +_The Sierra de los Tuxtlas_ + +Although actually located in the region of the Isthmus of Tehuantepec, +the Sierra de los Tuxtlas, because of its isolated position, need not +be considered in great detail in analyzing the distribution of animals +inhabiting the lowlands of the isthmus. Nevertheless because some +species living in the highlands adjacent to the isthmus also live in +the Tuxtlas, this range is briefly described here. The Sierra de los +Tuxtlas is a range of volcanos lying near the Gulf Coast in southern +Veracruz between the mouths of the Río Papaloapan and the Río +Coatzacoalcos. Volcán San Martín, the highest peak, rises above 1800 +meters. This range of volcanos is surrounded by lowlands, which +immediately to the south and west are covered with savanna and in +places by scrub forest. The luxuriant nature of the vegetation on these +volcanos indicates that this range receives much more rainfall than the +surrounding lowlands. Especially on the northern slopes, tropical +rainforest is well developed; this is replaced at about 1200 meters by +cloud forest. The southern and western slopes are drier, for the lower +slopes are covered with a scrubby, but evergreen, forest. + +Detailed comments on the herpetofauna of the Tuxtlas have been omitted +purposefully, for the reptiles and amphibians of the region currently +are being studied by Douglas Robinson. + + + + +GAZETTEER + + +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 position of a locality on the accompanying map +(Fig. 1). + + +_Oaxaca_ + + Agua Caliente.--Lat. 16° 38'; long. 94° 48'; elev. 140 m. A + hot spring, 6.9 km. north of La Ventosa on the + Trans-isthmian Highway; arid scrub forest [43]. + + Arenal, Cerro de.--Lat. 16° 18'; long. 95° 32'; elev. 925 m. + (crest). A ridge northeast of Tenango; scrub forest on + slopes and pine-oak forest on top [64]. + + Barrio, El.--Lat. 16° 38'; long. 95° 07'; elev. 314 m. A + village about 10 kilometers southwest of Matías Romero; + transition between scrub forest and broadleaf hardwood + forest [38]. + + Bisilana.--Lat. 16° 20'; long. 95° 13'; elev. 35 m. A place + name for a former ranch at the edge of Tehuantepec; open + arid scrub forest [62]. + + Chivela.--Lat. 16° 20'; long. 95° 01'; elev. 195 m. A + village on the Trans-isthmian Railroad, 26 kilometers by + rail south of Matías Romero and on the western edge of the + semi-arid Plains of Chivela [40]. + + Concepción.--Lat. 16° 17'; long. 95° 29'; elev. 1200 m. A + ranch on the slopes of Cerro Arenal, east-northeast of + Tenango; dry pine-oak forest [66]. + + Coyol.--Exact position unknown; according to Smith and + Taylor (1950: 10), Coyol is "between San Antonio and Las + Cruces." + + Donají.--Lat. 17° 13'; long. 95° 02'; elev. 90 m. A village + at Km. 155 on the Trans-isthmian Highway; rainforest [29]. + + Escurano.--Lat. 16° 25'; long. 95° 27'; elev. 500 m. A ranch + about 25 kilometers west-northwest of Tehuantepec; arid + scrub forest [51]. + + Guichicovi, San Juan.--Lat. 16° 58'; long. 95° 06'; elev. + 250 m. A village on the north slopes of the isthmus, 12 + kilometers north-northwest of Matías Romero; cleared + hardwood forest and coffee plantations [33]. + + Huilotepec.--Lat. 16° 14'; long. 95° 09'; elev. 30 m. A + small village on the Río Tehuantepec, 13 kilometers + south-southeast of Tehuantepec; open arid scrub forest [69]. + + Ixtepec.--Lat. 16° 34'; long. 95° 06'; elev. 60 m. A town + and railroad junction on the northwestern edge of the Plains + of Tehuantepec; arid scrub forest [45]. + + Juchitán.--Lat. 16° 26'; long. 95° 02'; elev. 15 m. A town + on the Plains of Tehuantepec, 22 kilometers by road + east-northeast of Tehuantepec; arid scrub forest [50]. + + Limón.--Lat. 16° 20'; long. 95° 29'; elev. 600 m. A former + agrarian colony and now a small ranch about 27 kilometers + west of Tehuantepec; arid scrub forest [60]. + + Matías Romero.--Lat. 16° 53'; long. 95° 02'; elev. 200 m. A + town on the Trans-isthmian Highway and railroad in the hills + near the crest of the isthmus; broadleaf hardwood forest and + open pine-oak forest [36]. + + Mixtequilla.--Lat. 16° 24'; long. 95° 18'; elev. 40 m. A + village on the Río Tehuantepec, northwest of Tehuantepec; + dense scrub forest [57]. + + Modelo, El.--Lat. 17° 07'; long. 94° 43'; elev. 200 m. An + old rubber plantation on the Río Chalchijapa, a tributary to + the Río Coatzacoalcos; rainforest [31]. + + Nanches, Portillo Los.--Lat. 16° 35'; long. 95° 37'; elev. + 500 m. A place name, about 4 kilometers southeast of + Totolapilla; scrub forest [44]. + + Nizanda.--Lat. 16° 42'; long. 95° 02'; elev. 150 m. A + village on the Trans-isthmian Railroad between Chivela and + Ixtepec; dense scrub forest [42]. + + Nueva Raza.--Exact location unknown; according to Thomas + MacDougall, this locality is in the lowlands of northern + Oaxaca; rainforest. + + Palmar.--Lat. 16° 43'; long. 94° 40'; elev. 300 m. A small + ranch on the west base of Cerro Atravesado; scrub forest + [39]. + + Papaloapan.--Lat. 18° 11'; long. 96° 06'; elev. 25 m. A + small village on the Río Papaloapan in northern Oaxaca; low + evergreen forest and savanna [11]. + + Princesa, La.--Lat. 16° 56'; long. 95° 02'; elev. 150 m. A + ranch on the northern slopes of the isthmus, 6 kilometers by + road north of Matías Romero; poorly developed rainforest + [34]. + + Quiengola, Cerro de.--Lat. 16° 24'; long. 95° 22'; elev. 900 + m. (crest). A hill 15 kilometers west-northwest of + Tehuantepec; dense scrub forest on slopes and scattered + pines on top [55]. + + Salazar.--Lat. 16° 25'; long. 95° 20'; elev. 45 m. A ranch + on the Río Tehuantepec, northwest of Tehuantepec; dense + scrub forest [52]. + + Salina Cruz.--Lat. 16° 10'; long. 95° 12'; sea level. A port + on the Golfo de Tehuantepec; open arid scrub forest [70]. + Collections were made in the vicinity of the town and in the + open scrub forest 2.4 kilometers north at an elevation of 20 + meters. + + San Antonio.--Lat. 16° 15'; long. 95° 22'; elev. 40 m. A + ranch about 25 kilometers west-southwest of Tehuantepec; + arid scrub forest [68]. + + San Pablo.--Lat. 16° 24'; long. 95° 18'; elev. 40 m. A ranch + on the Río Tehuantepec, northwest of Tehuantepec; dense + scrub forest [56]. Cerro San Pablo probably is the hill + north of this ranch; this is shown on some maps as Cerro de + los Amates. + + San Pedro, Cerro de.--Lat. 16° 18'; long. 95° 28'; elev. + about 1100 m. (crest). A ridge about 24 kilometers west of + Tehuantepec and east of Cerro Arenal; scrub forest on slopes + and pine-oak forest on top [65]. + + Santa Efigenia.--Lat. 16° 25'; long. 94° 13'; elev. 500 m. A + ranch on the southern slopes of the Sierra Madre de Chiapas, + 8 kilometers north-northwest of Tapanatepec; scrub forest. + Former home of Francis Sumichrast [53]. + + Santa Lucía.--Lat. 16° 18'; long. 95° 28'; elev. 800 m. A + place name for a former ranch on the east slopes of Cerro + Arenal; scrub forest [63]. + + Santa María Chimalapa.--Lat. 16° 55'; long. 94° 42'; elev. + 296 m. A village on the Río de los Milagros, a tributary to + the Río Coatzacoalcos; rainforest [35]. + + Santiago Chivela.--Lat. 16° 42'; long. 94° 53'; elev. 200 m. + A village on the Trans-isthmian Highway, 13.4 kilometers by + road south of Matías Romero; dry, grassy plains and + scattered clumps of scrubby trees and palms [41]. + Collections were made in the vicinity of the village and at + a rocky stream, 11 kilometers south on the Trans-isthmian + Highway at an elevation of 230 m. + + Santo Domingo (Petapa).--Lat. 16° 50'; long. 95° 08'; elev. + 225 m. A village about 13 kilometers west-southwest of + Matías Romero; semi-arid scrub forest [37]. + + Sarabia.--Lat. 17° 04'; long. 95° 02'; elev. 100 m. A + village 25 kilometers north of Matías Romero on the + Trans-isthmian Highway; rainforest [32]. Collections were + made in the vicinity of the village and in the rainforest + along the Río Sarabia, 5 kilometers north of the village at + an elevation of 80 meters. + + Tapanatepec.--Lat. 16° 32'; long. 94° 12'; elev. 90 m. A + town on the Pan-American Highway on the lower slopes of the + Sierra Madre de Chiapas; dense scrub forest [58]. + + Tehuantepec.--Lat. 16° 20'; long. 95° 14'; elev. 35 m. A + large town on the Plains of Tehuantepec; scrub forest [61]. + Collections were made in the vicinity of the town and in the + dense scrub forest 8.6 kilometers west at an elevation of 85 + meters and 14 kilometers west at an elevation of 120 meters. + + Tenango.--Lat. 16° 16'; long. 95° 30'; elev. 1100 m. A town + in the mountains about 40 kilometers west-southwest of + Tehuantepec; scrub forest [67]. + + Tequisistlán.--Lat. 16° 24'; long. 95° 37'; elev. 190 m. A + village in the valley of the Río Tequisistlán, a tributary + to the Río Tehuantepec; dense scrub forest [54]. Most + collections were made about one kilometer north of the + village where the Pan-American Highway crosses the Río + Tequisistlán. + + Tolosita.--Lat. 17° 12'; long. 95° 03'; elev. 80 m. A + village on the Río Tortuguero near the Trans-isthmian + Highway; rainforest [30]. + + Tres Cruces.--Lat. 16° 26'; long. 95° 51'; elev. 750 m. A + ranch near the Pan-American Highway, 70 kilometers by road + west-northwest of Tehuantepec; dense scrub forest [49]. + + Tuxtepec--Lat. 18° 06'; long. 96° 05'; elev. 80 m. A town on + the Río Papaloapan in northern Oaxaca; low evergreen forest + [12]. + + Ubero.--Lat. 17° 18'; long. 95° 00'; elev. 80 m. A lumber + camp and railroad station, 8.5 kilometers south of the Río + Jaltepec on the Trans-isthmian Highway; rainforest [28]. + + Unión Hidalgo.--Lat. 16° 27'; long. 94° 48'; elev. 7 m. A + village on the railroad, 20 kilometers east-northeast of + Juchitán; open scrub forest [48]. + + Ventosa, La.--Lat. 16° 30'; long. 94° 51'; elev. 25 m. A + village at the junction of the Pan-American and + Trans-isthmian highways; open scrub forest [46]. + + Zanatepec.--Lat. 16° 28'; long. 94° 22'; elev. 80 m. A + village on the Pan-American Highway at the eastern edge of + the Plains of Tehuantepec; dense scrub forest [47]. Most + collections were made in the scrub forest 5 to 8 kilometers + west-northwest of the village. + + Zarzamora.--Lat. 16° 21'; long. 95° 48'; elev. 800 m. A + ranch between La Reforma (16 kilometers west of + Tequisistlán) and Santa María Ecatepec; scrub forest with + oaks on higher ridges [59]. + + +_Veracruz_ + + Acayucan.--Lat. 17° 57'; long. 94° 55'; elev. 160 m. A large + town on the Trans-isthmian Highway; rainforest [21]. + Collections were made in the vicinity of the town, but + principally at Rancho Las Hojitas, 7 kilometers northwest of + town at an elevation of 150 meters. + + Alvarado.--Lat. 18° 47'; long. 95° 47'; sea level. A fishing + village at the mouth of the Río Papaloapan; coastal dunes + and marshes [1]. Most collections were made 1-3 kilometers + southeast of the village in marshes on the leeward side of + the coastal dunes. + + Amatitlán.--Lat. 18° 26'; long. 95° 45'; elev. 4 m. A + village on the bank of the Río Papaloapan; savanna and sugar + plantations [6]. + + Aquilera.--Lat. 17° 48'; long. 95° 01'; elev. 150 m. A + village 21 kilometers southwest of Acayucan on the + Trans-isthmian Highway; rainforest [22]. + + Ayentes.--Lat. 18° 10'; long. 94° 26'; elev. 2 m. A railroad + station on the east bank of the Río Coatzacoalcos, across + the river from the city of Coatzacoalcos; scrub forest and + marshes [17]. + + Berta.--Lat. 18° 07'; long. 94° 27'; elev. 5 m. A ranch just + south of Coatzacoalcos; scrub and low evergreen forest [15]. + + Chacaltianguis.--Lat. 18° 18'; long. 95° 52'; elev. 5 m. A + village on the Río Papaloapan; savanna [8]. + + Ciudad Alemán.--Lat. 18° 13'; long. 96° 07'; elev. 30 m. A + new government town, headquarters of the Comisión del + Papaloapan; scrub and low evergreen forest [10]. + + Coatzacoalcos (formerly Puerto México).--Lat. 18° 10'; long. + 94° 27'; elev. 2 m. A seaport at the mouth of the Río + Coatzacoalcos; scrub on coastal dunes; marshes and low + evergreen forest inland [16]. Most collections are from the + forest-savanna ecotone, 8 kilometers southwest of town. + + Cosamaloapan.--Lat. 18° 22'; long. 95° 50'; elev. 4 m. An + agricultural town on the Río Papaloapan; savanna and sugar + plantations [7]. + + Cosoleacaque.--Lat. 17° 59'; long. 94° 38'; elev. 55 m. A + village 8 kilometers by road west of Minatitlán; savanna + [19]. + + Cuatotolapam.--Lat. 18° 08'; long. 95° 16'; elev. 13 m. A + village on the Trans-isthmian Railroad; savanna and low + evergreen forest along streams [13]. + + Hueyapan.--Lat. 18° 08'; long. 19° 09'; elev. 85 m. A town + 32 kilometers by road northwest of Acayucan; savanna and low + evergreen forest [14]. Collections were made in the vicinity + of the town and from forest 10 kilometers southeast of town + at an elevation of 135 meters. + + Jesús Carranza (formerly Santa Lucrecia).--Lat. 17° 27'; + long. 95° 02'; elev. 80 m. A town and railroad junction in + the middle of the isthmus; rainforest [26]. Most of + Dalquest's specimens came from varying distances from Jesús + Carranza along the Río Coatzacoalcos and its tributaries. + + Minatitlán.--Lat. 17° 58'; long. 94° 32'; elev. 15 m. An oil + refinery center on the Río Coatzacoalcos; savanna [20]. + + Naranjo.--Lat. 17° 35'; long. 95° 07'; elev. 100 m. A + village on the Trans-isthmian Highway, 45 kilometers south + of Acayucan; rainforest and palm forest [24]. + + Novillero.--Lat. 18° 16'; long. 95° 59'; elev. 10 m. A + village on the Río Papaloapan; scrub forest and grassland + [9]. + + Oaxaqueña, La.--Lat. 17° 26'; long. 94° 53'; elev. 80 m. A + hacienda on the Río Coatzacoalcos about 12 kilometers east + of Jesús Carranza; rainforest [27]. + + Playas, Río de las.--Lat. 18° 08'; long. 94° 07'; elev. 3 m. + The river (sometimes known as the Río Tonolá) forming the + boundary between the states of Veracruz and Tabasco; + rainforest [18]. + + San Lorenzo.--Lat. 17° 44'; long. 94° 42'; elev. 25 m. A + village on the Río Chiquito, about 30 kilometers southeast + of Acayucan; rainforest [23]. + + Suchil.--Lat. 17° 31'; long. 95° 03'; elev. 40 m. A village + on the Trans-isthmian Railroad, about 10 kilometers north of + Jesús Carranza; rainforest [25]. + + Tecolapan.--Lat. 18° 24'; long. 95° 18'; elev. 275 m. A + village on a small river of the same name in the western + foothills of Los Tuxtlas; rainforest [5]. + + Tejada, Lerdo de.--Lat. 18° 37'; long. 95° 31'; elev. 60 m. + An agricultural village, 35 kilometers by road + east-southeast of Alvarado; scrub forest, marshes, and sugar + plantations [2]. Collections were made in a marsh, 5 + kilometers west-northwest of the village. + + Tlacotalpan.--Lat. 18° 37'; long. 95° 42'; elev. 3 m. A town + at the confluence of the Río San Juan and Río Papaloapan; + marshes and sugar plantations [3]. + + Tula.--Lat. 18° 36'; long. 95° 22'; elev. 150 m. A village + near the western base of Los Tuxtlas; low evergreen forest + and marshes [4]. Collections were made in a marsh 3 + kilometers northwest of the village. + + + + +THE AMPHIBIAN FAUNA OF THE LOWLANDS + + +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. + + +_Composition of the Fauna_ + +The amphibian fauna of the lowlands of the Isthmus of Tehuantepec +consists of 36 species definitely recorded from the area. These include +one genus and species of caecilian, one genus, including three species +of salamanders, and 14 genera and 32 species of anurans. + +In comparison with the known amphibian fauna of the forested and +savanna portions of El Petén, Guatemala (Stuart, 1935 and 1958), we +find that there are more species recorded from the isthmus than from El +Petén. Stuart found only 20 species of amphibians in both forest and +savanna habitats in El Petén. Of the 36 species of amphibians known +from the isthmus, 28 occur on the Gulf lowlands and live in forest or +savanna habitats. + +The geographic position of the isthmus with regard to major faunal +areas in Middle America, and the diversity of the environment are +important factors in understanding the presence of a large number of +species of amphibians in the isthmus. The large number of species +probably is a reflection of the diversity of the environment; this +diversity is the result of fluctuation of climate, and thus +environments, in the not too distant past. In no individual habitat, +such as rainforest, savanna, or scrub forest, does the number of +species approach the total for the region. + + +_Ecology of the Fauna_ + +In the preceding section on the description of the Isthmus of +Tehuantepec I have outlined the major environments in the region. With +respect to the distribution of amphibians we may recognize three major +environments in the isthmus--rainforest, semi-arid scrub forest, and +savanna. Each of these has varying combinations of physical and biotic +factors that are important in the ecology of amphibians. Because of the +importance of moisture, not only for the maintenance of life in these +animals, but in most species their dependence on water for breeding +purposes, this environmental factor is considered the most significant +in the ecological distribution of amphibians. A second factor is the +availability of necessary shelter, especially aestivation sites. These +factors will be compared in the three major environments in the region. + +Moisture is present in the environment in the form of free water or +atmospheric moisture. With respect to the latter, it is well known that +dense shaded forests have a considerably higher relative humidity than +do open plains or areas with only scattered trees. Thus, the +rainforests of the isthmus are characterized by a much higher relative +humidity than are the savannas or semi-arid scrub forests. Although +with regard to rainfall there is a pronounced dry season in the regions +supporting rainforest, there still remains considerable atmospheric +moisture in this environment throughout the year. The dense foliage +provides shade and protection from desiccating effects of wind and +sunlight; furthermore the foliage contributes moisture by +transpiration. The deep alluvial soils mixed with large quantities of +organic matter (decaying leaves and rotting logs) maintain considerable +quantities of moisture. + +Conversely, the savannas and scrub forests have little atmospheric +moisture during the dry season. In the former habitat there are few +trees to provide shade or moisture through transpiration; in the latter +most of the trees lose their leaves during the dry season. Thus, these +environments are desiccated by the dry winds and direct sunlight. +Furthermore, the soils in these environments become dry and caked. +There is little or no terrestrial matter to hold moisture. + +Free water in these environments is present in a variety of forms at +different times of the year. During the dry season the more extensive +marshes in the savannas persist; many ponds and most of the streams in +the rainforest are permanent throughout the year. In the scrub forest +all except the largest streams become dry during the dry season, and no +ponds exist through the dry season. With the advent of the first heavy +summer rains the stream beds fill with water, marshes expand, and many +depressions become ponds (Pl. 5, fig. 2). At this time the amount of +free water in the scrub forests and savannas greatly increases, much +more so than that in the rainforests. + +Environments are vertically stratified in the rainforests. There is the +deep alluvial soil, the ground litter of leaves and decaying logs, the +low bushes and small trees, and finally the tall trees of the forest. +Each of these provides certain types of shelter for amphibians. The +moist soil and litter on the forest floor is an important microhabitat +for fossorial and strictly terrestrial species. The dense foliage of +the trees, tree holes, and bromeliads growing on the trees provide +shelter for arboreal species. Arboreal and terrestrial bromeliads and +the terrestrial elephant-ear plants (_Xanthosoma_) contain water in the +axils of their leaves throughout the year and thus provide an important +habitat for amphibians. The low, spiny, deciduous trees of the scrub +forest and the grasses and scattered trees in the savannas provide +little shelter. In the savannas there are depressions, some of which +contain water throughout the year; these are often surrounded by trees +providing refugia for amphibians during the dry season. In the scrub +forest many species congregate along streams and in moist stream beds +during the dry season. + +Now that the important ecological factors of the major environments +have been outlined, we may examine the local distribution of amphibians +in each of these. Beginning with the rainforest, we find only one +fossorial species, _Gymnopis mexicanus_. A large number of species are +found on the forest floor; characteristic inhabitants of the leaf +litter are: _Bufo valliceps_, _Eleutherodactylus rhodopis_, +_Microbatrachylus pygmaeus_, and _Syrrhophus leprus_. Other terrestrial +amphibians usually are not scattered throughout the rainforest, as are +those named immediately above, but instead inhabit areas of forest +adjacent to ponds or streams; these species include: _Bufo marinus_, +_Eleutherodactylus natator_, _Eleutherodactylus rugulosus_, +_Leptodactylus labialis_, _Leptodactylus melanonotus_, _Rana palmipes_ +and _Rana pipiens_. The most striking ecological assemblage of +amphibians in the rainforest is the arboreal group of species, +including: + + _Bolitoglossa occidentalis_ + _Bolitoglossa platydactyla_ + _Eleutherodactylus alfredi_ + _Hyla baudini_ + _Hyla ebraccata_ + _Hyla loquax_ + _Hyla microcephala martini_ + _Hyla picta_ + _Phrynohyas modesta_ + _Phrynohyas spilomma_ + _Phyllomedusa callidryas taylori_ + +In the savannas _Rhinophrynus dorsalis_, _Engystomops pustulosus_, and +_Gastrophryne usta_ are fossorial species. _Bufo marinus_, +_Leptodactylus melanonotus_, _Leptodactylus labialis_, _Rana palmipes_, +and _Rana pipiens_ are found in the vicinity of permanent water in the +savannas. Although the savanna habitat does not provide the ecological +conditions for the existence of an arboreal fauna, many arboreal +species from the surrounding rainforest utilize the extensive marshes +and ponds in the savannas for breeding purposes. Thus, _Hyla baudini_, +_Hyla microcephala martini_, _Hyla picta_, and _Phrynohyas spilomma_ +have been found breeding in savannas. In parts of savannas where clumps +of trees surround depressions containing water throughout the year, +individuals of the species named above, together with _Hyla loquax_ and +_Phyllomedusa callidryas taylori_, may not only breed, but remain +throughout the year. + +In the semi-arid scrub forest the same fossorial species as exist in +the savannas are found. Likewise, _Bufo marinus_, _Leptodactylus +labialis_, _Leptodactylus melanonotus_, and _Rana pipiens_ are found +near permanent water. Terrestrial species in this semi-arid environment +include _Bufo canaliferus_, _Bufo coccifer_, _Bufo marmoreus_, +_Syrrhophus pipilans_, and _Diaglena reticulata_. Of these, _Syrrhophus +pipilans_ sometimes inhabits low trees and bushes; the others may be +fossorial. The arboreal species in the scrub forest include _Hyla +baudini_, _Hyla robertmertensi_, _Hyla staufferi_, and _Phyllomedusa +dacnicolor_. + +_Eleutherodactylus rugulosus_ and _Hylella sumichrasti_ live along +streams in the scrub forest. _Hylella sumichrasti_ lays its eggs in +these streams. + +In comparing the ecological differences in the amphibian assemblages in +the three major habitats, the most obvious difference is the great +percentage of arboreal species in the rainforest as compared with +savanna and scrub forest. Only four arboreal species are found in the +scrub forest, none in the savannas, but eleven in the rainforest. +Likewise, there is an absence of ground-dwelling forms in the arid +habitats; in the latter the only terrestrial species are those that +are found near water. A possible exception is _Syrrhophus pipilans_. + +From the above analysis of ecological distribution we may see that the +rainforest provides a variety of habitats for amphibians and that these +habitats are suitable for amphibian life throughout the year. On the +other hand, the savannas and scrub forests are characterized by extreme +conditions of desiccation, a factor of considerable importance in +limiting the ecological distribution of amphibians. However, there +still is a diversity of amphibians in these semi-arid environments. +Obviously, these species are adapted in various ways for survival +during the dry season, at which time environmental conditions are such +that the animals cannot carry on their normal activities. + +Although there is not an abundance of data concerning the seasonal +activity of the fauna, what is available shows some interesting +correlations with the environments. During the dry season in the scrub +forest there is essentially no amphibian activity; an occasional _Rana +pipiens_ may be seen along a river, or a _Bufo marinus_ may be seen at +night. In the rainforest the terrestrial-breeding amphibians are active +during the dry season. _Eleutherodactylus rugulosus_ is found at night +or by day along streams. _Eleutherodactylus rhodopis_, +_Microbatrachylus pygmaeus_, and _Bufo valliceps_ are active during the +day; these plus _Bolitoglossa occidentalis_, _Bolitoglossa +platydactyla_, _Eleutherodactylus alfredi_, _Eleutherodactylus +natator_, and an occasional _Hyla_ are active at night. + +With the onset of the heavy summer rains and the subsequent formation +of breeding ponds, amphibian activity reaches a peak. This is +especially noticeable in the semi-arid environments, where during the +dry season there is little activity. + +Among the anurans in the isthmus the four species of +_Eleutherodactylus_, the two species of _Syrrhophus_, and the one +species of _Microbatrachylus_ are either known, or presumed, to lay +eggs on the ground; these develop directly into small frogs. All of the +other anurans deposit their eggs in water or attach them to objects +over water (_Phyllomedusa_); these hatch into tadpoles, which later +metamorphose into frogs. _Hylella sumichrasti_ is known to breed only +in streams. All of the other species breed in ponds, but at times some +species deposit their eggs in streams; in this last group are _Bufo +valliceps_, _Bufo marmoreus_, _Phyllomedusa callidryas taylori_, and +_Rana pipiens_. + +Although the ecological data are incomplete, they do show that +ecological conditions differ greatly in the three major environments, +different species of amphibians inhabit these environments, and that +the fauna is ecologically diversified in each environment. + + +_Distribution of the Fauna_ + +Plotting the distributions of species of amphibians known to live in +the lowlands of the Isthmus of Tehuantepec results in an array of +geographic patterns. These may be analyzed with respect to those +species that are restricted either to the Gulf lowlands or the Pacific +lowlands, or those that occur on both the Gulf and Pacific lowlands. +Furthermore, the distributions may be analyzed with respect to those +species whose ranges extend from México across the Isthmus of +Tehuantepec into Central America, those that reach the isthmus from +Central America but do not extend into México proper, and those that +reach the isthmus from México but do not extend into Central America. +It should be kept in mind that the following analysis is of the lowland +inhabitants only. Species inhabiting the foothills and mountains will +be discussed later. + +1. SPECIES RESTRICTED TO THE GULF LOWLANDS. Of the 36 species of +amphibians recorded from the Isthmus of Tehuantepec, nine (25 per cent) +are in this group. Four of these (_Eleutherodactylus alfredi_, +_Syrrhophus leprus_, _Hyla loquax_, and _Hyla picta_) live in the Gulf +lowlands to the east and to the west of the isthmus. Three others +(_Hyla ebraccata_, _Hyla microcephala martini_ and _Phyllomedusa +callidryas taylori_) are primarily Central American in their +distribution and reach the northwestern limits of their ranges in the +Gulf lowlands of the isthmus, whereas _Bolitoglossa platydactyla_ and +_Eleutherodactylus natator_ reach the southern limits of their +distributions in the isthmus. + +2. SPECIES RESTRICTED TO THE PACIFIC LOWLANDS. This group includes six +species, or 17 per cent of the amphibian fauna of the isthmus. Two of +these (_Bufo coccifer_ and _Syrrhophus pipilans_) range to the east and +to the west of the isthmus on the Pacific lowlands. Two others (_Bufo +canaliferus_ and _Hyla robertmertensi_) range from the isthmus into +Central America, and _Diaglena reticulata_ and _Phyllomedusa +dacnicolor_ range on the Pacific lowlands of México southeastward to +the isthmus. + +3. SPECIES THAT OCCUR ON THE PACIFIC AND GULF LOWLANDS. This group +includes 19 species, or 53 per cent of the total amphibian fauna. Of +these, nine species (25 per cent of the entire amphibian fauna) are +widespread throughout the lowlands of México and Central America; these +are: + + _Gymnopis mexicanus_ + _Rhinophrynus dorsalis_ + _Bufo marinus_ + _Engystomops pustulosus_ + _Leptodactylus labialis_ + _Leptodactylus melanonotus_ + _Hyla baudini_ + _Hyla staufferi_ + _Rana pipiens_ + +Four species occur on the Gulf lowlands to the east and to the west of +the isthmus, but on the Pacific lowlands they occur only to the east; +this group includes _Bufo valliceps_, _Eleutherodactylus rhodopis_, +_Phrynohyas modesta_, and _Phrynohyas spilomma_. Three species live to +the east and to the west of the isthmus on the Pacific lowlands, but +only to the west on the Gulf lowlands; these include _Eleutherodactylus +rugulosus_, _Microbatrachylus pygmaeus_, and _Gastrophryne usta_. + +Six species that cross the isthmus live on the humid Gulf lowlands and +on the humid lowlands of Chiapas and Guatemala, but not on the +semi-arid Plains of Tehuantepec; these include _Bolitoglossa +occidentalis_, _Eleutherodactylus rhodopis_, _Microbatrachylus +pygmaeus_, _Phrynohyas modesta_, _Phrynohyas spilomma_, and _Rana +palmipes_. Of these, _Microbatrachylus pygmaeus_ also occurs in +scattered humid environments to the west of the isthmus on the Pacific +lowlands. + +Two species are endemic to the isthmian region. _Bolitoglossa +veracrucis_ is known only from the humid northern slopes of the +isthmus. _Hylella sumichrasti_ occurs on the Pacific slopes of the +isthmus and extends to the east into western Chiapas. + +In analyzing the distribution of the amphibians with respect to those +that are restricted to either the Pacific or Gulf lowlands or those +that cross the continental divide in the isthmus, we find that 25 per +cent of the species are restricted to the Gulf lowlands, 17 per cent +are restricted to the Pacific lowlands, and 53 per cent cross the +isthmus. In analyzing the distribution patterns with respect to those +that extend across the isthmus of Tehuantepec from east to west, we +find that 14 per cent of the species do not extend east of the isthmus +into Central America and that 19 per cent do not range west of the +isthmus into México proper; 61 per cent of the species range to the +east and to the west of the isthmus. Of the 36 species of amphibians +inhabiting the isthmus only nine species (25 per cent) range across the +isthmus, that is, occur on the Gulf and Pacific lowlands, and also +range to the east and to the west of the isthmus. To these wide-ranging +species the diversified environments of the isthmus do not present a +barrier to distribution. The other 27 species (75 per cent) either do +not cross the isthmus from east to west or from north to south; thus, +probably in one way or another the isthmus presents a barrier to their +distribution. + + + + +THE AMPHIBIAN FAUNA OF THE FOOTHILLS AND ADJACENT HIGHLANDS + + +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 genera _Chiropterotriton_, +_Magnadigita_, _Pseudoeurycea_, and _Ptychohyla_, as well as the +_eximia_ group of _Hyla_ are represented by different species in the +Guatemalan-Chiapan Highlands than in the mountains of México on the +other side of the isthmus. Several species of _Plectrohyla_ occur in +the Guatemalan-Chiapan Highlands, but none is known from the Mexican +Highlands, although one species occurs in the Tuxtlas. + +Living in the humid forests of the foothills are salamanders of the +genus _Lineatriton_, frogs of the _spatulatus_ group of +_Eleutherodactylus_, _Anotheca coronata_, _Hyla miotympanum_, and +_Phyllomedusa moreleti_. All of these occur in the foothills of the +Sierra Madre Oriental in eastern México and in Los Tuxtlas. +_Lineatriton_, _Hyla miotympanum_, and the _spatulatus_ group of +_Eleutherodactylus_ do not occur in the foothills of the +Guatemalan-Chiapan Highlands; those amphibians reach the end of their +ranges at the isthmus. _Phyllomedusa moreleti_ and _Anotheca coronata_ +are found in the northern foothills of the Guatemalan-Chiapan +Highlands, and _Phyllomedusa moreleti_ is found in the foothills on the +Pacific slopes of the Chiapan Highlands. + +Although the above analysis is not so detailed as that of the lowland +inhabitants, it does show that all of the genera and species of +amphibians known to inhabit the foothills and highlands adjacent to the +isthmus, only two species of amphibians cross the isthmus from one +highland mass to the other. Thus, it is evident that the Isthmus of +Tehuantepec presents a great barrier to dispersal of these groups of +amphibians. + + + + +ESTABLISHMENT OF PRESENT PATTERNS OF DISTRIBUTION + + +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 shifts, both vertically and latitudinally, resulting in +the establishment of alternating continuous and discontinuous lowland +and highland environments, although this climatic fluctuation was not +so great as to eliminate tropical lowland environments from the region. +I feel that the present patterns of distribution of the amphibians in +the Isthmus of Tehuantepec may be explained on this premise. + +Many authors dealing with the herpetofauna of Middle America have +followed Schuchert's (1935) suggestion of a seaway in the isthmus +during the Cenozoic. Thus, Burt (1931), Duellman (1956, 1958a), Gloyd +(1940), Oliver (1948), Smith and Laufe (1946), and Stuart (1941) +employed the presence of a seaway to explain distribution and +speciation in various genera. Durham, Arellano, and Peck (1952), Olson +and McGrew (1941), and Stirton (1954) have provided geological evidence +that there probably was no Cenozoic seaway in the Isthmus of +Tehuantepec. Even if there were a seaway in the Pliocene or Miocene +(the dating of this possible seaway is open to question), its presence +is not necessary to explain the present patterns of distribution in the +isthmus. + +In recent years the study of natural biotic environments, palynology, +and Pleistocene chronology in Middle America has produced a wealth of +data, which although still fragmentary begins to form a picture of past +climatic events in that part of the world. Sedimentary studies by +Hutchinson, Patrick, and Deevey (1956) and Sears, Foreman, and Clisby +(1955) have provided evidence of drastic climatic shifts in México +during the Pleistocene. Further evidence of bioclimatic fluctuation is +provided by Martin and Harrell (1957) and Martin (1958); the latter has +suggested that there was a displacement of the tropical zones in +southern México and northern Central America by as much as 3000 feet +during the glacial maximum. Much of the evidence of such drastic +vertical shifts in environments is based on the presence of +Pleistocene montane glaciers on Mexican volcanoes (White, 1956) and +Chirripo in Costa Rica (Weyl, 1955). Dorf (1959) supports this idea of +drastic climatic change. + +In his studies of the avifauna of México and Guatemala Griscom (1932 +and 1950) made an important issue of the continuity of the bird fauna +in what he called the Subtropical Life-zone, which essentially consists +of cloud forest, a widespread, but discontinuous, habitat on the Gulf +(windward) slopes of the Mexican and Central American highlands at +elevations between 1000 and 2000 meters. To account for this apparent +uniformity in the avifauna Griscom hypothesized a continuity of cloud +forest environment in the Pleistocene; this would result in the +depression of cloud forests to the coastal lowlands and the +displacement of tropical lowland environments far to the south in +Central America. Stuart (1951) objected to this displacement of lowland +tropical rainforest; he stated that a descent to sea level of a +subtropical zone would have brought about either widespread +extermination of the tropical fauna or acclimatization of that fauna to +subtropical conditions. + +Although palynological studies and some faunal studies of subtropical +and temperate animals suggest a drastic climatic fluctuation that might +have eliminated tropical environments in southern México and northern +Central America, there is much biological evidence indicating the +existence of tropical environments in this region even during the +glacial maximum. Especially significant is the diversity of species +inhabiting the present tropical environments; many of these have +differentiated from related taxa to the south. + +In the Pleistocene, climate fluctuated and vegetation shifted +correspondingly in southern México and northern Central America. Most +of the palynological studies and many studies of Pleistocene chronology +deal with montane regions, either the Mexican Plateau or the mountains +rising from the plateau. No such studies have been made in lowland +tropical environments. During glacial advances the tropical lowland +environments in México probably were not eliminated, for the great +diversity of animals in these environments supports the hypothesis that +they have been in existence for some time, although periodically they +may have been discontinuous. + +In order to understand the nature of bioclimatological events in the +Pleistocene in lowland tropical environments of southern México, +certain factors that are of little importance in the interpretation of +Pleistocene chronology in the highlands must be considered. These +factors are: 1) climatic moderation by oceans, 2) fluctuation in sea +level, and 3) fluctuation in level of the water table as affected by +sea level. + +It is well-known that large bodies of water moderate the temperature on +adjacent land. Furthermore, it is known that faunas of marine +invertebrates shifted latitudinally in the Pleistocene; Trask, Phleger, +and Stetson (1947) recorded cold-water Foraminifera then as far south +as the Sigsbee Deep in the middle of the Gulf of Mexico. Large bodies +of warm water, such as the Gulf of Mexico, Caribbean Sea, and Pacific +Ocean of today, probably were not sufficiently cooled at the time of +glacial advance to affect greatly the temperature of the winds blowing +across them. Even if these bodies of water were somewhat cooler than +now, the prevailing winds blowing from them onto the lowlands of México +and northern Central America would have aided in maintaining relatively +high temperatures there. These warm winds probably counteracted the +cooling effect of glaciation in the lowlands and thereby maintained +tropical conditions near the seas. + +Although no adequate studies of Pleistocene beach lines have been made +in southern México, such information is available for peninsular +Florida on the other side of the Gulf of Mexico (Cooke, 1945). +Fluctuation in sea level in the Pleistocene has been used by Hubbell +(1954), Goin (1958), and Duellman and Schwartz (1958) to explain +present patterns of distribution of animals in Florida. If Cooke's +interpretations can be applied to the western side of the Gulf of +Mexico, even generally, it would be supposed that sea level varied from +about 300 feet lower than at present during the Illinoian Glacial +Period to about 275 feet higher than at present during the Aftonian +Interglacial Period. Lowering of sea level would expand the lowlands in +the isthmus; rising sea level would restrict them, leaving only the +central ridges and many islands in the isthmus, but never forming a +seaway between the Gulf of Mexico and the Pacific Ocean. + +Probably the level of the water table in the coastal lowlands and the +gradients of the streams in the lowlands and foothills was closely +correlated with fluctuation in sea level. If sea level fluctuated as +much as 575 feet in the Pleistocene, changes in the level of the water +table must have been of considerable magnitude. + +During times of glacial advances the lowlands of the isthmus probably +were more extensive and had more semi-arid tropical environments than +at present, with patches of rainforest existing in sheltered valleys +along the major streams. In the course of bio-climatic fluctuation the +semi-arid environments (scrub forest and/or savanna) were continuous at +times from the Pacific lowlands across the isthmus to the Gulf +lowlands. At those times such typical inhabitants of the semi-arid +environments as _Rhinophrynus dorsalis_, _Engystomops pustulosus_, and +_Hyla staufferi_ could have made their way across the isthmus. At times +of most extensive glaciation, such as the Illinoian, temperatures in +the isthmus probably were low enough to permit the growth of pine-oak +forest and cloud forest continuously across the central ridges from the +Mexican to the Chiapan-Guatemalan highlands. At those times such +highland members of the fauna as _Chiropterotriton_, _Pseudoeurycea_, +_Magnadigita_, and the _eximia_ group of _Hyla_ could have crossed the +isthmus. During Wisconsin time, climate probably fluctuated less than +during previous glaciations; probably no montane environments, except +cloud forest, were represented in the isthmus during the Wisconsin. +Even at this relatively late date such animals as _Lineatriton +lineola_, _Anotheca coronata_, and _Phyllomedusa moreleti_ could have +crossed the isthmus. + +During the interglacial periods, which in the isthmian region were +characterized by warmer temperatures, higher sea level and consequently +more restricted areas of lowlands, and possibly more rainfall than in +the glacial periods, the continuity of pine-oak forest and cloud forest +from east to west across the isthmus was interrupted. Probably, too, +the semi-arid environments were restricted, and the rainforests were +more widespread. At those times animals now inhabiting the rainforests +of the Gulf lowlands and those inhabiting the Pacific lowlands of +Chiapas and Guatemala could have crossed the isthmus. In this group are +species such as _Bolitoglossa occidentalis_, _Eleutherodactylus +rhodopis_, _Microbatrachylus pygmaeus_, and _Rana palmipes_. + +The amount of differentiation in isolated populations of amphibians in +southern México and northern Central America gives some idea of +relative lengths of time of isolation from related populations. Those +populations inhabiting high mountain environments on either side of the +isthmus are specifically distinct. Some populations inhabiting cloud +forests lower on the mountains are specifically distinct from related +populations on the other side of the isthmus; between others there is +no recognizable differentiation. Even though many populations are +isolated from other populations of the same species in the lowlands of +the isthmus, there is no apparent speciation. This indicates that the +lowland environments and their inhabitants have been isolated from one +another for a shorter time than have the highland environments and +their inhabitants. + + + + +ACCOUNTS OF SPECIES + + +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 Natural History + MCZ Museum of Comparative Zoology, Harvard College + UIMNH University of Illinois Museum of Natural History + UMMZ University of Michigan Museum of Zoology + USNM United States National Museum + + +=Gymnopis mexicanus mexicanus= Duméril and Bibron + + _Oaxaca_: El Barrio (3); Matías Romero; Tehuantepec (2). + _Veracruz_: Cosamaloapan; Cuatotolapam (2). + +The two specimens from Cuatotolapam were collected by Ruthven in an +area of mixed savanna and forest. The three specimens (USNM 30535-7) +listed above from El Barrio were collected by Sumichrast; possibly they +came from another locality. The city of Tehuantepec is divided into +seven districts called "barrios." The two specimens listed from +Tehuantepec (MCZ 1604) merely bear the data "Tehuantepec, Mexico." They +may have come from the town, the district, or from anywhere in the +isthmus. The specimen from Matías Romero has 109 primary and 67 +secondary annuli, a length of 400 mm., and a diameter of 19 mm.; the +one from Cosamaloapan has 106 primary and 58 secondary annuli, a length +of 397 mm., and a diameter of 19 mm. Data on the other specimens were +recorded by Dunn (1942:475). + + +=Bolitoglossa occidentalis= Taylor + + _Oaxaca_: Río Sarabia (2); Ubero. _Veracruz_: La Oaxaqueña; + 14 km. E of Suchil. + +The specimens from Oaxaca are only tentatively assigned to +_occidentalis_. All are immature and lack maxillary teeth. Taylor +(1941:147) stated that the maxillary teeth are absent in young +_occidentalis_. One from Río Sarabia is a male with a body-length of 29 +mm. and a tail-length of 22 mm. The dorsum is reddish brown streaked +with dark gray; the venter is dark gray. Two small individuals (one +from Sarabia and one from Ubero) have body-lengths of 19 and 21 mm. and +tail-lengths of 10.5 and 11 mm. In life they were pale yellowish tan +above with a brown triangular mark on the occiput, but with no +middorsal stripe. Both were found in the axils of elephant ear plants +(_Xanthosoma_). + +This species has been noted by Goodnight and Goodnight (1956:146) on +the Atlantic lowlands at Palenque, Chiapas, and by Shannon and Werler +(1955:362) at several localities in Los Tuxtlas, Veracruz. I have +collected it at Vista Hermosa on the eastern slopes of the Sierra Madre +Oriental above Tuxtepec in northern Oaxaca. Both _B. occidentalis_ and +_B. rufescens_ have been reported from Palenque, Chiapas (Taylor and +Smith, 1945:547). Reëxamination of specimens from northern Chiapas and +Tabasco is needed to verify the sympatric occurrence of these two +similar species. + + +=Bolitoglossa platydactyla= Tschudi + + _Oaxaca_: La Oaxaqueña; Tolosita (2). _Veracruz_: Acayucan; + Cuatotolapam; 25 km. ESE of Jesús Carranza; 14 km. E of + Suchil; 2.7 km. N of Tula. + +Known only from the Gulf lowlands in the isthmian region, this species +has been taken in a variety of habitats within the humid forest area: +under outer leaves of banana plants, under a rock along a stream, under +a log in a plowed field, and on a reed in a pond at night. Three adult +males have an average snout-vent length of 44 mm. and a tail-length of +41 mm. In life the color of the dorsum varied from orange-yellow to +orange-tan, usually being more orange on the tail. The iris was a +reddish orange. + + +=Bolitoglossa veracrucis= Taylor + + _Veracruz_: 35 km. SE of Jesús Carranza (21). + +This species is known only from the type series collected at night on a +limestone cliff by Walter W. Dalquest. If this salamander is restricted +to this type of habitat, it should be found in the region of extensive +limestone outcroppings in northern Chiapas and southern Tabasco. + + +=Rhinophrynus dorsalis= Duméril and Bibron + + _Oaxaca_: Ixtepec; Limón; Salina Cruz (18); Tehuantepec + (57); Tuxtepec (3). _Veracruz_: Amatitlán (3); Cosamaloapan + (5); Novillero (2); San Lorenzo. + +This species inhabits the scrub forests of the Pacific coastal plain +and the savannas in southern Veracruz; apparently it does not occur in +rainforest. Consequently, its distribution in the isthmus is +discontinuous. + +PLATE 1 + +[Illustration: FIG. 1. Savanna about 75 kilometers east of +Coatzacoalcos, Veracruz. Photograph by L. C. Stuart.] + +[Illustration: FIG. 2. Low scrub forest near Alvarado, Veracruz. +Photograph by L. C. Stuart.] + +PLATE 2 + +[Illustration: FIG. 1. Rainforest near Tolosita, Oaxaca. March, 1956.] + +[Illustration: FIG. 2. Rainforest along the Río Sarabia, Oaxaca. March, +1956.] + +PLATE 3 + +[Illustration: FIG. 1. Transition forest near La Princesa, Oaxaca. +March, 1956.] + +[Illustration: FIG. 2. Palm Savanna on the Plains of Chivela, Oaxaca. +March, 1956.] + +PLATE 4 + +[Illustration: FIG. 1. Scrub forest on the Plains of Tehuantepec in dry +season. March, 1956.] + +[Illustration: FIG. 2. Scrub forest on the Plains of Tehuantepec in +rainy season. View toward the north. In the distance is the Continental +Divide in the hills of the Isthmus. July, 1958.] + +PLATE 5 + +[Illustration: FIG. 1. Low, dense scrub forest near La Ventosa, Oaxaca. +July, 1958.] + +[Illustration: FIG. 2. Temporary pond in scrub forest north of Salina +Cruz, Oaxaca. July 7, 1958. _Rhinophrynus dorsalis_, _Bufo marmoreus_, +and _Diaglena reticulata_ were breeding here the previous night.] + +PLATE 6 + +[Illustration: FIG. 1. Calling male of _Rhinophrynus dorsalis_, +photographed in a pond north of Santa Cruz, Oaxaca, on July 6, 1958. +× 2/3.] + +[Illustration: FIG. 2. Color pattern variation in two adults of _Bufo +canaliferus_ from Juchitán, Oaxaca. × 2/3.] + +PLATE 7 + +[Illustration: FIG. 1. Calling male of _Engystomops pustulosus_, +photographed in a pond west of Tehuantepec, Oaxaca, on July 5, 1956. +× 2.] + +[Illustration: FIG. 2. Foamy egg mass of _Engystomops pustulosus_ at +the edge of a pond west of Tehuantepec, Oaxaca. July 5, 1956. × 3/8.] + +PLATE 8 + +[Illustration: FIG. 1. Calling male of _Diaglena reticulata_, +photographed at a pond north of Salina Cruz, Oaxaca, on July 6, 1958. +× 1/2.] + +[Illustration: FIG. 2. Clasping pair of _Diaglena reticulata_ at the +edge of a pond north of Salina Cruz, Oaxaca, on July 6, 1958. × 1.] + +Breeding congregations were found after heavy rains at Tehuantepec on +July 5, 1956, at Cosamaloapan, Novillero, and Amatitlán on July 26, +1956, and at Salina Cruz on July 6, 1958. The call is a long "worrp" +made while the male is floating on the surface of the pond. The small +heads, small limbs, and greatly inflated bodies cause the calling males +to resemble miniature caricature balloons (Pl. 6, fig. 1). Amplexus is +inguinal. These toads are notably wary, even when calling. Often the +beam of a flashlight or the slightest disturbance of the water will +cause the males to stop calling. The body is deflated with one last +nauseous note, and the frog sinks beneath the surface of the water and +swims away with short slow kicks of the hind feet. + + +=Bufo canaliferus= Cope + + _Oaxaca_: Chivela; Salina Cruz; Santa Efigenia; Tapanatepec + (6); Tehuantepec (10); Zanatepec (4). + +This small toad apparently is restricted to the Pacific lowlands from +the Isthmus of Tehuantepec eastward to Guatemala. At Zanatepec on July +13, 1956, males were calling from a flooded field bordered by scrub +forest. The call is a rather loud nasal racket. Living individuals vary +greatly in coloration. Some have yellowish tan flanks and dorsum and an +orange middorsal stripe; others have a pale red dorsum, yellow flanks, +and a cream middorsal stripe (Pl. 6, fig. 2). + + +=Bufo coccifer= Cope + + _Oaxaca_: Juchitán (5); Tehuantepec. + +It is with some degree of hesitancy that these toads are referred to +the species _coccifer_. Although these and other specimens from +Guerrero and Michoacán display no striking differences from specimens +from Costa Rica, Nicaragua, and southeastern Guatemala, the ranges of +the populations are separated by a broad hiatus in Chiapas and +Guatemala. Possibly this species has utilized the sub-humid corridor +through northern Central America (Stuart, 1954) and subsequently +disappeared from the corridor in Guatemala and Chiapas. Specimens of a +_coccifer_-like toad collected by Stuart in the vicinity of +Jacaltenango, Departamento Huehuetenango, Guatemala, are much larger +than either the Central American or Mexican specimens of _coccifer_. A +final commitment on the systematic status must await a thorough study +of this group of toads. + +Males of this species were calling from a grassy rain-pool in open +scrub forest at the edge of Juchitán on July 6, 1956. The call is a +low "whirrr." The calling males were sitting in the shallow water at +the edge of pond, where they were hidden by the grass. None was +observed in open water, as is characteristic of calling males of _Bufo +canaliferus_ and _marmoreus_. + + +=Bufo marinus= Linnaeus + + _Oaxaca_: Agua Caliente; Guichicovi (3); Mixtequilla; + Tolosita (6); Tehuantepec (37); Tuxtepec; Unión Hidalgo. + _Veracruz_: Ciudad Alemán (4); Cosamaloapan; Cuatotolapam + (19); 20 km. SE of Jesús Carranza (4); 38 km. SE of Jesús + Carranza (10); 20 km. NE of Jesús Carranza (4); Novillero. + +This large toad is abundant throughout the lowlands of the isthmus. The +loud rattling call of males was heard on rainy nights throughout the +summer. In March, 1956, several adults were found in a small cave back +of a spring at Agua Caliente. + + +=Bufo marmoreus= Wiegmann + + _Oaxaca_: Cerro San Pedro (2); Chivela (5); Escurano (3); + Juchitán; Salina Cruz (101); Santa Lucía (2); 12 km. S of + Santiago Chivela (11); Santo Domingo; Tapanatepec; + Tehuantepec (100); Tequisistlán. _Veracruz_: Alvarado; + Coatzacoalcos. + +This toad is abundant on the Pacific lowlands, where it inhabits both +open and dense scrub forest. On the Gulf lowlands its distribution +seems to be limited to xeric coastal habitats. Aside from the specimens +from Alvarado and Coatzacoalcos, it is known in Veracruz only from Boca +del Río (Langebartel and Smith, 1959:27). + +The similarity in size of _Bufo marmoreus_ and _valliceps_ and their +almost completely allopatric ranges suggest that the two species may be +in competition at any one locality. Nevertheless, both were calling +from a small rocky stream south of Santiago Chivela on July 6, 1956. + +On the night of July 6, 1958, an estimated 400 toads of this species +made up a breeding congregation near Salina Cruz. The site was a +shallow muddy pond about 20 × 40 meters located in an area cleared of +scrub forest; the banks of the pond were devoid of vegetation (Pl. 5, +fig. 2). Breeding in the same pond were _Rhinophrynus dorsalis_ and +_Diaglena reticulata_. The following morning no more than a dozen +_Bufo_ were found in the pond, but several individuals were found +beneath debris and in small burrows near the pond. On July 7, 1958, +large numbers of tadpoles and recently metamorphosed young were in a +shallow grassy pool just east of Salina Cruz. + +Taylor (1943b:347) referred certain specimens from Tehuantepec to _Bufo +perplexus_, a species closely related to _Bufo marmoreus_. Evidence to +be presented elsewhere shows that _perplexus_ does not occur in the +isthmus. + + +=Bufo valliceps valliceps= Wiegmann + + _Oaxaca_: Guichicovi (2); Matías Romero; 32 km. N of Matías + Romero (2); Nueva Raza; Río Sarabia (3); Santa María + Chimalapa (14); Santiago Chivela; 12 km. S of Santiago + Chivela (5); Santo Domingo (5); Tolosita (7). _Veracruz_: + Acayucan (3); Alvarado; Amatitlán; Ayentes; Cosamaloapan + (3); Cosoleacaque (6); Cuatotolapam (14); Hueyapan; 20 km. + ENE of Jesús Carranza (6); 20 km. S of Jesús Carranza; 25 + km. SE of Jesús Carranza (23); 35 km. SE of Jesús Carranza; + 60 km. SW of Jesús Carranza (5); La Oaxaqueña (4); Novillero + (4); San Lorenzo (5). + +Individuals were found in both wet and dry seasons. In the dry season +they were most frequently found in rainforest, whereas in the rainy +season breeding congregations were found in savannas as well. This toad +occurs throughout the Gulf lowlands and on the Pacific slopes and in +the Grijalva Valley of Chiapas and Guatemala, but not on the Pacific +lowlands of the isthmus. + +I have not been able to recognize individuals referrable to the race +_macrocristatus_. Firschein and Smith (1957:219) described +_macrocristatus_ from the mountains of eastern Oaxaca and referred to +it specimens from the Gulf lowlands of northern Chiapas. None of the +present material shows the hypertrophied cranial crests supposedly +characteristic of _macroaristatus_, nor do specimens from the isthmus +resemble the population in the Grijalva Valley being described by L. C. +Stuart, who will discuss the variation in, and the validity of, the +named populations of _valliceps_. + +Five specimens from San Lorenzo, Veracruz (USNM 123516-20), were +identified as _Bufo cristatus_ by Smith (1947:408). Firschein (1950:83) +redefined the _cristatus_ group of _Bufo_ and assigned these specimens +to _valliceps_. + + +=Eleutherodactylus alfredi= Boulenger + + _Oaxaca_: Tolosita (2). _Veracruz_: 35 km. SE of Jesús + Carranza (6). + +These specimens were collected in rainforest. Shreve (1957:247) pointed +out the close resemblance between _E. alfredi_ and _E. conspicuus_ from +Piedras Negras, Guatemala, and treated them as subspecies. Examination +of the specimens from the isthmus, together with seven from central +Veracruz and one from Teapa, Tabasco, suggests an even closer +relationship. _Eleutherodactylus conspicuus_ was diagnosed by Taylor +and Smith (1945:567) as differing from _alfredi_ "in lacking a tarsal +fold, in having shorter hind legs with the tibiotarsal articulation +reaching only to the nostril instead of beyond the tip of the snout; +the vomerine teeth barely reach the posterior level of the choanae." +The specimen from Teapa has the vomerine teeth reaching to the +posterior edge of the choanae; in the eight specimens from the isthmus +the teeth reach the posterior edge of the choanae in two and to the +middle of the choanae in six; in seven specimens from central Veracruz +the teeth reach the posterior edge of the choanae in two and to the +middle in five. The tibiotarsal articulation extends beyond the tip of +the snout in the specimen from Teapa and in two from central Veracruz; +in three specimens from the isthmus and in one from central Veracruz it +extends only to the nostril; in the others it extends to the snout. The +tarsal fold is absent in the specimen from Teapa, in three from the +isthmus, and in all those from central Veracruz; it is weakly present +in the others. + +In the light of this evidence there seems to be little justification in +recognizing two species or even two subspecies in this group. +Consequently, _Eleutherodactylus conspicuus_ Taylor and Smith (1945) is +here placed in the synonymy of _Eleutherodactylus alfredi_ Boulenger +(1898), a species with a range extending from Cuautlapan and Potrero +Viejo in central Veracruz southward and eastward in forested habitats +to western El Petén, Guatemala. + + +=Eleutherodactylus natator= Taylor + + _Veracruz_: 35 km. SE of Jesús Carranza (3); 38 km. S of + Jesús Carranza; 55 km. SE of Jesús Carranza. + +The snout-vent length is 42.0 mm. in a male and averages 59.5 mm. in +three adult females. The tarsal fold is low and extends about half the +length of the tarsus; the first and second fingers are subequal in +length; the tibiotarsal articulation extends beyond the tip of the +snout. The patches of vomerine teeth lie between the posterior margins +of the choanae. The throat and belly are immaculate, and the soles of +the feet are dark. In the isthmus this species can be distinguished +from _Eleutherodactylus rugulosus_ by less rugose skin on the dorsum +and absence of dark ventral mottling. + +The specimens reported here extend the known range of _natator_ +eastward from Camotlán, Oaxaca; northward in Veracruz the species +inhabits foothills as far north as Huatusco. + + +=Eleutherodactylus rhodopis= Cope + + _Oaxaca_: 30 km. N of Matías Romero; Río Sarabia (5); + Tapanatepec (87); Tolosita (6); between Zanatepec and + Tapanatepec. _Veracruz_: 25 km. SE of Jesús Carranza; 35 km. + SE of Jesús Carranza (2); 22 km. SSW of Jesús Carranza; 20 + km. ENE of Jesús Carranza (7); Minatitlán; Tapalapan (5). + +For the purposes of the present study I am not recognizing +_Eleutherodactylus beati_, _E. dorsoconcolor_, and _E. venustus_ as +specifically, or even subspecifically distinct from the earlier named +_E. rhodopis_. Probably these are mere color varieties of a single +species. + +In the dry season frogs of this species were in humid forests, where +they were most frequently found along small streams and in ravines. The +species is widespread in the Gulf lowlands, but does not occur on the +Plains of Tehuantepec. It does inhabit the Pacific slopes on the +foothills of the Sierra Madre de Chiapas, the western part of which +extends into eastern Oaxaca near Tapanatepec. + + +=Eleutherodactylus rugulosus= Cope + + _Oaxaca_: La Princesa (30); Modelo; Santa Lucía (10); + Tapanatepec (26); Tehuantepec (6); Tres Cruces (8). + _Veracruz_: Tapalapan (5). + +In addition to the specimens from the lowlands of the isthmus, for the +purposes of the following discussion, I have included data on two +specimens from the southern slopes of the Sierra del Sur in Oaxaca +(Mirador and Chacalapa) and on several specimens from Los Tuxtlas in +Veracruz (Los Chaneques, 67; Salto de Eyipantla, 35; and San Andrés +Tuxtla, 11). + +Frogs of the _Eleutherodactylus rugulosus_ complex occur from southern +Veracruz and Sinaloa southward through Central America. Taylor +(1940:401) described _E. vocalis_ from Hacienda El Sabino, Michoacán; +Taylor and Smith (1945:580) described _E. avocalis_ from Tres Cruces, +Oaxaca. These have been considered as species distinct from +_rugulosus_, which is known to occur in Veracruz, Guerrero, and Chiapas +southward into Central America. Although the large number of specimens +collected in the isthmus does not aid in defining the ranges of the +taxa involved, these specimens do give some idea of the variation in +certain characters in a given population. + +In specimens from Los Tuxtlas the tarsal fold is well-developed and +extends two-thirds to three-fourths the length of the tarsus; the +tibiotarsal articulation reaches the nostril and sometimes slightly +beyond the tip of the snout. In males the tympanum is nearly equal to +the diameter of the eye; in females it is about one-half the diameter +of the eye. The posterior surfaces of the thighs are dark brown or +black with whitish or cream-colored spots, flecks, or irregular +mottling. The tarsal fold is dark; the throat is pale in some +individuals, but in most is mottled with dark brown or gray flecks. +Individuals from La Princesa near the continental divide in Oaxaca show +the same variation in body proportions and development of the tarsal +fold. The posterior surfaces of the thighs are dark brown indistinctly +mottled with lighter brown. The throat is dark brown. Specimens from +the Pacific slopes of Oaxaca, including the Plains of Tehuantepec, have +dark brown thighs mottled with dusty cream. The tibiotarsal +articulation extends slightly beyond the tip of the snout in all +specimens. In males the tympanum is equal to about two-thirds the +diameter of the eye. Duellman (1958b:6) discussed the variation in +these characters in populations in Colima, Jalisco, and Michoacán. + +Until the extent of variation of these characters is known throughout +the range of _rugulosus_, the recognition of populations either as +species or subspecies seems superfluous. Consequently, I have used the +oldest name; this does not necessarily imply, however, that all +populations of _rugulosus_ (_sensu lato_) are conspecific. + +Of the 200 specimens examined, 15 have a middorsal stripe that is red +or yellow. The iris varies from a copper to a dark golden color and +shines bright red at night. Many of the specimens are juveniles; these +were collected in the dry season, at which time they were found beneath +rocks along streams, in road culverts where there was some water, and +in holes in banks and cliffs. + + +=Microbatrachylus pygmaeus= Taylor + + _Oaxaca_: La Princesa (5); Matías Romero (9); Río Sarabia + (41); Tolosita (2). _Veracruz_: Jesús Carranza; 20 km. ENE + of Jesús Carranza. + +The specimens listed above vary widely in color patterns; some of the +patterns are characteristic of certain named "species": _albolabris_, +_imitator_, _lineatissimus_, and _minimus_. The large series from the +Río Sarabia contains all of the color patterns; this series was +obtained in one small ravine in the rainforest. At least in the +isthmian region, this species does not inhabit the Pacific slopes and +lowlands. + + +=Syrrhophus leprus= Cope + + _Oaxaca_: 33 km. N of Matías Romero; Santa Efigenia. + _Veracruz_: San Lorenzo. + +Although the type locality is stated to be Santa Efigenia on the +Pacific slopes of the Sierra Madre de Chiapas in eastern Oaxaca, the +type specimen probably came from the northern slopes of the mountains. +All other known specimens are from the Gulf slopes and lowlands, and +from several localities in Los Tuxtlas. Details concerning specimens +from the isthmus and other parts of the range were given by Duellman +(1958c:8). + +Smith (1947:408) reported a specimen of _Syrrhophus verruculatus_ +Peters from San Lorenzo, Veracruz; he stated that this specimen (USNM +123530) could not be _S. leprus_, because it had a gray belly, nor _S. +cystignathoides_, because of the dark and light dorsal coloration. +Firschein (1954:57) in his review of the species of _Syrrhophus_ in +eastern México referred the specimen to _S. cystignathoides_. The +specimen is in poor condition. Nevertheless, specific determination is +possible. Numerous specimens of _S. leprus_ from Los Tuxtlas have gray +bellies; some have heavier pigmentation than the specimen from San +Lorenzo. In preservative the dorsum is dark brown with lighter +mottling. There is little doubt that the specimen from San Lorenzo is +a _Syrrhophus leprus_, an abundant and widespread species in the +humid Gulf lowlands of southern México, and not _verruculatus_, if +this is a valid species (see Firschein, _op. cit._:58), and not +_cystignathoides_, a species known from San Luis Potosí southward to +central Veracruz. + + +=Syrrhophus pipilans pipilans= Taylor + + _Oaxaca_: Cerro Arenal; Cerro San Pedro; 6 km. N of Chivela; + 14 km. W of Tehuantepec (2). + +In the isthmian region this frog is known only from the Pacific slopes +and the Plains of Tehuantepec. Males call from the ground and from +trees to heights of about four meters. The call is a single, high, long +"peep." + + +=Engystomops pustulosus= Cope + + _Oaxaca_: Chivela; La Ventosa (3); Santo Domingo; + Tapanatepec (14); Tehuantepec (61); Unión Hidalgo (62). + _Veracruz_: Acayucan; Cuatotolapam (7); 10 km. SE of + Hueyapan (11). + +Large congregations were breeding at Tehuantepec on July 5, at +Tapanatepec on July 13, and at Hueyapan on July 24, 1956. The frogs +were breeding in open ponds in scrub forest and savanna; none was found +in the rainforest. Males call while floating on the water (Pl. 7, fig. +1); the call is a soft "do-ing, do-ing" with a rising tone on the last +note. Numerous individual egg masses were along the bank of a pond near +Tehuantepec; one large composite egg mass there had a surface area of +about one square meter (Pl. 7, fig. 2). The large series from Unión +Hidalgo was obtained by digging specimens out of a dry sandy river bank +in the dry season. Some of the individuals were buried to a depth of 25 +centimeters. + +In life individuals from the Pacific lowlands were dull brown and gray; +those from Acayucan were dark chocolate brown to black with pink or red +blotches, forearms, and dorsal stripe. Not all specimens from the +Atlantic lowlands are so colored; individuals from Cordoba and +Mirador, Veracruz, are like those from Tehuantepec. + + +=Leptodactylus labialis= Cope + + _Oaxaca_: Agua Caliente; Chivela (2); Matías Romero (12); 33 + km. N of Matías Romero (4); Mixtequilla; Santa Efigenia; + Tapanatepec; Tehuantepec (38); Tolosita (2); 33 km. W of + Zanatepec (49). _Veracruz_: Acayucan (3); Ciudad Alemán; + Cuatotolapam (10); Hueyapan; La Oaxaqueña (4); 38 km. SE of + Jesús Carranza; 20 km. ENE of Jesús Carranza; Novillero (3); + San Lorenzo (2). + +Although _Leptodactylus labialis_ does not appear to be so abundant as +_Leptodactylus melanonotus_, the former was found throughout the +lowlands of the isthmus. In the dry season individuals were found along +streams, and in the rainy season breeding congregations were found in +rain pools, marshes, ponds, and even small puddles. The call is a slow +"wort, wort, wort." Males call beneath the water and from beneath rocks +and from holes in the ground. The average snout-vent length of eight +adult males is 37.2 mm. A completely metamorphosed juvenile obtained at +Hueyapan on July 24, 1956, has a snout-vent length of 11 mm. + + +=Leptodactylus melanonotus= Hallowell + + _Oaxaca_: Agua Caliente (25); Cerro Arenal (2); Cerro + Quiengola (3); Cerro San Pedro (3); Chivela (2); Coyol; + Juchitán; Matías Romero (11); Mixtequilla (2); Papaloapan + (2); Salazar (9); Salina Cruz; 11 km. S of Santiago Chivela; + Tapanatepec (17); Tehuantepec (176); Tolosita; Unión + Hidalgo; 27 km. W of Zanatepec (6). _Veracruz_: Acayucan; + Cuatotolapam (9); Cosoleacaque; 20 km. ENE of Jesús Carranza + (2); 20 km. SE of Minatitlán (2); Novillero; San Lorenzo + (6). + +This frog is abundant throughout the lowlands of the isthmus, where in +the dry season individuals were found along streams and beneath rocks +at a spring seepage. In the rainy season males were calling from nearly +every bit of standing water. The call is a soft clicking sound +resembling that made by striking two small stones together. The average +snout-vent length of ten adult males is 41.8 mm. There is considerable +variation in the extent of the yellowish brown glandular areas on the +belly. Some have none, whereas others have a broad area on the chest, a +band along the flanks, and a thin band across the lower abdomen. +Individuals collected in the dry season vary in the same fashion as do +those collected in the rainy season, at which time they were breeding. +The glands are equally well-developed in adults of both sexes, and were +present in some juveniles with snout-vent lengths of less than 20 mm. +Apparently the development of the glands is not associated with +maturity, sex, or size. + + +=Diaglena reticulata= Taylor + + _Oaxaca_: Cerro Arenal; Chivela; Salina Cruz (26); San + Antonio (3); Tehuantepec (2); 8.6 km. W of Tehuantepec (11); + Zarzamora. + +Breeding congregations of this rare frog were found 8.6 kilometers west +of Tehuantepec on July 5, 1956, and at Salina Cruz on July 6, 1958. +Both choruses took place immediately after torrential rains. In both +instances the frogs were in and about open muddy pools in the scrub +forest (Pl. 5, fig. 2); males called from the bank near the water, and +clasping pairs were found only on land (Pl. 8, figs. 1-2). The call is +a loud, nasal "braaa," two to three seconds in duration. Amplexus is +axillary. + +The dorsal ground color is light yellowish green tending towards olive +on the head and fading to yellow on the flanks. The ventral surfaces, +including the vocal sac, are white; the iris is golden and flecked with +black. The present series agrees well with the description of +_reticulata_ (based on two specimens) given by Taylor (1942:60). A +detailed analysis of variation, comparison with related species, and +descriptions of tadpoles are reserved for a future report. + + +=Hyla baudini= Duméril and Bibron + + _Oaxaca_: Bisilana; Cerro Quiengola (2); Cerro San Pedro; + Coyol; Matías Romero (12); Mixtequilla; Río Sarabia (7); + Salazar; San Antonio; 11 km. S of Santiago Chivela; Santo + Domingo (3); Tapanatepec (2); Tehuantepec (23); Tolosita. + _Veracruz_: Acayucan; Amatitlán; Ciudad Alemán (3); + Cosamaloapan (2); Cuatotolapam (15); 10 km. SE of Hueyapan; + 20 km. S of Jesús Carranza; 38 km. S of Jesús Carranza (2); + 20 km. ENE of Jesús Carranza (4); La Oaxaqueña (2); + Minatitlán (2); Naranja (3); Novillero (9); Río de las + Playas (2); San Lorenzo (5); Tapalapan (2). + +Commonly found on both sides of the isthmus, this large tree frog +nearly always is associated with trees; it is not found in the +savannas, although it breeds in savannas adjacent to rainforest. It +appears to be somewhat more abundant in scrub forest than in +rainforest. In the daytime individuals were found under the outer +sheaths of banana plants, in the axils of leaves of elephant ears +(_Xanthosoma_), in cavities in trees, and on shaded limbs in the +forest. Recently metamorphosed individuals having snout-vent lengths +slightly more than 20 mm. were found in the latter part of July. + + +=Hyla ebraccata= Cope + + _Oaxaca_: Donají (17); 43 km. N of Matías Romero (27); + Sarabia (6); Tolosita (3); Ubero (17). _Veracruz_: Aquilera. + +This small species was found only in forested areas, where calling +males were on bushes and trees around rain pools. The call is a harsh +squawk repeated at intervals of 15 to 20 seconds, followed by a minute +or more of silence, and then repeated. Clasping pairs were found on +bushes and in the water. + +The dorsum bears a dark chocolate brown hour glass-shaped mark, which +in some individuals is broken into a large mark posteriorly and a +smaller triangular one on the head and nape. The dorsal ground color +varies from pale cream or ivory to yellow or tan. The intensity of the +dorsal pigmentation is subject to rather rapid change. The flanks, +hands, and anterior part of the venter are lemon yellow; the feet, +thighs, and posterior part of the venter are golden yellow. The dorsal +surface of the shank is yellow to tan with chocolate brown bars or +spots; the heel is pale yellow. There is a dark brown bar in the loreal +region and a dark brown bar extending posteriorly from the eye to a +point above the insertion of the forelimb. The iris is a copper color. +The toes are completely webbed; the fingers, one-third webbed. There is +a small axillary web that is evident when the forelimbs are at right +angles to the body. Twenty males have an average snout-vent length of +28.1 mm.; three females, 35.3 mm. There are no nuptial tuberosities on +the pollex of breeding males. + +This species has been collected at Coyame and Catemaco in Los Tuxtlas +and at various localities in Tabasco; it apparently ranges eastward +from southern Veracruz, México, in humid forests to El Petén, +Guatemala. + + +=Hyla loquax= Gaige and Stuart + + _Oaxaca_: Donají (7); 43 km. N of Matías Romero (21). + _Veracruz_: 19 km. N of Acayucan (4); Aquilera (3); 8 km. SW + of Coatzacoalcos (36); Cuototolapam (11); Naranja (13); San + Lorenzo (8). + +In the isthmus this species is known only from the humid forests of the +Gulf lowlands; it is also known from Boca del Río, Veracruz, and from +Teapa and Villa Hermosa, Tabasco. + +Calling males were found on aquatic plants above the water in deep +ponds in the forest where it was necessary for the collector to wade +waist-deep in water to obtain them. The call is a loud "hah-onk." +Individuals, when active at night, are yellowish tan above with light +olive green spots. The flanks, belly, and vocal sac are yellow, and the +anterior and posterior surfaces of the thighs and webbing of the feet +are bright orange-red or tomato red. Individuals found during the day +are grayish brown with olive markings or reddish brown with black +markings. Sleeping individuals are ivory-gray with faint gray markings. +The iris is a bright copper color. Fifteen adult males have an average +snout-vent length of 41.7 mm.; they have no horny nuptial pads on the +pollex. + +The relationships of this species are with _Hyla rickardsi_ Taylor, a +species known only from the foothills of the Sierra Madre Oriental in +the states of Puebla and Veracruz. The distinguishing characteristics +of these species are given in Table 1. Living individuals may be +distinguished immediately by the flash colors on the thighs--red in +_loquax_ and yellow in _rickardsi_. The calls of the two species are +distinctly different; that of _rickardsi_ is a high-pitched, loud +rattle continued for several seconds, notably different from the +goose-like honk of _loquax_. + +TABLE 1.--COMPARISON OF CERTAIN CHARACTERS IN HYLA LOQUAX +AND HYLA RICKARDSI + +=================================+================+==================== + CHARACTER | _loquax_ | _rickardsi_ +---------------------------------+----------------+-------------------- +Toe webbing | Full | Three-fourths + | | +Finger webbing | Three-fourths | One-half + | | +Average snout-vent length (Male) | 41.7 mm. | 37.4 mm. + | | +Tympanum/eye (Male) | 63.2% | 55.8% + | | +Dorsal leg pattern | Barred | Unmarked + | | +Tarsal fold | Tubercular | Absent + | | +Tarsal stripe | Absent or | Broad, indistinct, + | indistinct | or absent + | | +Dorsolateral stripe | Absent | Present + | | +Light line over anus | Broad | Narrow + | | +Flash colors | Red | Yellow + | | +Iris color | Copper | Bronze +---------------------------------+----------------+-------------------- + +The three specimens from San Lorenzo, Veracruz (USNM 123513-5), were +identified as _Hyla rickardsi_ by Smith (1947:409). The flash colors +have faded in preservative, and so are of no aid in identifying these +specimens. Two are adult females with snout-vent lengths of 35 and 39 +mm. In possessing a relatively large tympanum and barred thighs, and in +lacking a dorsolateral stripe they are typical of _loquax_, but in the +amount of webbing on the hands and feet, broad tarsal stripe, and +narrow anal stripe they are like _rickardsi_. The third specimen, a +juvenile, has a snout-vent length of 25 mm. In coloration it resembles +the adults; it has more distinct bars on the limbs. On the basis of +geography these specimens should be _loquax_, for the closest known +record of _rickardsi_ is more than 200 kilometers to the northwest, +whereas _loquax_ is known from several localities around San Lorenzo. + +Shannon and Werler (1955:383) described _Hyla axillamembrana_ from the +lower southern slopes of Los Tuxtlas. The unique type is a small male +(27 mm. snout-vent). I have examined the type and find no great +differences between it and small specimens of _loquax_. It is not +possible to determine the color of the thighs, nor was this information +given in the description. _Hyla axillamembrana_ is here considered to +be a synonym of _Hyla loquax_. + + +=Hyla microcephala martini= Smith + + _Oaxaca_: Donají (15); 43 km. N of Matías Romero (19); Río + Sarabia (2); Sarabia (11); Tolosita. _Veracruz_: Acayucan + (17); Alvarado (41); Aquilera (21); 8 km. SW of + Coatzacoalcos (10); Cosoleacaque (26); 10 km. SE of + Hueyapan; Naranja (3); Novillero. + +This frog is abundant in the Gulf lowlands of the isthmus, where large +breeding congregations were found in grassy ponds on the savannas and +in openings in the forest. Most frequently males were calling from +grasses and reeds in the ponds; many individuals were perched +precariously on thin blades as high as one meter above the water. The +call is a series of low squeaks. + +Individuals found at night were pale yellow above with light brown +lines arranged in an irregular pattern on the back, but often forming a +cross or an X-shaped mark in the scapular region. There is a brown +stripe from the nostril to the eye and thence to the groin. Anteriorly +this stripe is bordered above by a thin white or cream-colored line. +Numerous small brown flecks are scattered on the back and dorsal +surface of the shank. In most specimens there are thin transverse brown +bars on the shank. The thighs and undersides of the limbs are golden +yellow; the belly and vocal sac are lemon yellow. The iris is yellowish +brown. During the day individuals assume a pale reddish tan ground +color with darker brown markings. Twenty-five adult males from Alvarado +have an average snout-vent length of 24.1 mm. + + +=Hyla picta= Günther + + _Oaxaca_: Donají (8); Sarabia (11); Tolosita (15); Ubero + (6). _Veracruz_: 19 km. N of Acayucan (4); Alvarado (5); + Aquilera; 8 km. SW of Coatzacoalcos; 10 km. SE of Hueyapan + (7); Lerdo de Tejada; Tula (3). + +Widespread in the forests, scrub, and savannas on the Gulf lowlands of +the isthmus, these frogs were found breeding at numerous localities. +Males call from grasses and bushes growing in and about ponds. The +call is a high-pitched insect-like trill. At night these frogs are pale +yellow above; they change to light grayish tan during the day. A dark +stripe extends from the nostril to the eye and thence posteriorly to a +point between the axilla and groin. Above this dark stripe is a broader +white stripe. Scattered on the dorsum are brown flecks or spots; the +shanks are marked with poorly-defined cross-bars. The thighs are deep +yellow below and paler above with scattered dark flecks. The belly is +white, and the vocal sac is yellow. The iris is golden. Twenty males +have an average snout-vent length of 21.5 mm.; three females, 24.0 mm. + + +=Hyla robertmertensi= Taylor + + _Oaxaca_: Tapanatepec (28); 7.5 km. NW of Tapanatepec (38); + 7.2 km. WNW of Zanatepec (77). + +This species was found in the isthmian region only on the Pacific +lowlands at the southern base of the western part of the Sierra Madre +de Chiapas. On July 13, 1956, many large choruses were discovered. The +calling males were on reeds and thorn scrub in and at the edge of +temporary ponds; the call is a cricket-like "creak-creack," quickly +followed by a series of notes "creak-eek-eek-eek-eek." + +At night the dorsal ground color is pale yellow; this changes to +pinkish buff during the day. There is a grayish or brown dark stripe +from the nostril to the eye; the stripe continues to the groin. This +dark stripe is bordered above by a narrow white stripe. The belly is +white, and the vocal sac is yellow. The iris is dull reddish brown. +Twenty-five males have an average snout-vent length of 24.7 mm. + + +=Hyla staufferi= Cope + + _Oaxaca_: Chivela; Huilotepec (5); Juchitán (4); Matías + Romero (4); 25 km. N of Matías Romero; Mixtequilla (4); Río + Sarabia (11); 11 km. S of Santiago Chivela; Sarabia (3); + Tapanatepec (67); Tehuantepec (66); Tolosita (2); Ubero; + Unión Hidalgo; Zanatepec (6). _Veracruz_: Acayucan (7); + Alvarado (3); Amatitlán; Aquilera; Ciudad Alemán (3); 8 km. + SW of Coatzacoalcos (9); Cosamaloapan (4); Cosoleacaque (8); + 10 km. SE of Hueyapan; Lerdo de Tejada; Novillero (6); Tula + (2). + +This is the only species of small hylid that crosses the isthmus. +Calling males were found in and about ponds on the savannas in southern +Veracruz, in ponds in open forest in northern Oaxaca (not in forest +pools), and in temporary pools in the scrub forest on the Pacific +lowlands. Individuals usually called from bushes and reeds in or at the +edge of ponds. The call is a short "braaa." Dates of breeding choruses +indicate that by the time the other small species of hylids in the Gulf +lowlands reach the peak of their breeding season, that of _H. +staufferi_ is essentially over; no large breeding congregations were +found in July. On July 8, 1956, two metamorphosing young were found +clinging to blades of grass in a pond; they had snout-vent lengths of 8 +and 9 mm. and tail stumps less than 3 mm. in length. Others were found +on July 13 and 26. The juveniles are nearly unicolor olive green above +and white below. + +In life the adults vary greatly in color pattern. The dorsal ground +color is yellowish tan to olive brown with olive brown or dark brown +spots, some of which in certain individuals are connected to form +longitudinal dark stripes. On the posterior surface of the thighs are +small white flecks. The belly is white, and the vocal sac is a rich +yellow. Twenty males have an average snout-vent length of 26.3 mm.; +they have no horny nuptial pads. No noticeable differences in either +color or body proportions were found between the populations on either +side of the isthmus. + + +=Hylella sumichrasti= Brocchi + + _Oaxaca_: Cerro Arenal (5); Cerro San Pedro (2); Escurano; + La Concepción (41); Portillo Los Nanches (6); San Antonio + (16); 11 km. S of Santiago Chivela (18); Santa Lucía (7); + Tapanatepec (5); Tehuantepec (8); Tenango (49); Tres Cruces + (19). + +With the exception of the series from 11 kilometers south of Santiago +Chivela, most of these specimens were found in small arboreal +bromeliads during the dry season. Males were found along a clear, +shallow, rocky stream south of Santiago Chivela on July 6, 1956. The +frogs were calling from bushes and rocks in and along the stream. When +disturbed, they jumped into the water and floated downstream until they +were able to hold onto a rock or other object. The call is a loud +"bra-a-ah." In breeding individuals the dorsum is pale yellow; the +belly is white, and the vocal sac is yellow. The iris is pale golden +yellow. Eighteen males have an average snout-vent length of 25.2 mm. +All have dark brown nuptial tuberosities on the pollex. + +Certain diagnostic characters of this species as given by Taylor +(1943a:50) and Taylor and Smith (1945:598) are in need of revision. +_Hylella sumichrasti_ has been characterized as having no vocal sac, +rarely having vomerine teeth, and as having a relatively smooth throat. +The vocal sac in breeding males is quite evident; it is single, median, +and when expanded, spherical. The openings into the vocal sac are +narrow slits along the inner posterior border of the jaw rami. Of 151 +specimens studied, 74 have vomerine ridges between the choanae, and 36 +of these have one to three teeth on each ridge. The belly and +undersurfaces of the thighs are granular; the throat is only somewhat +less so. The granular condition may be correlated with breeding, for +specimens obtained from bromeliads in the dry season had rather smooth +throats. It seems that the vocal sac atrophys in the non-breeding +season. These seasonal changes may account for the diagnoses given by +Taylor (_op. cit._) and Taylor and Smith (_op. cit._); likewise, since +many of the specimens obtained by Smith in the dry season were +juveniles and subadults, the development of the vomerine ridges could +not be diagnosed properly. + +The range of this species encompasses the Pacific slopes of the Isthmus +of Tehuantepec eastward to the upper Cintalapa Valley and vicinity of +Tonalá in western Chiapas. Priscilla Starrett collected tadpoles of _H. +sumichrasti_ from a stream 19 km. N of Arriaga, Chiapas. These limited +observations on the ecology of this frog suggest that it breeds in the +fast-moving streams of the Pacific slopes, and that it seeks shelter in +arboreal bromeliads during the dry season. + + +=Phrynohyas modesta= Taylor and Smith + + _Oaxaca_: Tuxtepec. _Veracruz_: 20 km. S of Jesús Carranza; + 20 km. ENE of Jesús Carranza (2); Minatitlán. + +I have not collected this species in the isthmus. The locality records +indicate that the range is discontinuous (Duellman, 1956:27). The +species occurs on the humid Pacific slopes from south-central Chiapas +eastward to El Salvador and on the humid Gulf lowlands from southern +Veracruz eastward into Tabasco, but is unknown from the dry Pacific +slopes and plains in the isthmus. + +The acquisition of several specimens of this species in southern +Veracruz, Tabasco, and Oaxaca, together with a knowledge of the +variation displayed by _Phrynohyas spilomma_, suggests that _modesta_ +may be a color variety of _spilomma_. + + +=Phrynohyas spilomma= Cope + + _Oaxaca_: Tapanatepec (3). _Veracruz_: Amatitlán (12); + Chacaltianguis (2); Ciudad Alemán (6); Cosamaloapan; + Novillero (3). + +Like the preceding species, this frog is unknown from the arid Pacific +lowlands of the isthmus; its presence at Tapanatepec, a locality +situated in more mesic conditions than prevail on the Plains of +Tehuantepec, indicates that it may have a distribution on the Pacific +slopes much like that of _P. modesta_. Furthermore, this frog was not +detected in the rainforests of the Gulf lowlands; in that region it was +found only in scrub forest and savanna. + +On July 26, 1956, numerous choruses of these frogs were heard between +Ciudad Alemán and Tlacotalpan, Veracruz. The call is a loud, nasal +"grawl" repeated continuously. The males call from the water. Several +clasping pairs were found in shallow grassy ponds amidst the scrub +forest. The ground color varies from reddish brown to tan with dark +brown dorsal markings. The iris is golden, and the vocal sacs are dark +olive brown. After a light shower during the dry season, six +individuals were found on the low branches of trees at night near +Ciudad Alemán. + + +=Phyllomedusa callidryas taylori= Funkhouser + + _Oaxaca_: Donají (9); Sarabia (8); Tolosita (6); Ubero (27). + _Veracruz_: Alvarado (7); Aquilera; Berta; Coatzacoalcos + (9); 10 km. SE of Hueyapan (5); Naranja (17). + +In life this frog presents a striking array of colors. The dorsum +varies from pale green to dark olive green; there may be scattered +whitish or cream-colored spots on the back. On the flanks are bright +yellow to deep cream-colored vertical bars separated by pale blue or +purple interspaces. The thighs and undersurfaces of the hind limbs are +golden orange; the belly is yellow, and the throat is cream-colored. +The iris is crimson; the transparent part of the lower eyelid has +golden reticulations. When the frog is resting, the forefeet are folded +beneath the throat, and the limbs are folded tightly against the body. +In this position and with the eyes closed and head flattened, this +gaudy frog assumes the appearance of a small elliptical green leaf. + +Throughout the month of July, 1956, _Phyllomedusa_ was breeding in +ponds in or adjacent to the rainforest in northern Oaxaca and in +southern Veracruz. Only at Alvarado was it found breeding in a grassy +pond. Males and females alike were found on bushes and trees in and +around the ponds. The call is a single "wank." Amplexing males continue +to call, but the call is softer and less nasal in quality. The eggs are +encased in pale green gelatin and attached to leaves on branches +overhanging the water. Three egg clutches contained 38, 41, and 46 +eggs. + + +=Phyllomedusa dacnicolor= Cope + + _Oaxaca_: Escurano; Tehuantepec. + +Although it is abundant on the Pacific lowlands to the northwest in +Guerrero, Michoacán, and Colima, this species is known only from two +specimens from Tehuantepec. There is no apparent physical barrier to +their distribution in the isthmus; in the Balsas Basin the species +lives in a hotter, more arid environment than that at Tehuantepec. + + +=Gastrophryne usta= Cope + + _Oaxaca_: Santa Efigenia; Tehuantepec (10); 24 km. W of + Tehuantepec; Tolosita (2). _Veracruz_: Ayentes (6); La + Oaxaqueña; Novillero (2); San Lorenzo. + +Calling males were found in open scrub forest near Tehuantepec and in +savannas near Novillero. The specimens from Tolosita were found under +cover in a clearing in the forest (Fugler and Webb, 1957:106). + +Specimens from the Pacific lowlands are typical of _Gastrophryne usta +gadowi_ Boulenger in possessing a thin line on the posterior surface of +the thighs and a thin line from the snout to the vent. Of nine +specimens from the Gulf lowlands (Ayentes, Novillero, and San Lorenzo), +seven have a middorsal line; this is narrow in four and wide in three. +Five have the stripes on the thighs. Two specimens from the middle of +the isthmus (Tolosita) have no stripes on the thighs; one has a thin +middorsal line, and the other has a broad line. The adult males have a +black throat; females have a mottled one. The brown reticulations on +the bellies of specimens from the Gulf lowlands is bolder than on +specimens from the Pacific lowlands. The presence of certain characters +supposedly diagnostic of the subspecies _gadowi_ (line on dorsum and +thighs) in the population of _usta_ in southern Veracruz suggests that +a redefinition of the ranges of these subspecies will be in order when +sufficient material is available to delimit them accurately. For the +present I prefer to consider all specimens from the isthmus solely as +_Gastrophryne usta_ without referring them to subspecies. + + +=Rana palmipes= Spix + + _Oaxaca_: Matías Romero (11); 11 km. S of Santiago Chivela; + Santo Domingo; Sarabia. _Veracruz_: Coatzacoalcos; + Cuatotolapam; 25 km. SE of Jesús Carranza (4); Tlacotalpan + (2); Tula. + +Adults were found along streams and in marshes in savannas and +rainforest. These frogs are wary and difficult to capture, even at +night. _Rana palmipes_ is another species that has a discontinuous +distribution in the isthmus. The species does not occur on the Pacific +lowlands of the isthmus, but does occur on the more humid Pacific +slopes of Chiapas and Guatemala. + +Tadpoles were found in a small sluggish tributary to the Río Sarabia. + + +=Rana pipiens= Schreber + + _Oaxaca_: Agua Caliente; Cerro Quiengola; Escurano (14); Río + Sarabia (2); Tapanatepec (5); Tehuantepec (24). _Veracruz_: + Acayucan; Cuatotolapam (15); Jesús Carranza (2); 20 km. S of + Jesús Carranza (11); 25 km. SE of Jesús Carranza; 20 km. ENE + of Jesús Carranza (10); San Lorenzo (10). + +As in most other places in México and northern Central America, this +species occurs wherever there is permanent water. Males were heard +calling from woodland ponds and from savanna ponds. + + + + +SUMMARY + + +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 amphibian fauna. + +Analysis of present patterns of distribution shows that certain species +are restricted to the rainforests on the Gulf lowlands; others live +only in the semi-arid scrub forests on the Pacific lowlands. A third +group of species lives on both the Gulf and Pacific lowlands; most of +these species occur only in the scrub forests or savannas on the Gulf +lowlands, but some also inhabit the rainforest. In one way or another +the isthmus presents a barrier to the distribution of 75 per cent of +the species of amphibians living in the lowlands; it is a greater +barrier still to the species inhabiting the highlands on either side. + +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. + + 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 climatologias de la Republica + Mexicana. México, D. 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Bull. + Florida State Mus., vol. 3 (5):181-324. + +DUNN, E. R. + + 1942. The American caecilians. Bull. Mus. Comp. Zool., vol. + 91 (6):439-540. + +DURHAM, J. W., ARELLANO, A. R. V., and PECK, JR., J. H. + + 1952. No Cenozoic Tehuantepec seaways. Bull. Geol. Soc. + Amer., vol. 63:1245. + +FIRSCHEIN, I. L. + + 1950. A new toad from Mexico with a redefinition of the + _cristatus_ group. Copeia, 1950 (2):81-87, pl. 1. + + 1954. Definition of some little-understood members of the + leptodactylid genus _Syrrhophus_, with a description of a + new species. Copeia, 1954 (1):48-58. + +FIRSCHEIN, I. L., and SMITH, H. M. + + 1957. A high-crested race of toad (_Bufo valliceps_) and + other noteworthy reptiles and amphibians from southern + Mexico. Herpetologica, vol. 13 (3):219-222. + +FUGLER, C. M., and WEBB, R. G. + + 1957. Some noteworthy reptiles and amphibians from the + states of Oaxaca and Veracruz. Herpetologica, vol. 13 + (2):103-108. + +GLOYD, H. K. + + 1940. The rattlesnakes, genera _Sistrurus_ and _Crotalus_. + Chicago Acad. Sci. Special Publ., No. 4, vii + 266 pp., pls. + 1-31. + +GOIN, C. J. + + 1958. Comments upon the origin of the herpetofauna of + Florida. Quart. Jour. Florida Acad. Sci., vol. 21 (1):61-70. + +GOLDMAN, E. A. + + 1951. Biological investigations in Mexico. Smithsonian Misc. + Publ., vol. 115, xiii + 476 pp., pls. 1-71. + +GOODNIGHT, C. J., and GOODNIGHT, M. L. + + 1956. Some observations in a tropical rain forest in + Chiapas, Mexico. Ecology, vol. 37 (1):139-150. + +GRISCOM, L. + + 1932. The distribution of bird-life in Guatemala. Bull. + Amer. Mus. Nat. Hist., vol. 64:1-439. + + 1950. Distribution and origin of the birds of Mexico. Bull. + Mus. Comp. Zool., vol. 103:341-382. + +HARTWEG, N., and OLIVER, J. A. + + 1940. A contribution to the herpetology of the Isthmus of + Tehuantepec. IV. An annotated list of the amphibians and + reptiles collected on the Pacific slope during the summer of + 1936. Misc. Publ. Mus. Zool. Univ. Michigan, No. 47:1-31. + +HUBBELL, T. H. + + 1954. Relationships and distribution of _Mycotrupes_. In The + burrowing beetles of the genus _Mycotrupes_, Olson, A. L., + Hubbell, T. H., and Howden, H. F. Misc. Publ. Mus. Zool. + Univ. Michigan, No. 84:1-59, pls. 1-8. + +HUTCHINSON, G. E., PATRICK, R., and DEEVEY, E. S. + + 1956. Sediments of Lake Patzcuaro, Michoacán, Mexico. Bull. + Geol. Soc. Amer., vol. 67:1491-1504. + +LANGEBARTEL, D. A., and SMITH, P. W. + + 1959. Noteworthy records of amphibians and reptiles from + eastern Mexico. Herpetologica, vol. 15 (1):27-29. + +MARTIN, P. S. + + 1958. Pleistocene ecology and biogeography of North America. + Zoogeography. Amer. Assoc. Advanc. Sci., Publ. No. + 51:375-420. + +MARTIN, P. S., and HARRELL, B. E. + + 1957. The Pleistocene history of temperate biotas in Mexico + and eastern United States. Ecology, vol. 38:468-480. + +OLIVER, J. A. + + 1948. The relationships and zoogeography of the genus + _Thalerophis_ Oliver. Bull. 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The herpetofauna of the Guatemalan Plateau, with + special reference to its distribution on the southwestern + highlands. Contrib. Lab. Vertebrate Biol., Univ. Michigan, + No. 49:1-71, pls. 1-7. + + 1954. A description of a subhumid corridor across northern + Central America, with comments on its herpetofaunal + indicators. Contrib. Lab. Vertebrate Biol., Univ. Michigan, + No. 65:1-26, pls. 1-6. + + 1958. A study of the herpetofauna of the Uaxactun-Tikal area + of northern El Petén, Guatemala. Contrib. Lab. Vertebrate + Biol., Univ. Michigan, No. 75:1-30. + +TAYLOR, E. H. + + 1940. New species of Mexican Anura. Univ. Kansas Sci. Bull., + vol. 26 (11):385-405. + + 1941. New amphibians from the Hobart M. Smith Mexican + collections. Univ. Kansas Sci. Bull., vol. 27 (8):141-167. + + 1942. The frog genus _Diaglena_ with a description of a new + species. Univ. Kansas Sci. Bull., vol. 28 (4):57-65. + + 1943a. A new _Hylella_ from Mexico. Proc. Biol. Soc. + Washington, vol. 56:49-52. + + 1943b. Herpetological novelties from Mexico. Univ. Kansas + Sci. Bull., vol. 29 (8):343-361. + +TAYLOR, E. H., and SMITH, H. M. + + 1945. Summary of the collections of amphibians made in + Mexico under the Walter Rathbone Bacon Traveling + Scholarship. Proc. U. S. Natl. Mus., vol. 95:521-613, pls. + 18-32. + +TRASK, P. D., PHLEGER, F. B., and STETSON, H. C. + + 1947. Recent changes in sedimentation in the Gulf of Mexico. + Science, vol. 106:460-461. + +WEYL, R. + + 1955. Vestigios de una glaciacion del Pleistoceno en la + Cordillera de Talamanca, Costa Rica, A. C. Informe + Trimestral, Inst. Geog. de Costa Rica, pp. 9-32. + +WHITE, S. E. + + 1956. Probable substages of glaciation on Ixtaccihuatl, + Mexico. Jour. Geol., vol. 64:289-295. + +WILLIAMS, L. + + 1939. Arboles y arbustos del Istmos de Tehuantepec, Mexico. + Lilloa., vol. 4:137-171. + +_Transmitted May 23, 1960._ + + + + +UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY + + +Institutional libraries interested in publications exchange may obtain +this series by addressing the Exchange Librarian, University of Kansas +Library, Lawrence, Kansas. Copies for individuals, persons working in a +particular field of study, may be obtained by addressing instead the +Museum of Natural History, University of Kansas, Lawrence, Kansas. +There is no provision for sale of this series by the University +Library, which meets institutional requests, or by the Museum of +Natural History, which meets the requests of individuals. However, when +individuals request copies from the Museum, 25 cents should be +included, for each separate number that is 100 pages or more in length, +for the purpose of defraying the costs of wrapping and mailing. + +* An asterisk designates those numbers of which the Museum's supply +(not the Library's supply) is exhausted. Numbers published to date, in +this series, are as follows: + + Vol. 1. Nos. 1-26 and index. Pp. 1-638, 1946-1950. + +*Vol. 2. (Complete) Mammals of Washington. By Walter W. Dalquest. + Pp. 1-444, 140 figures in text. April 9, 1948. + + Vol. 3. *1. The avifauna of Micronesia, its origin, evolution, and + distribution. By Rollin H. Baker. Pp. 1-359, 16 figures + in text. June 12, 1951. + + *2. A quantitative study of the nocturnal migration of birds. + By George H. Lowery, Jr. Pp. 361-472, 47 figures in text. + June 29, 1951. + + 3. Phylogeny of the waxwings and allied birds. By M. Dale + Arvey. Pp. 473-530, 49 figures in text, 13 tables. + October 10, 1951. + + 4. Birds from the state of Veracruz, Mexico. By George H. + Lowery, Jr., and Walter W. Dalquest. Pp. 531-649, 7 + figures in text, 2 tables. October 10, 1951. + + Index. Pp. 651-681. + +*Vol. 4. (Complete) American weasels. By E. Raymond Hall. Pp. 1-466, + 41 plates, 31 figures in text. December 27, 1951. + + Vol. 5. Nos. 1-37 and index. Pp. 1-676, 1951-1953. + +*Vol. 6. (Complete) Mammals of Utah, _taxonomy and distribution_. By + Stephen D. Durrant. Pp. 1-549, 91 figures in text, 80 + tables. August 10, 1952. + + Vol. 7. *1. Mammals of Kansas. By E. Lendell Cockrum. Pp. 1-303, 73 + figures in text, 37 tables. August 25, 1952. + + 2. Ecology of the opossum on a natural area in northeastern + Kansas. By Henry S. Fitch and Lewis L. Sandidge. Pp. + 305-338, 5 figures in text. August 24, 1953. + + 3. The silky pocket mice (Perognathus flavus) of Mexico. By + Rollin H. Baker. Pp. 339-347, 1 figure in text. February + 15, 1954. + + 4. North American jumping mice (Genus Zapus). By Philip H. + Krutzsch. Pp. 349-472, 47 figures in text, 4 tables. + April 21, 1954. + + 5. Mammals from Southeastern Alaska. By Rollin H. Baker and + James S. Findley. Pp. 473-477. April 21, 1954. + + 6. Distribution of Some Nebraskan Mammals. By J. Knox Jones, + Jr. Pp. 479-487. April 21, 1954. + + 7. Subspeciation in the montane meadow mouse. Microtus + montanus, in Wyoming and Colorado. By Sydney Anderson. + Pp. 489-506, 2 figures in text. July 23, 1954. + + 8. A new subspecies of bat (Myotis velifer) from southeastern + California and Arizona. By Terry A. Vaughan. Pp. 507-512. + July 23, 1954. + + 9. Mammals of the San Gabriel mountains of California. By + Terry A. Vaughan. Pp. 513-582, 1 figure in text, 12 + tables. November 15, 1954. + + 10. A new bat (Genus Pipistrellus) from northeastern Mexico. + By Rollin H. Baker. Pp. 583-586. November 15, 1954. + + 11. A new subspecies of pocket mouse from Kansas. By E. + Raymond Hall. Pp. 587-590. November 15, 1954. + + 12. Geographic variation in the pocket gopher, Cratogeomys + castanops, in Coahuila, Mexico. By Robert J. Russell and + Rollin H. Baker. Pp. 591-608. March 15, 1955. + + 13. A new cottontail (Sylvilagus floridanus) from northeastern + Mexico. By Rollin H. Baker. Pp. 609-612. April 8, 1955. + + 14. Taxonomy and distribution of some American shrews. By + James S. Findley. Pp. 613-618. June 10, 1955. + + 15. The pigmy woodrat, Neotoma goldmani, its distribution and + systematic position. By Dennis G. Rainey and Rollin H. + Baker. Pp. 619-624. 2 figures in text. June 10, 1955. + + Index. Pp. 625-651. + + Vol. 8. 1. Life history and ecology of the five-lined skink, Eumeces + fasciatus. By Henry S. Fitch. Pp. 1-156, 26 figures in + text. September 1, 1954. + + 2. Myology and serology of the Avian Family Fringillidae, a + taxonomic study. By William B. Stallcup. Pp. 157-211, 23 + figures in text, 4 tables. November 15, 1954. + + 3. An ecological study of the collared lizard (Crotaphytus + collaris). By Henry S. Fitch. Pp. 213-274, 10 figures in + text. February 10, 1956. + + 4. A field study of the Kansas ant-eating frog, Gastrophryne + olivacea. By Henry S. Fitch. Pp. 275-306, 9 figures in + text. February 10, 1956. + + 5. Check-list of the birds of Kansas. By Harrison B. Tordoff. + Pp. 307-359, 1 figure in text. March 10, 1956. + + 6. A population study of the prairie vole (Microtus + ochrogaster) in northeastern Kansas. By Edwin P. Martin. + Pp. 361-416, 19 figures in text. April 2, 1956. + + 7. Temperature responses in free-living amphibians and + reptiles of northeastern Kansas. By Henry S. Fitch. Pp. + 417-476, 10 figures in text, 6 tables. June 1, 1956. + + 8. Food of the crow, Corvus brachyrhynchos Brehm, in + south-central Kansas. By Dwight Platt. Pp. 477-498, 4 + tables. June 8, 1956. + + 9. Ecological observations on the woodrat, Neotoma floridana. + By Henry S. Fitch and Dennis G. Rainey. Pp. 499-533, 3 + figures in text. June 12, 1956. + + 10. Eastern woodrat, Neotoma floridana: Life history and + ecology. By Dennis G. Rainey. Pp. 535-646, 12 plates, 13 + figures in text. August 15, 1956. + + Index. Pp. 647-675. + + Vol. 9. 1. Speciation of the wandering shrew. By James S. Findley. + Pp. 1-68, 18 figures in text. December 10, 1955. + + 2. Additional records and extensions of ranges of mammals + from Utah. By Stephen D. Durrant, M. Raymond Lee, and + Richard M. Hansen. Pp. 69-80. December 10, 1955. + + 3. A new long-eared myotis (Myotis evotis) from northeastern + Mexico. By Rollin H. Baker and Howard J. Stains. Pp. + 81-84. December 10, 1955. + + 4. Subspeciation in the meadow mouse, Microtus pennsylvanicus, + in Wyoming. By Sydney Anderson. Pp. 85-104, 2 figures in + text. May 10, 1956. + + 5. The condylarth genus Ellipsodon. By Robert W. Wilson. + Pp. 105-116, 6 figures in text. May 19, 1956. + + 6. Additional remains of the multituberculate genus + Eucosmodon. By Robert W. Wilson. Pp. 117-123, 10 figures + in text. May 19, 1956. + + 7. Mammals of Coahuila, Mexico. By Rollin H. Baker. Pp. + 125-335, 75 figures in text. June 15, 1956. + + 8. Comments on the taxonomic status of Apodemus peninsulae, + with description of a new subspecies from North China. By + J. Knox Jones, Jr. Pp. 337-346, 1 figure in text, 1 + table. August 15, 1956. + + 9. Extensions of known ranges of Mexican bats. By Sydney + Anderson. Pp. 347-351. August 15, 1956. + + 10. A new bat (Genus Leptonycteris) from Coahuila. By Howard + J. Stains. Pp. 353-356. January 21, 1957. + + 11. A new species of pocket gopher (Genus Pappogeomys) from + Jalisco, Mexico. By Robert J. Russell. Pp. 357-361. + January 21, 1957. + + 12. Geographic variation in the pocket gopher, Thomomys + bottae, in Colorado. By Phillip M. Youngman. Pp. 363-384, + 7 figures in text. February 21, 1958. + + 13. New bog lemming (genus Synaptomys) from Nebraska. By J. + Knox Jones, Jr. Pp. 385-388. May 12, 1958. + + 14. Pleistocene bats from San Josecito Cave, Nuevo León, + México. By J. Knox Jones, Jr. Pp. 389-396. December 19, + 1958. + + 15. New Subspecies of the rodent Baiomys from Central America. + By Robert L. Packard. Pp. 397-404. December 19, 1958. + + 16. Mammals of the Grand Mesa, Colorado. By Sydney Anderson. + Pp. 405-414, 1 figure in text. May 20, 1959. + + 17. Distribution, variation, and relationships of the montane + vole, Microtus montanus. By Emil K. Urban. Pp. 415-511. + 12 figures in text, 2 tables. August 1, 1959. + + 18. Conspecificity of two pocket mice, Perognathus goldmani + and P. artus. By E. Raymond Hall and Marilyn Bailey + Ogilvie. Pp. 513-518, 1 map. January 14, 1960. + + 19. Records of harvest mice, Reithrodontomys, from Central + America, with description of a new subspecies from + Nicaragua. By Sydney Anderson and J. Knox Jones, Jr. Pp. + 519-529. January 14, 1960. + + 20. Small carnivores from San Josecito Cave (Pleistocene), + Nuevo León, México. By E. Raymond Hall. Pp. 531-538, 1 + figure in text. January 14, 1960. + + 21. Pleistocene pocket gophers from San Josecito Cave, Nuevo + León, México. By Robert J. Russell. Pp. 539-548, 1 figure + in text. January 14, 1960. + + 22. Review of the insectivores of Korea. By J. Knox Jones, + Jr., and David H. Johnson. Pp. 549-578. February 23, 1960. + + 23. Speciation and evolution of the pygmy mice, genus Baiomys. + By Robert L. Packard. Pp. 579-670, 4 plates, 12 figures in + text. June 16, 1960. + + Index Pp. 671-690. + +Vol. 10. 1. Studies of birds killed in nocturnal migration. By + Harrison B. Tordoff and Robert M. Mengel. Pp. 1-44, 6 + figures in text, 2 tables. September 12, 1956. + + 2. Comparative breeding behavior of Ammospiza caudacuta and + A. maritima. By Glen E. Woolfenden. Pp. 45-75, 6 plates, + 1 figure. December 20, 1956. + + 3. The forest habitat of the University of Kansas Natural + History Reservation. By Henry S. Fitch and Ronald R. + McGregor. Pp. 77-127, 2 plates, 7 figures in text, 4 + tables. December 31, 1956. + + 4. Aspects of reproduction and development in the prairie + vole (Microtus ochrogaster). By Henry S. Fitch. Pp. + 129-161, 8 figures in text, 4 tables. December 19, 1957. + + 5. Birds found on the Arctic slope of northern Alaska. By + James W. Bee. Pp. 163-211, pls. 9-10, 1 figure in text. + March 12, 1958. + + 6. The wood rats of Colorado: distribution and ecology. By + Robert B. Finley, Jr. Pp. 213-552, 34 plates, 8 figures + in text, 35 tables. November 7, 1958. + + 7. Home ranges and movements of the eastern cottontail in + Kansas. By Donald W. Janes. Pp. 553-572, 4 plates, 3 + figures in text. May 4, 1959. + + 8. Natural history of the salamander, Aneides hardyi. By + Richard F. Johnston and Schad Gerhard. Pp. 573-585. + October 8, 1959. + + 9. A new subspecies of lizard, Cnemidophorus sacki, from + Michoacán, México. By William E. Duellman. Pp. 587-598, + 2 figures in text. May 2, 1960. + + 10. A taxonomic study of the Middle American Snake, Pituophis + deppei. By William E. Duellman. Pp. 599-610, 1 plate, 1 + figure in text. May 2, 1960. + + Index Pp. 611-626. + +Vol. 11. 1. The systematic status of the colubrid snake, Leptodeira + discolor Günther. By William E. Duellman. Pp. 1-9, 4 + figs. July 14, 1958. + + 2. Natural history of the six-lined racerunner, Cnemidophorus + sexlineatus. By Henry S. Fitch. Pp. 11-62, 9 figs., 9 + tables. September 19, 1958. + + 3. Home ranges, territories, and seasonal movements of + vertebrates of the Natural History Reservation. By Henry + S. Fitch. Pp. 63-326, 6 plates, 24 figures in text, 3 + tables. December 12, 1958. + + 4. A new snake of the genus Geophis from Chihuahua, Mexico. + By John M. Legler. Pp. 327-334, 2 figures in text. + January 28, 1959. + + 5. A new tortoise, genus Gopherus, from north-central + Mexico. By John M. Legler. Pp. 335-343. April 24, 1959. + + 6. Fishes of Chautauqua, Cowley and Elk counties, Kansas. By + Artie L. Metcalf. Pp. 345-400, 2 plates, 2 figures in + text, 10 tables. May 6, 1959. + + 7. Fishes of the Big Blue River Basin, Kansas. By W. L. + Minckley. Pp. 401-442, 2 plates, 4 figures in text, 5 + tables. May 8, 1959. + + 8. Birds from Coahuila, México. By Emil K. Urban. Pp. + 443-516. August 1, 1959. + + 9. Description of a new softshell turtle from the + southeastern United States. By Robert G. Webb. Pp. + 517-525, 2 pls., 1 figure in text, August 14, 1959. + + 10. Natural history of the ornate box turtle, Terrapene + ornata ornata Agassiz. By John M. Legler. Pp. 527-669, + 16 pls., 29 figures in text. March 7, 1960. + + Index will follow. + +Vol. 12. 1. Functional morphology of three bats: Eumops, Myotis, + Macrotus. By Terry A. Vaughan. Pp. 1-153, 4 plates, 24 + figures in text, July 8, 1959. + + 2. The ancestry of modern Amphibia: a review of the + evidence. By Theodore H. Eaton, Jr. Pp. 155-180, 10 + figures in text. July 10, 1959. + + 3. The baculum in microtine rodents. By Sydney Anderson. + Pp. 181-216, 49 figures in text. February 19, 1960. + + 4. A new order of fishlike Amphibia from the Pennsylvanian + of Kansas. By Theodore H. Eaton, Jr., and Peggy Lou + Stewart. Pp. 217-240, 12 figures in text. May 2, 1960. + + More numbers will appear in volume 12. + +Vol. 13. 1. Five natural hybrid combinations in minnows (Cyprinidae). + By Frank B. Cross and W. L. Minckley. Pp. 1-18. June 1, + 1960. + + 2. A distributional study of the amphibians of the isthmus + of Tehuantepec, México. By William E. Duellman. + Pp. 19-72, pls. 1-8, 3 figs. August 16, 1960. + + More numbers will appear in volume 13. + + * * * * * + + +Transcriber's Notes + + +Page 26: Changed "19. Cosaleacaque" to "19. Cosoleacaque". + +Page 30: Changed "Brysonima crassifolia" to "Byrsonima crassifolia". + +Page 34: Changed "long. 95' 29°;" to "long. 95° 29';". + +Page 35: Changed "Matías Romera" to "Matías Romero". + +Page 47: Changed "kown" to "known". + +Pages 50 and 59: Changed "axills" to "axils". + +Plate 1, Fig. 2: Changed "Veracuz" to "Veracruz". + +Page 53: Changed "valadity" to "validity". + +Page 61, Table 1: Changed male symbol to "(Male)" (plain text version). + +Page 67: Changed "refering" to "referring". + +Page 68: Changed "survided" to "survived". + +Page 71: Changed "subhimid" to "subhumid" and "Amerca" to "America". + +Moved University of Kansas Publications list to end of report. +Vol. 9, No. 12: Changed pages from "363-387" to "363-384". +Vol. 10, No. 10: Changed pages from "599-612" to "599-610". + + + + + + + + +End of the Project Gutenberg EBook of A Distributional Study of the +Amphibians of the Isthmus of Tehuantepec, Mexico, by William E. 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