Middle American Frogs of the Hyla Microcephala Group

Part 1

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University of Kansas Publications

Museum of Natural History

Volume 17, No. 12, pp. 517-557, pls. 13-16, 9 figs. March 20, 1968

Middle American Frogs of the Hyla microcephala Group

WILLIAM E. DUELLMAN AND M. J. FOUQUETTE, JR.

University of Kansas Lawrence 1968

University of Kansas Publications, Museum of Natural History

Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Frank B. Cross

Volume 17, No. 12, pp. 517-557, 4 pls. 9 figs. Published March 20, 1968

University of Kansas Lawrence, Kansas

PRINTED BY ROBERT R. (BOB) SANDERS, STATE PRINTER TOPEKA, KANSAS 1968

31-9419

Middle American Frogs of the Hyla microcephala Group

BY WILLIAM E. DUELLMAN AND M. J. FOUQUETTE, JR.

CONTENTS

PAGE

Introduction 519 Acknowledgments 520 Materials and Methods 520

Hyla microcephala Group 521 Key to Species and Subspecies 522

Accounts of Species and Subspecies 523

Cranial Osteology 540

Analysis of Mating Calls 544

Life History 550

Phylogenetic Relationships 552

Literature Cited 556

INTRODUCTION

The small yellow tree frogs, Hyla microcephala and its relatives, are among the most frequently heard and commonly collected frogs in the lowlands of southern Mexico and Central America. The similarities in size, proportions, and coloration of the different species have resulted not so much in a multiplicity of specific names, but in differences of opinion on the application of existing names to the various taxa. For example, the populations on the Atlantic lowlands have been known by three names, two of which have been applied to other taxa. Much of the confusion has been the result of previous workers' unfamiliarity with the animals in life and unawareness of the intraspecific geographic variation in the most widespread species.

Independently we undertook studies of these frogs in the field. The second author worked on the interspecific relationships and isolating mechanisms in Panama (Fouquette, 1960b) and later studied the species in southern Mexico. As part of his survey of the hylids of Middle America, the first author accumulated field and laboratory data on the frogs throughout their ranges in Mexico and Central America. The purpose of this report is to present our findings on the four species of Middle American frogs that we place in the Hyla microcephala group. In addition to conventional taxonomic characters, we have utilized the features of the cranial osteology and have relied heavily on the data obtained from an analysis of the mating calls. Furthermore, we have included ecological and distributional data in our synthesis of interspecific relationships.

Part 2

ACKNOWLEDGMENTS

Examination of specimens was made possible by the provision of working space at various institutions or through the loan of specimens. For their generosity in this manner we are grateful to Richard J. Baldauf, Charles M. Bogert, James E. Boehlke, Doris M. Cochran, Robert F. Inger, John M. Legler, Alan E. Leviton, Gerald Raun, Jay M. Savage, Hobart M. Smith, Robert C. Stebbins, Wilmer W. Tanner, Charles F. Walker, Ernest E. Williams, and Richard G. Zweifel.

Duellman is especially grateful to Charles W. Myers, Linda Trueb, Jerome B. Tulecke, and John Wellman for their assistance in the field and to Linda Trueb for her work on the cranial osteology that is incorporated in this report. Fouquette is indebted to H. Morgan Smith and A. C. Collins for assistance in the field, to A. J. Delahoussaye for assistance in the laboratory, and to W. Frank Blair for use of the facilities of the sound laboratory at the University of Texas and for much help in the early stages of this study.

The research reported herein was accomplished mainly through support by the National Science Foundation (grants NSF G-9827 and GB-1441 to Duellman and GB-599 to Fouquette). The latter's field work in Mexico was assisted in part by NSF Grant G-4956 to W. Frank Blair. Some of the field studies carried out in Panama by Duellman were supported by a grant from the National Institutes of Health (NIH GM-12020).

We are grateful to many persons, too numerous to mention, who in various ways aided our field work in Middle America. We are especially indebted to Dr. Rodolfo Hernandez Corzo and the late Ing. Luis Macias Arellano of the Direccion General de la Fauna Silvestre of the Mexican government for providing permits to collect in Mexico.

Materials and Methods

For this report, data has been obtained from 2829 preserved frogs, 42 skeletal preparations, 8 lots of tadpoles and young, and 4 lots of eggs. Much of the material was collected in our independent field work, which has extended over a period of 11 years.

Measurements were taken in the manner described by Duellman (1956). Osteological data were obtained from specimens that were cleared in potassium hydroxide, stained with alizarin red, and stored in glycerine. Recordings were made by means of Magnemite portable tape recorders (Amplifier Corp. America). The calls recorded by Fouquette were analyzed on a Sonagraph (Kay Electric Co.) at the University of Texas; those recorded by Duellman were analyzed mainly on a Vibralyzer (Kay Electric Co.) at the University of Kansas and in part on a Sonagraph at the University of Southwestern Louisiana. Sample calls were analyzed on all three instruments; the slight differences in results were found to be less than the error in measurement, so the data from all sources were combined without correction. The techniques and terminology of the calls are those defined by Fouquette (1960a, 1960b).

In the accounts of the species we have attempted to give a complete synonymy. At the end of each species account the localities from which specimens were examined are listed alphabetically within each state, province, or department, which in turn are listed alphabetically within each country. The countries are arranged from north to south. Localities preceded by an asterisk (*) are not plotted on the accompanying maps due to the crowding of symbols that would have resulted. Abbreviations for museum specimens are listed below:

AMNH --American Museum of Natural History ANSP --Academy of Natural Sciences of Philadelphia BMNH --British Museum (Natural History) BYU --Brigham Young University CAS --California Academy of Sciences FMNH --Field Museum of Natural History KU --University of Kansas Museum of Natural History MCZ --Museum of Comparative Zoology MVZ --Museum of Vertebrate Zoology SU --Stanford University UIMNH--University of Illinois Museum of Natural History UMMZ --University of Michigan Museum of Zoology USC --University of Southern California USNM --United States National Museum UU --University of Utah TCWC --Texas Cooperative Wildlife Collection TNHM --Texas Natural History Museum

HYLA MICROCEPHALA GROUP

Definition.--Small hylids attaining a maximum snout-vent length of 27 mm. in males and 32 mm. in females; dorsum yellowish tan with brown markings; thighs uniformly yellow, vocal sac in breeding males yellow; snout truncate in lateral profile; tympanum distinct, usually slightly smaller than one-half diameter of eye; vocal sac single, median, subgular; fingers about one-third webbed; toes webbed nearly to bases of discs, except only to middle of antepenultimate or base of penultimate phalanx of fourth toe; tarsal fold weak; inner metatarsal tubercle low, flat, elliptical; axillary membrane present; pupil horizontally elliptical; palpebral membrane unmarked; cranial elements reduced in ossification; sphenethmoid small, short; frontoparietal fontanelle large; tegmen tympani not extensive; quadratojugal greatly reduced; anterior arm of squamosal extending only about one-fourth distance to maxillary; posterior arm of squamosal not having bony connection with prootic; nasals lacking maxillary processes; medial ramus of pterygoid not having bony attachment to prootic; maxillary, premaxilary, and prevomerine teeth present; palatine and parasphenoid teeth absent; Mentomeckelians ossified; tadpoles having xiphicercal tails with deep caudal fins and terminal mouth lacking teeth; mating call consisting of one primary note followed by a series of shorter secondary notes; haploid number of chromosomes, 15 (known only in H. microcephala and H. phlebodes.)

Content.--As recognized here the Hyla microcephala group contains four species, one having two subspecies. An alphabetical list of the specific and subspecific names that we consider to be applicable to the Hyla microcephala group are listed below.

Names Proposed Valid Names

Hyla cherrei Cope, 1894 ? = H. m. microcephala Hyla microcephala Cope, 1886 = H. m. microcephala Hyla microcephala Boulenger, 1898 (nec Cope, 1886) = H. microcephala underwoodi Hyla microcephala martini Smith, 1951 = H. microcephala underwoodi Hyla microcephala sartori Smith, 1951 = H. sartori Hyla phlebodes Stejneger, 1906 = H. phlebodes Hyla robertmertensi Taylor, 1937 = H. robertmertensi Hyla underwoodi Boulenger, 1899 = H. microcephala underwoodi

Discussion.--The color pattern is the most useful character in distinguishing the species of the Hyla microcephala group from one another. Except in Hyla microcephala, little geographic variation in color pattern is noticeable. The features of color pattern that are helpful in identifying the species are: 1) presence or absence of lateral dark brown stripe; 2) longitudinal extent and width of lateral stripe, if present; 3) presence or absence of a narrow white line just dorsal to the lateral dark stripe; 4) presence or absence of an interorbital dark mark; 5) the arrangement of dark markings on the back, either as longitudinal lines or series of dashes, or in the form of various kinds of transverse markings; 6) presence of dark flecks, longitudinal line, or transverse marks on shanks.

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