A Review of the Frogs of the Hyla Bistincta Group

Part 1

Produced by Chris Curnow, Joseph Cooper and the Online Distributed Proofreading Team at https://www.pgdp.net

UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY

Volume 15, No. 9, pp. 469-491, 4 figs. March 2, 1964

A Review of the Frogs Of the Hyla bistincta Group

WILLIAM E. DUELLMAN

UNIVERSITY OF KANSAS LAWRENCE 1964

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Theodore H. Eaton, Jr.

Volume 15, No. 9, 469-491, 4 figs. Published March 2, 1964

UNIVERSITY OF KANSAS Lawrence, Kansas

PRINTED BY THE STATE PRINTER TOPEKA, KANSAS 1964

29-8590

A Review of the Frogs Of the Hyla bistincta Group

WILLIAM E. DUELLMAN

CONTENTS

PAGE INTRODUCTION 471 Acknowledgments 471 THE HYLA BISTINCTA GROUP 472 Analysis of Characters 473 Key to the Species of the Hyla Bistincta Group 474 ACCOUNTS OF THE SPECIES 475 Hyla bistincta Cope 475 Hyla charadricola new species 478 Hyla robertsorum Taylor 481 Hyla pachyderma Taylor 485 Hyla crassa (Brocchi) 486 RELATIONSHIPS 489 LITERATURE CITED 491

INTRODUCTION

In the mountainous regions of Middle America there are several groups of hylid frogs that inhabit mountain streams. Some of these groups, such as Plectrohyla and Ptychohyla, have been elevated to generic rank, whereas others are retained in the large and complex genus Hyla. In the mountains of México five species of hylids that seem to compose a phyletic unit are herein referred to as the Hyla bistincta group. Since 1955 I have been accumulating specimens of, and data on, this group with the result that all specimens known to me, including the types of all named taxa, have been studied. Detailed observations have been made on the ecology and life histories of three of the species; the other two species are known to me only from preserved specimens.

Acknowledgments

For permission to examine specimens in their care I am indebted to Charles M. Bogert, American Museum of Natural History (AMNH); Doris M. Cochran, United States National Museum (USNM); Jean Guibé, Museum National d'Histoire Naturelle, Paris (MNHN); Robert F. Inger, Chicago Natural History Museum (CNHM); Hobart M. Smith, University of Illinois Museum of Natural History (UIMNH); Charles F. Walker, University of Michigan Museum of Zoology (UMMZ). (Abbreviations of institutions given above in parentheses are used throughout; the Museum of Natural History, University of Kansas is abbreviated KU.)

For their willing assistance in the field I am grateful to Ann S. Duellman, Dale L. Hoyt, and John Wellman. Permits for collecting in México were generously issued by the late Ing. Luis Macías Arellano, Departamento de la Fauna Silvestre, Dirección General de Caza. The drawings in figures 1 and 3 were executed by Gail Selfridge. This research has been supported by the National Science Foundation (NSF G-9827).

THE HYLA BISTINCTA GROUP

The five species comprising the Hyla bistincta group are moderate-sized hylids having rather blunt heads and robust bodies. The fingers are long and have little webbing (Fig. 1). The skin of the dorsum is thick and glandular, but not tuberculate. An anal sheath is present. The skull is rather broad, flat, and solidly roofed. The ethmoid is broad, curved downward laterally, and solidly sutured to the frontoparietal. The nasals are broad, sutured for their entire width with the ethmoid, and broadly in contact medially. The premaxillaries are in contact medially; each has a long, flat nasal process. The quadratojugal is absent, and the maxillary tapers to a point posteriorly. There is no squamosal-maxillary connection. The maxillary and premaxillary teeth are rather long, bifid, and moderately spatulate. Some teeth on the premaxillary and anterior part of the maxillary are hooked. The vomerine teeth are spatulate and bifid. A broad, flat, ossified prepollex is present but does not project as a spine. The known tadpoles have ventral mouths, 2/3 tooth-rows, two or more rows of labial papillae, and long tails with low fins.

As thus defined the Hyla bistincta group can be distinguished from all other groups of Middle American frogs by the combination of absence of the quadratojugal, non-projecting prepollex, long fingers with little webbing, and stream-inhabiting tadpoles having 2/3 tooth rows and two or more rows of labial papillae.

Possibly Hyla arborescandens and Hyla hazelae belong in this group. Because these species are somewhat different from the included species and because their tadpoles are as yet unknown, I have refrained from including these two species in the Hyla bistincta group. Taylor (1948:261) assigned Hyla proboscidea (= H. dalquesti) and (1949:272) Hyla cyclomaculata to this group, but because these two species have a quadratojugal and notably different tadpoles, they are excluded from the group.

Frogs of the genus Plectrohyla closely resemble species in the Hyla bistincta group but differ principally in having a projecting prepollex. In the highlands of Costa Rica a group of species, of which Hyla moesta is best known, resembles species in the Hyla bistincta group. At present insufficient information is available on the Costa Rican species to determine their affinities.

Analysis of Characters

The characters used in the systematic study of the frogs in this group are those usually employed in anuran systematics. Of the various measurements and proportions, the snout-vent length and the relative size of the tympanum to the eye apparently are of more taxonomic importance than the others (Table 1). In all of the species the tympanum is at least partially covered by a heavy, dermal supratympanic fold, and in some specimens of H. pachyderma the tympanum is completely obscured. In two species (H. bistincta and H. charadricola) the snout is square, whereas in the other species it is round.

Part 2

The fingers are long and slender in H. crassa, pachyderma, and robertsorum and somewhat shorter with more webbing in H. bistincta and charadricola. Breeding males of Hyla pachyderma have moderately large nuptial spines; the other species have small spines, except H. charadricola in which spines apparently are absent. A well-defined thoracic fold is present in H. pachyderma, and a weak fold is present in H. robertsorum; the other species lack folds. In all species there is an anal sheath; this sheath is longest in H. bistincta, in which the anal opening is directed ventrally at the level of the lower edge of the thighs.

TABLE 1.--COMPARISON OF CERTAIN MEASUREMENTS AND PROPORTIONS IN THE SPECIES OF THE HYLA BISTINCTA GROUP. (DATA FROM ADULT MALES; MEANS ARE GIVEN IN PARENTHESES BELOW THE RANGES.)

A: Snout-vent length B: Tibia length / Snout-vent length C: Head width / Snout-vent length D: Tympanum / Eye

==================================================================== SPECIES | N | | | | ---------------+----+-----------+-----------+-----------+----------- H. bistincta | 38 | 43.0-53.8 | 0.47-0.52 | 0.32-0.37 | 0.35-0.48 | | (46.3) | (0.49) | (0.34) | (0.42) | | | | | H. | 10 | 35.3-44.4 | 0.50-0.54 | 0.31-0.33 | 0.30-0.37 charadricola | | (40.4) | (0.52) | (0.32) | (0.34) | | | | | H. | 26 | 39.9-47.9 | 0.48-0.51 | 0.30-0.36 | 0.36-0.47 robertsorum | | (43.1) | (0.49) | (0.32) | (0.41) | | | | | H. pachyderma| 1 | 39.9 | 0.53 | 0.32 | ... | | | | | H. crassa | 1 | 53.7 | 0.50 | 0.33 | 0.28 ---------------+----+-----------+-----------+-----------+-----------

Frogs in this group are rather drab in appearance. The dorsal color varies from dull green to various shades of brown. The most distinct aspect of the coloration is the different color patterns on the flanks and posterior surfaces of the thighs. The flanks in all species are marked with spots or reticulations.

Hyla bistincta differs from other members of the group in having vocal slits and a distensible vocal sac. Only this species has been reported to call (Shannon, 1951:473). Insofar as is known, the other species are mute. Examination of skeletal preparations of H. bistincta, charadricola, and robertsorum and X-rays of the other species shows no notable specific differences in the osteology. Since the tadpoles of only H. bistincta (Duellman, 1961:47) and H. robertsorum (Rabb and Mosimann, 1955) are known, larval characters are of limited use in intra-group systematics.

Key to the Species of the Hyla bistincta Group

1. Snout, in dorsal profile, short and bluntly rounded; canthus rounded, sometimes indistinct, vocal slits absent 2

Snout, in dorsal profile, longer, squared; canthus distinct, vocal slits present or absent 4

2. Feet webbed to base of discs; dorsum dull olive green; flanks having cream-colored spots H. crassa, p. 486

Feet not webbed to base of discs; dorsum brown 3

3. Tarsal fold strong; thoracic fold heavy; webbing on feet extending to middle of penultimate phalanx of fourth toe; distinct white stripe above anus; cluster of largo spines on thumb in breeding males, H. pachyderma, p. 485

Tarsal fold weak and short; thoracic fold absent or barely indicated; webbing of feet extending to base of penultimate phalanx of fourth toe; no distinct white stripe above anus; nuptial tuberosities in breeding males consisting of small spines H. robertsorum, p. 481

4. Tarsal fold strong; anal flap elongate; anus opening at lower edge of femur; dorsum tan or brown; flanks mottled with cream and brown; venter immaculate creamy white; no anal stripe; vocal slits present, H. bistincta, p. 475

Continue reading A Review of the Frogs of the Hyla Bistincta Group free in the Wunder reader →