Part 12

Oaxaca: Donaji (7); 43 km. N of Matias Romero (21). Veracruz: 19 km. N of Acayucan (4); Aquilera (3); 8 km. SW of Coatzacoalcos (36); Cuototolapam (11); Naranja (13); San Lorenzo (8).

In the isthmus this species is known only from the humid forests of the Gulf lowlands; it is also known from Boca del Rio, Veracruz, and from Teapa and Villa Hermosa, Tabasco.

Calling males were found on aquatic plants above the water in deep ponds in the forest where it was necessary for the collector to wade waist-deep in water to obtain them. The call is a loud "hah-onk." Individuals, when active at night, are yellowish tan above with light olive green spots. The flanks, belly, and vocal sac are yellow, and the anterior and posterior surfaces of the thighs and webbing of the feet are bright orange-red or tomato red. Individuals found during the day are grayish brown with olive markings or reddish brown with black markings. Sleeping individuals are ivory-gray with faint gray markings. The iris is a bright copper color. Fifteen adult males have an average snout-vent length of 41.7 mm.; they have no horny nuptial pads on the pollex.

The relationships of this species are with Hyla rickardsi Taylor, a species known only from the foothills of the Sierra Madre Oriental in the states of Puebla and Veracruz. The distinguishing characteristics of these species are given in Table 1. Living individuals may be distinguished immediately by the flash colors on the thighs--red in loquax and yellow in rickardsi. The calls of the two species are distinctly different; that of rickardsi is a high-pitched, loud rattle continued for several seconds, notably different from the goose-like honk of loquax.

TABLE 1.--COMPARISON OF CERTAIN CHARACTERS IN HYLA LOQUAX AND HYLA RICKARDSI

=================================+================+==================== CHARACTER | loquax | rickardsi ---------------------------------+----------------+-------------------- Toe webbing | Full | Three-fourths | | Finger webbing | Three-fourths | One-half | | Average snout-vent length (Male) | 41.7 mm. | 37.4 mm. | | Tympanum/eye (Male) | 63.2% | 55.8% | | Dorsal leg pattern | Barred | Unmarked | | Tarsal fold | Tubercular | Absent | | Tarsal stripe | Absent or | Broad, indistinct, | indistinct | or absent | | Dorsolateral stripe | Absent | Present | | Light line over anus | Broad | Narrow | | Flash colors | Red | Yellow | | Iris color | Copper | Bronze ---------------------------------+----------------+--------------------

The three specimens from San Lorenzo, Veracruz (USNM 123513-5), were identified as Hyla rickardsi by Smith (1947:409). The flash colors have faded in preservative, and so are of no aid in identifying these specimens. Two are adult females with snout-vent lengths of 35 and 39 mm. In possessing a relatively large tympanum and barred thighs, and in lacking a dorsolateral stripe they are typical of loquax, but in the amount of webbing on the hands and feet, broad tarsal stripe, and narrow anal stripe they are like rickardsi. The third specimen, a juvenile, has a snout-vent length of 25 mm. In coloration it resembles the adults; it has more distinct bars on the limbs. On the basis of geography these specimens should be loquax, for the closest known record of rickardsi is more than 200 kilometers to the northwest, whereas loquax is known from several localities around San Lorenzo.

Shannon and Werler (1955:383) described Hyla axillamembrana from the lower southern slopes of Los Tuxtlas. The unique type is a small male (27 mm. snout-vent). I have examined the type and find no great differences between it and small specimens of loquax. It is not possible to determine the color of the thighs, nor was this information given in the description. Hyla axillamembrana is here considered to be a synonym of Hyla loquax.

=Hyla microcephala martini= Smith

Oaxaca: Donaji (15); 43 km. N of Matias Romero (19); Rio Sarabia (2); Sarabia (11); Tolosita. Veracruz: Acayucan (17); Alvarado (41); Aquilera (21); 8 km. SW of Coatzacoalcos (10); Cosoleacaque (26); 10 km. SE of Hueyapan; Naranja (3); Novillero.

This frog is abundant in the Gulf lowlands of the isthmus, where large breeding congregations were found in grassy ponds on the savannas and in openings in the forest. Most frequently males were calling from grasses and reeds in the ponds; many individuals were perched precariously on thin blades as high as one meter above the water. The call is a series of low squeaks.

Individuals found at night were pale yellow above with light brown lines arranged in an irregular pattern on the back, but often forming a cross or an X-shaped mark in the scapular region. There is a brown stripe from the nostril to the eye and thence to the groin. Anteriorly this stripe is bordered above by a thin white or cream-colored line. Numerous small brown flecks are scattered on the back and dorsal surface of the shank. In most specimens there are thin transverse brown bars on the shank. The thighs and undersides of the limbs are golden yellow; the belly and vocal sac are lemon yellow. The iris is yellowish brown. During the day individuals assume a pale reddish tan ground color with darker brown markings. Twenty-five adult males from Alvarado have an average snout-vent length of 24.1 mm.

=Hyla picta= Guenther

Oaxaca: Donaji (8); Sarabia (11); Tolosita (15); Ubero (6). Veracruz: 19 km. N of Acayucan (4); Alvarado (5); Aquilera; 8 km. SW of Coatzacoalcos; 10 km. SE of Hueyapan (7); Lerdo de Tejada; Tula (3).

Widespread in the forests, scrub, and savannas on the Gulf lowlands of the isthmus, these frogs were found breeding at numerous localities. Males call from grasses and bushes growing in and about ponds. The call is a high-pitched insect-like trill. At night these frogs are pale yellow above; they change to light grayish tan during the day. A dark stripe extends from the nostril to the eye and thence posteriorly to a point between the axilla and groin. Above this dark stripe is a broader white stripe. Scattered on the dorsum are brown flecks or spots; the shanks are marked with poorly-defined cross-bars. The thighs are deep yellow below and paler above with scattered dark flecks. The belly is white, and the vocal sac is yellow. The iris is golden. Twenty males have an average snout-vent length of 21.5 mm.; three females, 24.0 mm.

=Hyla robertmertensi= Taylor

Oaxaca: Tapanatepec (28); 7.5 km. NW of Tapanatepec (38); 7.2 km. WNW of Zanatepec (77).

This species was found in the isthmian region only on the Pacific lowlands at the southern base of the western part of the Sierra Madre de Chiapas. On July 13, 1956, many large choruses were discovered. The calling males were on reeds and thorn scrub in and at the edge of temporary ponds; the call is a cricket-like "creak-creack," quickly followed by a series of notes "creak-eek-eek-eek-eek."

At night the dorsal ground color is pale yellow; this changes to pinkish buff during the day. There is a grayish or brown dark stripe from the nostril to the eye; the stripe continues to the groin. This dark stripe is bordered above by a narrow white stripe. The belly is white, and the vocal sac is yellow. The iris is dull reddish brown. Twenty-five males have an average snout-vent length of 24.7 mm.

=Hyla staufferi= Cope

Oaxaca: Chivela; Huilotepec (5); Juchitan (4); Matias Romero (4); 25 km. N of Matias Romero; Mixtequilla (4); Rio Sarabia (11); 11 km. S of Santiago Chivela; Sarabia (3); Tapanatepec (67); Tehuantepec (66); Tolosita (2); Ubero; Union Hidalgo; Zanatepec (6). Veracruz: Acayucan (7); Alvarado (3); Amatitlan; Aquilera; Ciudad Aleman (3); 8 km. SW of Coatzacoalcos (9); Cosamaloapan (4); Cosoleacaque (8); 10 km. SE of Hueyapan; Lerdo de Tejada; Novillero (6); Tula (2).

This is the only species of small hylid that crosses the isthmus. Calling males were found in and about ponds on the savannas in southern Veracruz, in ponds in open forest in northern Oaxaca (not in forest pools), and in temporary pools in the scrub forest on the Pacific lowlands. Individuals usually called from bushes and reeds in or at the edge of ponds. The call is a short "braaa." Dates of breeding choruses indicate that by the time the other small species of hylids in the Gulf lowlands reach the peak of their breeding season, that of H. staufferi is essentially over; no large breeding congregations were found in July. On July 8, 1956, two metamorphosing young were found clinging to blades of grass in a pond; they had snout-vent lengths of 8 and 9 mm. and tail stumps less than 3 mm. in length. Others were found on July 13 and 26. The juveniles are nearly unicolor olive green above and white below.

In life the adults vary greatly in color pattern. The dorsal ground color is yellowish tan to olive brown with olive brown or dark brown spots, some of which in certain individuals are connected to form longitudinal dark stripes. On the posterior surface of the thighs are small white flecks. The belly is white, and the vocal sac is a rich yellow. Twenty males have an average snout-vent length of 26.3 mm.; they have no horny nuptial pads. No noticeable differences in either color or body proportions were found between the populations on either side of the isthmus.

=Hylella sumichrasti= Brocchi

Oaxaca: Cerro Arenal (5); Cerro San Pedro (2); Escurano; La Concepcion (41); Portillo Los Nanches (6); San Antonio (16); 11 km. S of Santiago Chivela (18); Santa Lucia (7); Tapanatepec (5); Tehuantepec (8); Tenango (49); Tres Cruces (19).

With the exception of the series from 11 kilometers south of Santiago Chivela, most of these specimens were found in small arboreal bromeliads during the dry season. Males were found along a clear, shallow, rocky stream south of Santiago Chivela on July 6, 1956. The frogs were calling from bushes and rocks in and along the stream. When disturbed, they jumped into the water and floated downstream until they were able to hold onto a rock or other object. The call is a loud "bra-a-ah." In breeding individuals the dorsum is pale yellow; the belly is white, and the vocal sac is yellow. The iris is pale golden yellow. Eighteen males have an average snout-vent length of 25.2 mm. All have dark brown nuptial tuberosities on the pollex.

Certain diagnostic characters of this species as given by Taylor (1943a:50) and Taylor and Smith (1945:598) are in need of revision. Hylella sumichrasti has been characterized as having no vocal sac, rarely having vomerine teeth, and as having a relatively smooth throat. The vocal sac in breeding males is quite evident; it is single, median, and when expanded, spherical. The openings into the vocal sac are narrow slits along the inner posterior border of the jaw rami. Of 151 specimens studied, 74 have vomerine ridges between the choanae, and 36 of these have one to three teeth on each ridge. The belly and undersurfaces of the thighs are granular; the throat is only somewhat less so. The granular condition may be correlated with breeding, for specimens obtained from bromeliads in the dry season had rather smooth throats. It seems that the vocal sac atrophys in the non-breeding season. These seasonal changes may account for the diagnoses given by Taylor (op. cit.) and Taylor and Smith (op. cit.); likewise, since many of the specimens obtained by Smith in the dry season were juveniles and subadults, the development of the vomerine ridges could not be diagnosed properly.

The range of this species encompasses the Pacific slopes of the Isthmus of Tehuantepec eastward to the upper Cintalapa Valley and vicinity of Tonala in western Chiapas. Priscilla Starrett collected tadpoles of H. sumichrasti from a stream 19 km. N of Arriaga, Chiapas. These limited observations on the ecology of this frog suggest that it breeds in the fast-moving streams of the Pacific slopes, and that it seeks shelter in arboreal bromeliads during the dry season.