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diff --git a/34604.txt b/34604.txt new file mode 100644 index 0000000..ff5d48c --- /dev/null +++ b/34604.txt @@ -0,0 +1,2482 @@ +The Project Gutenberg EBook of Middle American Frogs of the Hyla +microcephala Group, by William E. Duellman and M. J. Fouquette + +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: Middle American Frogs of the Hyla microcephala Group + +Author: William E. Duellman + M. J. Fouquette + +Release Date: December 9, 2010 [EBook #34604] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK MIDDLE AMERICAN FROGS *** + + + + +Produced by Chris Curnow, Tom Cosmas, Joseph Cooper and +the Online Distributed Proofreading Team at +https://www.pgdp.net + + + + + + + + + +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 + +BY + +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. + + +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. + +Few consistent differences in measurements and proportions exist among +the species (Table 1). The most obvious morphological difference is +that the head is noticeably narrower in _H. robertmertensi_ than in +the other species. _Hyla phlebodes_ is the smallest species; adult +males attain snout-vent lengths of only 23.6 mm. The body is slender +in _H. microcephala_ and _robertmertensi_, slightly wider in +_phlebodes_, and noticeably broader in _sartori_. + +_Distribution._--The composite range of the Middle American frogs of +the _Hyla microcephala_ group includes the lowlands of southern Mexico +and Central America, in some places to elevations of 1200 meters, +southeastward from southern Jalisco and southern Veracruz, excluding +arid regions (northern Yucatan Peninsula, Balsas-Tepalcatepec Basin, +Plains of Tehuantepec, Grijalva Valley, Salama Basin, and upper +Motagua Valley) to the Pacific lowlands and the Cauca and Magdalena +valleys in Colombia. + + +Key to Species and Subspecies + + +1. Lateral dark stripe, bordered above by narrow white line, + extending from snout at least to sacral region 2 + + Lateral dark stripe, if present, not extending posteriorly to + sacral region and not bordered above by narrow white line 4 + +2. Lateral dark stripe continuous to groin; dark flecks or + longitudinal line on shanks; interorbital dark bar absent; + dorsal pattern usually consisting of pair of longitudinal dark + lines or series of dashes 3 + + Lateral dark stripe usually extending only to sacral region; + dark transverse bars on shanks; interorbital bar usually + present; dorsal pattern usually consisting of interconnecting + dark lines, sometimes forming transverse marks + _H. microcephala underwoodi_ + +3. Lateral dark stripe narrow, covering only upper edge of + tympanum; dorsal longitudinal stripes continuous, extending to + vent _H. microcephala microcephala_ + + Lateral dark stripe wide, encompassing entire tympanum; dorsal + markings consisting of longitudinal series of flecks or dashes, + or of two lines, usually not extending to vent _H. robertmertensi_ + +4. Lateral dark stripe indistinct, present only above tympanum and + insertion of arm; dorsal markings consisting of narrow lines + and dashes, sometimes interconnected; transverse bars on shanks + narrow relative to interspaces _H. phlebodes_ + + Lateral dark stripe absent; dorsal markings consisting of two broad + chevron-shaped marks; transverse bars on shanks wide relative to + interspaces _H. sartori_ + + + + +ACCOUNTS OF SPECIES AND SUBSPECIES + + +_Hyla microcephala_ Cope + + +_Diagnosis._--Lateral dark stripe narrow, covering only upper edge of +tympanum, bordered above by narrow white stripe; dorsal pattern +consisting of pair of longitudinal brown lines and no interorbital bar +(eastern populations), or of irregular dark markings forming an X- or +)(-shaped mark in scapular region and an interorbital bar (western +populations). + +_Content._--The populations inhabiting the Pacific lowlands of +southeastern Costa Rica eastward to Colombia are recognized herein as +_Hyla microcephala microcephala_ Cope; the populations in western +Costa Rica northward to Mexico are assigned to _Hyla microcephala +underwoodi_ Boulenger. + +_Distribution._--Southern Veracruz and northern Oaxaca southeastward +through the Atlantic lowlands of Central America to north-central +Nicaragua, thence southeastward on the Pacific lowlands to eastern +Panama, and thence into the Cauca and Magdalena valleys (Caribbean +drainage) of Colombia (Fig. 1). + + + [Illustration: Fig. 1. Map showing locality records for _Hyla + microcephala_.] + + +Table 1.--Variation in Certain Measurements and Properties in the + Hyla microcephala Group. (All Data Based on Adult Males; + Mean and Standard Error of Mean Below Observed Range.) + +======================================================================== + Locality | N | Snout-vent | Tibia length |Foot length| + | | length | ------------ | --------- | + | | (S-V L) | S-V L | S-V L | +------------------------------------------------------------------------ + | _H. m. microcephala_ + | +Panama: Canal Zone | 25 | 21.5-24.1 | 50.2-56.0 | 40.9-46.6 | + | | 22.8+-0.20 | 52.9+-0.37 | 43.5+-0.28 | + | | | | | +Costa Rica: Golfito | 25 | 18.5-24.5 | 49.1-54.4 | 41.8-48.0 | + | | 22.4+-0.27 | 51.6+-0.26 | 45.1+-0.32 | + | + | _H. m. underwoodi_ + | | +Nicaragua: La Cumplida | 25 | 23.0-25.6 | 51.0-55.7 | 41.3-46.5 | + | | 24.1+-0.19 | 52.9+-0.25 | 43.7+-0.25 | + | | | | | +Guatemala: Finca Chama | 25 | 21.8-25.0 | 51.0-57.2 | 41.2-47.8 | + | | 23.5+-0.16 | 54.3+-0.39 | 44.4+-0.30 | + | | | | | +Tabasco: Teapa | 25 | 22.7-25.8 | 48.0-54.5 | 40.7-46.8 | + | | 24.3+-0.14 | 51.5+-0.29 | 43.3+-0.25 | + | | | | | +Oaxaca: Donaji-Sarabia | 25 | 22.1-25.9 | 49.8-55.6 | 40.5-46.6 | + | | 23.8+-0.19 | 52.8+-0.33 | 43.4+-0.27 | + | | | | | +Veracruz: Alvarado | 25 | 21.9-25.4 | 49.6-54.4 | 40.7-47.5 | + | | 24.1+-0.17 | 51.1+-0.28 | 42.6+-0.34 | + | + | _H. robertmertensi_ + | +Guatemala: La Trinidad | 21 | 21.8-24.6 | 47.1-52.8 | 40.9-51.3 | + | | 23.4+-0.15 | 49.9+-0.34 | 43.5+-0.17 | + | | | | | +Chiapas: Acacoyagua | 25 | 21.4-25.7 | 47.8-52.4 | 41.7-46.3 | + | | 24.1+-0.20 | 50.4+-0.45 | 43.9+-0.23 | + | | | | | +Oaxaca: Tapanatepec | 25 | 22.4-26.4 | 44.1-48.3 | 39.1-44.5 | + | | 24.7+-0.18 | 46.4+-0.23 | 41.7+-0.23 | + | + | _H. phlebodes_ + | +Panama: Canal Zone | 25 | 19.6-23.2 | 49.1-56.9 | 41.9-47.1 | + | | 22.2+-0.16 | 52.8+-0.35 | 45.4+-0.26 | + | | | | | +Costa Rica: Turrialba | 25 | 19.7-23.6 | 47.4-55.7 | 38.1-46.4 | + | | 22.0+-0.18 | 51.1+-0.35 | 42.8+-0.38 | + | + | _H. sartori_ + | +Guerrero: Tierra Colorada| 25 | 23.7-26.0 | 47.2-51.4 | 42.4-47.8 | + | | 24.8+-0.13 | 49.6+-0.23 | 45.2+-0.27 | +------------------------------------------------------------------------ +Table 1. (continued) +=============================================================== + Locality | Head length | Head width | Tympanum + | ----------- | ---------- | -------- + | S-V L | S-V L | Eye +--------------------------------------------------------------- + | _H. m. microcephala_ + | +Panama: Canal Zone | 28.5-32.8 | 28.1-30.9 | 44.0-54.1 + | 31.0+-0.22 | 29.4+-0.11 | 49.0+-0.55 + | +Costa Rica: Golfito | 30.2-35.5 | 29.0-32.7 | 40.0-57.8 + | 33.1+-0.25 | 30.8+-0.16 | 48.4+-1.10 + | + | _H. m. underwoodi_ + | +Nicaragua: La Cumplida | 29.7-33.5 | 28.9-31.8 | 42.3-60.0 + | 31.6+-0.19 | 30.4+-0.17 | 49.3+-0.97 + | +Guatemala: Finca Chama | 30.8-35.3 | 29.6-33.6 | 37.5-56.4 + | 33.0+-0.16 | 31.3+-0.36 | 45.2+-0.89 + | +Tabasco: Teapa | 29.5-33.0 | 28.7-31.8 | 40.7-53.8 + | 31.7+-0.17 | 30.3+-0.16 | 45.5+-0.38 + | +Oaxaca: Donaji-Sarabia | 30.4-34.8 | 28.9-32.6 | 37.0-54.1 + | 32.8+-0.19 | 30.8+-0.17 | 45.1+-0.76 + | +Veracruz: Alvarado | 29.9-33.8 | 29.1-32.9 | 40.7-53.8 + | 31.4+-0.18 | 30.5+-0.17 | 46.6+-0.65 + | + | _H. robertmertensi_ + | +Guatemala: La Trinidad | 30.0-33.3 | 27.3-29.8 | 44.4-50.0 + | 31.3+-0.20 | 28.5+-0.23 | 47.4+-0.46 + | | | +Chiapas: Acacoyagua | 29.1-32.7 | 26.0-30.3 | 42.8-53.8 + | 31.2+-0.29 | 28.1+-0.20 | 46.5+-0.50 + | | | +Oaxaca: Tapanatepec | 26.1-30.4 | 25.4-28.1 | 45.8-58.3 + | 28.4+-0.16 | 26.8+-0.14 | 52.9+-0.77 + | + | _H. phlebodes_ + | +Panama: Canal Zone | 33.6-37.4 | 32.3-36.0 | 37.9-46.4 + | 34.8+-0.18 | 33.8+-0.18 | 41.6+-0.49 + | | | +Costa Rica: Turrialba | 32.6-35.9 | 30.5-35.0 | 35.7-48.2 + | 34.1+-0.16 | 32.9+-0.17 | 40.1+-0.53 + | + | _H. sartori_ + | +Guerrero: Tierra Colorada| 29.4-31.8 | 28.9-31.0 | 42.3-52.0 + | 30.6+-0.13 | 30.0+-0.12 | 47.4+-0.59 +--------------------------------------------------------------- + + + + +_Hyla microcephala microcephala_ Cope + + + _Hyla microcephala_ Cope, Proc. Amer. Philos. Soc., 23:281, February + 11, 1886 [Syntypes.--USNM 13473 (2 specimens, now lost) from + Chiriqui, Panama; Mr. MacNeil collector]; Bull. U.S. Natl. Mus., + 32:14, 1887. Guenther, Biologia-Centrali Americana, Reptilia and + Batrachia, p. 265, June, 1901. Dunn, Occas. Papers Boston Soc. + Nat. Hist., 5:413, October 10, 1931; Occas. Papers Boston Soc. + Nat. Hist., 8:72, June 7, 1933. Stebbins and Hendrickson, Univ. + California Publ. Zool., 56:524, February 17, 1959. Fouquette, + Evolution, 14:484, December 16, 1960. Busack, Copeia, 2:371, + June 21, 1966. + + ? _Hyla cherrei_ Cope, Proc. Acad. Nat. Sci. Philadelphia, 1894, + p. 195, 1894 [Holotype.--location unknown, apparently lost; + type-locality: "Alajuela, Costa Rica;" R. Alfaro collector]. + Guenther, Biologia Centrali-Americana: Reptilia and Batrachia, + p. 264, June, 1901. Taylor, Univ. Kansas Sci. Bull., 35:846, + July 1, 1952. + + _Hyla underwoodi_, Ruthven, Misc. Publ. Mus. Zool., Univ. Michigan, + 8:55, September 15, 1922. Barbour, Proc. New England Zool. Club, + 10:31, March 2, 1928. + + _Hyla microcephala microcephala_, Smith, Herpetologica, 7:185, + December 31, 1951. Taylor, Univ. Kansas Sci. Bull., 39:23, + November 18, 1958. + + +_Diagnosis._--Brown lateral stripe narrow, extending from nostril +along canthus, along upper edge of tympanum to groin, bordered above +by narrow white line; pair of dark brown longitudinal lines on dorsum +extending to vent; shanks having dark longitudinal line or flecks, no +transverse bars; interorbital dark mark lacking. + +_Description and Variation._--The color pattern is nearly constant. Of +103 males from the Canal Zone, all lack an interorbital dark bar, and +all have a dark longitudinal line on the dorsal surface of the shank +and a narrow lateral dark stripe, bordered above by a narrow white +line, extending to the groin. The longitudinal dark lines on the +dorsum are continuous to the groin in 95 specimens and fragmented in +two specimens. In two others the lines converge and fuse in the +scapular region, and in four specimens auxiliary, fragmented lines are +present dorsolaterally. + +In all specimens from southeastern Costa Rica (Golfito, Palmar Sur, +and Villa Neilly) the pattern is constant, except that in about 10 per +cent of the specimens the longitudinal line on the dorsal surface of +the shank is replaced by a row of brown flecks. + +Of the limited number of Colombian specimens examined, all are +patterned normally, except three from Sautata, Choco, three from +Curumani, and three from Arcataca, Magdalena, which have flecks on the +dorsal surfaces of the shanks, and one from Espinal, Tolima, which has +no markings on the shanks. + +When active at night most individuals are pale yellowish tan dorsally; +the white dorsolateral line is noticeable, but the brown lateral +stripe, dorsal brown lines, and lines on shanks are so pale that often +they are barely discernible. By day the dorsum changes to tan or pale +reddish brown; the stripes are dark brown, and the dorsolateral stripe +that is white at night becomes creamy yellow (Pl. 13). Small brown +flecks are present on the dorsum of most individuals. The venter +always is white, and the iris is pale bronze with a brown tint +immediately anterior and posterior to the pupil. In breeding males the +vocal sac is pale yellow. + +_Tadpoles._--Tadpoles of this species have been found in weed-choked +ponds in eastern Panama Province. The following description is based +on KU 104097, a specimen in developmental stage 34 (Gosner, 1960). + +Total length, 20.5 mm.; body length, 8.2 mm.; body slightly wider +than deep; snout pointed; nostrils large, situated dorsally, much +closer to snout than eyes, directed anteriorly; eyes moderately +small, situated dorsolaterally and directed laterally; spiracle +sinistral, located just posteroventral to eye; anal tube dextral. +Tail xiphicercal; caudal musculature moderately deep, becoming +slender posteriorly, extending beyond caudal fin; fins deepest at +about one-third distance from body to tip of tail; dorsal fin +extending onto body, deeper than deepest part of caudal +musculature; ventral fin slightly shallower than musculature. +Mouth small, terminal, lacking teeth and fringing papillae, but +having finely serrate beaks. In preservative, top of head pale +brown; dark stripe from tip of snout through eye to posterior edge +of body, narrowing to thin line on proximal one-fourth of tail; +venter white; tail creamy tan with fine black flecks most numerous +posteriorly; posterior two-thirds of fins edged with black. In +life, top of head yellowish tan; lateral stripe brown; belly +white; anterior half of tail lacking pigment; posterior half deep +orange; iris pale bronze (Pl. 15). + +_Remarks._--Evidence for intergradation of _Hyla microcephala_ with +_H. underwoodi_ is provided by four specimens [USC 818 (2), 6081-2] +from 6.1 kilometers northeast of the mouth of the Rio Tarcoles, and +nine specimens [USC 8254 (2), 8255, 8256 (4), 8258 (2)] from Parrita, +both in Puntarenas Province, Costa Rica. These localities lie about +two-thirds the distance from the northwesternmost locality for _H. +m. microcephala_ (Palmar Sur) to the southeasternmost locality for +_H. m. underwoodi_ (Barranca). Although in most aspects of coloration +the frogs are more nearly like _H. m. underwoodi_ than _H. m. +microcephala_, some specimens have longitudinal lines on their shanks, +such as are characteristic of _H. m. microcephala_. The dorsal pattern +varies from nearly complete longitudinal lines to broken lines, fused +into an X-shaped scapular mark or not. + +As noted by Rivero (1961:135), _Hyla microcephala_ seems to be closely +related to _Hyla misera_ Werner, a species having a wide distribution +east of the Andes in South America. Despite the similarity in color +pattern, size, and structure, we are reluctant to place the two taxa +in the same species until data on coloration in life, mating calls, +and life history are available for _Hyla misera_ and compared with +those of _Hyla microcephala_. + +The status of Cope's _Hyla cherrei_ is questionable. Since the type, +the only specimen ever referred to the species, apparently is lost, +the only extant information regarding the taxon is contained in the +original description (Cope, 1894). There the species was characterized +as having a narrow dorsolateral white stripe and lacking pigment on +the upper arms and thighs. These characteristics of the color pattern +combined with the statements "vomerine teeth few, opposite the middle +of the very large choanae" and "tympanic drum distinct, one half the +area of eye" serve to distinguish _H. cherrei_ from all other Costa +Rican hylids, except _H. m. microcephala_ and _H. m. underwoodi_. No +statements in the type description will definitely associate _cherrei_ +with one or the other of these subspecies. Since it seems obvious that +_H. cherrei_ can be associated with _H. microcephala_, we prefer to +place the name in the synonymy of the nominate subspecies, thereby +preserving the commonly used name _H. underwoodi_ (Boulenger, 1899) as +a subspecies of _H. microcephala_. + +_Distribution._--_Hyla microcephala microcephala_ inhabits coastal +lowlands from the area of Golfo Dulce (apparently absent from the +Osa Peninsula) in southeastern Costa Rica eastward in Panama, +including the Azuero Peninsula to northern Colombia and thence +southward in the valleys of the Rio Cauca and Rio Magdalena in +Colombia (Fig. 1). Except for the central area of the Canal Zone +the subspecies is unknown from the Caribbean drainage in Central +America, but in Colombia the subspecies occurs only in the +Caribbean drainage. In Central America this frog occurs mostly on +the coastal lowlands; the highest recorded elevation is 560 meters +at El Valle, Cocle, Panama. Throughout most of its range _Hyla +microcephala microcephala_ occurs in disturbed habitats--cut-over +forests, secondary growth, and pastureland. It does not seem to be +an inhabitant of either primary forest or of _Curatella_-savanna. + +_Specimens examined._--522, as follows: +Costa Rica+: Puntarenas: +Golfito, KU 32172-207; 3 km. E Golfito, KU 86399, USC 2757-8; +Palmar Sur, KU 64591-608, USC 2650 (14), UU 3907-32; *1.5-2.5 km. +ESE Palmar Sur, KU 68293-7 (skeletons), 93957-62; Parrita, USC +8254 (2), 8255, 8256 (4), 8258 (2) [intergrades with _H. m. +underwoodi_]; 3 km. NW Piedras Blancas, KU 103689; 6.1 km. NE +mouth of Rio Tarcoles, USC 818 (2), 6081-2 [intergrades with _H. +m. underwoodi_]; Villa Neilly, USC 2651; *1-5 km. WNW Villa +Neilly, USC 6182-4, 8003 (4), 8031 (3), 8032; *10.5 km. WNW Villa +Neilly, KU 64609-27, 68398 (eggs). + ++Panama+: Canal Zone: Albrook Air Base, TNHC 23389, 23497; Balboa, +ANSP 19555-6; *Fort Clayton, UIMNH 42008-12; *2.8 km. SW Fort +Kobbe, KU 96015-25; *Frijoles, MCZ 19208; *Bamboa, MCZ 21507; *8.3 +km. N Gatun Locks, TNHC 23441; *Juan Diaz, MCZ 13747; *Juan Mina, +AMNH 55436-7, ANSP 21811-2, UMMZ 126734, 126735 (6), UU 3900-6; +*8-14 km. N Miraflores Locks, TNHC 23374-88, 23390-409, 23411-38, +23440, 23442-60, 23462-76; 23478-83, 23492, 23555-60, 23562-76; +*Rio Chagres, AMNH 55430, 55439; *Rio Cocoli, 3.5 km. N Miraflores +Locks, TNHC 23410; *Summit, ANSP 23365-71, FMNH 22966-9, KU +97783-87. Chiriqui: 5.5 km. E Concepcion, AMNH 69772; *14.4 km. E +Concepcion, AMNH 69773-8; 2 km. S David, AMNH 69779; *Progreso, +UMMZ 58252, 58253 (2), 58254, 58436; Rio Gariche, 8.3 km. ESE Paso +Canoas, KU 103065-8. Cocle: 1 km. SE El Cano, KU 103042-51; El +Valle de Anton, AMNH 59614-18 (10), 69785, ANSP 23502-5, KU +77201-14, MVZ 66578-83, UIMNH 46532. Colon: Cement Plant, +Transisthmian Highway, FMNH 60394-5. Darien: El Real, KU 80454-5, +103052-64, UMMZ 125036 (10), USNM 140567-8; Rio Canclon at Rio +Chucunaque, UMMZ 125035; *Rio Chucunaque, near Yavisa, AMNH 59523. +Los Santos: Tonosi, KU 101606-9. Panama: 5 km. S Bejuco, AMNH +69782; 3 km. W Chepo, KU 77172-4, 104097-8 (tadpoles); *6 km. WSW +Chepo, KU 77175; *Chico, Rio La Jagua, USNM 129070; *La Joya, +Cacora, ANSP 25129-33; Madden Dam, FMNH 67819; Nueva Gorgona, AMNH +69780-1; *1.6 km. W Nueva Gorgona, AMNH 69783-4; 1.5 km. W Pacora, +77176-200; *Rio La Laja, near Chame, ANSP 21845; *Rio Tapia, MCZ +10048; *Tapia, AMNH 18930, 18950, 18952-3; *18 km. E Tocumen, MVZ +78662. + ++Colombia+: Choco: Sautata, Atrato, FMNH 74918 (2), 74919. +Magdalena: Aracataca, ANSP 19755-7; Curumani, MCZ 21465-74, UIMNH +28855; UMMZ 90168, USNM 118247; El Banco, Rio Magdalena, ANSP +25061; Fundacion, UMMZ 48281-2. Tolima: Espinal, MCZ 15068; +Mariquita, FMNH 81822-3. Valle: Sevilla, MCZ 13751-3. + + + + +_Hyla microcephala underwoodi_ Boulenger + + + _Hyla microcephala_ Boulenger, Proc. Zool. Soc. London, p. 481, + October 1, 1898 [Syntypes.--BMNH 94. 11. 1532-33 from Bebedero, + Guanacaste Province, Costa Rica; C. F. Underwood collector] (not + _Hyla microcephala_ Cope, Proc. Amer. Philos. Soc., 23:281, + February 11, 1886, from Chiriqui, Panama). + + _Hyla underwoodi_ Boulenger, Ann. Mag. Nat. Hist., ser. 7, 3:277, + April, 1899 (substitute name for _Hyla microcephala_ Boulenger, + preoccupied). Guenther, Biologia-Centrali Americana, Reptilia and + Batrachia, p. 278, September, 1901. Dunn and Emlen, Proc. Acad. + Nat. Sci. Philadelphia, 84:25, March 22, 1932. Stuart, Misc. Publ. + Mus. Zool., Univ. Michigan, 29:39, October 1, 1935. Taylor, Proc. + Biol. Soc. Washington, 50:44, April 21, 1937. Stuart, Occas. + Papers Mus. Zool., Univ. Michigan, 471:15, May 17, 1943. Taylor + and Smith, Proc. U. S. Natl. Mus., 95:586, June 30, 1945. Stuart, + Misc. Publ. Mus. Zool., Univ. Michigan, 69:35, June 12, 1948. + Smith and Taylor, Bull. U. S. Natl. Mus., 194:85, June 17, 1948; + Univ. Kansas Sci. Bull., 33:316, March 20, 1950. Stuart, Contr. + Lab. Vert. Biol., Univ. Michigan, 45:48, May, 1950. Taylor, Univ. + Kansas Sci. Bull., 35:891, July 1, 1952; Univ. Kansas Sci. Bull., + 39:25, November 18, 1958. + + _Hyla phlebodes_, Cole and Barbour, Bull. Mus. Comp. Zool., 50:154, + November, 1906. Kellogg, Bull. U. S. Natl. Mus., 160:172, + March 31, 1932. + + _Hyla microcephala martini_ Smith, Herpetologica, 7:187, December + 31, 1951 [Holotype.--UIMNH 20965 from Encarnacion, Campeche, + Mexico; H. M. Smith collector]. Stuart, Contr. Lab. Vert. Biol., + Univ. Michigan, 68:46, November, 1954. Fugler and Webb, + Herpetologica, 13:105, July 10, 1957. Stuart, Contr. Lab. Vert. + Biol., Univ. Michigan, 75:17, June, 1958. Neill and Allen, Publ. + Research Div., Ross Allen's Reptile Inst., 2:26, November 10, + 1959. Duellman, Univ. Kansas Publ., Mus. Nat. Hist., 13:62, + August 16, 1960. Stuart, Herpetologica, 17:74, July 11, 1961. + Hensley and Smith, Herpetologica, 18:70, April 9, 1962. Stuart, + Misc. Publ. Mus. Zool., Univ. Michigan, 122:36, April 2, 1963. + Holman and Birkenholz, Herpetologica, 19:144, July 3, 1963. + Duellman, Univ. Kansas Publ., Mus. Nat. Hist., 15:225, October 4, + 1963; Univ. Kansas Publ., Mus. Nat. Hist., 15:588, June 22, 1965. + + _Hyla microcephala underwoodi_, Smith, Herpetologica, 7:188, + December 31, 1951. + + +_Diagnosis._--Brown lateral stripe narrow, extending to groin or +only to sacral region, bordered above by narrow white line; dorsal +pattern bold, consisting of X- or )(-shaped mark in scapular +region or pair of interconnected dark lines on back; interorbital +dark mark usually present; shanks usually having dark transverse +bars. + +_Description and Variation._--The dorsal color pattern is highly +variable. The various permutations of the X-shaped scapular mark +and dark sacral marks differ proportionately in different samples. +The variation in color pattern in 12 samples is summarized in +Table 2. In samples from the southern part of the range (southern +Nicaragua and Guanacaste Province, Costa Rica) more (40-93%) +individuals have the lateral stripes extending to the groin than +in northern samples (0-42%) from southern Mexico and Guatemala. +Likewise, the percentage of specimens lacking bars on the shanks and +a dark interorbital bar is higher in the Costa Rican samples than +elsewhere in the range. The X- or )(-shaped scapular markings and +/\- or / \-shaped sacral markings are most prevalent in northern +samples, whereas to the south the dorsal markings are more commonly +arranged in a pattern of paired lines, which usually are discontinuous +and usually extend posteriorly only to the sacral region. Thus, the +color pattern in _H. m. underwoodi_ in the southern part of its range +shows trends towards the pattern characteristic of _H. m. +microcephala_. Intergrades between these two subspecies have +been discussed in the account of the nominate subspecies. + + + + + Table 2.--Variation in Color Pattern in Hyla microcephala underwoodi +========================================================================== + Population | N | Shanks || Interorbital || Dorsolateral | + | | || bar || stripe | + | |-------------||----------------||--------------| + | | Bars |Flecks|| Present| Absent|| Groin| Sacrum| +-------------------------------------------------------------------------- +Oaxaca: | 27 | 22 | 5 || 27 | 0 || 0 | 27 | + Donaji-Sarabia | | | || | || | | + | | | || | || | | +Tabasco: | 55 | 46 | 9 || 55 | 0 || 0 | 55 | + Teapa-Villahermosa| | | || | || | | + | | | || | || | | +Guatemala: | 51 | 51 | 0 || 51 | 0 || 17 | 34 | + La Libertad | | | || | || | | + | | | || | || | | +Guatemala: | 32 | 32 | 0 || 32 | 0 || 0 | 32 | + Finca Chama | | | || | || | | + | | | || | || | | +Guatemala: | 31 | 31 | 0 || 31 | 0 || 14 | 17 | + Puerto Barrios | | | || | || | | + | | | || | || | | +Honduras: | 13 | 13 | 0 || 13 | 0 || 9 | 4 | + Lago Yojoa | | | || | || | | + | | | || | || | | +Nicaragua: | 56 | 44 | 12 || 54 | 2 || 13 | 43 | + La Cumplida | | | || | || | | + | | | || | || | | +Nicaragua: | 10 | 10 | 0 || 10 | 0 || 8 | 2 | + Tipitapa | | | || | || | | + | | | || | || | | +Nicaragua: | 10 | 10 | 0 || 10 | 0 || 8 | 2 | + Santo Thomas | | | || | || | | + | | | || | || | | +Costa Rica: | 12 | 0 | 12 || 6 | 6 || 7 | 5 | + Tenorio-Tilaran | | | || | || | | + | | | || | || | | +Costa Rica: | 38 | 21[A]| 15 || 34 | 4 || 25 | 13 | + Las Canas-Liberia | | | || | || | | + | | | || | || | | +Costa Rica: | 32 | 26 | 6 || 29 | 3 || 30 | 2 | + Esparta | | | || | || | | +-------------------------------------------------------------------------- + +========================================================================== + Population | Scapular markings || Sacral | + | || markings | + |----------------------------||----------------------| + | X | )( | ][ | Other || /\ | / \ | Other | +-------------------------------------------------------------------------- +Oaxaca: | 23 | 4 | 0 | 0 || 7 | 6 | 14 | + Donaji-Sarabia | | | | || | | | + | | | | || | | | +Tabasco: | 53 | 2 | 0 | 0 || 19 | 11 | 23 | + Teapa-Villahermosa| | | | || | | | + | | | | || | | | +Guatemala: | 45 | 6 | 0 | 0 || 16 | 14 | 21 | + La Libertad | | | | || | | | + | | | | || | | | +Guatemala: | 32 | 0 | 0 | 0 || 26 | 2 | 4 | + Finca Chama | | | | || | | | + | | | | || | | | +Guatemala: | 23 | 0 | 4 | 4 || 6 | 4 | 21 | + Puerto Barrios | | | | || | | | + | | | | || | | | +Honduras: | 3 | 2 | 3 | 5 || 2 | 1 | 10 | + Lago Yojoa | | | | || | | | + | | | | || | | | +Nicaragua: | 11 | 35 | 8 | 2 || 0 | 19 | 37 | + La Cumplida | | | | || | | | + | | | | || | | | +Nicaragua: | 0 | 5 | 3 | 2 || 0 | 3 | 7 | + Tipitapa | | | | || | | | + | | | | || | | | +Nicaragua: | 3 | 0 | 7 | 0 || 0 | 5 | 5 | + Santo Thomas | | | | || | | | + | | | | || | | | +Costa Rica: | 0 | 0 | 12 | 0 || 0 | 0 | 12 | + Tenorio-Tilaran | | | | || | | | + | | | | || | | | +Costa Rica: | 0 | 11 | 19 | 8 || 0 | 0 | 38 | + Las Canas-Liberia | | | | || | | | + | | | | || | | | +Costa Rica: | 0 | 0 | 14 | 18 || 0 | 0 | 32 | + Esparta | | | | || | | | +-------------------------------------------------------------------------- + +[Footnote A: Longitudinal stripes present in two specimens.] + + + +When this frog is active at night its dorsum is pale yellow; faint +flecks are present in some individuals. The white dorsolateral line +usually is evident in the tympanic region, but in many individuals a +dorsal pattern of lines and other marks is not evident. By day the +dorsum changes to yellowish tan or pale brown with dark brown or +reddish brown markings (Pl. 13). The venter is white, and the vocal +sac in breeding males is yellow. The iris is pale bronze with a brown +tint anterior and posterior to the pupil. + +_Remarks._--_Hyla microcephala underwoodi_ has had a confused +nomenclatural history. The taxon was first named _Hyla microcephala_ +by Boulenger (1898); this name was preoccupied by _Hyla microcephala_ +Cope (1886). Cole and Barbour (1906) and Kellogg (1932) used the name +_Hyla phlebodes_ Stejneger (1906) for specimens of this frog from +Mexico. Dunn (1931, 1933, 1934) applied the name _Hyla underwoodi_ to +Panamanian specimens that we identify as _Hyla phlebodes_. Smith +(1951) named _Hyla microcephala martini_ from southern Mexico and +Guatemala and considered the northern populations to represent a +subspecies distinct from the Costa Rican _Hyla microcephala +underwoodi_, despite the fact the Stuart (1935:39) stated that +comparisons of specimens from El Peten, Guatemala, with the holotype +of _Hyla underwoodi_ showed only trivial differences. + +Much of the confusion regarding the name _Hyla underwoodi_ stems from +the illustration given by Boulenger (1898:pl. 39, fig. 3) and +reproduced by Taylor (1952:892), which shows a frog having a unicolor +dorsum, dorsolateral white lines, and dark flanks. This pattern is in +marked contrast to the pattern seen in most preserved specimens, which +have the dorsum variously marked by dark brown lines or irregular +marks. Smith (1951:185), in his description of _Hyla microcephala +martini_ from southern Mexico, considered _H. underwoodi_ to be a +subspecies of _H. microcephala_ that lacked dorsal dark markings. + +Data accumulated in 1961 through field studies by the senior author at +the type locality, Bebedero, and other localities in Guanacaste and +Puntarenas provinces in Costa Rica provide a reasonable explanation of +the differences in color pattern. As noted in the preceding description +of this subspecies, at night the dorsal markings are not evident in +many living individuals, whereas by day the dorsal markings are +prominent. Most collectors prepare their specimens by day; consequently +the majority of specimens have a pronounced dorsal pattern. Of the +frogs collected in Costa Rica in 1961, some specimens were preserved +at night; others from the same series were preserved by day. The +differences are striking. In those preserved at night, dorsal markings +are faint, if present at all. Some specimens closely match the figure +given by Boulenger (1898). + +It is extremely doubtful if the frog described and illustrated by +Boulenger could be associated with either _Hyla phlebodes_ or _H. +microcephala microcephala_. Individuals of the former species lack +a dorsolateral white line and always have some dorsal markings +evident at night; furthermore, _H. phlebodes_ is not known to occur +on the Pacific lowlands. _Hyla microcephala microcephala_ occurs +farther southeast. Since there is no reason to doubt the type locality +of _H. underwoodi_, since specimens from the area around the type +locality that have been preserved at night are like the holotype in +pattern, and since the characteristics of the populations of the frogs +in Guanacaste are the same as, or gradually blend into those of, +populations in northern Central America and southern Mexico, the +frogs from throughout the entire range can be referred to one taxon, +the earliest name for which is _Hyla underwoodi_ Boulenger, which +herein is considered to be a subspecies of _H. microcephala_ Cope. + +_Distribution._--_Hyla microcephala underwoodi_ inhabits the +Atlantic slopes and lowlands from southern Veracruz and extreme +northern Oaxaca eastward across the base of the Yucatan Peninsula +(possibly the species is extant in the northern part of the +peninsula) to British Honduras and thence southeastward through +the Caribbean lowlands and interior valleys in Honduras to central +Nicaragua, where it apparently avoids the forested Caribbean +lowlands and the dry Pacific lowlands of northwestern Nicaragua, +but in the vicinity of Managua invades the Pacific lowlands and +continues southward into northwestern Costa Rica as far as the +Puntarenas Peninsula (Fig. 1). In Mexico and Guatemala the species +has not been taken at elevations of more than 350 meters, whereas +farther south it occurs at higher elevations--780 meters at +Silencio, Costa Rica, 830 meters on Montana de Guaimaca, Honduras, +960 meters at Finca Tepeyac, Nicaragua, and 1200 meters at Finca +Venecia, Nicaragua. + +_Specimens examined._--1270, as follows: +Mexico+: Campeche: Balchacaj, +FMNH 100406, UIMNH 20944-6; Encarnacion, FMNH 27069-70, 75784, +MCZ 28360, 29637, UIMNH 20948-58, 20965, USNM 134264-5; Escarcega, +UMMZ 122999; *7.5 km. W Escarcega, KU 71229-43; Laguna Alvarado, 65 km. +S Xpujil, KU 75084-9; Pacaitun, Rio Candelaria, FMNH 83118-20; +*Tres Brazos, FMNH 113101-22, UIMNH 20947; 10 km. W Xpujil, KU 75082-3. +Chiapas: Palenque, UIMNH 47984, 49139-50, USNM 114973-8. Oaxaca: *5 km. +N Chiltepec, KU 87015-23; 3 km. N Donaji UMMZ 115249 (9); *3.7 km. +N Donaji, UMMZ 115250 (5); *43 km. N Matias Romero, UIMNH 42550-68; +*3.5 km. N Palomares, TNHC 25185, 25321-31, 25341-68; 4.6 km. N +Sarabia, UMMZ 115247 (2); *6.1 km. N Sarabia, UMMZ 115248 (11), *3 km. +N Tolocita, KU 39655; Tuxtepec, KU 87024-40. Tabasco: 24 km. N +Frontera, MCZ 35665-70; 0.8 km. E Rio Tonola, TNHC 25189; Teapa, UMMZ +119218 (4); *2.7 km. N Teapa, UMMZ 119216 (4); *10 km. N Teapa, UMMZ +119217 (6); *11.5 km. N Teapa, UMMZ 119219; *15.2 km. N Teapa, UMMZ +119220 (4); *17.6 km. N Teapa, UMMZ 119221 (12), 3.3 km. S Villahermosa, +UMMZ 119215 (12), *17.6 km. S Villahermosa, UMMZ 119214 (12). +Veracruz: 2.1 km. N Acayucan, UIMNH 42547-9; *6.4 km. NW Acayucan, +UMMZ 115254 (14); 1.6 km. ESE Alvarado, UMMZ 115258 (39); *2.4 km. ESE +Alvarado, UMMZ 115251 (2); *4.5 km. S Aquilera, UMMZ 115252 (21); +*8 km. SW Coatzacoalcos, UMMZ 119213 (10); 2.2 km. E Cosoleacaque, +UMMZ 119222 (26); 10 km. SE Hueyapan, UMMZ 115255; 0.8 km. S Lerdo de +Tejada, UMMZ 122778; *3.6 km. NE Minatitlan, TNHC 25150-2; 1.9 km. S +Naranja, UMMZ 115253 (3); 4.5 km. NE Novillero, UMMZ 115256; San Andres +Tuxtla, FMNH 113124-8, UIMNH 20942-3. Yucatan: Chichen-Itza, FMNH 36570, +MCZ 2463 (2). + ++British Honduras+: Cayo: 6.2 km. S El Cayo, MCZ 37885-92. Stann Creek: +Stann Creek, FMNH 49068. + ++Guatemala+: Alta Verapaz: 28.3 km. N Campur, KU 64578-90; Chinaja, +KU 57425; Cubilquitz, UMMZ 90887, 90888 (4); Finca Chama, UMMZ 90879 +(13), 90880 (4), 90881, 90882 (28), 90883 (12), 90884 (46), 90885 (39), +90886 (20); *Finca Tinaja, BYU 16032; Panzos, UMMZ 90889 (2). +Chiquimula: Chiquimula, UMMZ 98113; 2 km. N Esquipulas, UMMZ 106844. +El peten: La Libertad, KU 57447-97, 59907-11 (skeletons), MCZ 21461, +UMMZ 75332 (13), 75333 (11), 75334 (14), 75335 (10); Piedras Negras, +FMNH 113123, UIMNH 20966; *5 km. S Piedras Negras, USNM 114951-72; +Tikal, UMMZ 117981 (2); Toocog, 15 km. SE La Libertad, KU 57426-46. El +Quiche: Finca Tesoro, UMMZ 89165 (5). Huehuetenango: Finca San Rafael, +16 km. SE Barillas, FMNH 40917-9. Izabal: Puerto Barrios, FMNH +20004-7; 8 km. S Puerto Barrios, KU 57507-37, 59991 (eggs), 59992 +(tadpoles); Quirigua, CAS 69657-701; 2.5 km. NE Rio Blanco, KU 57539; +San Felipe, FMNH 35065. Zacapa: 14 km. ENE Mayuelas, KU 57502-6; 8 km. +ENE Rio Hondo, KU 57498-501. + ++Honduras+: Atlantidad: La Ceiba, UMMZ 91948 (2), USNM 117593-600; +Lancetilla, MCZ 17981. Cortes: Lago Yojoa, AMNH 54917-9, 54957, 55134, +KU 64563-77. El Paraiso: Valle de Jamastran, AMNH 54807-12. +Francisco-Moranza: El Zamorano, AMNH 54873-81, KU 103223, UMMZ 123101; +Montana de Guaimaca, AMNH 54900-4 (8); Ranch San Diego, 19 km. SW +Guaimaca, AMNH 53939. Itibuca: Vieja Itibuca, AMNH 54912-3. + ++Nicaragua+: Chontales: 3 km. SW Santo Tomas, KU 64770-9, 68308 +(skeleton). Esteli: Finca Venecia, 7 km. N, 16 km. E Condega, KU +85296; 2.4 km. N Esteli, MCZ 28933-7. MANAGUA: 12-13 km. E Managua, +KU 85297-301; *10 km. SW Tipitapa, UMMZ 119977 (10). Matagalpa: *Finca +Tepeyac, 10.5 km. N, 9 km. E Matagalpa, KU 85302-3; Hacienda La +Cumplida, KU 64780-96, 68309-11 (skeletons), UMMZ 116482 (8), 116483 +(23), 116484 (3), 116485 (5), 119984 (3). Rivas: *Finca Amayo, 13 km. +S, 14 km. E Rivas, KU 85304-7; 16 km. S Rivas, MCZ 29011-7; *20.5 km. +SE Rivas, KU 85308-10; 5 km. SE San Pablo, KU 43111-4. + ++Costa Rica+: Guanacaste: Arenal, USC 6254 (2); *3 km. W Bagaces, USC +7019 (10); *3 km. NE Boca del Barranca, USC 8017 (21), *Finca San +Bosco, USC 6272 (6), 6276 (3); *Guayabo de Bagaces, USC 7022 (4), 7023 +(3), 7025; 12 km. S La Cruz, USC 8091 (2); *Laguna Arenal, USC 6262; +*27 km. N Las Canas, USC 8171 (6); *16 km. E Las Canas, KU 102252-8; +16 km. SSE Las Canas, KU 65090-5; *20 km. SE Las Canas, KU 102251; +Liberia, KU 30827-39; *7.3 km. N Liberia, USC 8096 (4); *10 km. N +Liberia, USC 8085 (9); *7.5 km. SE Liberia, KU 65102-8, 68621-2 +(skeletons); *14.7 km. S Liberia, USC 8238 (3); *4 km. W Liberia, KU +36847-57; 2 km. S Nicoya, USC 8230; *3-10 km. ESE Playa del Coco, USC +8012 (16), 8137 (14); *21.6 km. ESE Playa del Coco, USC 8138 (13); +*Penas Blancas, KU 102247-50; *Rio Bebedero, 5 km. S Bebedero, KU +65089; *Rio Higueron, USC 7168 (2); Santa Cruz, USC 8232 (2); +*Silencio, USC 6248; *Tenorio, KU 32313; Tilaran, KU 36858-60; *2 km. +E Tilaran, KU 86403, *5 km. NE Tilaran, KU 36840-6 USC 6269. +Puntarenas: Barranca, KU 32305-12, *5 km. WNW Barranca, UMMZ 119976 +(2); *10 km. E Esparta, KU 86400-2; 1 km. WNW Esparta, KU 65101; *4 km. +WNW Esparta, KU 65088; *10 km. WNW Esparta, KU 65063-87, 68616-20 +(skeletons); *12 km. WNW Esparta, KU 65096-100, USC 8251; 21.8 km. +W San Ramon, USC 8242 (15). + + + + ++Hyla robertmertensi+ Taylor + + + _Hyla robertmertensi_ Taylor, Proc. Biol. Soc. Washington, 50:43, + April 21, 1937 [Holotype.--CNHM 100096 (formerly EHT-HMS 2270) + from Tapachula, Chiapas, Mexico; H. M. Smith and E. H. Taylor + collectors]. Smith and Taylor, Bull. U. S. Natl. Mus., 194:84, + June 17, 1948; Univ. Kansas Sci. Bull., 33:326, March 20, 1950. + Mertens. Senckenbergiana, 33:170, June 15, 1952; + Senckenbergischen Naturf. Gesell., 487:30, December 1, 1952. + Stuart, Contr. Lab. Vert. Biol., Univ. Michigan, 68:47, + November, 1954. Duellman, Univ. Kansas Publ., Mus. Nat. Hist., + 13:63, August 16, 1960. Duellman and Hoyt, Copeia, 1961 (2): 417, + December 19, 1961. Porter, Herpetologica, 18:168, October 17, + 1962. Stuart, Misc. Publ. Mus. Zool., Univ. Michigan, 122:36, + April 2, 1963. Duellman and Trueb, Univ. Kansas Publ., Mus. Nat. + Hist., 17:348, July 14, 1966. + + +_Diagnosis._--Brown lateral stripe wide, including loreal region and +entire tympanum, extending to groin, bordered above by narrow white +line; dorsum unicolor or with pair of dark lines (or rows of dashes) +usually extending only to the sacral region; shanks having dark flecks, +no transverse bars; interorbital bar lacking. + +_Description and Variation._--Males attain a maximum snout-vent length +of 26.4 mm. in Oaxaca, whereas in a sample from Acacoyagua, Chiapas, +the largest male has a snout-vent length of 25.7 mm., and from La +Trinidad, Guatemala, 24-6 mm. Specimens from the western part of the +range (eastern Oaxaca) have slightly smaller heads and proportionately +larger tympani than the more eastern populations (Table 1). + +The color pattern shows little variation, except in the nature of the +dorsal markings. In a few specimens from throughout the range, but +especially in the eastern part of the range, the dorsum lacks markings +between the dorsolateral white lines. In most specimens the dorsal +pattern consists of flecks or dashes arranged in two parallel +longitudinal rows, and in some specimens the marks are fused into +parallel lines. Small brown flecks are present on the dorsal surfaces +of the shanks; in some specimens these flecks tend to form a +longitudinal stripe on the shank. An interorbital dark mark is +invariably absent. + +When active at night _Hyla robertmertensi_ is pale yellow above with a +white dorsolateral line and pale brown lateral stripe; the dorsal +markings are faint. By day the dorsum is yellowish tan with brown +markings. The dorsolateral stripe is creamy white, and the lateral +stripe is dark brown (Pl. 14). The venter is white, and the iris is +dull bronze. In breeding males the vocal sac is yellow. + +_Remarks._--Although this species superficially resembles _Hyla +microcephala microcephala_, the latter is easily distinguished by the +narrow brown lateral stripe, as compared with the much wider stripe +in _H. robertmertensi_. No other hylids in northern Central America +and southern Mexico can be confused with this species. + +_Distribution._--_Hyla robertmertensi_ inhabits the Pacific slopes (to +elevations of 700 meters) and lowlands from eastern Oaxaca (east of +the Plains of Tehuantepec) southeastward to central El Salvador. The +species also occurs in the Cintalapa Valley (Atlantic drainage) in +southwestern Chiapas (Fig. 2.) The distribution seems to be limited on +the northwest and southeast by arid environments. The region in which +_Hyla robertmertensi_ lives is characterized by higher rainfall and +more luxuriant vegetation than occur on the Plains of Tehuantepec or +on the Pacific lowlands of eastern El Salvador and southern Honduras. +In addition to the localities listed below, Mertens (1952:30) +recorded the species from Hacienda Cuyan-Cuya, Depto. Sonsonate, El +Salvador. + + + [Illustration: Fig. 2. Map showing locality records for + _Hyla robertmertensi_.] + + +_Specimens examined._--490, as follows: +Mexico+: Chiapas: Acacoyagua, +USNM 114754-61; *2 km. W Acacoyagua, UMMZ 87843 (28), 87844 (50), +87845 (50), 87846 (45), 87847 (27), 87848 (3); 32 km. N Arriaga, KU +57619-24, 59917-8 (skeletons); Asuncion, FMNH 100413, 100501-4, UIMNH +26989-90, USNM 134267; *La Esperanza, USNM 114737-48, 114750-3, 17 km. +S Las Cruces, KU 57625-49, 59997 (eggs); 8.5 km. N Puerto Madero, UMMZ +119981 (2); *11.7 km. N Puerto Madero, UMMZ 119982; Tapachula, FMNH +100096, UIMNH 26987; *11 km. S Tapachula, KU 57605-18, 59916 (skeleton); +Tonola, FMNH 27073, 100505-10, UIMNH 26988. Oaxaca: Tapanatepec, +UMMZ 115245 (2), *1.6 km. E Tapanatepec, UMMZ 115244 (14); *4.3 km. +E Tapanatepec, UIMNH 38368-9; *7.5 km. W Tapanatepec, UMMZ 115246 +(39); 12.8 km. W Tapanatepec, KU 65007-14; 7.2 km. WNW Zanatepec, +UMMZ 115243 (77); *13.6 km. WNW Zanatepec, TNHC 25213-22; 22.7 km. +WNW Zanatepec, TNHC 25203-9. + ++Guatemala+: Jutiapa: Jutiapa, UMMZ 106848; La Trinidad, UMMZ +107733 (23). Retalhueleu: Casa Blanca, UMMZ 107732. + ++El Salvador+: La Libertad: 16 km. NW Santa Tecla, KU 44112. San +Salvador: 21.9 km. N San Salvador, UMMZ 119983 (6). + + + + ++Hyla phlebodes+ Stejneger + + + _Hyla phlebodes_ Stejneger, Proc. U. S. Natl. Mus., 30:817, June 4, + 1906 [Holotype.--USNM 2997 from "San Carlos," Costa Rica; + Burgdorf and Schild collectors]. Taylor, Proc. Biol. Soc. + Washington, 50:44, April 21, 1937; Univ. Kansas Sci. Bull., + 35:888, July 1, 1952; Univ. Kansas Sci. Bull., 39:25, November + 18, 1958. Fouquette, Evolution, 14:484, December 16, 1960. + Duellman and Trueb, Univ. Kansas Publ., Mus. Nat. Hist., 17:348, + July 14, 1966. + + _Hyla underwoodi_, Dunn, Occas. Papers Boston Soc. Nat. Hist., 5:413, + October 10, 1931; Occas. Papers Boston Soc. Nat. Hist. 8:72, + June 7, 1933; Amer. Mus. Novitiates, 747.2, September 17, 1934, + Gaige, Hartweg, and Stuart, Occas. Papers Mus. Zool., Univ. + Michigan, 357:5, October 26, 1937. Breder, 1946, Bull. Amer. Mus. + Nat. Hist., 86:416, August 22, 1946. + + +_Diagnosis._--Dark brown lateral stripe, if present, usually extending +only to insertion of forearm, never posteriorly to sacral region; +white line above brown stripe absent or faint; dorsal pattern weak, +usually consisting of irregular dashes or interconnected lines; +interorbital dark mark present; shanks having weakly defined +transverse bars. + +_Description and variation._--In the majority of specimens (70%) the +lateral dark stripe extends from the nostril to the eye and thence +above the tympanum to a point above the insertion of the arm; in 17 +per cent the stripe extends to the mid-flank, whereas in 13 per cent +the stripe is absent. A narrow and faint white line is present on the +canthus in some specimens, but no distinct white stripe is present +above the lateral dark line posterior to the eye. An interorbital bar +and transverse marks on the shanks are invariably present. The dorsal +markings are variable, but in most specimens (92%) consist of either +an X- or )(-shaped mark in the scapular region; in the other specimens +the markings are irregular short lines or absent. Approximately equal +numbers of specimens have a transverse bar, chevron, or broken lines +in the sacral region, whereas about eight per cent of the specimens +lack markings in the sacral region. + +When active at night, individuals are pale yellowish tan with faint +brown dorsal markings. By day they are tan with more distinct brown +markings (Pl. 14). The thighs are pale yellow; the belly is white. The +iris is pale creamy tan with brown flecks. In breeding males the vocal +sac is yellow. + +_Tadpoles._--Tadpoles of this species have been found in an extensive +grassy pond at Puerto Viejo, Costa Rica. The following description is +based on KU 104099, a specimen in development stage 36 (Gosner, 1960). + +Total length, 21.0 mm.; body length, 6.7 mm.; body slightly wider than +deep, snout pointed; nostrils large, directed anteriorly, situated +near end of snout; eyes small, situated dorsolaterally, directed +laterally; spiracle sinistral, located just posteroventral to eye; +anal tube dextral. Tail xiphicercal; caudal musculature moderately +deep, extending far beyond posterior edge of fins; fins deepest at +about midlength; dorsal fin extending onto body, slightly deeper than +caudal musculature; ventral fin slightly shallower than musculature. +Mouth small, terminal, lacking teeth and fringing papillae, but having +finely serrate beaks. In preservative top of head olive-tan with brown +flecks; dark stripe from snout through eye to posterior edge of body; +belly white, flecked with brown anteriorly; tail creamy tan with +grayish brown blotches. In life, dorsum of body reddish tan mottled +with darker brown; lateral stripe dark brown; belly white, mottled +with brown and black; caudal musculature heavily pigmented with +grayish tan; posterior tip of tail marked with dark gray; caudal fins +heavily blotched with grayish tan; iris orange-tan peripherally, red +centrally (Pl. 15). + +_Remarks._--This species has been confused with _Hyla microcephala +underwoodi_ by many workers. Dunn (1931, 1933, 1934) and Breder (1946) +referred Panamanian specimens of _H. phlebodes_ to _H. underwoodi_; +likewise, Gaige, Hartweg, and Stuart (1937) made the same error. Cole +and Barbour (1906) and Kellog (1932) used the name _H. phlebodes_ for +Mexican specimens of _H. microcephala underwoodi_. The similarity in +color pattern of _H. microcephala underwoodi_ and _H. phlebodes_ +easily accounts for the misapplication of names. Although both species +have nearly identical dorsal color patterns, that of _H. microcephala +underwoodi_ usually is bolder. Furthermore, in that species a narrow +white line usually is present above the well-defined lateral dark +stripe, whereas the lateral dark stripe is short and posterior to the +eye is not bordered above by a white line in _H. phlebodes_. + +The type locality "San Carlos, Costa Rica" given by Stejneger +(1906:817) apparently refers to a region, the Llanuras de San Carlos, +in the northern part of Alajuela Province, Costa Rica. + + + [Illustration: Fig. 3. Map showing locality records for + _Hyla phlebodes_.] + + +_Distribution._--_Hyla phlebodes_ inhabits humid tropical forests from +southeastern Nicaragua southeastward on the Caribbean slopes and +lowlands to the Canal Zone in Panama, thence eastward in the Chucunaque +Basin of eastern Panama and onto the Pacific lowlands of Colombia +(Fig. 3). The species also reaches the Pacific slopes in the Arenal +Depression in northwestern Costa Rica and in the Panamanian isthmus, +where it occurs in humid forests on the Pacific slope of El Valle and +Cerro La Campana. Mostly the species is found at low elevations, but +it occurs at 600 meters at Turrialba and at 700 meters at Finca San +Bosco in Costa Rica. + +_Specimens examined._--410, as follows: +Nicaragua+: Zelaya: Isla +Grande del Maiz, MCZ 14848; Rio Mico, El Recrero, UMMZ 79720 (6). + ++Costa Rica+: Alajuela: 12.4 km. N Florencia, MVZ 76108-10, USC 2628; +*Las Playuelas, 11 km. S Los Chiles, USC 7216; Los Chiles, USC 7217, +7219; 3 km. NE Muelle de Arenal, USC 2644 (2); *"San Carlos," USNM +29970. Cartago: Chitaria, KU 103690; *1.6 km. E Rio Reventazon Bridge, +east of Turrialba, UMMZ 119978 (2); *Tunnel Camp, near Peralta, +KU 32456, 32458-69, 41098 (skeleton); Turrialba, FMNH 101794, 103188-9, +KU 25725-9, 32439-48, 41095-7 (skeletons), 64797-827, 68300-2 +(skeletons), 68403 (eggs), 68404 (tadpoles), MCZ 29224-5, 29310-2, +UMMZ 119979 (6), USC 31, 256 (2), 458 (2), 580, 594, 599 (7), 7074 (2), +USNM 29933. Guanacaste: Arenal, USC 6254; *Finca San Bosco, USC 62724, +6276 (3), Guayabo de Bagaces, USC 7022 (3), 7023; *Laguna Arenal, +USC 6262 (4); 3 km. NE Tilaran, USC 524; *5 km. NE Tilaran, USC 6269; +*6 km. NE Tilaran, UMMZ 122653 (6), S-2680 (skeleton), USC 523 (8). +Heredia: Puerto Viejo, KU 64828-63, 68303-7 (skeletons), 68405-6 +(tadpoles), 104099-100 (tadpoles); *1.5 km. N Puerto Viejo, KU 64871; +*1 km. S Puerto Viejo, KU 86432-40; *4.2 km. W Puerto Viejo, KU +64864-5; *5.9 km. W Puerto Viejo, KU 64866-70; *7.5 km. W Puerto Viejo, +KU 86431. Limon: Batan, UMMZ 119980 (2); La Castilla, ANSP 23707; +Puerto +Limon+, KU 32449-55. + ++Panama+: Bocas del Toro: 3.2 km. NW Almirante, KU 96026; Cayo de +Agua, KU 96027-31; Fish Creek, KU 96032-4. Canal Zone: Barro Colorado +Island, AMNH 69790, ANSP 23244-50; FMNH 13380, 22972-4; Juan Mina, +AMNH 55429, UU 3899; *8.6-13.8 km. N Miraflores Locks, TNHC 23439, +23477, 23484-8, 23491, 23494-9, 23501-2, 23504-8, 23510-17, 23519-30, +23532-8, 23541-54, 23561. *Rio Chagres, AMNH 55431-4; Rio Cocoli, +3.5 km. N Miraflores Locks, TNHC 23461, 23489-90, 23493, 23500, 23503, +23509, 23518, 23531, 23539-40; *Summit, ANSP 23361, KU 97788; *Three +Rivers Plantation, SU 2130. Cocle: El Valle de Anton, AMNH 55435, +69786-9, ANSP 23506-9. Colon: Achiote, KU 77215-78; Ciricito, CAS +71499-500, 71505-6. Darien: Rio Canclon at Rio Chucunaque, UMMZ 126733; +Rio Chucunaque, near Yavisa, AMNH 51783. Panama: Cero La Campana, FMNH +67847-50. + ++Colombia+: Choco: Andagoya, FMNH 81856; Boca de Raspadura, AMNH +13570-8. + + + + ++Hyla sartori+ Smith + + + _Hyla underwoodi_ (in part), Smith and Taylor, Bull. U. S. Natl. + Mus., 194:85, June 17, 1948. + + _Hyla microcephala sartori_ Smith, Herpetologica, 7:186, + December 31, 1951 [Holotype.--UIMNH 20934 from 1 mile north of + Organos, south of El Treinte, Guerrero, Mexico; H. M. Smith and + E. H. Taylor collectors]. Duellman, Univ. Kansas Publ., Mus. Nat. + Hist., 15:124, December 20, 1961. Porter, Herpetologica, 18:168, + October 17, 1962. Davis and Dixon, Herpetologica, 20:230, + January 25, 1965. Duellman, Univ. Kansas Publ. Mus. Nat. Hist., + 15:652, December 30, 1965. + +_Diagnosis._--Dorsum tan with broad dark brown chevrons or transverse +bars; shanks marked with two or three broad transverse bars; +dorsolateral stripes absent. + +_Description and variation._--No noticeable geographic variation is +apparent in either structural features or coloration in this species. +All specimens lack a dorsolateral dark stripe and white line, although +a dark line is present on the canthus and dissipates in the loreal +region. A broad interorbital brown bar is present in all specimens. +The color pattern on the dorsum invariably consists of a broad, dark, +chevron-shaped mark in the scapular region and a broad dark chevron or +transverse bar in the sacral region. The shanks invariably have two or +three dark brown transverse bars. + +When active at night individuals are yellowish tan above with chocolate +brown markings (Pl. 14). The belly is white, and the thighs are pale +yellowish tan. The iris is dark bronze-color. In breeding males the +vocal sac is yellow. By day some individuals were observed to change +to creamy gray with distinct darker markings. + +_Remarks._--Although tadpoles of this species have not been found, +observations on the breeding sites indicate that the tadpoles probably +develop in ponds. Except for calling males observed around a pool in a +stream-bed 11.8 kilometers west-northwest of Tierra Colorada, Guerrero, +all breeding congregations have been found at temporary ponds. + +Smith (1951:186) named _Hyla sartori_ as a subspecies of _Hyla +microcephala_. This subspecific relationship seemed reasonable until +analysis of the mating calls showed that the call of _H. sartori_ is +more nearly like that of _H. phlebodes_ than that of _H. microcephala_. +The broad hiatus separating the ranges of _H. microcephala_ and _H. +sartori_ is additional evidence for considering _H. sartori_ as a +distinct species. + + + [Illustration: Fig. 4. Map showing locality records for + _Hyla sartori_.] + + +_Distribution._--_Hyla sartori_ occurs in mesophytic forests to +elevations of about 300 meters on the Pacific slopes of southern Mexico +from southwestern Jalisco to south-central Oaxaca (Fig. 4). The lack of +specimens from Colima and Michoacan probably reflects inadequate +collecting instead of the absence of the species there. On the basis of +available habitat the species would be expected to occur in Nayarit, +but extensive collecting there has failed to reveal its presence. The +semi-arid Plains of Tehuantepec apparently limit the distribution to +the east. + +_Specimens examined._--190, as follows: +Mexico+: Guerrero: 5 km. E +Acapulco, AMNH 54611-2; 23.2 km. N Acapulco, UIMNH 26404-7; Colonia +Buenas Aires, 23 km. E Tecpan de Galeana, UMMZ 119223 (7); *El +Limoncito, FMNH 75785, 100390-402, 104631, 104633, UMMZ 117250, USNM +134266; El Treinte, FMNH 100403, UIMNH 20935-7; Laguna Coyuca, AMNH +59686; La Venta, MCZ 29635; *Morjonares, UIMNH 26392-402; 1.6 km. +N Organos, FMNH 100404-5, UIMNH 20933-4; 19.2 km. S Petaquillas, +UIMNH 26408; 6.1 km. E. Tecpan de Galeana, TNHC 23396-408; *11.2 km. +N Tierra Colorada, UIMNH 26403; 11.8 km. WNW Tierra Colorada, UMMZ +119225 (51), S-2677-9 (skeletons); Zacualpan, UMMZ 119224 (6). Jalisco: +6.4 km. NE La Resolana, KU 67853-69; 24 km NE La Resolana, KU 67870-3. +Oaxaca: 3 km. N Pochutla, KU 57539; 13.4 km. N Pochutla, UMMZ +123495 (40). + + + + +CRANIAL OSTEOLOGY + + +The frogs of the _Hyla microcephala_ group have a minimal amount +of cranial ossification as compared to more generalized hylid skulls, +such as _Smilisca_ (Duellman and Trueb, 1966). In the _Hyla +microcephala_ group the sphenethmoid is small and short, and a large +frontoparietal fontanelle is present. The quadratojugal exists only +as a small spur and is not in contact with the maxillary. The prootics +are poorly developed. The anterior and posterior arms of the squamosal +are short; the anterior arm extends no more than one-fourth of the +distance to the maxillary, and the posterior arm does not have a bony +connection with the prootic. The nasal lacks a maxillary process, and +the medial ramus of the pterygoid lacks a bony connection to the +prootic. + +Teeth are absent on the parasphenoid and palatines, but present on the +maxillaries, premaxillaries, and prevomers. The teeth are simple, +pointed, and slightly curved. Although the number of teeth varies +(Table 3), no consistent differences between the species are apparent. + + +Table 3.--Variation in the Number of Teeth in the Species of the Hyla + Microcephala Group. (N=Number of Jaws, or Twice the Number of + Individuals; Means are Given in Parentheses After the Observed + Ranges). + +========================+====+=============+==============+========== + Species | N | Maxillary | Premaxillary | Prevomer +------------------------+----+-------------+--------------+---------- +_H. microcephala_ | 32 | 31-47(37.8) | 4-13(8.9) | 2-4(3.2) + | | | | +_H. phlebodes_ | 10 | 38-45(40.1) | 8-13(10.3) | 2-5(3.9) + | | | | +_H. robertmertensi_ | 6 | 23-43(32.8) | 7-12(10.5) | 2-3(2.7) + | | | | +_H. sartori_ | 6 | 27-43(38.2) | 9-10(9.3) | 3-4(3.7) +------------------------+----+-------------+--------------+---------- + + + [Illustration: PLATE 13 + Upper figure, _Hyla microcephala microcephala_ (KU 64593); + middle figure, _H. microcephala underwoodi_ (KU 64565); + lower figure, _H. microcephala underwoodi_ (UMMZ 115247). + All approximately x3.] + + + [Illustration: PLATE 14 + Upper figure, _Hyla robertmertensi_ (UMMZ 115243); + middle figure, _H. phlebodes_ (KU 64798); lower figure, + _H. sartori_ (UMMZ 119225). All approximately x3.] + + + [Illustration: PLATE 15 + Tadpoles of _Hyla microcephala_ group: upper figure, _H. m. + microcephala_ (KU 104097); lower figure, _H. phlebodes_ + (KU 104099). Both x4.] + + + [Illustration: PLATE 16 + Audiospectrograms and sections of mating calls of _Hyla + microcephala_ group: + (a) _H. m. microcephala_ (KU Tape No. 19); + (b) _H. robertmertensi_ (KU Tape No. 41); + (c) _H. phlebodes_ (KU Tape No. 6); + (d) _H. sartori_ (KU Tape No. 190).] + + +Table 4.--Comparative Cranial Osteology of Hyla microcephala Group + +===============+=======================+========================+ + Character | _H. microcephala_ | _H. robertmertensi_ | +---------------+-----------------------+------------------------+ +Frontoparietal | Minimally ossified | Ossification extensive | + | with large fontanelle | anteriorly with narrow | + | extending from | medial separation; | + | sphenethmoid to | fontanelle largest in | + | occipital ridge. | parietal region. | + | | | + | | | +Nasals | Moderately long and | Moderate in size; | + | slender; arcuate in | slightly wider | + | dorsal view. | anteriorly than | + | | posteriorly in dorsal | + | | view. | + | | | +Sphenethmoid | Extremely short in | Moderately short in | + | dorsal view. | dorsal view. | + | | | + | | | + | | | +Columella | Distal and greatly | Distal and slightly | + | expanded. | expanded or not. | +---------------+-----------------------+------------------------+ +Table 4. (Continued) +===============+========================+======================== + Character | _H. phlebodes_ | _H. sartori_ +---------------+------------------------+------------------------ +Frontoparietal | Ossification extensive | Ossification moderately + | anteriorly with narrow | extensive anteriorly; + | medial separation; | medial separation of + | fontanelle largest in | about uniform width + | parietal region. | throughout length of + | | fontanelle. + | | +Nasals | Moderate in size; | Long and broad; + | slightly wider | arcuate in dorsal + | anteriorly than | view. + | posteriorly in dorsal | + | view. | + | | +Sphenethmoid | Moderately short in | Moderately short in + | dorsal view. | dorsal view; ossified + | | anteriorly between + | | nasals. + | | +Columella | Distal and not | Distal and not + | expanded. | expanded. +---------------+------------------------+------------------------ + + + [Illustration: Fig. 5. Dorsal views of the skulls of (a) _Hyla m. + microcephala_ (KU 68293) and (b) _H. sartori_ (UMMZ S-2677). + Both x 12.] + + + [Illustration: Fig. 6. Dorsal views of skulls of (a) _Hyla phlebodes_ + (KU 68303) and (b) _H. robertmertensi_ (KU 59917). Both x 12.] + + +Despite the great reduction in the ossification of the cranial +elements, certain apparently consistent differences exist between the +species seem to be consistent. The most notable differences are: +1) amount of ossification of the frontoparietals and consequent shape +and size of the frontoparietal fontanelle, 2) shape of the nasals, +3) shape and extent of the sphenethmoid, and 4) shape of the columella +(Table 4, Figs. 5-6). On the basis of these characters, _Hyla +microcephala_ can be set apart from the other species and characterized +as having a poorly ossified frontoparietal and correspondingly large +frontoparietal fontanelle; long, slender, arcuate nasals; extremely +short sphenethmoid; and expanded distal end of the columella. The other +species in the group (_phlebodes_, _robertmertensi_, and _sartori_) +have more ossification of the frontoparietals, broader nasals, only a +moderately short sphenethmoid, and an unexpanded distal end of the +columella. Among these three species, the skulls of _phlebodes_ and +_robertmertensi_ are most nearly alike, whereas the skull of _sartori_ +differs by having a differently shaped frontoparietal fontanelle, +broader nasals, and an ossified anterior extension of the sphenethmoid +between the nasals (compare Fig. 5b with Fig. 6 a-b). + +Although all skulls examined belong to breeding adults, the extent of +the ossification of the frontoparietals and the resulting shape of the +frontoparietal fontanelle might be correlated with the age of the frog. +Nevertheless, in the 24 skulls of _Hyla microcephala_ examined, the +frontoparietals are less extensively ossified than in the skulls of the +other species. The trivial differences among the other three species +certainly are suggestive of close relationship, but on the basis of +present knowledge of the evolutionary trends in hylid cranial +osteology, the differences offer little evidence for determining +phylogenetic lineage. + + + + +ANALYSIS OF MATING CALLS + + +Calls of all five taxa were compared in several characteristics, of +which three are deemed most significant systematically. These are +1) the pattern and duration of the notes of a call-group, 2) the +fundamental frequency, and 3) the dominant frequency. Air temperatures +were noted at the time the calls were recorded, but no valid +correlation could be determined between this factor and any of the +parameters of the calls; consequently recordings made at all +temperatures (21-29 deg. C.) were grouped together. + +_Pattern and duration of notes._--In all five taxa the basic pattern +consists of a call-group made up of one primary note followed by a +series of shorter secondary notes. In some species the secondary notes +differ from the primary in other characteristics. Both subspecies of +_Hyla microcephala_ have a long, unpaired primary note followed by 0 +to 18 (usually about 4) somewhat shorter paired secondary notes. In +calls of _Hyla m. microcephala_ the mean duration of the primary is +0.131 (0.10-0.16) second and that of the secondaries is 0.101 +(0.05-0.14) second, whereas in _H. m. underwoodi_ the mean duration of +the primary is 0.018 (0.05-0.15) second and that of the secondaries is +0.086 (0.06-0.11) second. + +_Hyla robertmertensi_ has a reverse of this pattern in that the primary +note is paired and the secondaries are unpaired. In the sample studied +a call-group contains 0-28 secondary notes (generally about 3). The +mean duration of the primary is 0.091 (0.07-0.11) second and that of +the secondaries is 0.040 (0.025-0.06) second. + +_Hyla phlebodes_ and _sartori_ have call-groups composed of a rather +short, unpaired primary and several short, unpaired secondaries +(0-28 in _phlebodes_, 0-23 in _sartori_). The mean duration of the +primary of _phlebodes_ is 0.105 (0.07-0.16) second and that of the +secondaries is 0.067 (0.035-0.12) second. The mean duration of the +primary of _sartori_ is 0.080 (0.07-0.09) second and that of the +secondaries is 0.053 (0.035-0.07) second. + +The two subspecies of _H. microcephala_ are identical in call pattern +and agree closely in duration of notes, although those of the nominate +subspecies tend to be slightly longer. _Hyla robertmertensi_ is +distinctive in call pattern in that it is the only species having a +paired primary; the duration of the primary is completely overlapped by +that in the other species, but the secondaries tend to be the shortest +in the group. The call patterns of _H. phlebodes_ and _H. sartori_ are +identical and the range of duration of notes of _phlebodes_ completely +overlaps that of _sartori_, although both the primary and secondary +notes of the latter tend to be somewhat shorter (Table 5, Pl. 16). + +_Fundamental frequency._--This parameter was analyzed for the primary +notes. It was measured for the secondaries as well and was found to +differ in magnitude in the same way as the primary note. In a few +examples of both subspecies of _H. microcephala_ a high primary note, +in which the fundamental frequency is exceptionally high, is sometimes +emitted (Fouquette, 1960b). None of these notes was used in this +analysis; only the fundamental frequencies of normal primary notes are +compared (Table 5, Fig. 7). + + +Table 5.--Comparison of Normal Mating Calls in the Hyla microcephala + Group. (Observed Range Given in Parentheses Below Mean; + Unless Otherwise Noted Data Are for Primary Notes.). + +----------------+--+---------+---------+-------------------+-------------- + | |Dominant | Funda- |Duration of notes | Repetition + | | | mental| (seconds) | rate of + Species |N |frequency|frequency+---------+---------+ secondaries + | | (cps) | (cps) | Primary |Secondary|(notes/minute) +----------------+--+---------+---------+---------+---------+-------------- +_H. m. |44| 5637 | 205 | 0.13 | 0.10 | 268 + microcephala_ | |(5150 |(184-244)|(0.11 |(0.05 | (192-353) + | | -5962)| | -0.16)| -0.14)| + | | | | | | +_H. m. |47| 5772 | 220 | 0.11 | 0.09 | 283 + underwoodi_ | |(5177 |(192-275)|(0.05 |(0.06 | (197-384) + | | -6200)| | -0.15)| -0.11)| + | | | | | | +_H. |25| 5388 | 162 | 0.09 | 0.04 | 418 + robertmertensi_| |(5150 |(140-178)|(0.07 |(0.03 | (368-570) + | | -5785)| | -0.11)| -0.06)| + | | | | | | +_H. phlebodes_ |34| 3578 | 148 | 0.11 | 0.07 | 284 + | |(3220 |(125-158)|(0.07 |(0.04 | (210-350) + | | -4067)| | -0.16)| -0.12)| + | | | | | | +_H. sartori_ |10| 3217 | 126 | 0.08 | 0.05 | 434 + | |(2950 |(116-135)|(0.07 |(0.04 | (396-477) + | | -3600)| | -0.09)| -0.07)| +----------------+--+---------+---------+---------+---------+-------------- + + +The two subspecies of _H. microcephala_ agree closely in fundamental +frequency. There is considerable overlap, but the difference +between the means is significant at the 0.001 level of probability +(t = 4.2406). The call of _H. robertmertensi_ does not overlap that +of _H. sartori_ or either subspecies of _H. microcephala_ in this +parameter; but it does overlap that of _H. phlebodes_, although again +the difference between the means is significant at the 0.001 level +(t = 9.360). _Hyla phlebodes_ and _sartori_ have the lowest fundamental +frequencies, and there is some overlap, but here too the difference +between the means is significant at the 0.001 level (t = 4.923). + +_Dominant frequency._--A dominant band of frequencies cuts across +the harmonics of the fundamental, obscuring the harmonic pattern and +generally shifting upward in frequency. The midpoint of this band is +measured at the terminal border as the dominant frequency. As with the +fundamental frequency, only the normal primary notes were utilized in +the comparisons (Table 5, Fig 8). + + + [Illustration: Fig. 7. Variation in the fundamental frequency of the + normal primary notes in the _Hyla microcephala_ group. The + horizontal lines = range of variation, vertical lines = mean, + solid bars = twice the standard error of the mean, and open + bars = one standard deviation. The number of specimens in each + sample is indicated in parentheses after the name of the taxon.] + + +The two subspecies of _H. microcephala_ agree more closely in this +parameter than in fundamental frequency. The overlap is great, but the +difference between the means is significant at the 0.001 level +(t = 3.658). The calls of both subspecies completely overlap that of +_robertmertensi_ in this parameter, but the difference between the +means is significant at the 0.001 level. The calls of _H. phlebodes_ +and _H. sartori_ overlap considerably in this characteristic, although +the difference between the means is significant at the 0.001 level +(t = 7.504) (Fig. 9). The call of neither species overlaps those of +_H. microcephala_ and _robertmertensi_. + + + [Illustration: Fig. 8. Variation in the mid-point of the dominant + frequency band of the normal primary notes in the _Hyla + microcephala_ group. The horizontal lines = range of variation, + vertical lines = mean, solid bars = twice the standard error of + the mean, and open bars = one standard deviation. The number of + specimens in each sample is indicated in parentheses after the + name of the taxon.] + + + [Illustration: Fig. 9. Scatter diagram relating the dominant and + fundamental frequencies of the normal primary notes in the + _Hyla microcephala_ group. Each symbol represents a different + individual.] + + +_Repetition rate._--The repetition rate of the secondary notes, in +calls consisting of more than one secondary, was measured for each +form. A considerable amount of variation in this parameter was found +in all of the taxa (Table 5). This variation probably is due in part +to the effect of temperature differences. Repetition rate is the only +parameter analyzed for which there is a correlation with the +air-temperature, but even here the correlation is weak, probably due +to the microenvironmental effects of humidity, air-movement, and other +factors in addition to the ambient air temperature that influences the +body temperature of the frogs. These rates are nearly alike in both +subspecies of _H. microcephala_ and in _phlebodes_. The repetition +rates in _H. robertmertensi_ and _H. sartori_ are considerably faster +than in the other three taxa. _Hyla sartori_ has the fastest +repetition rate of the group. + +In all characteristics of the mating calls the two subspecies of +_H. microcephala_ agree closely, as might be expected, although the +differences are statistically significant. _Hyla robertmertensi_ is +distinctive in call pattern and seems to be closer to _microcephala_ +in dominant frequency but closer to _H. phlebodes_ in fundamental +frequency. Thus, it is somewhat intermediate between _microcephala_ +and _phlebodes_. The identical pattern and similarity in fundamental +and dominant frequencies of the calls of _H. phlebodes_ and _H. sartori_ +possibly indicate close relationship. + +_Geographic variation in call._--_Hyla m. microcephala_ has higher +fundamental and dominant frequencies in Costa Rica than in Panama. In +Costa Rican _H. m. underwoodi_ the fundamental and dominant frequencies +are lower than in other parts of the range. Frogs of this subspecies +recorded in Nicaragua and Honduras have slightly lower dominant +frequencies and higher fundamental frequencies than those recorded in +Guatemala or Oaxaca. The duration of both primary and secondary notes +decreases to the south; samples from Nicaragua and Costa Rica have the +shortest notes. Comparison of duration of notes in the two subspecies +shows that the Panamanian _H. m. microcephala_ have slightly longer +notes than do any _H. m. underwoodi_; the more northern populations of +_H. m. underwoodi_ from Mexico most closely approach _H. m. +microcephala_ in this characteristic. + +The calls of _H. robertmertensi_ in Oaxaca have higher dominant and +fundamental frequencies and longer secondary notes than do those in +Chiapas. + +The calls of _H. phlebodes_ recorded at Puerto Viejo, Costa Rica, +have slightly lower dominant frequencies than do those recorded at +Turrialba, Costa Rica, and in Panama, whereas those recorded at +Turrialba have lower fundamental frequencies than in other samples. +The duration of notes is slightly shorter in both Costa Rican samples +than in those recorded in Panama. + + + + +LIFE HISTORY + + +The frogs of the _Hyla microcephala_ group breed in shallow grassy +ponds. In some places they breed in permanent ponds, but usually +congregate around temporary pools, such as depressions in forests, +flooded fields, and roadside ditches. At the height of their breeding +season, usually in the early part of the rainy season, the +congregations are made up of large numbers of individuals. In April, +1961, and in June, 1966, the senior author noted nearly continuous +choruses of _H. m. microcephala_ in roadside ditches along the 75 +kilometers of road between Villa Neily and Palmar Sur, Puntarenas +Province, Cost Rica; on June 20, 1966, at Puerto Viejo, Heredia +Province, Costa Rica, he estimated approximately 900 _Hyla phlebodes_ +in one pond, and two nights later noticed that the number of +individuals had increased substantially. Other observations by the +first author on size of breeding congregations include nearly +continuous choruses of _H. m. underwoodi_ between Villahermosa and +Teapa, Tabasco, in July of 1958, an estimated 400 _Hyla robertmertensi_ +in a road side ditch 7.2 kilometers west-northwest of Zanatepec, +Oaxaca, on July 13, 1956, and approximately 150 _Hyla sartori_ around +a rocky pool in a riverbed, 11.8 kilometers west-northwest of Tierra +Colorada, Guerrero, on June 28, 1958. + +The length of the breeding season seemingly is more dependent on +climatic conditions in various parts of Middle America than on +behavioral differences in the various species. Thus, Fouquette (1960b) +found in the Canal Zone that _H. m. microcephala_ formed breeding +choruses from May through January, the entire rainy season in that +area. In the wetter coastal region of Puntarenas Province, Costa Rica, +the species breeds as early as mid-March, whereas in the drier region +encompassing Guanacaste Province, Costa Rica, and southwestern +Nicaragua breeding activity is initiated by the first heavy rains of +the season, usually in June. + +_Hyla phlebodes_ inhabits regions having rainfall throughout the year. +Although large breeding congregations are most common in the early +parts of the rainy season, males probably call throughout the year. At +Puerto Viejo in Costa Rica the senior author has heard _Hyla phlebodes_ +in February, April, June, July, and August. Charles W. Myers noted +calling males of this species in the area around Almirante, Bocas del +Toro Province, Panama, in September, October, and February. An +exception to the correlation between rainfall and breeding activity +was noted by the junior author in _Hyla phlebodes_ in the Canal Zone, +where he noticed a decrease in activity of that species in October and +November, when the rains are heaviest and most frequent. Furthermore, +independent observations made by both of us indicate that _H. +phlebodes_ does not reach peaks of activity during or immediately +after heavy rains, but instead builds up to peaks of activity two or +three days after a heavy rain. This is in contrast to the other +species, all of which characteristically inhabit drier environments +than does _H. phlebodes_. Peaks of breeding activity in the other +species occur immediately after, or even during, heavy rains. + +The calling location of the males generally is on vegetation above, +or at the edge of, the water. _Hyla microcephala_ and _H. phlebodes_ +call almost exclusively from grasses and sedges; _phlebodes_ usually +calls from taller and more dense grasses than does _microcephala_. +Except for some minor differences in calling location observed by +the junior author (Fouquette, 1960b) in the Canal Zone, the differences +in density and height of grasses utilized for calling-locations +probably is dependent primarily on the nature of the available +vegetation. Although bushes and broad-leafed herbs are usually present +at the breeding sites, males of these species seldom utilize them for +calling locations. Both _H. robertmertensi_ and _H. sartori_ have been +observed calling from grasses, herbs, bushes, and low trees. Calling +males of _robertmertensi_ have been found two meters above the ground +in small trees. + +Daytime retreats in the breeding season sometimes are no more than +shaded clumps of vegetation adjacent to a pond or in clumps of grass +in a pond. Individuals of _H. m. underwoodi_ were found by day under +the outer sheaths of banana plants next to a water-filled ditch. Dry +season refuges are unknown. + +Amplexus is axillary in all four species. Egg deposition has been +observed in _H. m. microcephala_, _m. underwoodi_, and _phlebodes_. +In all three the eggs are deposited in small masses that float near +the surface of the water and usually are at least partly attached to +emergent vegetation. Each clutch does not represent the entire egg +complement of the female. + +Tadpoles are definitely known of only _H. m. microcephala_ and +_phlebodes_; these have been described in the preceding accounts of +the species. The tadpoles of these two species can be distinguished +readily (Pl. 15). The tadpole of _H. microcephala_ has a uniformly +white venter and nearly transparent tail, whereas in _H. phlebodes_ +the venter is flecked anteriorly and the tail is mottled. In life, _H. +microcephala_ is easily recognized by the orange posterior half of +the tail, whereas the tail in _H. phlebodes_ is mottled tan and grayish +brown. + + + + +PHYLOGENETIC RELATIONSHIPS + + +The evidence already presented on osteology, external structure, +coloration, mating call, and life history emphatically show that the +four species under consideration are a closely related assemblage. +Now the question arises: To what other groups in the genus is the +_Hyla microcephala_ group related? Furthermore, it is pertinent to +this discussion to attempt a reconstruction of the phylogeny of the +group as a whole and of the individual species in the _Hyla +microcephala_ group. With regard to the relationships of the group we +must take into account certain species in South America. Our endeavors +there are hampered by the absence of data on the mating calls and life +histories of most of the relevant species. + +As mentioned in the account of _Hyla m. microcephala_, the species +_microcephala_ possibly is subspecifically related to _Hyla misera_, a +frog widespread in the Amazon Basin. _Hyla misera_ resembles +_microcephala_ in coloration, external structure, and cranial +characters. The frontoparietals are equally poorly ossified, and the +frontoparietal fontanelle is extensive. Our principal reason for not +considering the two taxa conspecific at this time is our lack of +knowledge concerning the color of living _H. misera_, the structure of +the tadpoles, and the characteristics of the mating call. Even with the +absence of such data that we think essential to establish the +nomenclature status of the taxa, we are confident that the two are +sufficiently closely related that any discussion of the phylogenetic +relationships of one species certainly must involve consideration of +the other. + +_Hyla misera_ possibly is allied to other small yellowish tan South +American _Hyla_ that lack dark pigmentation on the thighs. Probable +relatives are _Hyla elongata_, _minuta_ (with _goughi_, _pallens_, +_suturata_, _velata_, and possibly others as synonyms), _nana_, and +_werneri_. The consideration of the interspecific relationships of +these taxa is beyond the scope of this paper, but we can say that each +of these species has a pale yellowish tan dorsum, relatively broad +dorsolateral brown stripe, and narrow longitudinal brown lines or +irregular marks on the dorsum. Furthermore, examination of the skulls +of _elongata_, _nana_, and _werneri_ reveals that they are like +_misera_ and _microcephala_ in the nature of the frontoparietal +fontanelle and in having a greatly reduced quadratojugal. Thus, on the +basis of cranial and external characters the _Hyla microcephala_ group +can be associated with _Hyla misera_ and its apparent allies in South +America. This association can be only tentative until the mating calls, +tadpoles, and chromosome numbers of the South American species are +known. + +Among the Middle American hylids, only the _Hyla microcephala_ group +and _H. ebraccata_ have a haploid number of 15 chromosomes (Duellman +and Cole, 1965). All other New World _Hyla_, for which the number is +known, have a haploid number of 12; the only other _Hyla_ having 15 +is a Papuan _Hyla angiana_ (Duellman, 1967). + +_Hyla ebraccata_ occurs in the humid tropical lowlands of Middle +America and the Pacific lowlands of northwestern South America. It is +the northernmost, and only Central American, representative of the +_Hyla leucophyllata_ group, which is diverse (about 10 species +currently recognized) and widespread in tropical South America east of +the Andes. This group is characterized by having broad, flat skulls +with larger nasals and more ossification of the frontoparietals than +in the _Hyla microcephala_ group. The quadratojugal is present as a +small anteriorly projecting spur that does not connect with the +maxillary. Externally, the _Hyla leucophyllata_ group is characterized +by having a well-developed axillary membrane, uniformly yellow thighs, +and a dorsal color pattern in many species consisting of a dark lateral +band, a pale dorsolateral band or dorsal ground color, and a large +middorsal dark mark. In some species, the dorsal pattern consists of +small dark markings or is nearly uniformly pale. At least in the +Central American _Hyla ebraccata_, the mating call consists of a +single primary note followed by a series of shorter secondary notes, +the tadpoles have xiphicercal tails and lack teeth, and the haploid +number of chromosomes is 15. On the strength of these observations it +seems imperative to consider the _Hyla leucophyllata_ group as a close +ally to the _Hyla microcephala_ group. Successful artificial +hybridization supports the close relationship of _H. m. microcephala_ +and _phlebodes_; partial success of artificial hybridization of these +two with _ebraccata_ (Fouquette, 1960b) provides further evidence for +close relationship between the _Hyla leucophyllata_ and _Hyla +microcephala_ groups. + +In Mexico and northern Central America two small species, _Hyla picta_ +and _Hyla smithi_, comprise the _Hyla picta_ group. These frogs +resemble members of the _Hyla microcephala_ group by having a +yellowish tan dorsum with a dorsolateral white stripe and uniformly +yellow thighs. Furthermore the mating call is not unlike those of +the species in the _Hyla microcephala_ group. Despite these +similarities, the _Hyla picta_ group differs from the _Hyla +microcephala_ group by having a well-developed quadratojugal that +connects to the maxillary, tadpoles with teeth present and caudal fins +completely enclosing the caudal musculature, and a haploid number of +12 chromosomes. In all of these characteristics the frogs of the + +_Hyla picta_ group more closely resemble other Middle American _Hyla_ +than they do the _Hyla microcephala_ group. Therefore, it can best be +presumed that the superficial resemblances of coloration and the +mating call are the result of convergence. + +Since the _Hyla microcephala_ and _leucophyllata_ groups apparently +are related and since the greatest diversity of these frogs is in +South America (if _Hyla misera_ and its relatives are placed with the +_Hyla microcephala_ group), it seems appropriate to place the centers +of origins of these groups in South America. Therefore, the _Hyla +microcephala_ group and _Hyla ebraccata_ of the _Hyla leucophyllata_ +group either have immigrated into Central America, or they are +representatives of those groups that were isolated in Central America +during most of the Cenozoic when South America was separated from +Central America. + +The interspecific relationships of the species in the _Hyla +microcephala_ group are not clear. On the basis of coloration, _H. m. +microcephala_ and _H. robertmertensi_ are close, and _H. m. underwoodi_ +and _H. phlebodes_ are nearly identical. The mating calls of _H. +phlebodes_ and _sartori_ closely resemble one another, whereas the call +of _robertmertensi_ is intermediate between these and _microcephala_. + +In most respects _Hyla microcephala_ is distinct from the other +species, and with the exception of the amount of ossification of the +frontoparietals, the other species can be easily derived from a +_microcephala_-like ancestor. Possibly the slightly increased +ossification of the frontoparietals in _robertmertensi_, _phlebodes_, +and _sartori_ is secondary, or possibly after differentiation of the +species the amount of ossification was further reduced in +_microcephala_. If so, the species fall into a reasonable phylogenetic +scheme that has _microcephala_ as the extant species most like the +ancestral stock. + +We visualize the evolutionary history of the group to have followed +a course that began with the invasion of Central America by a +_microcephala_ ancestral stock that differentiated into two populations +in lower Central America--a _microcephala_-like frog on the Pacific +lowlands and a _phlebodes_-like frog on the Caribbean lowlands. +Differentiation could have been brought about by isolation by montaine +or marine barriers. The population on the Pacific lowlands either was +preadapted for subhumid conditions or became so adapted and dispersed +northward onto the Pacific lowlands of northern Central America. +Simultaneously the frogs on the Caribbean lowlands, which were adapted +to humid environments, dispersed northward in the humid forested +regions to southern Mexico and crossed the Isthmus of Tehuantepec onto +the Pacific slopes of Oaxaca and Guerrero northward to Jalisco. +Subsequent development of arid conditions, possibly in the Pliocene, +Pleistocene, or even as late as the Thermal Maximum in post-Wisconsin +time, resulted in a restriction of the ranges in northern Central +America, thereby isolating part of the _phlebodes_-stock on the +Pacific slopes of Mexico, where it adapted to drier conditions and +evolved into _sartori_. The rest of the _phlebodes_-stock was +restricted to the humid forests on the Caribbean lowlands of lower +Central America. The increased aridity on the Pacific lowlands +eliminated the _microcephala_-stock from southern Honduras and +northwestern Nicaragua and in so doing left an isolated population on +the lowlands of Chiapasand Guatemala, which differentiated into +_robertmertensi_. The original stock on the Pacific lowlands of Panama +and southeastern Costa Rica became _microcephala_. + +If the _microcephala_-stock was, as we believe, better adapted for +existence under subhumid conditions than was the _phlebodes_-stock, +the development of subhumid conditions in much of the lowland region +of northern Central America and southern Mexico would have permitted +the expansion of the range of _microcephala_ into the area now +inhabited by _H. m. underwoodi_, while _phlebodes_ was being eliminated +from this area by climatic conditions that were unsuited to its +survival there. Perhaps the similarity in coloration of _H. m. +underwoodi_ and _phlebodes_ is the result of convergence or possibly +hybridization occurred at the time the former was expanding its range +and the latter's range was being restricted. If hybridization did +occur, the differences in mating call subsequently were enhanced, +thereby providing a valid isolating mechanism in sympatric populations. + +_Hyla microcephala_ and _phlebodes_ range into northern South America. +Probably both species entered South America in relatively recent times +after they had differentiated from one another in Central America. + + + + +LITERATURE CITED + + +Boulenger, G. A. + 1898. Fourth report on additions to the batrachian collection in the + Natural-History Museum. Proc. Zool. Soc. London, 1898, + pp. 373-482, pls. 38-39. October 1. + 1899. Descriptions of new batrachians in the collection of the + British Museum (Natural History). Ann. Mag. Nat. Hist, ser. + 7, 3:273-277, pls. 11-12. + +Breder, C. M. Jr. + 1946. Amphibians and reptiles of the Rio Chucunaque Drainage, Darien, + Panama, with notes on their life histories and habits. Bull. + Amer. Mus. Nat. Hist, 86:375-436, pls. 42-60, August 26. + +Cole, L. J. and Barbour, T. + 1906. Vertebrata from Yucatan: Reptilia; Amphibia; Pisces. Bull. Mus. + Comp. Zool., 50:146-159. November. + +Cope, E. D. + 1886. Thirteenth contribution to the herpetology of tropical America. + Proc. Amer. Philos. Soc, 23:271-287. February 11. + 1894. Third addition to a knowledge of the Batrachia and Reptilia of + Costa Rica. Proc. Acad. Nat. Sci. Philadelphia, 1894, pp. + 194-206. + +Duellman, W. E. + 1956. The frogs of the hylid genus _Phrynohyas_ Fitzinger, 1843. + Misc. Publ. Mus. Zool., Univ. Michigan, 96:1-47, pls. 1-6. + February 21. + 1967. Additional studies of chromosomes of anuran amphibians. Syst. + Zool., 16:38-43, March 17. + +Duellman, W. E. and Cole, C. J. + 1965. Studies of chromosomes of some anuran amphibians (Hylidae and + Centrolenidae). Syst. Zool., 14:139-143. July 9. + +Duellman, W. E. and Trueb, L. + 1966. Neotropical hylid frogs, genus Smilisca. Univ. Kansas Publ., + Mus. Nat. Hist., 17:281-375, pls. 1-12. July 14. + +Dunn, E. R. + 1931. The amphibians of Barro Colorado Island. Occas. Papers Boston + Soc. Nat. Hist., 5:403-421. October 10. + 1933. Amphibians and reptiles from El Valle de Anton, Panama. + _Ibid._, 8:65-79. June 7. + 1934. Two new frogs from Darien. Amer. Mus. Novit., 747:1-2. + September 17. + +Fouquette, M. J. Jr. + 1960a. Call structure in frogs of the family Leptodactylidae. Texas + Jour. Sci., 12:201-215. October. + 1960b. Isolating mechanisms in three sympatric tree frogs in the Canal + Zone. Evolution, 14:484-497. December 16. + +Gaige, H. T., Hartweg, N. and Stuart, L. C. + 1937. Notes on a collection of amphibians and reptiles from + eastern Nicaragua. Occas. Papers Mus. Zool., Univ. Michigan, + 357:1-18. October 26. + +Gosner, K. L. + 1960. A simplified table for staging anuran embryos and larvae with + notes on identification. Herpetologica, 16:183-190. + September 23. + +Kellogg, R. + 1932. Mexican tailless amphibians in the United States National + Museum. Bull. U.S. Natl. Mus., 160:1-224. March 31. + +Rivero, J. A. + 1961. Salientia of Venezuela. Bull. Mus. Comp. Zool., 126:1-207. + November. + +Smith, H. M. + 1951. The identity of _Hyla underwoodi_ Auctorum of Mexico. + Herpetologica, 7:184-190. December 31. + +Stejneger, L. + 1906. A new tree toad from Costa Rica. Proc. U. S. Natl. Mus., + 30:817-818. June 4. + +Stuart, L. C. + 1935. A contribution to a knowledge of the herpetology of a portion + of the savanna region of central Peten, Guatemala. Misc. Publ. + Mus. Zool., Univ. Michigan, 29:1-56, pls. 1-4. October 4. + +Taylor, E. H. + 1952. The frogs and toads of Costa Rica. Univ. Kansas Sci. Bull., + 35-577-942. July 1. + + +_Transmitted July 11, 1967._ + + + +Transcriber's Notes + +This file was derived from scanned images. With the exception of the +list of typographical errors that were corrected below, the original +text is presented. + +In the copy of the original, the Plate text contains the notation +"X 2" after the caption to let the reader know that the image was +enlarged by a factor of two. + + +Emphasis Notation + + _Text_ = Italic + + +Text+ = Bold + + +Typographical Errors Corrected: + +Several minor typographical corrections were made (missing periods, +commas, incomplete italicization, etc.); but are not indicated here. +More substantial changes are listed below: + +Page 533 - UMZ => UMMZ +Page 534 - Diganosis => Diagnosis +Page 544 - fontanells => fontanelle +Page 545 - prrimary => primary +Page 547 - band of of frequencies => band of frequencies +Page 550 - ad => had +Page 551 - clumbs => clumps +Page 552 - acount => account +Page 557 - Minchigan => Michigan + + + + + + + +End of the Project Gutenberg EBook of Middle American Frogs of the Hyla +microcephala Group, by William E. 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