Hyla microcephala sartori Smith, Herpetologica, 7:186, December 31, 1951 [Holotype.—UIMNH 20934 from 1 mile north of Organos, south of El Treinte, Guerrero, México; H. M. Smith and E. H. Taylor collectors]. Duellman, Univ. Kansas Publ., Mus. Nat. Hist., 15:124, December 20, 1961. Porter, Herpetologica, 18:168, October 17, 1962. Davis and Dixon, Herpetologica, 20:230, January 25, 1965. Duellman, Univ. Kansas Publ. Mus. Nat. Hist., 15:652, December 30, 1965.
Diagnosis.—Dorsum tan with broad dark brown chevrons or transverse bars; shanks marked with two or three broad transverse bars; dorsolateral stripes absent.
Description and variation.—No noticeable geographic variation is apparent in either structural features or coloration in this species. All specimens lack a dorsolateral dark stripe and white line, although a dark line is present on the canthus and dissipates in the loreal region. A broad interorbital brown bar is present in all specimens. The color pattern on the dorsum invariably consists of a broad, dark, chevron-shaped mark in the scapular region and a broad dark chevron or transverse bar in the sacral region. The shanks invariably have two or three dark brown transverse bars.
When active at night individuals are yellowish tan above with chocolate brown markings ([Pl. 14]). The belly is white, and the thighs are pale yellowish tan. The iris is dark bronze-color. In breeding males the vocal sac is yellow. By day some individuals were observed to change to creamy gray with distinct darker markings.
Remarks.—Although tadpoles of this species have not been found, observations on the breeding sites indicate that the tadpoles probably develop in ponds. Except for calling males observed around a pool in a stream-bed 11.8 kilometers west-northwest of Tierra Colorada, Guerrero, all breeding congregations have been found at temporary ponds.
Smith (1951:186) named Hyla sartori as a subspecies of Hyla microcephala. This subspecific relationship seemed reasonable until analysis of the mating calls showed that the call of H. sartori is more nearly like that of H. phlebodes than that of H. microcephala. The broad hiatus separating the ranges of H. microcephala and H. sartori is additional evidence for considering H. sartori as a distinct species.
Fig. 4. Map showing locality records for Hyla sartori.
Distribution.—Hyla sartori occurs in mesophytic forests to elevations of about 300 meters on the Pacific slopes of southern México from southwestern Jalisco to south-central Oaxaca ([Fig. 4]). The lack of specimens from Colima and Michoacán probably reflects inadequate collecting instead of the absence of the species there. On the basis of available habitat the species would be expected to occur in Nayarit, but extensive collecting there has failed to reveal its presence. The semi-arid Plains of Tehuantepec apparently limit the distribution to the east.