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UNIVERSITY OF KANSAS PUBLICATIONS



MUSEUM OF NATURAL HISTORY





Volume 18, No. 6, pp. 505-545, 7 figs., 4 pls.



December 2, 1969





The Systematics of the Frogs of the

_Hyla rubra_ Group in Middle America







BY



JUAN R. LEON







University of Kansas

Lawrence

1969







UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY



Editors: Frank B. Cross, Philip S. Humphrey, Robert M. Mengel.





Volume 18, No. 6, pp. 505-545, 7 figs., 4 pls.

Published December 2, 1969



UNIVERSITY OF KANSAS

Lawrence, Kansas





PRINTED BY

ROBERT R. (BOB) SANDERS, STATE PRINTER

TOPEKA, KANSAS

1969









The Systematics of the Frogs of the _Hyla rubra_ Group in Middle

America



BY



JUAN R. LEON









CONTENTS





                                                    PAGE



INTRODUCTION                                         508

  Acknowledgments                                    508

  Materials and Methods                              509



THE HYLA RUBRA GROUP                                 509

  Key to Species and Subspecies                      510

  Key to Known Tadpoles                              511



ACCOUNTS OF SPECIES AND SUBSPECIES                   511

  _Hyla boulengeri_ (Cope)                           511

  _Hyla foliamorta_ Fouquette                        520

  _Hyla rubra_ Laurenti                              524

  _Hyla elaeochroa_ Cope                             525

  _Hyla staufferi_ Cope                              532

  _Hyla staufferi staufferi_ Cope                    537

  _Hyla staufferi altae_ Dunn                        540



EVOLUTIONARY HISTORY                                 540



LITERATURE CITED                                     543









INTRODUCTION





The tree frogs of the _Hyla rubra_ group are abundant and form a

conspicuous element of the Neotropical frog fauna. Representatives of

the group occur from lowland Mexico to Argentina; the greatest

diversity is reached in the lowlands of southeastern Brazil (Cochran,

1955). The group apparently originated in South America; the endemic

Central American species evolved from stocks that invaded Middle

America after the closure of the Colombian Portal in the late Pliocene.



Dunn (1933) partially defined the _rubra_ group as it occurs in Central

America. Cope (1865, 1876, 1887), Brocchi (1881), Boulenger (1882),

Guenther (1901), Noble (1918), Kellogg (1932), Dunn and Emlen (1932),

Stuart (1935), and Gaige (1936) dealt with the Middle American species

now considered to make up the _rubra_ group. More recently, Taylor

(1952, 1958), Fouquette (1958), Starrett (1960), and Duellman (1960,

1963, 1966a) studied aspects of the taxonomy and biology of the species

of this group. The five species of the _rubra_ group in Central America

have received ten different names. One species, _Hyla staufferi_, has

received five names (two subspecies are recognized herein). _Hyla

boulengeri_ was named in the genus _Scytopis_, but the type species of

_Scytopis_ is a member of the genus _Phrynohyas_ Fitzinger, 1843

(Duellman, 1956.)



Little has been published concerning the ecology, life history,

osteology, and mating calls of the Middle American species of this

group. The purpose of the present report is to describe the species

occurring in Middle America and to comment on their distributions,

ecology, cranial osteology, and mating calls, and in so doing provide

evidence for the evolutionary history of the species inhabiting Middle

America.





Acknowledgments



For permission to examine specimens in their care, I am grateful to

Drs. Richard G. Zweifel, American Museum of Natural History (AMNH);

Robert F. Inger, Field Museum of Natural History (FMNH); Ernest E.

Williams, Museum of Comparative Zoology (MCZ); Hobart M. Smith,

University of Illinois Museum of Natural History (UIMNH); Charles F.

Walker, University of Michigan Museum of Zoology (UMMZ); Jay M. Savage,

University of Southern California (USC); James A. Peters, United States

National Museum (USNM); Richard J. Baldauf, Texas Cooperative Wildlife

Collection (TCWC); and W. Frank Blair, Texas Natural History Collection

(TNHC). KU refers to specimens in the Museum of Natural History,

University of Kansas. For the loan of tape-recordings of mating calls I

thank Drs. W. Frank Blair, University of Texas, and Richard G. Zweifel,

American Museum of Natural History.



I am indebted to the Ford Foundation-Universidad de Oriente (Venezuela)

Science Project for a scholarship which enabled me to study for two

years at The University of Kansas, foster institution of the project. I

have benefited by being able to work in the Museum of Natural History

at The University of Kansas and I am grateful to Dr. E. Raymond Hall,

Director, for providing space and equipment.



I gratefully acknowledge the assistance and advice of Dr. William E.

Duellman, who suggested and directed this work, made available

specimens under his care and gave much of his time in reading the

manuscript and suggesting improvements. I am grateful to Dr. Frank B.

Cross who critically read the manuscript and made many editorial

suggestions. I am indebted to Linda Trueb for assistance with the

osteological aspects of this study; she helped to clarify many

confusing points. I am grateful to Charles W. Myers for making

available his field notes on these frogs in Panama, to Arthur C.

Echternacht for reading part of the manuscript, and to John D. Lynch

for many suggestions and helpful criticisms. The illustrations were

executed by David M. Dennis.





Materials and Methods



For the purposes of the present study I examined 1383 preserved

specimens, 50 skeletons, and 9 lots of tadpoles. External

characteristics used in the analysis of variation are those currently

employed in the study of anuran systematics. Twelve measurements

and six proportions were taken in the manner described by Duellman

(1956). Only the most important references are given in the synonymies,

except those of the two subspecies of _Hyla staufferi,_ which are

more nearly complete. The taxonomic history of each frog is discussed

under _Remarks_ in each account. The cranial osteology was studied

by using skeletons and cleared and stained specimens of all species.

Developmental stages of tadpoles were determined from Gosner's (1960)

table. Personal field work in Central America in the summer of 1966

provided an opportunity to make observations on the ecology, calling

sites, and color in life; these data were supplemented by field notes

from, and discussions with, Dr. William E. Duellman and Charles W.

Myers.



The mating calls of the frogs were recorded in the field on Magnemite

and Uher Tape Recorders by Dr. Duellman in the course of his work on

the hylid frogs of Middle America--supported by grants from the

National Science Foundation (G-9827 and GB-1441). These recordings,

plus those borrowed from other institutions, provided 50 tapes for

analysis of the mating calls. The calls were analyzed on a Vibralyzer

(Kay Electric Company).









THE HYLA RUBRA GROUP





_Definition._--The species forming the group are small to moderate-sized

tree frogs (maximum snout-vent length of males of various species 20-49

mm.), distinguished from other groups in the genus _Hyla_ as follows:

Brown, grayish brown, or yellowish tan above; thighs plain, marbled

with dark brown, or having vertical bands; vocal sac single, median,

subgular; snout flat, protruding, rounded or pointed; webbing between

fingers reduced or absent; web between first and second toes reduced to

fringe on second toe, rest of toes about half webbed; tarsal fold

reduced or absent; shanks robust; inner metatarsal tubercle larger than

outer; prevomerine teeth on transverse ridges between small to large

sized choanae; skull generally longer than wide; nasals large (length

more than 40 per cent total length of skull) and having pointed

maxillary processes; maxillary bearing small ventromedial palatine

process; quadratojugal slender, always joined to maxillary by bony

suture; auditory region of prooetic slender and short; delicate

spatulate columella ventral to crista parotica, broad basally,

compressed anterolaterally, slightly rounded distally; anterior arm of

squamosal extending about half distance to maxillary; sphenethmoid

wider than long; frontoparietal fontanelle present or absent;

prevomerine, premaxillary, and maxillary teeth present; prevomer with

two lateral processes forming incomplete bony margin to internal nares;

tadpoles having pointed xiphicercal tail, snout short, rounded; 2/3

tooth rows; dorsal fin deeper than ventral fin; sinistral spiracle;

short dextral anal tube not reaching edge of ventral fin; mating calls

consisting of single long note or series of short notes.



_Composition._--This group contains about 24 currently recognized

species, most of which occur in Brazil. Only five species--_boulengeri,_

_elaeochroa_, _foliamorta_, _rubra_, and _staufferi_ with two

subspecies--occur in Central America. _Hyla boulengeri_ and _rubra_ are

widespread in South America, and _foliamorta_ occurs in Colombia,

whereas the other species are known only from Middle America.



_Distribution._--The species of the _Hyla rubra_ group range from the

lowlands of northern Argentina and Bolivia to southern Tamaulipas and

Guerrero, Mexico.



_Comments._--In Central America two subgroups of species can be

recognized. _Hyla boulengeri_ and _H. foliamorta_ are distinctive in

the large size of adults (snout-vent lengths 41-49 mm.); both have

prominent bars on the thighs, a well-defined interorbital triangular

mark, blotches or spots dorsally, and large choanae. _Hyla elaeochroa,_

_H. rubra,_ and _H. staufferi_ are smaller (snout-vent lengths 29-40

mm.); they have the thighs weakly barred or vermiculate anteriorly and

posteriorly or unmarked, an ill-defined interorbital triangular mark,

linear markings dorsally, and small choanae.





Key to Species and Subspecies



    1. Larger frogs (males to 49 mm. snout-vent length); thighs

    strongly barred; supratympanic fold black; dorsum blotched or

    spotted                                                         2



    Smaller frogs (males to 40 mm. snout-vent length); thighs weakly

    barred or plain; supratympanic fold pale brown; dorsum usually

    having linear pattern                                           3



    2. Dorsum tuberculate; snout subacuminate; vocal sac flecked with

    brown; tarsal fold rudimentary; web absent between fingers; black

    spots absent in scapular region                   _H. boulengeri_



    Dorsum smooth; snout pointed; vocal sac dark gray; tarsal fold

    absent; trace of web between fingers; two or more elongate dark

    spots in scapular region                          _H. foliamorta_



    3. Snout-vent length more than 30 mm.; tympanum 2/3 to 3/4 diameter

    of eye; prevomerine elevations about size of choanae            4



    Snout-vent length less than 30 mm.; tympanum less than 1/2 diameter

    of eye; prevomerine elevations smaller than choanae             5



    4. Thighs mottled posteriorly; discs on fingers about 1/2 size of

    tympanum; faint dark line from nostril to eye          _H. rubra_



    Thighs faintly barred or plain posteriorly; discs on fingers

    about size of tympanum; distinct dark line from nostril to eye

                                                      _H. elaeochroa_



    5. Dorsum brown with irregular dorsolateral stripes and

    interrupted paravertebral stripes; two transverse bars on shanks;

    interorbital bar present                 _H. staufferi staufferi_



    Dorsum gray with complete dorsolateral and paravertebral stripes;

    longitudinal stripe on shank; interorbital bar absent

                                                 _H. staufferi altae_





Key to Known Tadpoles



    1. Entire lower beak black; beaks moderate-sized, serrate; dorsal

    fin high, extending to middle of back                           2



    No more than half of lower beak black; beaks small, finely serrate;

    dorsal fin lower, barely extending onto body                    3



    2. Papillae present only laterally                _H. boulengeri_

    Papillae present laterally and ventrally          _H. foliamorta_



    3. Distinct brown stripe from nostril to eye; two stripes below

    eye,                                              _H. elaeochroa_



    Faint stripe from nostril to eye; no stripe below eye

                                                       _H. staufferi_









ACCOUNTS OF SPECIES AND SUBSPECIES





_Hyla boulengeri_ (Cope)



    _Scytopis boulengeri_ Cope, Bull. U.S. Natl. Mus., 32:12, December

    1, 1887 [Holotype.--USNM 13974, from "Nicaragua"; J. A. McNiel,

    collector].



    _Hyla boulengeri:_ Guenther, Biologia Centrali-Americana, Reptilia

    and Batrachia, p. 267, June 1901. Noble, Bull. Amer. Mus. Nat.

    Hist, 38:339, June 1918. Taylor, Univ. Kansas Sci. Bull., 35:856,

    July 1, 1952.



_Diagnosis._--Size large (Male to 49 mm., Female to 53 mm.); skull as

long as wide; frontoparietal fontanelle present; snout subacuminate;

canthus not pronounced; choanae large; tongue cordiform, slightly

longer than broad; interorbital triangle tubercular; skin on dorsum

tuberculate; tarsal fold reduced or absent; thighs, shanks, and tarsi

boldly barred with dark brown and pale yellow-green in life.



_Description._--Head flattened, longer than wide; snout projecting

beyond lower lip; loreal region oblique; canthus not pronounced; length

of eye less than interorbital distance; tympanum large, about 70 per

cent of diameter of eye; interorbital triangle distinct; arms short;

fingers lacking web; palmar tubercle tripartite; subarticular tubercles

distinct; long tubercle on base of first finger; discs truncate; legs

long; tarsal fold reduced or absent; inner metatarsal tubercle rounded,

larger than outer, both elevated; subarticular tubercles distinct; one

phalanx free of web on second, third, and fifth toes, three free on

fourth toe (Fig. 1A and B); skin tuberculate on dorsum, less so on

flanks; skin of belly granular, that on chest and throat weakly

granular; tongue cordiform, longer than wide, free and notched behind;

vocal slits large, lateral to tongue.



  [Illustration: Fig. 1. A and B.--Hand and foot of _Hyla boulengeri_

  (KU 102173), x 3. C and D.--Hand and foot of _Hyla s. staufferi_x (KU

  57790), x 6]



In life, dorsum tan or brown with dark spots on snout, head, and

scapular region; interorbital triangle and blotch posteriorly on dorsum

dark brown; flanks pale green; groin pale green or orange, mottled with

dark brown; thighs tan or brown above with dark transverse bars on

anterior and posterior surfaces; spaces between bars green or orange;

inner surfaces of shanks and outer surfaces of tarsi brown and orange;

foot brown above; forelimbs brown and pale green above, weakly barred;

belly creamy white with scattered brown spots; vocal sac creamy white

flecked with brown; lower jaw brown with white spots on lips (Pl. 1A).



In preservative, head and dorsum dark brown with triangular spot

between eyes; dark spots on head and scapular region and dark brown

blotch posteriorly on dorsum; flanks creamy white with brown spots;

groin creamy white mottled with dark brown; thighs brown above with

dark brown transverse bars on anterior and posterior surfaces; inner

surfaces of shanks and outer surfaces of tarsi barred with pale brown;

dorsal surface of foot mottled brown and creamy white; ventral surface

of foot and toes pale brown; forelimbs faintly barred with pale brown;

belly white with a few pale brown spots; vocal sac flecked with pale

brown; lower jaw marked with small white spots on lips.



_Variation._--Geographic variation is evident in the snout-vent length,

tibia length, and foot length, all in relation to snout-vent length,

and the relative size of the tympanum to the eye (Table 1). The largest

specimens are from the humid Pacific lowlands of Costa Rica;

individuals from the Caribbean lowlands of Costa Rica, Canal Zone, and

South America are smaller. A general trend for increase in size extends

from South America to the Pacific lowlands of Costa Rica.



Most variation in color does not seem to be correlated with geography;

color variation is nearly as great within a given population as between

separated populations. However, most specimens from Rincon de Osa,

Puntarenas Province, Costa Rica, are dusky brown, but a few are darker.

In comparison with specimens from the Caribbean lowlands of Central

America, specimens from the Pacific slopes in Costa Rica have a darker

interorbital triangle. In some specimens from the latter area

rugosities are present on the borders of the interorbital triangle, on

the snout, on the upper eyelid, and on the heel. Specimens from the

Caribbean lowlands are less tuberculate, and most individuals from

there lack rugosities on the tarsus. Living individuals from Puerto

Viejo, Heredia Province, Costa Rica, and from the Canal Zone, Panama,

are brown above with a metallic green tint. Rugosities are present on

the posterior edges of the forelimbs in some specimens from throughout

the range. In most respects, specimens from the Canal Zone resemble

those from the Caribbean lowlands of Costa Rica more than they resemble

those from the Pacific lowlands of Costa Rica, but some individuals

from the Canal Zone are less metallic above and have small white spots

dorsally on the body, head, and limbs.



A moderate amount of color change from night to day has been noted. At

night, a male from Puerto Viejo, Heredia Province, Costa Rica, was

grayish tan above with slightly darker markings; the flanks were pale

yellowish green. By day, the dorsum was brown with darker markings, and

the throat was pale gray with white flecks; the rest of the venter was

creamy white. The groin was pale green with black mottling; the

anterior and posterior surfaces of the thighs and inner edges of the

tarsi were greenish yellow with black bars.



TABLE 1.--Geographic Variation in Size and Proportions in Males of

_Hyla boulengeri_. (Means in parentheses below observed ranges.)



=========================================================================

                    |    | Snout-vent|   Tibia   |         |

                    |    |  length   |   length/ |Tympanum/|Foot length/

Locality            |  N |   (mm.)   | snout-vent|   eye   | snout-vent

--------------------+----+-----------+-----------+---------+-------------

Costa Rica: Tilaran | 23 | 37.4-48.7 | 0.52-0.58 |0.62-0.76| 0.39-0.45

                    |    |   (43.8)  |  (0.55)   | (0.71)  |  (0.42)

                    |    |           |           |         |

Costa Rica: Rincon  | 10 | 41.4-46.1 | 0.54-0.60 |0.68-0.80| 0.40-0.45

  de Osa            |    |   (44.0)  |  (0.57)   | (0.74)  |  (0.43)

                    |    |           |           |         |

Costa Rica: Alajuela| 13 | 35.6-43.1 | 0.55-0.60 |0.63-0.78| 0.41-0.46

  Province          |    |   (39.8)  |  (0.57)   | (0.69)  |  (0.44)

                    |    |           |           |         |

Costa Rica: Puerto  | 25 | 37.5-42.9 | 0.51-0.62 |0.63-0.79| 0.38-0.46

  Viejo             |    |   (41.6)  |  (0.55)   | (0.71)  |  (0.43)

                    |    |           |           |         |

Costa Rica: Suretka |  9 | 38.7-42.0 | 0.56-0.58 |0.53-0.72| 0.35-0.45

                    |    |   (41.0)  |  (0.56)   | (0.62)  |  (0.42)

                    |    |           |           |         |

Panama: Canal Zone  | 16 | 36.7-42.9 | 0.52-0.58 |0.70-0.78| 0.40-0.44

                    |    |   (39.0)  |  (0.54)   | (0.74)  |  (0.42)

                    |    |           |           |         |

Venezuela: Santome  |  4 | 35.5-40.9 | 0.45-0.48 |0.63-0.67| 0.36-0.40

                    |    |   (38.5)  |  (0.46)   | (0.65)  |  (0.38)





TABLE 2.--Comparison of Mating Calls in the _Hyla rubra_ Group. (Means

in parentheses below observed ranges.)



============================================================================

               |   |Notes|        |       |           |  Major frequencies

               |   | per |Duration| Pulses|Fundamental|       (cps)

               |   |call | of note|  per  | frequency |---------------------

Species        | N |group| (sec.) | second|  (cps)    |  Lower  |  Upper

---------------+---+----+---------+-------+-----------+---------+-----------

H. boulengeri  | 8 |   1 | 0.24-  | 80-120|  70-74    |1400-1820|2520-3182

               |   |     | 0.47   |  (101)|   (71)    |  (1611) | (2840)

               |   |     | (0.35) |       |           |         |

               |   |     |        |       |           |         |

H. foliamorta  | 7 |   1 | 0.23-  | 50-60 |  52-61    | 912-1026|2736-3477

               |   |     | 1.86   |  (51) |   (56)    |  (918)  | (3055)

               |   |     | (0.69) |       |           |         |

               |   |     |        |       |           |         |

H. elaeochroa  |15 | 2-95| 0.12-  | 40-50 |  48-65    |1254-1586|2562-3477

               |   | (19)| 0.24   |  (42) |   (57)    |  (1499) |  (2911)

               |   |     | (0.17) |       |           |         |

               |   |     |        |       |           |         |

H. s. staufferi|18 | 2-77| 0.13-  |100-130|  96-130   |1582-1872|1962-3744

               |   | (23)| 0.23   | (120) |   (106)   |  (1743) |  (3056)

               |   |     | (0.18) |       |           |         |

               |   |     |        |       |           |         |

H. s. altae    | 7 | 2-22| 0.14-  |110-130| 104-117   |1853-2106|3379-4056

               |   | (11)| 0.18   | (120) |   (112)   |  (2008) |  (3775)

               |   |     | (0.15) |       |           |         |



_Cranial Osteology._--The skull of _Hyla boulengeri_ is as long as it

is wide, and is flat; the premaxillary is small and bears 13 to 17

teeth (mean for 6 specimens, 14.9). The alary processes of the

premaxillaries are widely separated, concave posteriorly, and vertical.

Ventrally, the premaxillary is connected to the prevomer by bony

tissues. The maxillary is slender and bears 70 to 91 teeth (mean for 6

specimens 78.1). The pars facialis of the maxillary is laterally convex

and about four times as high as the pars dentalis.



The nasal is large (its length about 40 per cent of total length of

skull), and pointed anteriorly and posteriorly in dorsal view. The

nasals are separated anteromedially by the cartilaginous septum nasi.

One or two protuberances are present on the midlateral concavity of the

nasal. Posteriorly, the nasal overlaps the sphenethmoid and articulates

with the palatine. Dorsally the sphenethmoid is large, pentagonal, and

completely ossified. The frontoparietal is elongate, smooth, and bears

a small supraorbital process on the anterior edge of the orbit. A

keyhole-shaped frontoparietal fontanelle is present; the fontanelle is

narrow anteriorly and wide posteriorly.



The bony part of the prooetic is separated dorsally from the squamosal

by the cartilaginous crista parotica. The squamosal is small, its

anterior arm slender and pointed. The posterior arm of the squamosal is

pointed terminally and articulates with the prooetic medially.



The prevomer is large and elongate. Anteriorly the prevomer is

connected to the maxillary-premaxillary articulation; posteriorly, the

prevomer is separated from the sphenethmoid by cartilage. Each prevomer

bears six to nine teeth. The palatine is present and edentate. The

anterior end of the parasphenoid is broad (less pointed than in _Hyla

foliamorta_). The pterygoid is slender and well developed.



_Natural History._--_Hyla boulengeri_ inhabits humid lowland tropical

forests and breeds in temporary ponds. Clasping pairs and gravid

females were observed at Puerto Viejo, Heredia Province, Costa Rica, on

June 21, 1966. Males were calling from depressions in decaying logs and

stumps, in forked stems, and from leaves of broad-leafed plants near

the pond. Males were observed in late July and early August calling

from _Calathea_ and _Heliconia_ leaves at the edge of a pond in the wet

forest of the Osa Peninsula. William E. Duellman informed me that he

collected calling males in January at El Real, Darien, and in March at

Almirante, Bocas del Toro, Panama. Taylor (1952) found calling males in

June at Turrialba, Cartago Province, Costa Rica, and Dunn (1931a)

observed males calling in July, November, and December in Panama.

Gravid females have been found from April to August. Breeding

activities of _Hyla boulengeri_ always seem to be associated with

temporary ponds; in Central America breeding apparently takes place

throughout most of the year.



The mating call of _Hyla boulengeri_ consists of one short, moderately

low-pitched note. Each note has a duration of 0.24 to 0.47 second and

is repeated at intervals of one second to several minutes. The notes

have 80 to 120 pulses per second, a fundamental frequency of about 70

cycles per second, and a dominant frequency of 2,840 cycles per second

(Table 2, Pl. 3A).



The eggs are deposited in a mass in the water. No information is

available concerning early development. Tadpoles in advanced stages of

development were found in a temporary pond at Rincon de Osa, Puntarenas

Province, Costa Rica. The pond was about 10 cm. deep, had a muddy

bottom and lacked vegetation. Three recently metamorphosed young were

found in mid-August, 1966, on grass at the edge of another temporary

pond in the forest.



_Tadpoles_--Twelve tadpoles are available. These were collected at

Rincon de Osa, Puntarenas Province, Costa Rica. The maximum size

represented is 34.0 mm., total length (stage 42 of development).



A typical tadpole in stage 36 of development (KU 104295) has a body

length of 12.0 mm., tail length of 20.0 mm., and total length of 32.0

mm. Other characters are as follows: depth of tail equal to length of

body; body deeper than wide; distance between eye and nostril equal to

that between nostril and tip of snout; mouth anteroventral, upper and

lower lips bare; papillae present laterally; tooth rows 2/3; upper rows

about equal in length; first upper row slightly, and second upper row

widely, interrupted medially; lower rows about equal in length, shorter

than upper rows; third lower row containing 5-10 large teeth; beak

strong, serrate; spiracle nearer anus than eye; anal aperture not

extending to border of ventral fin; caudal musculature slender

posteriorly, extending to tip of pointed tail; dorsal fin extending to

middle of body, slightly deeper than ventral fin; posterior three

fourths of tail spotted; rest of tail and body gray-brown or

transparent; hindlimbs flecked or spotted with brown (Table 3, Fig. 2A

and 3A).



TABLE 3.--Sizes of Tadpoles of _Hyla boulengeri_ in Relation to

Developmental Stages. (Means in parentheses below observed ranges;

measurements in mm.)



    =======================================================

    Stage   | N | Body length | Tail length | Total length

    --------+---+-------------+-------------+--------------

      30    | 1 |     11.0    |     22.2    |     33.2

            |   |             |             |

      35    | 1 |     11.0    |     12.0    |     23.0

            |   |             |             |

      36    | 3 |   9.5-12.0  |  20.0-21.5  |  31.0-32.0

            |   |    (11.2)   |    (20.5)   |    (31.7)

            |   |             |             |

      38    | 2 |     11.5    |     22.0    |     33.5

            |   |             |             |

      42    | 2 |  10.5-13.0  |  21.0-22.0  |  32.5-34.0

            |   |    (11.8)   |    (21.5)   |    (33.3)

            |   |             |             |

      44    | 2 |  14.0-15.0  |   8.0-15.0  |  22.0-30.0

            |   |    (14.5)   |    (12.5)   |    (26.0)

            |   |             |             |

      46    | 1 |     15.0    |     15.0    |



A recently metamorphosed young has a snout-vent length of 15 mm.; the

head is as long as wide, the eyes are prominent; the limbs are weakly

barred; the skin is rugose above and granular below. The venter is

immaculate; the dorsum and limbs are gray-brown in preservative (pale

green in life). The interorbital space, supratympanic fold, and

scapular region are darker than the rest of the body; the fingers lack

webbing; the webbing on the foot is the same as in adults; small

metatarsal tubercles are present, but the tarsal fold is absent.



  [Illustration: Fig. 2. Tadpoles of (A) _Hyla boulengeri_ (KU 104295)

  and (B) _Hyla elaeochroa_ (KU 104134), x 3.]



  [Illustration: Fig. 3. Mouthparts of tadpoles of (A) _Hyla

  boulengeri_ (KU 104295) and (B) _Hyla elaeochroa_ (KU 104134), x 25.]



_Remarks._--Cope (1887:12) described _Scytopis boulengeri_ from

Nicaragua. Guenther (1901:267) placed _boulengeri_ in the genus _Hyla_,

and stated that Cope possibly placed _boulengeri_ in the genus

_Scytopis_ on the supposition that it had an accumulation of

"sebaceous glands" above the tympanum. Noble (1918:339) redescribed

_Hyla boulengeri_ on the basis of three specimens from Zelaya

Province, Nicaragua, and noted that the glands were not prominent in

any of the specimens. Duellman (1956:8) showed that _Scytopis hebes_

(generotype of _Scytopis_ by monotypy) is a Phrynohyas, and thus

placed _Scytopis_ Cope, 1862, in the synonymy of _Phrynohyas_

Fitzinger, 1843.



Dunn and Emlen (1932:25) placed _Hyla lancasteri_ Barbour in the

synonymy of _Hyla boulengeri_; the former was known solely from one

juvenile. They made no qualifying statements, but probably they were

impressed by the strongly barred thighs, a coloration known among

Central American hylids at that time only in _Hyla boulengeri_

(Duellman, 1966a:271). Taylor (1952:856) followed Dunn and Emlen with

reservation and noted some differences. Duellman (1966a:271) showed

that the holotype of _lancasteri_ was a juvenile of a species

subsequently named as _Hyla moraviaensis_ by Taylor (1952:865).



In Central America, _Hyla boulengeri_ can be confused only with _Hyla

foliamorta;_ the latter is restricted to central and eastern Panama

and northern Colombia. The snout of _foliamorta_ is more pointed and

protruding, and the vocal sac is darker than in _boulengeri_; the

groin of _foliamorta_ usually is creamy white, whereas _boulengeri_

usually has a dark spot. The skulls differ in that _boulengeri_ has a

frontoparietal fontanelle, the prevomer is larger and elongate,

anteriorly connected to the premaxillary, and posteriorly separated

from the sphenethmoid by cartilage; _foliamorta_ lacks a fontanelle,

the prevomer is smaller, anteriorly separated from the premaxillary by

cartilage, but connected by a bony suture to the sphenethmoid. The

mating call of _boulengeri_ differs by having shorter notes, twice as

many pulses per second, a higher fundamental frequency, and more

closely approximated major frequencies than does that of _foliamorta_.



_Hyla boulengeri_ need not be compared in detail with the other Central

American members of the _Hyla rubra_ group, because all of them are

smaller and have shorter snouts, smoother skin, and dissimilar color

patterns.



_Distribution._--In Central America _Hyla boulengeri_ inhabits the

forested lowlands in locally humid areas in Guanacaste Province, Costa

Rica, and in the humid Golfo Dulce region of Costa Rica; it occurs on

the Carribbean lowlands from central Nicaragua to South America, where

it ranges to Guyana and Ecuador. The highest elevations where _H.

boulengeri_ has been found are 620 meters at Turrialba, Cartago

Province, and 700 meters at Tilaran, Guanacaste Province, Costa Rica

(Fig. 4).



_Specimens Examined._--Costa Rica: _Alajuela_: 9 km N Ciudad Quesada,

near La Florencia, USC 8059 (4); 18 km N Florencia, USC 2624; Laguna

Monte Alegre, KU 64334; Las Playuelas, 11 km S Los Chiles, USC 7216,

7217 (2), 7219; 3 km NE Muelle del Arenal, USC 2644 (5). _Cartago_:

Turrialba, KU 24741. _Guanacaste_: 7 km N Liberia, USC 8096 (2), 8138

(6); 13.6 km N Liberia, USC 8151, 8171 (2); 20.5 km S Liberia, USC

8205; Taboga, 20 km SE Las Canas, KU 102170, USC 7166; 4 km NE Tilaran,

USC 8023; 6 km NE Tilaran, USC 523 (3), 6262, 7019. _Heredia_: Puerto

Viejo, KU 64323-7 (skeletons), 104351-3 (skeletons), 64330-3,

103592-620; 1 km NE Puerto Viejo, UMMZ 126042; 1 km S Puerto Viejo, KU

84983-4 (skeletons), 86317-22, 87774 (skeleton); 4.2 km W Puerto Viejo,

KU 64329, 64328 (skeleton). _Limon_: Mountain Cow Creek, near Banano,

KU 37031, 41067 (skeleton); 3 km S Rio Tortuguero, AMNH 69057; Suretka,

KU 36482-8, 36699. _Puntarenas_: 4.8 km S Bahia Rincon on NW side Rio

Rincon, USC 705; Parrita, USC 6163; 4.5 km W Rincon de Osa, KU

102177-9, 104295-6 (tadpoles); 6 km SW Rincon de Osa, KU 102171-6; 4.4

km NW Villa Neilly, USC 8003; 10.5 km WNW Villa Neilly, KU 64321. _San

Jose_: 21 km WSW San Isidro el General, KU 34104-6.



  [Illustration: Fig. 4. Map showing locality records for _Hyla

  boulengeri_ (circles) and _H. foliamorta_ (dots).]



Panama: _Bocas del Toro_: 3.2 km W Almirante, KU 95978. _Canal Zone_:

Barro Colorado Island, FMNH 13379; near Clayton Reservation, UIMNH

42000; 2.6 km SW Fort Kobbe, KU 95977; Miraflores Locks, AMNH 69764-5;

Summit, AMNH 73445, KU 97777, 101540-9, 104350 (skeleton). _Colon_: Rio

Gatuncillo, near Nuevo San Juan, KU 95976. _Darien_: El Real, KU

80451-3.





_Hyla foliamorta_ Fouquette



    _Hyla foliamorta_ Fouquette, Herpetologica, 14:125, April 25,

    1958 [Holotype.--TNHC 23109, 11 km. NW Miraflores Locks, Canal

    Zone, Panama; M. J. Fouquette, Jr. collector].



_Diagnosis._--Size medium (Male to 43 mm., Female to 41 mm.); skull

longer than wide; frontoparietal fontanelle absent; snout acuminate,

projecting; interorbital triangle bordered by white lines; scapular

region having two or more elongate spots; dorsum smooth; vocal sac

dark gray; groin creamy white; traces of web between fingers.



_Description._--Head flattened, longer than wide; snout flat, pointed,

protruding beyond lower lip; loreal region slightly concave; canthus

moderately prominent; eyes smaller than interorbital space; tympanum

distinct, 55 to 75 per cent of diameter of eye, smaller than

internarial space; arms short; fingers having rudimentary webs; median

palmar tubercle tripartite; inner palmar tubercle on base of first

finger flat; subarticular tubercles distinct; discs of fingers smaller

than diameter of tympanum; legs long; tarsal fold lacking; inner

metatarsal tubercle larger than outer; one phalanx free on second,

third, and fifth toes, two and one half phalanges free on fourth toe;

narrow fringe continuing from web to discs of toes; discs of toes

about the size of those on fingers; skin smooth on dorsum and flanks,

that on belly and posterior part of thighs granular; tongue oval,

longer than wide; vocal slits oblique, about one half length of

tongue.



In life, dorsum pale tan to pale reddish brown with irregular reddish

brown markings; small dark spots on head; distinct dark brown

triangular mark between eyes, bordered by thin white lines; apex of

triangle always directed backward; supratympanic fold with black edge;

scapular region having two to five small, elongate black spots; belly

creamy tan with small brown spots; vocal sac uniformly dark brown with

scattered creamy tan flecks; upper jaw dark brown; limbs creamy white

below with scattered brown spots; groin marked with small brown spots

in some specimens; anterior and posterior surfaces of thighs

yellow-orange with three distinct black blotches; two dark bands on

upper surface of shanks; webbing of feet yellowish tan with brown

mottlings (Pl. 1B).



In preservative, dorsum brown or gray with darker markings; interorbital

triangle distinct, bordered by white lines; supratympanic fold with

black edge; two or more small elongate black spots in scapular region;

belly white with numerous brown flecks; edge of upper lip dark brown;

vocal sac dark gray; undersides of limbs creamy white; groin creamy

white with or without brown spots; anterior and posterior surfaces of

thighs having three black blotches separated by creamy white spaces;

shanks having two brown bands; webbing of feet mottled with brown.



_Variation._--Twenty-eight breeding males from the area between Chepo

and Tocumen, Panama, have snout-vent lengths of 39.0 mm. to 46.0 mm.

(mean 42.5 mm.). In these specimens, the ratio of the tibia length

to the snout-vent length is 0.54 to 0.61 (mean, 0.57); the ratio

of the diameter of the tympanum to that of the eye is 0.55 to 0.75

(mean, 0.67). One female has a snout-vent length of 41.0 mm.,

tibia/snout-vent length ratio of 0.57, and tympanum/eye ratio of 0.76.

Two to five (usually three) elongate black spots are present in the

scapular region in different individuals. The flanks in some are

spotted with brown; in others they are creamy white. A small black

spot is present in the groin of some specimens. Usually two to four

blotches are present on the anterior and posterior surfaces of the

thighs; in some specimens the blotches are reduced to small spots. One

or two brown spots are present proximally on the shanks in most

specimens. In some individuals tuberculations are scattered on the

head and in the tympanic and scapular regions, but the dorsum is

smooth in most specimens; the belly is creamy white flecked with

brown.



_Cranial Osteology._--The skull of _Hyla foliamorta_ is flat and

longer than it is wide. The premaxillary is small and bears 13 to 16

teeth (mean for 2 specimens, 14.8). The alary process of the

premaxillary is vertical and concave posteriorly. Ventrally, the

premaxillary is completely separated from the prevomer by cartilage.

The maxillary is slender; each bears 77 to 84 teeth (mean for 2

specimens, 81). The pars facialis of the maxillary is laterally convex

and less than three times the height of the pars dentalis.



The nasal is large and pointed anteriorly and posteriorly in dorsal

view. The length of the nasal comprises about 40 per cent of the total

length of the skull. The nasals are separated anteromedially by the

cartilaginous septum nasi. One protuberance is present on the

midlateral concavity of the nasal. Posteriorly, the nasal overlaps the

sphenethmoid; posterolaterally the nasal articulates with the

palatine. The sphenethmoid is completely ossified and pentagonal in

dorsal view. The frontoparietal is elongate, without a pronounced

anterior supraorbital process. The frontoparientals are sutured

medially throughout their lengths; the frontoparietal fontanelle is

absent.



The bony part of the prooetic is narrowly separated dorsolaterally from

the squamosal by the cartilaginous crista parotica. The squamosal is

large; the anterior arm is pointed. The posterior arm of the squamosal

is broad, rounded terminally, and articulates with the prooetic

medially.



The prevomer is short and separated anteriorly from the premaxillary

and maxillary by cartilage. The posterior margin of the prevomer has a

bony articulation with the sphenethmoid. Each prevomer bears five to

seven teeth. The palatine is small and edentate. The anterior end of

the parasphenoid is narrow (more pointed than in _Hyla boulengeri_).

The pterygoid is slender and well developed (Fig. 5A).



  [Illustration: Fig. 5. Dorsal views of the skulls of (A) _Hyla

  foliamorta_ (KU 77687) and (B) _H. elaeochroa_ (KU 68289), x 3.]



_Natural History._--_Hyla foliamorta_ inhabits lowland forests in

eastern Panama and breeds in temporary ponds. Males have been observed

calling from grasses, bushes, and emergent vegetation near temporary

ponds and ditches along roads. William E. Duellman informed me that he

found a breeding congregation of this species in June near Chepo,

Panama, where males were calling from spiny palms at the edge of a

woodland pond. Fouquette (1958) found calling males in May, August,

and September near Miraflores Locks, Canal Zone. Calling stations vary

from one to two meters above ground. No clasping pairs have been

found; only one female is known (KU 101589, from 8 km NE Tocumen,

Panama); this gravid individual was collected in early June.



The mating call of _Hyla foliamorta_ consists of one pulsed,

low-pitched, moderate trill of about O.5 second duration. Each note is

repeated at intervals of 5 seconds to a few minutes. The notes have

about 50 pulses per second, a fundamental frequency of 56 cycles per

second and a dominant frequency of about 3000 cycles per second (Table

2, Pl. 3B).



Egg deposition sites are unknown. No information is available

concerning early development, and little is known about the breeding

season of _Hyla foliamorta_. Probably its breeding activities are

restricted to the rainy months.



_Tadpoles._--Eight tadpoles were collected from a weedy temporary pond

near Chepo, Panama, in early June.



A typical tadpole in stage 35 of development (KU 104244) has a body

length of 9.5 mm., tail length of 25.0 mm., and a total length of 34.5

mm. Other characters are as follows: depth of tail equal to length of

body; body deeper than wide; distance between eye and nostril equal to

distance between eye and spiracle; mouth anteroventral; median part of

upper lip bare; rest of lip having one row of papillae; a few other

rows of small papillae at corners of mouth; tooth rows 2/3; first

upper row entire, second upper row interrupted medially, shorter than

first; lower rows shorter than upper rows, third shortest; beak

moderately robust; spiracle nearer eye than anus; anal tube short,

aperture not extending to border of ventral fin; caudal musculature

slender, extending to tip of pointed tail; dorsal fin extending onto

body (Table 4).



TABLE 4.--Sizes of Tadpoles of _Hyla foliamorta_ in Relation to

Developmental Stages. (Means in parentheses below observed ranges;

measurements in mm.)



    =======================================================

    Stage   | N | Body length | Tail length | Total length

    --------+---+-------------+-------------+--------------

      25    | 2 |   5.0-5.2   |   8.0-8.5   |  13.0-13.7

            |   |    (5.1)    |    (8.3)    |    (13.4)

            |   |             |             |

      26    | 3 |   7.0-7.5   |  12.0-12.4  |  17.0-19.5

            |   |    (7.2)    |   (12.1)    |    (18.6)

            |   |             |             |

      28    | 2 |   6.5-7.0   |    18.0     |     25.0

            |   |    (6.8)    |             |

            |   |             |             |

      35    | 1 |     9.5     |    25.0     |     34.5



In life, yellow above, white below; caudal fin greenish yellow with

black or gray reticulations; dark line from snout to eye; dark spot

behind eye; tail unpigmented except for fine dark reticulations. In

preservative body creamy white, transparent below with dark pigment

above in some specimens.



_Remarks._--_Hyla foliamorta_ can be confused only with _Hyla

boulengeri_. The differences between adults of these species were

discussed in _Remarks_ on _H. boulengeri_. The tadpoles of

_foliamorta_ have labial papillae on the lower lip and a stripe

between the eye and the tip of the snout. By comparison the tadpoles

of _boulengeri_ have a bare lower lip and no stripe between the eye

and the tip of the snout.



_Distribution._--_Hyla foliamorta_ inhabits the subhumid Pacific

lowlands (elevations of less than 100 meters) of Central Panama and

Caribbean lowlands of northern Colombia (Fig. 4).



_Specimens Examined._--Panama: _Panama_: 3 km WSW Chepo, KU 77164-9,

101573-5, 104243-4 (tadpoles); 6 km WSW Chepo, KU 77170, 101576-8; 1.5

km SW Naranjal, KU 77171, 77687 (skeleton); 2 km N Tocumen, KU

101579-83, 104349 (skeleton); 8 km NE Tocumen, KU 101584-92.



No specific locality: TNHC 24401.





_Hyla rubra_ Laurenti



    _Hyla rubra_ Laurenti, Synopsis Reptilium Emendatum, p. 35, 1768.

    Daudin, Hist. Nat. Rainettes Grenouilles Crapauds, II:26, 1802.

    Daudin, Hist. Nat. Particuliere Reptiles, 8:53, 1803. Guenther,

    Catalogue Batrachia Salientia Brit. Mus., p. 110, 1859. Boulenger,

    Catalogue Batrachia Salientia s. Ecaudata, p. 403, February 1,

    1882. Dunn, Occas. Papers, Boston Soc. Nat. Hist., 5:413, October

    10, 1931.



    _Hyla elaeochroa_ (part): Dunn and Emlen, Proc. Acad. Nat. Sci.

    Philadelphia, 84:25, March 22, 1932.



_Diagnosis._--Size medium; skull longer than wide; frontoparietal

fontanelle absent in adults; snout subovoid; choanae rounded; dorsal

stripes present; black vermiculations on posterior surfaces of thighs.



_Description._--Head flat, longer than wide; snout long, subovoid,

slightly protruding beyond lower lip; loreal oblique, concave; canthus

rounded, indistinct; diameter of eye about equal to interorbital

space; tympanum large, about three fifths diameter of eye, smaller

than internarial distance; supratympanic fold indistinct; arms short;

fingers free of webs; subarticular tubercles distinct; median palmar

tubercle large, bifid; inner palmar tubercle on base of first finger

flat, elongate; disc of third finger about one half diameter of

tympanum; legs moderately long; tarsal fold absent; inner metatarsal

tubercle distinct, oval; toes about half webbed; web on fourth toe

extending to disc; discs of toes about size of those on fingers; skin

smooth above with small granules on head and in scapular region in

some specimens; skin on flanks, throat, belly, and lower surfaces of

thighs granular; tongue oval, longer than wide, not free behind;

choanae small, oval; vocal slits long, lateral to tongue.



In preservative, dorsum pale brown with darker dorsolateral stripes;

narrow dark brown line from nostril to eye; groin, anterior surface of

thighs, and posteroventral surfaces of shanks creamy tan with dark

brown vermiculations; white spots present on thighs in some specimens;

throat flecked with brown; belly creamy white or gray.



_Remarks._--The taxonomic history of _Hyla rubra_ Laurenti is

confused. Seba (1734:70) illustrated and diagnosed a frog for which

he used the name _Ranula, Americana, Rubra_. Linnaeus (1758:213)

considered Seba's frog to be a variety of _Hyla arborea_. Laurenti

(1768:35) apparently examined the same individual that Seba called

_Ranula, Americana, Rubra_. For this specimen, Laurenti used the

binominal _Hyla rubra_ and provided a brief diagnosis. The type

locality was given as America.



Daudin (1802:26) redescribed the same specimen(s?) treated by Seba and

Laurenti and provided a fairly good description and figures. Daudin

restricted the type locality to Surinam and indicated that Marin de

Baize was the probable collector. Daudin (1802:26 and 1803:53)

neglected to consider Laurenti's work, but he applied the same name

used by Laurenti. Most authors have credited _Hyla rubra_ to Daudin,

but Rivero (1961:120) noted that _Hyla rubra_ Laurenti, 1768, has

priority over _Hyla rubra_ Daudin, 1802. Since both Laurenti and

Daudin worked on Seba's material, it is reasonable to assume that

Daudin redescribed the same frog that was named by Laurenti; this was

not an uncommon practice in the early nineteenth century. Thus I

conclude that _Hyla rubra_ Daudin, 1802, is a junior synonym of _Hyla

rubra_ Laurenti, 1768.



Dunn (1931a:413) first reported _Hyla rubra_ from Central America; he

recorded the species from the Canal Zone and San Pablo, Panama. I have

examined the material of _Hyla rubra_ from Panama deposited in various

museums. Most of the specimens are faded, discolored, and do not have

distinct brown vermiculations on the thighs. The specimens seem to be

more like _Hyla rubra_ than any of the other species in the _rubra_

group. The presence of oval choanae and a tympanum larger than the

largest finger disc separate these specimens from _Hyla elaeochroa_, a

species with which _rubra_ has been confused. _Hyla elaeochroa_ does

not occur in the Canal Zone or eastern Panama. All museum specimens

from Nicaragua, Costa Rica, and western Panama that have been called

_Hyla rubra_, plus those mentioned by Dunn and Emlen (1932:25) and

Dunn (1933:61) are _Hyla elaeochroa_.



The taxonomic status of the many South American populations referred

to _Hyla rubra_ and of other populations now recognized as different

species is not clear at the present time. Considerable variation in

external characters and in cranial features has been observed in South

American _rubra_. A review of the taxonomy of these populations is

beyond the scope of this paper. Possibly the Central American

specimens herein referred to _rubra_ will ultimately be found to be

specifically distinct from those in Surinam. Since I have no

osteological material from Central America, I have been unable to

describe the cranium in this account. Furthermore, I have no data on

the ecology and life history of _rubra_ in Central America.



_Distribution._--_Hyla rubra_ inhabits lowland tropical forests from

central-eastern Panama to northern South America and thence through

lowlands east of the Andes to northern Argentina (Fig. 6).



_Specimens Examined._--Panama: _Canal Zone_: Gatun, UMMZ 52720 (2);

Madden Dam, FMNH 67820; no specific locality, UMMZ 56517 (3), USNM

37863. _Colon_: Cerro Bruja, MCZ 13248. _Darien_: El Real, USNM

140569-70, 140573. _Panama_: Juan Diaz, MCZ 17973; Las Sabanas, MCZ

17581; Rio Trinidad, UMMZ 64003; San Pablo, MCZ 1398-9.





_Hyla elaeochroa_ Cope



    _Hyla elaeochroa_ Cope, Jour. Acad. Nat. Sci. Philadelphia, 8:105,

    1876 [Holotype.--USNM 30689, Sipurio, Limon Province, Costa Rica;

    William M. Gabb collector]. Guenther, Biologia Centrali-Americana,

    Reptilia and Batrachia, p. 265, June 1901. Taylor, Univ. Kansas

    Sci. Bull., 35:859, July 1, 1952. Duellman, Univ. Kansas Publ.,

    Mus. Nat. Hist., 17:270, June 17, 1966.



    _Hyla quinquevittata_ Cope, Proc. Amer. Philos. Soc., 23:273,

    April 1887 [Holotype.--USNM 14187, Nicaragua; J. F. Bransford

    collector]. Guenther, Biologia Centrali-Americana, Reptilia and

    Batrachia, p. 268, June 1901. Noble, Bull. Amer. Mus. Nat. Hist.,

    38:340, June 1918.



    _Hyla rubra_ (part): Dunn and Emlen, Proc. Acad. Nat. Sci.

    Philadelphia, 84:25, March 22, 1932.



    _Hyla dulcensis_ Taylor, Univ. Kansas Sci. Bull., 39:37, November

    18, 1958 [Holotype.--KU 32168, Golfito, Puntarenas Province, Costa

    Rica; Edward H. Taylor collector].



_Diagnosis._--Size medium (Male to 38 mm., Female to 40 mm.); skull

wider than long; nasals truncate anteriorly; frontoparietal fontanelle

moderate in size; snout slightly protruding; tympanum about size of

largest discs on fingers; dorsum marked by longitudinal stripes; dark

stripe between eye and nostril; in life tan to olive-green with or

without dark mark between eyes; bones greenish blue.



_Description._--Head flat, longer than wide; snout long, rounded,

protruding beyond mouth; canthus indistinct; length of eye equal to

interorbital distance; loreal region not pronounced; tympanum distinct

and about two-fifths diameter of eye; interorbital triangle present or

absent; arms short; trace of web between fingers, extending as fringe

along sides of fingers; first finger very short with small disc; other

discs about size of those on toes; discs on third finger and fourth

toe as large as tympanum; outer palmar tubercle moderate in size,

partly bifid; inner palmar tubercle large, elongate, flat;

subarticular tubercles distinct; legs moderately long; tarsal fold

absent; inner metatarsal tubercle flat; outer metatarsal tubercle

smaller, indistinct; subarticular tubercles moderate in size; fringe

on toes to tip of disc of second toe; rest of toes about two-thirds

webbed; foot length about two fifths snout-vent length; tibia length

about one half snout-vent length; skin above smooth or with minute

pustules; belly finely granular; ventral surfaces of thighs and areas

below anus granular; skin on ventral surfaces of limbs smooth; tongue

relatively large, longer than wide, barely notched behind; vocal slits

elongate, lateral to tongue; choanae medium in size. In life, dorsum

yellowish brown, olive green, or grayish brown with dark brown spots

on snout, dark brown stripe from nostril to eye, dark yellow-brown

interorbital triangle, and dark supratympanic region; generally five

interrupted longitudinal dark brown stripes on dorsum (one on each

flank, pair of paravertebral and one vertebral); flanks pale yellow;

groin yellowish brown; thighs marked with one or two transverse

yellow-brown blotches; shanks with two or three yellow-brown blotches

above; spaces between blotches on thighs, shanks, tarsi, and feet

yellow; brown spots on tarsi and in some specimens on feet; arm pale

yellow with pale brown spots; belly creamy white having slight

blue-green tint; vocal sac and chin yellow; axillary region yellow,

blue-green in some specimens (Pl. 2A).



In preservative, head and dorsum yellowish brown; dark brown stripe

from nostril to eye; dark brown spots on snout; a dark brown

interorbital triangle with apex directed backward; dark brown

supratympanic region; dorsal stripes same as in living individuals;

flanks pale yellow with brown spots in some specimens; groin creamy

white; thighs and shanks having or lacking transverse dark brown

blotches; spaces between blotches creamy white or yellow-brown; arms

pale yellowish brown; belly and vocal sac creamy white.



_Variation._--Geographic variation in size and some proportions, such

as the ratio of tibia length to snout-vent length and the ratio of the

diameter of the tympanum to that of the eye, have been observed in

this species. The largest individuals are from the Golfo Dulce region

(samples from Piedras Blancas and Rincon de Osa), Puntarenas Province,

Costa Rica. The smallest individuals are from El Recreo, Zelaya

Province, Nicaragua, and from the Caribbean lowlands of Costa Rica.



The diameter of the tympanum is proportionately larger (relative to

the size of the eye) in males from Tilaran, Guanacaste Province; the

tympanum is nearly as large in males from Piedras Blancas, Puntarenas

Province, and Puerto Viejo, Heredia Province, Costa Rica. The lowest

ratios occur in individuals from Almirante, Bocas del Toro, Panama, in

specimens from the Caribbean lowlands of Costa Rica (except Puerto

Viejo), and in those from El Recreo, Zelaya Province, Nicaragua. In

general, the tympanum is proportionately larger in females than in

males; the tympanum is largest in females from the Pacific lowlands

of Costa Rica (Table 5).



Color variation has been observed in individuals from the same

population, as well as in individuals from different localities,

between males and females, and from night to day. In life, most

individuals from the Pacific lowlands of Costa Rica are dark tan to

greenish gray above with dark brown longitudinal stripes that are

entire or broken, but some specimens (mostly males) are dusky brown

and lack longitudinal stripes or an interorbital triangle; females

usually have the dark interorbital triangle and the stripes on the

dorsum. Individuals from Turrialba, Cartago Province, Costa Rica, are

pale olive-tan with olive-brown markings. Individuals from Puerto

Viejo, Heredia Province, Costa Rica, are uniformly yellowish brown

with or without dark longitudinal stripes. Specimens from El Recreo,

Zelaya Province, Nicaragua, are like those from Puerto Viejo. Males

from Almirante, Bocas del Toro, Panama, are pale brown with dark brown

longitudinal stripes and an indistinct interorbital triangle. Females

have a distinct interorbital triangle and dark brown blotches on the

thighs and shanks.



By night, the dorsum usually is pale yellow, and the belly is creamy

white. By day, the dorsum is dark tan; the stripes and spots are

darker, and the belly is yellowish white. Taylor (1952) noticed that

considerable variation in color pattern occurred from night to day in

individuals from Turrialba, Cartago Province, Costa Rica. At night

some individuals lacked a dorsal pattern, but by day many of these

individuals developed dorsal stripes.



_Cranial Osteology._--The skull of _Hyla elaeochroa_ is slightly wider

than it is long, and flat. The premaxillary is small and bears 10 to

15 teeth (mean for 9 specimens, 12.3). The alary process of the

premaxillary is small, vertical, and slightly concave posteriorly.

Ventrally, the premaxillary is partially united to the prevomer by

ossification. The maxillary is slender and bears 70 to 82 teeth (mean

for 9 specimens, 74.3). The pars facialis of the maxillary is

laterally convex and is about twice as high as the pars dentalis.



The nasal is large, robust, anteriorly truncate, but pointed

posteriorly in dorsal view. The nasal comprises about 45 per cent of

the total length of the skull. There is an anterior cartilaginous

septum nasi separating the two nasals; the latter overlap the

sphenethmoid posteriorly. Each nasal bears a shallow concavity in the

midlateral side and lacks a maxillary process. Dorsally, the

sphenethmoid is wider than long, roughly pentagonal in shape; the

frontoparietal is elongate, smooth, and bears a small anterior

supraorbital process. The sphenethmoid and frontoparietal form the

anterior margin of the frontoparietal fontanelle; the fontanelle is

narrow anteriorly and wider posteriorly (Fig. 5B).



The entire distal surface of the prooetic is in contact with the

posterior arm of the squamosal. A narrow cartilaginous crista parotica

is visible dorsally in some specimens. The squamosal is broad

posteriorly but its anterior arm is slender and not in contact with

the maxillary.



TABLE 5.--Geographic Variation in Size and Proportions in Males of

_Hyla elaeochroa_. (Means in parentheses below observed ranges.)



==========================================================================

                     |    |Snout-vent|   Tibia    |         |

                     |    | length   |   length/  |Tympanum/|Foot length/

Locality             |  N |  (mm.)   | snout-vent |   eye   | snout-vent

---------------------+----+----------+------------+---------+-------------

Nicaragua: El Recreo |  9 | 28.0-30.3|  0.51-0.57 |0.47-0.59| 0.39-0.54

                     |    |  (29.3)  |   (0.55)   | (0.51)  |  (0.41)

                     |    |          |            |         |

Costa Rica: Tilaran  | 21 | 28.8-33.6|  0.47-0.57 |0.48-0.65| 0.40-0.46

                     |    |  (30.6)  |   (0.52)   | (0.59)  |  (0.41)

                     |    |          |            |         |

Costa Rica: Puerto   | 22 | 26.3-32.4|  0.49-0.54 |0.48-0.65| 0.38-0.45

  Viejo              |    |  (29.7)  |   (0.52)   | (0.57)  |  (0.42)

                     |    |          |            |         |

Costa Rica: Turrialba| 95 | 28.1-35.0|  0.47-0.56 |0.47-0.68| 0.37-0.46

                     |    |  (30.6)  |   (0.51)   | (0.56)  |  (0.41)

                     |    |          |            |         |

Costa Rica: Bataan,  | 26 | 26.3-32.7|  0.47-0.54 |0.45-0.66| 0.36-0.44

  Limon, and Suretka |    |  (30.0)  |   (0.51)   | (0.50)  |  (0.41)

                     |    |          |            |         |

Costa Rica: Piedras  | 21 | 33.3-37.7|  0.50-0.54 |0.48-0.64| 0.40-0.46

  Blancas            |    |  (35.2)  |   (0.51)   | (0.57)  |  (0.43)

                     |    |          |            |         |

Costa Rica: Rincon de| 24 | 31.4-35.9|  0.50-0.56 |0.45-0.61| 0.40-0.46

  Osa                |    |  (34.1)  |   (0.53)   | (0.54)  |  (0.43)

                     |    |          |            |         |

Panama: Bocas del    |  6 | 31.0-33.5|  0.49-0.54 |0.47-0.50| 0.41-0.43

  Toro               |    |  (32.1)  |   (0.51)   | (0.48)  |  (0.42)





  [Illustration: PLATE 1



  Living _Hyla_: (A) _H. boulengeri_ (KU 86322) and (B) _H.

  foliamorta_ (KU 101576), x 2.]



  [Illustration: PLATE 2



  Living _Hyla:_ (A) _H. elaeochroa_ (KU 91688), (B) _H. staufferi

  staufferi_ (KU 57791), and (C) _H. staufferi altae_ (KU 101688), x

  2.]



  [Illustration: PLATE 3



  Audiospectrograms and sections of mating calls of (A) _Hyla

  boulengeri_ (KU Tape No. 511) and (B) _H. foliamorta_ (KU Tape No.

  511) and (B) _H. foliamorta_ (KU Tape No. 288).]



  [Illustration: PLATE 4



  Audiospectrograms and sections of mating calls of (A) _Hyla

  elaeochroa_ (KU Tape No. 97), (B) _H. s. staufferi_ (KU Tape No.

  93), and (C) _H. staufferi altae_ (KU Tape No. 502).]



The prevomer is short, and broadest anteriorly. The prevomer is joined

to the premaxillary by ossification. The posterior margin of the

prevomer bears a narrow cartilaginous articulation with the

sphenethmoid. The anterolateral and posterolateral processes of the

prevomer form an incomplete bony margin to the small choanae; each

prevomer bears four to seven teeth. The palatine is small, curved

anteriorly and edentate. The anterior part of the parasphenoid is

robust and ends in a point. The pterygoid is slender and weakly

developed.



_Natural History._--_Hyla elaeochroa_ inhabits humid lowland tropical

forests in lower Central America and breeds in temporary ponds.

Clasping pairs, gravid females, and calling males have been found

mostly in June, July, and August. William E. Duellman informed me that

he also found males calling in mid-February, late April, and May.

Duellman (1967) reported detailed observations of the social

organization in the mating call of _Hyla elaeochroa_. The choruses in

this species are initially organized, but when many individuals call,

the chorus loses organization. I observed this species breeding in a

temporary pond at Puerto Viejo, Heredia Province, Cost Rica, in late

June. Calling males and clasping pairs were extremely abundant within a

few hours after a heavy rain. Males were mostly found calling from low

emergent herbs in the pond and less commonly from bushes and trees to

heights of six meters above the water. Calling males were also observed

at Ricon de Osa, Puntarenas Province, Costa Rica, in late July. These

breeding individuals were found in a shallow pond at the edge of a wet

forest. Calling stations were less than two meters in height. John D.

Lynch informed me that after a heavy rain in early August, he found

several hundred individuals congregated in a small grassy pond less

than a foot deep, at Rincon de Osa. Males were calling from sites on

grass stems a few centimeters above the water.



The mating call of _Hyla elaeochroa_ consists of short notes, repeated

at intervals of about 0.40 second. Each note has a duration of 0.12 to

0.24 second. The fundamental frequency varies from 48 to 65 cycles per

second, and the notes have 40-50 pulses per second; the dominant

frequency is at about 2,900 cycles per second (Table 2, Pl. 4A).



The eggs are deposited in a mass in the water near floating vegetation.

William E. Duellman informed me that he observed hatchlings oriented

vertically with the tip of the mouth at the surface of the water. They

gradually sank to bottom, but swam back to surface again. No additional

information is available concerning early development. Tadpoles have

been found in shallow grassy ponds in clearings and in temporary

woodland ponds.



_Tadpoles._--Three hundred and thirty-one tadpoles in various stages of

development are available. Thirty-five tadpoles in stage 35 have a mean

body length of 8.1 mm. (8.0-9.0 mm.), tail length of 17.7 mm.

(15.0-19.5 mm.), and total length of 25.9 mm. (23.0-27.5 mm.). The

largest tadpole examined is in stage 40 and has a total length of 34.5

mm. (Table 6).



A typical tadpole, stage 35 of development (KU 104134, from Puerto

Viejo, Heredia Province, Costa Rica), has a body length of 9.1 mm.,

tail length of 17.7 mm., and a total length of 26.8 mm. Other

characters are as follows: body depressed anteriorly; body length

greater than depth of tail; internarial space as broad as interorbital

distance; nostril equidistant between eye and tip of snout; eyes

moderately large; mouth anteroventral and triangular; median fourth of

upper lip bare; rest of lip bordered by one row of papillae; clumps of

small papillae at corners of mouth; tooth rows 2/3; upper rows equal in

length; second row interrupted medially; lower rows shorter than upper

rows, diminishing in length; beak rather weak with small serrations;

spiracle short and nearer eyes than anus; anal opening not reaching

edge of ventral fin; caudal musculature attenuated distally (Figs. 2B

and 3B).



TABLE 6.--Sizes of Tadpoles of _Hyla elaeochroa_ in Relation to

Developmental Stages. (Means in parentheses below observed ranges;

measurements in mm.)



    ------+---+-------------+-------------+--------------

    Stage | N | Body length | Tail length | Total length

    ------+---+-------------+-------------+--------------

      24  | 2 |  4.0-4.0    |  8.5-9.0    |  12.5-13.0

          |   |   (4.0)     |   (8.8)     |   (12.8)

          |   |             |             |

      25  |64 |  5.0-6.5    |  8.5-15.0   |  13.5-21.5

          |   |   (5.7)     |   (11.8)    |   (17.6)

          |   |             |             |

      27  |30 |  7.0-7.5    | 13.0-16.0   |  20.0-23.0

          |   |   (7.1)     |   (14.2)    |   (21.3)

          |   |             |             |

      30  |15 |  7.0-8.0    | 13.0-16.5   |  20.0-24.0

          |   |   (7.3)     |   (15.0)    |   (22.4)

          |   |             |             |

      32  |30 |  7.5-8.5    | 15.0-17.0   |  22.5-25.0

          |   |   (7.8)     |   (16.1)    |   (23.8)

          |   |             |             |

      35  |35 |  8.0-9.0    | 15.0-19.5   |  23.0-27.5

          |   |   (8.1)     |   (17.7)    |   (25.9)

          |   |             |             |

      37  |22 |  8.5-9.5    | 16.0-22.0   |  25.0-31.0

          |   |   (9.0)     |   (18.8)    |   (27.8)

          |   |             |             |

      39  |14 |  9.5-10.5   | 19.0-24.9   |  28.5-33.5

          |   |   (9.9)     |   (21.1)    |   (31.0)

          |   |             |             |

      40  |27 |  7.0-11.5   | 15.0-23.0   |  23.0-34.5

          |   |   (9.1)     |   (22.0)    |  (31.2)

          |   |             |             |

      43  |10 |  8.0-12.0   | 11.0-17.0   | 20.0-26.0

          |   |  (10.2)     |   (13.5)    |  (23.7)

          |   |             |             |

      45  |16 | 10.0-12.0   |  1.0-7.0    | 12.0-17.0

          |   |  (11.2)     |   (3.4)     |  (14.6)

          |   |             |             |

      46  |45 | 11.0-13.0   |             |

          |   |  (11.8)     |             |



In life, dorsum yellowish tan with gray-brown mottling; belly and

ventrolateral surfaces silvery-gold or white; black stripe from tip of

snout to eye; two black blotches below eye, another blotch extending

from eye to base of caudal musculature; caudal musculature and fins

gray-brown. In preservative, yellowish tan and silvery-gold colors

lost; black reticulations present on tail.



_Remarks._--Cope (1876:105) described _Hyla elaeochroa_ from Sipurio,

Limon Province, Costa Rica. He based his description on a small

specimen, 26.0 mm. in snout-vent length, having a dorsum uniformly

colored and lacking an interorbital triangle and blotches on the

thighs. Cope (1887) described pigmented specimens from Nicaragua as

_Hyla quinquevittata_, which he diagnosed as having dark brown bars on

the hind limbs and five dark brown longitudinal stripes on the dorsum,

the median one of which was expanded anteriorly so as to form a large

triangular spot between the eyes. He thought this species was related

to _Hyla eximia_ Baird and noted that "the hinder legs are much larger;

the muzzle is more acuminate and the color bands are much wider" than

in _eximia_. Cope did not compare _quinquevittata_ with _elaeochroa_,

which he had described ten years before. Guenther (1901:268), Noble

(1918:340), and Nieden (1923:251) regarded both _elaeochroa_ and

_quinquevittata_ as valid species. Dunn and Emlen (1932:25) regarded

both as synonyms of _Hyla rubra_, but they made no qualifying

statements. Taylor (1952:859) placed _quinquevittata_ as a synonym of

_elaeochroa_ and indicated that _rubra_ was another species.



Taylor (1958:37) described _Hyla dulcensis_ from the humid tropical

forests of Golfo Dulce, Puntarenas Province, Costa Rica. He thought

this species was "related to _H. elaeochroa_ but differs in its

somewhat larger size, smaller finger and toe discs, the obsolete

canthus rostralis; the loreal region concave and the choanae larger."

Duellman (1966a:270) compared adults, tadpoles, and mating calls of

_dulcensis_ and _elaeochroa_ and concluded that a single species was

involved.



_Hyla elaeochroa_ can be easily confused with the closely related _Hyla

staufferi_. Although the durations of the calls are similar, the call

of _elaeochroa_ has only about one third the number of pulses per

second, a much lower fundamental frequency, and a lower dominant

frequency than that of _staufferi_. _Hyla elaeochroa_ is larger and has

a less pointed snout than does _staufferi_. Although the skulls of the

two species are similar, that of _elaeochroa_ differs in having broad

palatines and comparatively larger nasals that are truncate anteriorly.

In _staufferi_ the nasal is rounded anteriorly and the palatine is

absent.



_Distribution._--_Hyla elaeochroa_ occurs on the Caribbean lowlands

from western Panama through Costa Rica to eastern Nicaragua, and on the

Pacific lowlands of southeastern Costa Rica and extreme western Panama.

Most localities where it has been collected are below 800 meters, but

the species has been found at two localities above 1000 meters (El

Silencio and Pacuare, Cartago Province) on the Caribbean slopes of the

Cordillera de Talamanca, Costa Rica (Fig. 6).



_Specimens Examined._--Nicaragua: _Zelaya_: El Recreo, UMMZ 79721 (9).



Costa Rica: _Alajuela_: Laguna Monte Alegre, KU 64499. _Cartago_: 2 km E

Chitaria, KU 107058; El Silencio, 14.4 km NE Turrialba, KU 107059-60;

4.6 km ENE Pacuare, KU 64451-75, 64628-37; 4 km S Pavones, KU 64500;

Turrialba (Instituto Interamericano de Ciencias Agricolas), KU 30305-26,

24616-57, 30337-54, 31776-91, 31803, 31807-15, 64413-50, 68283-87

(skeletons), 68390-1 (young), 35042 (eggs), 25207-8 (skeletons), 25221

(skeleton), 41073-83 (skeletons). _Guanacaste_: 2 km E Tilaran, KU

86356-77, 87667-8 (young). _Heredia_: Puerto Viejo, KU 36696, 46466,

64501-17, 68288-91, 68387, 68388-9 (young), 91803 (young), 91688-9,

104134 (tadpoles), 104135 (young), 104354-6 (skeletons); 1.5 km N Puerto

Viejo, KU 64518-23, 68386 (tadpoles); 1 km S Puerto Viejo, KU 84985-6

(skeletons), 87669 (young), 87772-3 (skeletons). _Limon_: Bataan, KU

30327-36; La Lola, KU 64478-98, 68281-2 (skeletons); Los Diamantes, KU

31800-02, 64476-7; Peralta, KU 31816-21; Puerto Limon, KU 31792-99;

Suretka, KU 36467-79, 36697, 41084. _Puntarenas_: 5 km NW Buenos Aires,

KU 107057; 10 km E Esparta, KU 87666 (tadpoles); Golfito, KU 32166-8; 8

km E Palmer Norte KU 93939; 10.7 km SE Palmar Sur, KU 93938 (skeleton),

93940-51, 93952 (eggs), 93953-6 (tadpoles); Piedras Blancas, KU

103646-59; 4.5 km W Rincon de Osa, KU 102208-41, 104298 (tadpoles).



  [Illustration: Fig. 6. Map showing locality records for _Hyla

  elaeochroa_ (circles) and _H. rubra_ (dots).]



Panama: _Bocas del Toro_: Almirante, KU 80079; Isla Bastimentos, KU

96008-11; Rio Cricamola, 3.7 km from coast, KU 96012. _Chiriqui_: Rio

Gariche, 8.3 km ESE Paso de Canoas, KU 101571-2.





_Hyla staufferi_ Cope



    _Hyla staufferi_ Cope, Proc. Acad. Nat. Sci. Philadelphia, 17:165,

    October 1, 1865 [Holotype.--USNM 15317, Orizaba, Veracruz, Mexico;

    Francis Sumichrast collector].



_Diagnosis._--Small frogs (Male to 29 mm., Female to 31.6 mm.); skull

longer than wide; palatine absent; large cartilaginous crista parotica

present; snout flat, elongate and protruding; dark interorbital bar and

dorsal stripes usually present.



_Description._--Head flat, especially in females, longer than wide;

snout long, protruding beyond mouth; loreal region concave; canthus

ill-defined; length of eye greater than internarial distance or width

of eyelid; length of eye less than interorbital space; tympanum

distinct; interorbital spot irregular; supratympanic fold faint; arms

short; fingers free of webs; discs on third and fourth fingers equal to

diameter of tympanum; inner metatarsal tubercle on base of first finger

distinct; first finger shorter than second; palmar tubercle distinct

(Fig. 1C); legs short (usually less than 50 per cent of snout-vent

length); tarsal fold absent; metatarsal tubercles small, outer tubercle

smaller than inner; subarticular tubercles small, simple, distinct;

toes less than half webbed (Fig. 1D); skin smooth above with a few

small pustules on head, scapular region, flanks, and supratympanic

region; arms and legs smooth; skin of belly coarsely granular;

posteroventral surfaces of thighs finely granular; tongue small,

rounded, longer than wide, slightly free and notched posteriorly; vocal

slits small, lateral to tongue; choanae moderate in size.



_Variation._--The largest males of _Hyla staufferi_ are from Jalapa,

Guatemala, and from San Salvador, El Salvador. In these samples the

average snout-vent length is 27 mm. In Panamanian specimens the average

snout-vent length is 23.6 mm. Slight variation in the ratio of tibia

length to snout-vent length exists throughout the range; more variation

exists in the ratio of the diameter of the tympanum to that of the eye;

the tympanum is proportionately larger in northern populations (Table

7). The primary differences between Panamanian and more northern

populations are in size, color pattern on the dorsum and shanks, amount

of webbing between the toes, and duration of notes in the mating call

(Table 2, Pl. 4).



The color in Panamanian _staufferi_ is gray or gray-brown with a pair

of distinct, complete, dark brown dorsolateral stripes, a pair of

entire paravertebral stripes, and in some specimens a vertebral stripe.

About five per cent of the individuals have interrupted stripes on the

dorsum, whereas in the more northern populations complete paravertebral

stripes are present in less ten per cent of the specimens; when

complete stripes are present, they are irregular. The dorsal ground

color in non-Panamanian specimens is brown, olive-brown, or dark brown.



Transverse bars are present on the shanks in _Hyla staufferi_ from

Costa Rica northward to Mexico, whereas in Panama all the individuals

have a longitudinal stripe on the shank (Table 7, Pl. 2). The

interorbital spot or bar is more noticeable in northern populations

than in specimens from Panama. Frogs from Costa Rica and northward have

the toes about three fourths webbed, whereas in Panama the toes are

about two fifths webbed. The mating calls of the northern and

Panamanian populations are similar, but the notes have a longer

duration in the northern populations and a higher dominant frequency in

Panamanian populations.



_Hyla staufferi_ is the most variable member of the _Hyla rubra_ group

in Central America. The Panamanian populations are geographically

separated from the Costa Rican and more northern populations by an area

of tropical rainforest in the Golfo Dulce region in southeastern Costa

Rica and adjacent Panama. _Hyla staufferi_ does not occur on the

Caribbean versant of Costa Rica and Panama. The Golfo Dulce region and

the Caribbean versant are humid and inhabited by _Hyla elaeochroa_.

_Hyla staufferi_ is an inhabitant of subhumid and xeric areas.



On the basis of the discontinuous variation in several characters which

correlate with the disjunct distribution of the two populations, two

subspecies of _Hyla staufferi_ are recognized. The accounts that follow

apply equally to each.



_Cranial Osteology._--The skull of _Hyla staufferi_ is flat and longer

than wide. The premaxillary is small and bears 9 to 13 teeth (mean for

5 specimens, 11.3). The alary process of the premaxillary is small,

concave posteriorly and vertical. Ventrally, the premaxillary is united

to the prevomers by partially ossified cartilage. The maxillary is

slender and usually bears 49 to 70 teeth (mean for 5 specimens, 60.7).

The pars facialis of the maxillary is convex and less than twice the

height of the pars dentalis.



The nasal is large, rounded anteriorly, and pointed posteriorly in

dorsal view. The nasal comprises about 40 per cent of the total length

of the skull. Anteromedially the two nasals converge; posteriorly they

overlap the sphenethmoid. The nasals lack a concavity in the midlateral

surface. Dorsally, the sphenethmoid is wider than long, roughly

pentagonal in shape; the frontoparietal is elongate, narrow, and

smooth, with a small supraorbital process anteriorly. The

frontoparietal fontanelle is narrow anteriorly and wide posteriorly.



TABLE 7.--Geographic Variation in Size and Color in Males of _Hyla

staufferi_. (Means in parentheses below observed ranges.)



    =================================================================

                   |     |            |Complete dorsal|

                   |     |Snout-vent  |    stripes    |Barred shanks

    Locality       |  N  |length (mm.)|  (per cent)   |  (per cent)

    ---------------+-----+------------+---------------+--------------

    Veracruz       |  47 |  23.0-27.3 |      0.0      |     100

                   |     |   (25.4)   |               |

                   |     |            |               |

    Campeche       |  20 |  24.6-27.5 |      0.0      |     100

                   |     |   (25.5)   |               |

                   |     |            |               |

    Oaxaca         |  75 |  24.0-28.7 |      9.3      |     100

                   |     |   (26.4)   |               |

                   |     |            |               |

    Chiapas        |  20 |  23.2-27.8 |     10.0      |     100

                   |     |   (25.5)   |               |

                   |     |            |               |

    Guatemala      |  22 |  25.0-29.0 |     10.9      |     100

                   |     |   (26.9)   |               |

                   |     |            |               |

    El Salvador    |  21 |  24.7-28.6 |      0.0      |     100

                   |     |   (27.0)   |               |

                   |     |            |               |

    Honduras       |  34 |  20.6-27.0 |      3.3      |     100

                   |     |   (24.9)   |               |

                   |     |            |               |

    Nicaragua      |  67 |  21.5-26.8 |      3.0      |      92.7

                   |     |   (24.9)   |               |

                   |     |            |               |

    Costa Rica     |  54 |  20.7-26.6 |      5.5      |      98.1

                   |     |   (24.2)   |               |

                   |     |            |               |

    Total          | 360 |  20.7-29.0 |      5.4      |      98.3

    Non-Panamanian |     |   (25.9)   |               |

                   |     |            |               |

    Panama         |  72 |  21.7-26.0 |     94.5      |       0.0

                   |     |   (23.6)   |               |



Only a narrow connection exists between the posterior, pointed arm of

the squamosal and the lateral edge of the prooetic. The crista parotica

is visible dorsally along the lateral edge of the bony prooetic. The

squamosal is narrow anteriorly and posteriorly.



The prevomers are short and separated anteriorly by partly ossified

cartilage of the overlying solum nasi. The prevomer is joined to the

premaxillary by cartilage. The posterior margin of the prevomer

articulates directly with the sphenethmoid. The anterolateral and

posterolateral processes of the prevomers form the incomplete bony

internal margin of the choanae. Each prevomer bears three to six teeth.

The palatine is absent. The anterior part of the parasphenoid is narrow

and ends in a point. The pterygoid is slender and weakly developed.



_Natural History._--Throughout its range _Hyla staufferi_ occurs in

subhumid forests and savannas; consequently, the breeding activities

are limited by the seasonal occurrence of rainfall, which accumulates

in temporary ponds where this species breeds. Clasping pairs and gravid

females have been found mostly from June to August throughout its

range. This species was observed calling at Finca Taboga, Guanacaste

Province, Costa Rica, in mid-July. The males were calling from

temporary grassy and weedy ponds in which _Hyla microcephala_ also was

calling, but the two species had different calling sites. _Hyla

staufferi_ called at stations at heights of five to 80 cm. near the

edge of the pond, whereas _Hyla microcephala_ called from emergent

vegetation in the middle of the pond. Charles W. Myers informed me that

at Penonome, Cocle, Panama, he found _staufferi_ calling from grass in

puddles where _microcephala_ was absent, and at El Cano, Cocle, Panama,

_staufferi_ was calling from higher sites ("several inches to a few

feet above water") than _microcephala_.



Stuart (1948:34) reported breeding individuals from La Libertad,

Guatemala, after rainfall in late May, and Schmidt and Stuart

(1941:239) reported _staufferi_ breeding in July in the Salama basin,

Alta Verapaz, Guatemala. Stuart (1935:38) and Duellman (1960:63 and

1963:226) agreed that this species breeds early in the rainy season.

However, Rand (1957:519) stated that in El Salvador "these frogs did

not begin to call until almost a month and a half after the beginning

of the rains." Blair (1960:133) reported that males call in June and

July in Chiapas, Oaxaca, Veracruz, and Tamaulipas, Mexico.



The mating call of this species is a series of closely spaced notes

having a fundamental frequency of about 100 cycles per second. Each

note has a duration of 0.13 to 0.23 second, repeated at intervals that

are longer than the duration of the call. The notes are moderately

low-pitched and have a dominant frequency of more than 3,000 cycles per

second and about 120 pulses per second (Table 2).



_Tadpoles._--Measurements of the 33 tadpoles that are available are

given in Table 8. The largest tadpole examined is in stage 38 and has a

total length of 29.5 mm.



A typical tadpole in stage 38 of development (KU 104162, 5 km ESE

Cordoba, Veracruz, Mexico) has a body length of 10 mm., tail length of

19.5 mm., and a total length of 29.5 mm. Other characters are as

follows: body as deep as wide, depressed anteriorly; body as long as

depth of tail; interorbital space greater than distance between eye and

snout but equal to internarial space; nostril equidistant between eye

and tip of snout; distance between spiracle and eye less than distance

between eye and snout; eyes large, situated dorsolaterally; mouth

anteroventral, approximately triangular in outline; one row of papillae

covering lower lip and all except median fourth of upper lip; scattered

papillae at corners of mouth; tooth rows 2/3; first upper row entire,

second row interrupted medially, shorter than first; lower rows shorter

than upper rows; beak weak; spiracle short and nearer eyes than anus;

anal opening not reaching edge of ventral fin; dorsal fin barely

extending onto body; caudal musculature pointed distally.



TABLE 8.--Sizes of Tadpoles of _Hyla s. staufferi_ in Relation to

Developmental Stages. (Means in parentheses below observed ranges;

measurements in mm.)



    ======================================================

    Stage   | N | Body length| Tail length | Total length

    --------+---+------------+-------------+--------------

      25    | 3 |  6.0-7.0   |  12.0-13.0  |  18.0-20.0

            |   |   (6.7)    |   (12.5)    |   (19.2)

            |   |            |             |

      26    | 2 |  7.0-7.5   |  14.0-15.0  |  21.5-22.0

            |   |   (7.3)    |   (14.5)    |   (21.8)

            |   |            |             |

      27    | 9 |  7.0-8.0   |  13.0-17.0  |  21.0-25.0

            |   |   (7.6)    |   (14.5)    |   (22.0)

            |   |            |             |

      32    | 1 |   8.5      |    15.5     |    24.0

            |   |            |             |

      36    | 2 |   8.0-10.0 |  16.5-17.0  |  25.0-26.5

            |   |   (9.0)    |   (16.8)    |   (25.8)

            |   |            |             |

      38    | 6 |   9.0-10.0 |  19.0-20.5  |  28.0-29.5

            |   |   (9.6)    |   (19.5)    |   (29.1)

            |   |            |             |

      41    | 1 |  10.0      |    14.0     |    24.0

            |   |            |             |

      42    | 6 |  11.0-14.0 |  10.0-13.0  |  20.0-29.0

            |   |   (11.8)   |   (11.9)    |   (24.8)

            |   |            |             |

      45    | 1 |  12.5      |     0.5     |    13.0

            |   |            |             |

      46    | 1 |  13.0      |     --      |     --



In life, body pale olive-tan, belly silvery white with pinkish-orange

reticulations in some specimens; tail creamy white with silvery flecks

and black or brown reticulations. In preservative, tan and

pinkish-orange coloration lost; body transparent, reticulations on tail

present.



_Remarks._--_Hyla staufferi_ was described by Cope (1865:195) on the

basis of specimens from Orizaba, Veracruz, Mexico. He described the

color pattern as "color above dark olive, with a short black bar over

each scapula, and one from eye to eye, with a trace along the coccyx."

Cope (1887:14) placed _staufferi_ as a subspecies of _Hyla eximia_, but

he did not justify his action. Guenther (1901:262) also considered

_staufferi_ to be conspecific with _eximia_ without making any

qualifying statement. Dunn and Emlen (1932:24) named _Hyla culex_ from

Tela, Honduras, on the basis of a male (MCZ 16098) having a snout-vent

length of 25.1 mm., and a female (USNM 20267) from Patuca, Honduras.

They diagnosed the species as having "discs larger than tympanum ...

black interorbital triangle, traces of black dorsal marking; three

black bars on anterior and posterior face of thighs, two black bars on

tibia, on tarsus and on forearm." The holotype now is faded but has

some of the pattern described. Dunn and Emlen did not compare _culex_

with _staufferi_ but did compare it with _boulengeri_ and _rubra_.



Dunn (1933:61) named _Hyla altae_ from Summit, Canal Zone. His

description was based on a male (MCZ 17972) having a snout-vent length

of 25.1 mm., the color pattern was described as "gray with four darker

dorsal stripes ... a faint trace of mid-dorsal striping...." Dunn

defined the _Hyla rubra_ group and recognized _boulengeri_, _altae_,

_culex_, and _rubra_ as members. _Hyla elaeochroa_ and _staufferi_ were

omitted from his key to the group in Central America.



Kellogg (1932:174) compared _staufferi_ with _eximia_ and concluded

that the two were probably distinct species. Stuart (1935:38)

considered _altae_ to be a synonym of _culex_. Gaige (1936:293)

considered _altae_ and _culex_ to be conspecific but regarded

_staufferi_ as a different species. She also suggested that _staufferi_

was not related to _eximia_ but belonged to the _rubra_ group. Taylor

(1952:865) and Duellman (1966a:274) considered _altae_ and _culex_ to

be synonyms of _staufferi_.



The only other worker besides Cope and Guenther to consider _Hyla

staufferi_ as a member of the _eximia_ group was Blair (1960:129), who

suggested the relationship on the basis of similarities in the

structure of the calls of _eximia_ and _staufferi_. Taylor (1938:421)

and Smith and Taylor (1948:78) excluded _staufferi_ from the _eximia_

group on the basis of morphological characteristics. I consider _culex_

to be inseparable from _staufferi_, whereas _altae_ is recognizable as

a Panamanian subspecies of _staufferi_.





_Hyla staufferi staufferi_ Cope, New Combination



    _Hyla staufferi_ Cope, Proc. Acad. Nat. Sci. Philadelphia, 17:195,

    October 1865 [Holotype.--USNM 15317, Orizaba, Veracruz, Mexico;

    Francis Sumichrast collector], Brocchi, Mission Scientifique au

    Mexique et dans L'Amerique Centrale, 1881, p. 36. Boulenger,

    Catalogue, of the Bratrachia Salientia s. Ecaudata, p. 400,

    February 1, 1882. Kellogg, Bull. U.S. Natl. Mus., 160:173, March

    31, 1932. Smith and Taylor, Bull. U.S. Natl. Mus., 194:88, 1948.

    Taylor, Univ. Kansas Sci. Bull., 35:862, July 1, 1952. Rand,

    Fieldiana Zool. Chicago Nat. Hist. Mus., 34:518, April 18, 1957.

    Duellman, Univ. Kansas Publ, Mus. Nat. Hist., 17:274, June 17,

    1966.



    _Hyla eximia staufferi_ Cope, Bull. U.S. Natl. Mus., 32:14, January

    16, 1887.



    _Hyla eximia_ (part): Guenther, Biologia Centrali-Americana,

    Reptilia and Batrachia, p. 261, June 1901. Nieden, Das Tierreich,

    Anura I, p. 245, June 1923.



    _Hyla culex_ Dunn and Emlen, Proc. Acad. Nat. Sci. Philadelphia,

    84:24, March 22, 1932 [Holotype.--MCZ 16098, Tela Honduras; Raymond

    A. Stadelman collector]. Stuart, Misc. Publ., Univ. Michigan Mus.

    Zool., 29:38, October 1935. Gaige, Carnegie Inst. Washington Publ.,

    457:293, 1936.



_Diagnosis._--Small frogs (Male to 29 mm., Female to 31.6 mm.);

dorsolateral stripes irregular; paravertebral stripes usually broken;

two or three transverse bars on shanks; thighs spotted or not; arms

usually barred; interorbital bar usually present; toes about three

fourths webbed; color brown, tan, or olive-green.



_Variation._--Three hundred and sixty males chosen at random from

throughout the range have snout-vent lengths of 20.7 to 29 mm. (25.9

mm.). The smallest individuals are from Costa Rica and Nicaragua (means

24.2 and 24.4 mm., respectively). The largest individuals are from

Guatemala and El Salvador (mean of each 27.0 mm.). The ratio of the

diameter of the tympanum to that of the eye is more than 60 per cent in

most samples, but in those from Costa Rica and British Honduras it is

smaller. The color pattern is highly variable. Some specimens are dark

brown or pale brown in color. Incomplete dorsal stripes are present in

94.6 per cent of the specimens, and transverse bars are present on the

shanks in 98.3 per cent of the specimens. The interorbital spot varies

from transverse to longitudinal in position, and an irregular white

line extends from the upper jaw to the arm in some specimens (Table 7).



_Distribution._--_Hyla staufferi staufferi_ inhabits savanna and

subhumid and xeric forests in the lowlands and moderate elevations from

southern Tamaulipas southward to Nicaragua on the Caribbean versant and

from Guerrero, Mexico to northwestern Costa Rica on the Pacific

lowlands (Fig. 7). Duellman (1963:226) commented that a specimen from

Chinaja, Guatemala, possibly was transported there in the cargo from

Toocog, because with this one exception the species is unknown in

tropical rainforest in Guatemala.



  [Illustration: Fig. 7. Map showing locality records for _Hyla

  staufferi staufferi_ (circles) and _H. staufferi altae_ (dots).]



_Specimens Examined._--Mexico: _Campeche_: 5 km S Champoton KU 71296-7;

7 km W Escarcega, KU 71298-308; 13 km W, 1 km N Escarcega, KU 71309-10,

75090-4. _Chiapas_: 32 km S Arriaga, KU 57789-92; 4 km N Ixtapa, KU

5776-81; 3.6 km SW Las Cruces, KU 37740; 17 km S Las Cruces, KU

57793-4; 24 km S Las Cruces, KU 104160 (tadpoles); 11 km S Tapachula,

KU 57782-8, 60000 (young). _Guerrero_: El Limoncito, near La Venta, KU

31392-401; Mexcala, near Balsa River, KU 31391; Organos, S El Trienta,

KU 31390. _Oaxaca_: 26 km N Matias Romero, KU 33878-82; 2.5 km S

Pochutla, KU 59924-7 (skeletons); 5 km S Pochutla, KU 57795-801; 3.2 km

E Tapanatepec, KU 37877-902; 17.6 km WNW Tapanatepec, KU 65033-4;

Temascal, USC 8243 (8); 3.2 km S Tolocita, KU 39657-8; 0.5 km Tuxtepec,

KU 87073-81, 87610 (tadpoles); 17 km S Tuxtepec, KU 65035-7; 1 km W

Zanatepec, KU 104161 (tadpoles). _Quintana Roo_: Isla Cozumel, 3.5 km N

San Miguel, KU 71710-11 (young). _San Luis Potosi_: Valles, KU 31490.

_Tabasco_: Teapa, UMMZ 118887 (3), 119203 (13); 9.6 km N Teapa, UMMZ

119202; 24 km N Teapa, UMMZ 119961 (5); 29 km N Teapa, UMMZ 119960; 3.5

km S Villahermosa, UMMZ 119201 (2); 17.6 km S Villahermosa, UMMZ 119200

(8). _Tamaulipas_: 1 km E Chamal, UMMZ 110706; Gomez Farias, UMMZ

110701 (3); 5 km SE Gomez Farias, UMMZ 110705; 8 km NE Gomez Farias,

UMMZ 11282 (2), 11283 (3); Kilometer 615 between Rio Limon and Llera,

UMMZ 80455 (2); 5 km W San Geraldo, UMMZ 110702 (4), 110703 (3); 8 km W

San Geraldo, near Rio Frio, UMMZ 110704 (5). _Veracruz_: 3 km SW Boca

del Rio, KU 10494-8; 5 km SW Boca del Rio, KU 23701; 5 km ESE Cordoba,

KU 104162 (tadpoles); Cuautlapan, KU 57098-102, 26787; Hacienda

Tamiahua, Cabo Rojo, KU 62871; 2 km ENE Mata Oscura, KU 105627; 5 km SE

Paso del Toro, KU 40144; Portrero Viejo, KU 23911-2, 26786, 27413,

57094-7.



Guatemala: _Alta Verapaz_: Chinaja, KU 57769; Finca La Cubilquitz, UMMZ

90871, 90872 (5), 91379 (2). _Baja Verapaz_: 1 km S San Jeronimo, UMMZ

84077 (7), 84078 (14). _Chiquimula_: 1.6 km SE Chiquimula, UMMZ 98114

(2); Esquipulas, UMMZ 106784 (4), 106785 (14). _El Peten_: No specific

locality, USNM 25143, 24825-6; La Libertad, FMNH 27096-7, KU 57770,

UMMZ 75339 (15), 75340 (15), UMMZ 94341-2. _Esquintla_: 20 km N San

Jose, AMNH 74369-76. _Guatamala_: 16 km NE Guatamala, KU 43539. Izabal:

Puerto Barrios, TCWC 16671-73, 16646-56; 2.5 km NE Rio Blanco, KU

57774-5. _Jalapa_: Jalapa, UMMZ 106788 (44). _Jutiapa_: Finca La

Trinidad, UMMZ 107730 (12), 107731 (16); Jutiapa, UMMZ 106786 (2).

_Zacapa_: 14 km ENE Mayuelas, KU 57773; 7 km ENE Rio Hondo, KU 57771-2,

59999 (young).



British Honduras: BELIZE: Belize, FMNH 4406. _El Cayo_: San Agustin,

UMMZ 80741 (8). _Stann Creek_: 10 km S Stann Creek on Hummingbird

Highway, UMMZ 125720-1.



El Salvador: _Cuscatlan_: 7 km WNW Cojutepeque, TNHC 32004-10. _La

Libertad_: 16 km NW Santa Tecla, KU 43540-1. _La Union_: 2.5 km Santa

Rosa, TCWC 16669-70. _Morazan_: Dividendero, USNM 73288-92. _San

Salvador_: San Salvador, FMNH 65101-06, KU 61932-44, 61989-92, 62152

(eggs), USNM 117588, 118391 (3), 118394; 1.6 km NW San Salvador, KU

43162-3.



Honduras: _Atlantidad_: Ceiba, USNM 117592. _Choluteca_: Choluteca, KU

85361-6; 2 km E Choluteca, UMMZ 118395 (7); 3.2 km NE Choluteca, KU

100500-01; 6.2 km E Choluteca, KU 65046-56; 10 km E Choluteca, KU

65045: 5 km S Choluteca, USC 2700 (4). _Colon_: Isla Guanaja (Islas de

la Bahia), TCWC 21551, TNHC 32011. _Cortes_: Agua Azul, TCWC 19178-9;

East side Lago Yojoa, KU 65038-44. _El Paraiso_: Valle de Jamastran,

AMNH 54800-04. _Francisco Morazan_: Escuela Agricola Panamericana, AMNH

54963-73; 14.5 km NW Comayaguela, KU 100499; El Zamorano, KU 103224; 29

km N Tegucigalpa, TNHC 32003, 32012.



Nicaragua: _Chinandega_: Finca San Isidro, 10 km S Chinandega, KU

85311-33. _Managua_: 13 km E Managua, KU 85339; 2 km S Tipitapa, KU

85334-8. _Rivas_: 9.5 km SE Rivas, KU 85355-6; 18 km SE Rivas, KU

85354; 7.7 km NE San Juan del Sur, KU 85346-53; 16.5 km NE San Juan del

Sur, KU 85340-5; 5 km SE San Pablo, KU 43151-61. _Zelaya_: Isla Grande

del Maiz, KU 85357-60.



Costa Rica: _Alajuela_: _Los Chiles_, USC 7215 (2), 7217. _Guanacaste_:

4 km W Bagaces, USC 7019 (5); Finca Taboga, KU 102265-5; 12 km S La

Cruz, USC 8091; Las Canas, KU 41113 (skeleton); 27 km N Las Canas, USC

8171 (5); Guardia, Rio Tempisque, USC 8214; 10 km N Guardia, KU

102266-7; 1.6 km N Guayabo de Bagaces, USC 7023 (3); Liberia, KU

36510-22; 4 km W Liberia, KU 36449-64, USC 102 (10), 103 (9), 104 (7),

105; 6 km N Liberia. USC 8096; 8 km NNW Liberia, KU 65032; 14.5 km N

Liberia, USC 8079, 8138 (2); 14.5 km S Liberia, USC 8238 (5); 6 km N

Nicoya, USC 8229 (11); 4 km S Nicoya, USC 8230, 8231; Penas Blancas, KU

102263; 8.6 km ESE Playa del Coco, USC 8137 (14); 21 km E Playa del

Coco, USC 8138 (2); Santa Cruz, USC 8232 (2); 3 km E Santa Rosa, TCWC

16663-68; Tenorio, KU 32159; Tilaran, KU 36509. _Puntarenas_: 10 km WNW

Esparta, KU 65022-9, 68614 (skeleton); 4.5 km WNW Esparta, KU 65030; 12

km WNW Esparta, KU 65031; 6 km E Esparta, KU 86477; Hotel Maribella, KU

32157-8; 3 km W Puntarenas, TCWC 16657-62.





_Hyla staufferi altae_ Dunn, New Combination



    _Hyla altae_ Dunn, Occas. Papers Boston Soc. Nat. Hist., 8:61, June

    7, 1933 [Holotype.--MCZ 17972, Summit, Canal Zone, Panama; Emmett

    R. Dunn collector].



    _Hyla culex_: Stuart, Misc. Publ. Univ. Michigan Mus. Zool., 29:38,

    October 1, 1935. Gaige, Carnegie Inst. Washington Publ., 457:293,

    1936.



    _Hyla staufferi_: Taylor, Univ. Kansas Sci. Bull., 35:862, July 1,

    1952. Duellman, Univ. Kansas Publ., Mus. Nat. Hist., 17:274, June

    17, 1966.



_Diagnosis._--Small frogs (Male to 26 mm., Female to 27 mm.);

dorsolateral and paravertebral stripes complete; longitudinal dark gray

stripe on shank; thighs unmarked; interorbital bar usually absent; toes

about three fifths webbed; gray to brownish gray above.



_Variation._--_Hyla staufferi altae_ is less variable in size,

proportions, and color pattern than is _H. s. staufferi_. The size

varies from 21.7 to 26 mm. (23.6) in 72 males. The ratio of tibia to

snout-vent length is 0.42 to 0.50 (0.45), slightly less than in the

northern subspecies. In color pattern 94.5 per cent of the individuals

have complete dorsal stripes, and all have a longitudinal stripe on the

shank (Table 7).



_Distribution._--This subspecies is restricted to subhumid forests and

savannas on the Pacific lowlands of Panama. _Hyla s. altae_ is

presently known to occur from Chepo in east-central Panama through the

Azuero Peninsula to Concepcion, Chiriqui, in western Panama (Fig. 7).



_Specimens Examined._--Panama: _Canal Zone_: No specific locality, TNHC

24406; 2.8 km SW Fort Kobbe, KU 101679. _Chiriqui_: 14.4 km E

Concepcion, AMNH 69799-801; 6.6 km N David, TNHC 32013-4; 2 km S David,

AMNH 68802. _Cocle_: 1 km NE El Cano, KU 101662-75; El Valle de Anton,

AMNH 59601-5, KU 77333-47; 7 km SSW Penonome, KU 101654-61. _Los

Santos_: Tonosi, KU 101246 (tadpoles), 101697-701. _Panama_: 2 km WSW

Chepo, KU 101680-8; 6 km WSW Chepo, KU 77324-27; El Cangrejo (Panama),

KU 101676-8; Nueva Gorgona, AMNH 69991, 69798; 1.5 km W Pacora, KU

77328-32; 2 km N Tocumen, KU 101689-95; 8 km NE Tocumen, KU 101696.









EVOLUTIONARY HISTORY





My assumptions regarding the evolutionary history of the _Hyla rubra_

group in Central America were derived partly from interpretations of the

evolutionary history of other animal groups (Simpson, 1943, 1965; Dunn,

1931b; Stuart, 1950; Duellman, 1958, 1960, 1963, 1965; and Duellman and

Trueb, 1966). The origin and early evolution of the group probably

occurred prior to the Mid-Pliocene in the lowlands of South America,

because the greatest diversity of the group is in Brazil. Differentiation

into two or more subgroups took place in South America prior to the late

Pliocene. At the end of the Pliocene, shortly after the closure of the

Colombian Portal, many South American animals migrated into Central

America (Simpson, 1943, Maldonado-Koerdell, 1964, and Savage, 1966). It

is likely that the _Hyla rubra_ group entered Central America at that

time; apparently two stocks (_rubra-elaeochroa-staufferi_ stock and

_boulengeri-foliamorta_ stock) migrated into Central America.



_Hyla elaeochroa_ is closely related to _rubra_ and probably

differentiated from _rubra_ through spatial isolation. Thus, we have

_elaeochroa_ in Central America and _rubra_ in South America; most

likely only in relatively recent times has _rubra_ migrated into

eastern Panama from northern South America. The differentiation and

dispersal of _elaeochroa_ and _staufferi_ took place in Central America

after the Pliocene. Probably the events of the Pleistocene resulted in

the isolation of populations. One of these (_Hyla staufferi_ stock) was

restricted in the subhumid Pacific lowlands, whereas the _Hyla

elaeochroa_ stock occupied the tropical wet forests of the Caribbean

lowlands. _Hyla elaeochroa_ apparently more closely resembled the

parental stock by being restricted to the tropical rain forests,

whereas _staufferi_ adapted to subhumid environments and thereby was

able to disperse throughout most of the subhumid regions of Central

America.



After geographical separation took place the initial genetic divergence

between the two populations was maintained by means of ecological and

ethological isolating mechanisms. Under these circumstances it can be

supposed that the different ecological preferences of _elaeochroa_ and

_staufferi_ depend on the climatic changes that took place during the

Pleistocene. On this basis it may be proposed that when the original

prototype broke up into the two incipient species, the _staufferi_

stock became physiologically and behaviorally adapted to subhumid

conditions and dispersed into dry areas of the lowlands of Middle

America. The tropical evergreen forests on the Caribbean side of lower

Central America and the uplift of the Talamanca range in the Pliocene

were barriers to the dispersal of _staufferi_. Consequently, this frog

dispersed along the Pacific lowlands.



At the present time _staufferi_ occupies the length of the Pacific

lowlands in Central America, except in the rainforest of the Golfo Duce

region, which apparently is a relict stand and now separates the ranges

of two subspecies of _Hyla staufferi_. This species crossed the central

Nicaraguan lowlands and reached the Caribbean lowlands of Nicaragua and

nuclear Central America. The species migrated through the subhumid

corridor in northern Honduras and eastern Guatemala (Comayagua Valley

in Honduras and the Motagua Valley of Guatemala) to the Isthmus of

Tehuantepec. Duellman (1960) hypothesized "that during the times of

glacial advances (Pleistocene) the lowlands of the Isthmus probably

were more extensive and had more semiarid tropical environments than at

the present" and that when semiarid environments were continuous from

the Pacific slope across the isthmus to the Gulf lowlands _staufferi_

and other amphibians migrated northward to southeastern Tamaulipas,

Mexico.



_Hyla elaeochroa_ dispersed along Caribbean lowland routes. This

species not only occurs in the wet forests of the Golfo Dulce region

but also in Guanacaste. It is possible that _elaeochroa_ entered

Guanacaste and moved to the Golfo Dulce region when the intervening

area was less xeric than now (Duellman, 1966b). _Hyla elaeochroa_

extended its range to eastern Nicaragua, but even though northeastern

Nicaragua has over 2,000 mm. of precipitation annually (Vivo Escoto,

1964), this species has not spread into Honduras and Guatemala.



_Hyla boulengeri_ is widespread in Amazonian and northern South

America, whereas _foliamorta_ occurs only in eastern Panama and in

north-central Colombia. The ancestral _boulengeri-foliamorta_ stock

probably invaded Central America in the late Pliocene and dispersed

through humid forested environments to Nicaragua. Apparently a

peripheral population established itself in the dry Pacific lowlands of

Panama. This population differentiated from _boulengeri_ of the humid

Caribbean lowlands and evolved into _foliamorta_, which subsequently

expanded its range into Colombia.









LITERATURE CITED





BLAIR, W. F.



1960. Mating call as evidence of relations in the _Hyla eximia_ group.

Southwestern Nat., 5(3):129-135. November 1.



BOULENGER, G. A.



1882. Catalogue of the Batrachia Salientia s. Ecaudata, 2nd. ed., pp.

1-503, pls. 1-30. February.



BROCCHI, P.



1881-1883. Etude des batraciens de l'Amerique Centrale. Mission

Scientifique au Mexique et dans l'Amerique Centrale, Liv. 1, pp. 1-122,

pls. 1-21.



COCHRAN, D. M.



1955. Frogs of southeastern Brazil. Bull. U.S. Natl. Mus., 206:1-423.



COPE, E. D.



1865. Third contribution to the Herpetology of Tropical America. Proc.

Acad. Nat. Sci. Philadelphia, 17:195.



1876. On the batrachia and reptilia of Costa Rica. Jour. Acad. Nat.

Sci. Philadelphia, new series, 8:93-154, pls. 23-28. 1887. Thirteenth

contribution to the Herpetology of Tropical America. Proc. Amer.

Philos. Society, 23:273. April.



DAUDIN, F. M.



1802. Histoire naturelle des rainettes, des grenouilles et des

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_Transmitted February 7, 1969._