Part 2

I am indebted to the following persons for permitting me to examine specimens in their care: Miguel Alvarez del Toro, Museo Zoologia de Tuxtla Gutierrez, Mexico (MZTG); Charles M. Bogert and Richard G. Zweifel, American Museum of Natural History (AMNH); Doris M. Cochran, United States National Museum (USNM); Norman Hartweg and Charles F. Walker, University of Michigan Museum of Zoology (UMMZ); Robert F. Inger, Chicago Natural History Museum (CNHM); Hobart M. Smith, University of Illinois Museum of Natural History (UIMNH); Heinz Wermuth, Zoologisches Museum Berlin (ZMB); and Ernest E. Williams, Museum of Comparative Zoology (MCZ). The abbreviations following names of institutions will be used throughout the text; the Museum of Natural History at the University of Kansas is abbreviated KU.

Throughout my work on these frogs I have profited from discussions with L. C. Stuart, who has made many valuable suggestions and with his characteristic generosity has placed at my disposal his extensive collections of tadpoles from Guatemala. For his aid I am indeed grateful. I am grateful to Thomas E. Moore for tapes of breeding calls of two species.

My own field work was made more enjoyable and profitable through the assistance of Dale L. Hoyt, Craig E. Nelson, Jerome B. Tulecke, and John Wellman, all of whom spent many hours in often unsuccessful attempts to collect specimens and record breeding calls of Ptychohyla. I am indebted to many residents of Mexico, Guatemala, and El Salvador for permission to work on their land and for providing shelter, food, and guides. I am especially grateful to Mr. and Mrs. Horatio Kelly of "Colegio Linda Vista" at Pueblo Nuevo Solistahuacan, Chiapas, for a pleasant stay at their school; Jordi Julia Z. of the Comision del Papaloapan, Ciudad Aleman, Veracruz, for arranging for field work in northern Oaxaca in 1959; Walter Hannstein and Lothar Menzel for the use of facilities at Finca La Paz, Guatemala, in 1960; Alan Hempstead for the use of facilities at Finca Los Alpes, Guatemala in 1960 and 1961; and Julio Aguirre C. of the Instituto Tropical de Investigaciones Cientificas, San Salvador, El Salvador, for providing comfortable working quarters and transportation and guides to the mountains in northern El Salvador. Without the cheerful efforts of Jorge A. Ibarra, Director of the Museo Nacional de Historia Natural in Guatemala, my field work would have been greatly restricted during politically precarious times in that country. Permits to collect in Mexico were furnished by the late Luis Macias Arellano of the Direccion General de Caza. Each of these individuals has my profound thanks for his indispensable aid.

Field work on hylid frogs in Middle America has been supported by the National Science Foundation, Grant NSF-G9827, and this is the 9th publication on the results of study of the material from America.

Materials and Methods

During the course of this study I have examined 247 frogs that I assign to the genus Ptychohyla, plus 40 lots of tadpoles and 12 skeletal preparations. Furthermore, I have examined all of the type specimens. I have studied each of the species and subspecies in the field and have examined from seven (P. euthysanota macrotympanum) to 33 (P. spinipollex) living individuals of each species.

Measurements given in the analysis of data and in the descriptions of the species are those described by Duellman (1956). In the descriptions of living colors the capitalized names are from Ridgway (1912). All interpretations of osteological characters are based on specimens cleared in potassium hydroxide and stained with alizarin red.

Recordings of the breeding calls were made with a Magnemite Portable Tape-recorder; audiospectrographs were made on a vibralyzer (Kay Electric Company) using normal pattern and wide bandwidth.

ANALYSIS OF DATA

Data that are used to arrive at a systematic arrangement of the species of Ptychohyla are analyzed and discussed below for the values inherent in the analysis. These data are of some value also in the recognition of species and subspecies but if employed for that purpose the data must be used in combination with the keys and the diagnoses of the individual species and subspecies.

External Morphology

Each of the external morphological characters used in the systematic treatment of Ptychohyla, as well as the nature of the tongue, is discussed below.

SIZE AND PROPORTIONS.--Comparisons of size and certain proportions are given in Table 1. Frogs of this genus are small; the largest specimen examined is a female of P. euthysanota euthysanota having a snout-vent length of 53.3 mm. The species comprising the Ptychohyla schmidtorum group are smaller; the largest specimen examined is a female of P. schmidtorum schmidtorum having a snout-vent length of 38.0 mm. An analysis of the various measurements and proportions shows few constant differences. Ptychohyla ignicolor differs from all of the other species in having the head slightly wider than long and the tympanum noticeably less than half the size of eye. Ptychohyla spinipollex has a relatively narrow interorbital distance, approximately equal to the width of the eyelid, whereas in all of the other species that distance is much more than the width of the eyelid.

SNOUT.--All species have a blunt snout. In P. leonhardschultzei and P. ignicolor the snout is nearly square in lateral profile; in P. schmidtorum the snout is slightly rounded above and below, and in the other species it is rounded above. Ptychohyla leonhardschultzei and P. spinipollex have a vertical fleshy rostral keel on the snout; in these species, because of this keel, the snout in dorsal profile is pointed. The nostrils are slightly protuberant in all species, and in P. schmidtorum the internarial region is slightly depressed.

HAND.--The species in the Ptychohyla euthysanota group have a vestige of web between the first and second fingers; the other fingers are about one-third webbed. Breeding males have a cluster of horny nuptial spines on the thumb. The spines are largest in P. spinipollex (Fig. 1) and vary in number from 35 to 66 (average 47.4) on each thumb. In the other species of the Ptychohyla euthysanota group the spines are smaller and usually more numerous; the numbers of spines on each thumb (means in parentheses) in members of this group are: P. euthysanota euthysanota, 44-143 (83.8); P. euthysanota macrotympanum, 40-110 (63.0); P. leonhardschultzei, 24-80 (54.7). The species in the Ptychohyla schmidtorum group have no web between the first and second fingers and only a vestige of web between the other fingers. Furthermore, these species lack nuptial spines in breeding males. Like the usual horny excrescences on the thumbs of many species of frogs, the horny spines on the thumbs of members of the Ptychohyla euthysanota group are seasonal in development.

TABLE 1.--VARIATION IN CERTAIN CHARACTERS IN THE SPECIES OF PTYCHOHYLA. (MEANS ARE IN PARENTHESES BELOW THE RANGES.)

Key to Table Columns

A) Number of specimens B) Maximum snout-vent length C) Tibia length/Snout-vent length D) Tympanum/Eye E) Vomerine teeth

==================+========+======+=======+=========+=========+======= Species | Sex | A | B | C | D | E ------------------+--------+------+-----------------+----------------- | | | | | | P. euthysanota | | 17 | 38.1 |44.4-55.0|48.6-63.8| 4-6 euthysanota | | | | (48.7) | (56.3) | (5.1) | | | | | | |[Female]| 15 | 53.3 |46.5-56.6|42.9-56.4| 6-18 | | | | (51.4) | (51.4) | (9.6) | | | | | | P. euthysanota | | 5 | 38.0 |48.8-52.0|50.0-57.1| 0-4 macrotympanum| | | | (50.2) | (54.1) | (2.6) | | | | | | |[Female]| 5 | 44.8 |46.4-54.1|48.7-58.9| 8-10 | | | | (50.2) | (53.7) | (9.2) | | | | | | P. leonhard | | 16 | 35.6 |48.8-56.1|48.7-61.9| 6-9 schultzei | | | | (51.2) | (52.1) | (6.5) | | | | | | |[Female]| 3 | 41.6 |52.3-59.5|47.5-48.6| 7-12 | | | | (54.7) | (48.1) | (9.5) | | | | | | P. spinipollex | | 32 | 41.2 |46.9-53.1|45.0-55.2| 3-7 | | | | (49.0) | (49.5) | (4.9) | | | | | | |[Female]| 6 | 44.6 |46.1-50.2|47.7-53.8| 6-10 | | | | (48.8) | (50.4) | (7.6) | | | | | | P. schmidtorum | | 25 | 32.8 |45.3-52.4|51.5-59.3| 5-11 schmidtorum | | | | (48.1) | (54.7) | (6.2) | | | | | | |[Female]| 9 | 38.0 |46.5-49.1|51.3-58.3| 7-11 | | | | (47.7) | (54.9) | (8.7) | | | | | | P. schmidtorum | | 40 | 30.5 |46.0-51.9|48.2-65.6| 4-6 chamulae | | | | (48.2) | (54.9) | (4.7) | | | | | | |[Female]| 4 | 31.8 |48.1-52.4|51.4-61.7| 4-9 | | | | (50.5) | (55.7) | (6.2) | | | | | | P. ignicolor | | 13 | 30.5 |45.9-52.2|37.1-47.1| 3-9 | | | | (49.6) | (43.2) | (6.1) ------------------+--------+------+-------+---------+---------+-------

Many workers have used the presence of a bifid subarticular tubercle beneath the fourth finger as a diagnostic character of certain species of hylids. Examination of the subarticular tubercles in Ptychohyla reveals considerable intraspecific variation. Bifid tubercles beneath the fourth finger are found in all species except P. ignicolor, which is known from only two specimens. In P. euthysanota euthysanota nearly 60 per cent and in P. schmidtorum schmidtorum about 90 per cent of the specimens have a bifid tubercle beneath the fourth finger on one or both hands. All specimens of P. leonhardschultzei have either a bifid or double tubercle beneath the fourth finger, and some have a bifid distal tubercle beneath the third finger.

FEET.--Members of the Ptychohyla euthysanota group have a weak tarsal fold, whereas in the species comprising the Ptychohyla schmidtorum group the tarsal fold is absent. Webbing on the foot extends to the discs of the third and fifth toes and to the base of the penultimate phalanx of the fourth toe, except in P. ignicolor, which has less webbing.

VENTROLATERAL GLANDS.--Breeding males develop thickened, pigmented glandular areas on the sides of the body. In living specimens of P. schmidtorum and P. ignicolor the glands are not readily visible, but in preservative they show as distinctive orange-colored areas. These glands are most distinct in P. euthysanota; in many specimens of this species the glands are elevated above the surrounding skin. The extent of the glands is variable (Fig. 2); probably this variability is due to different degrees of development in individual frogs rather than to interspecific differences. All Ptychohyla ignicolor and some P. schmidtorum chamulae have a small, round glandular area on the chin; to my knowledge this does not occur in the other species. Superficial examination of microscopic preparations of the glands reveals no histological differences between species. The glands occupy most of the thickened area and have narrow ducts leading to the exterior. Detailed studies of the histology will be reported elsewhere. Since the glands are developed only in breeding males, it is surmised that the glands are associated with some phase of the breeding activity.

TONGUE.--The shape of the tongue varies intraspecifically. Usually the tongue is ovoid; in some specimens it is barely notched posteriorly, whereas in others it is deeply notched, making the tongue cordiform. Deeply notched cordiform tongues are found in P. leonhardschultzei and P. schmidtorum; with the exception of these two species, some individuals of all species have emarginate tongues. Some individuals of all species have tongues that are shallowly notched posteriorly.

Color and Pattern

The dorsum in living frogs of the genus Ptychohyla is primarily yellowish or reddish brown, except in P. schmidtorum chamulae and P. ignicolor in which it is green. Usually there are some darker blotches or reticulations on the dorsum. The venter usually is white; in P. ignicolor it is yellow. The venter is spotted in all members of the Ptychohyla euthysanota group; the species, arranged from least to most spotting ventrally, are: P. euthysanota euthysanota, P. euthysanota macrotympanum, P. leonhardschultzei, and P. spinipollex. The last two species also have bold dark spots on the flanks. Ptychohyla schmidtorum lacks spots on the venter, whereas P. ignicolor has small dark flecks ventrally.

Ptychohyla euthysanota and P. schmidtorum have white stripes on the upper lips and on the flanks. All species have some form of a pale stripe above the anus and usually rather distinct white or pale stripes along the ventrolateral edges of the tarsi and forearms. There are no bright or boldly marked flash-colors (colors that are revealed only when the hind limbs are extended), except in P. ignicolor, which has bright red flash-colors in the groin and on the thighs. In life the iris varies from several different shades of bronze color to deep red in P. schmidtorum schmidtorum.

The degree of metachrosis is moderate. Usually any change of color in life consists only of change in the intensity of color. At times when the over-all coloration is darkened some markings are obscured.

Osteology