A Synopsis of Neotropical Hylid Frogs, Genus Osteocephalus

by Linda Trueb; William Edward Duellman

The holotype of Hyla cabrerai is a female having a snout-vent length of 52.7 mm; the diameter of the tympanum is 4.0 mm, 76.9 percent of the diameter of the eye. The skin on the dorsum is weakly tuberculate and that on the anterior part of the flanks is areolate. The dorsum is creamy tan with dark brown markings (interorbital bar, reticulations on occiput, three longitudinal streaks on back, and broad transverse bars on limbs). Irregular dark brown spots are present on the flanks. The venter is pinkish tan with small reddish brown spots on the throat and darker brown spots on the chest and belly.

In their description of Hyla cabrerai, Cochran and Goin (1970:217) stated: "This species, together with buckleyi and pearsoni certainly make a closely knit groupߪ. Both buckleyi and cabrerai have long hind legs, with the extended heel reaching to the tip of the snout, while in pearsoni the extended heel reaches only to the eye. H. buckleyi has the belly dusky, while it is heavily spotted in cabrerai and is reticulated in pearsoni. H. cabrerai seems to have the heaviest hands with the most webbing between the fingers; the other two species have the webbing reduced between the fingers." The description of Hyla cabrerai was based on three specimens. We have examined the holotype and one paratype (WCAB 13284 from Territorio do Amapá, Brasil). Another paratype in the private collection of C. J. Goin from Caño Tuí, between Mitú and Raudal de Yurupari, Comisaria de Vaupés, Colombia, was not examined.

Cochran and Goin (1970:211) based their description of Hyla carri on one gravid female and stated: "A large Hyla with the vomerine teeth in two ʌʌ shaped patches between the somewhat squarish choanae; reduced webs between the fingers; and a pattern of dorsal dark blotches bordered by light margins. The species is not similar to any other species known in Colombia. It is perhaps most closely related to Hyla claresignata of Brazil, from which it can be differentiated by its more heavily spotted dorsum, larger tympanum, and lack of dark anal spots."

Except for the inclusion of the name in checklists, Hyla festae has not been mentioned in the literature since the original description.

The wholesale synonymization of names, which, on the bases of their published diagnoses, seem to apply to distinctly different species, is possible with the application of uniform criteria to the types and series of other specimens. In measurements and proportions the type specimens of the nominal taxa all fall within the range of variation exhibited by a series of 18 males and 15 females from Provincia Pastaza, Ecuador, except the ratio of the diameter of the tympanum to that of the eye in the female holotype of Hyla festae. In that specimen the ratio is 0.574, whereas the ratio in the 15 females from Provincia Pastaza is 0.587-0.905 (mean 0.736).

Ventral coloration is the most variable character among the types. The venter in the type of Hyla festae is boldly spotted; it is distinctly spotted in cabrerai, uniform tan in carri, and tan, flecked, or spotted in the type series of buckleyi. The ventral coloration in series of specimens from Amazonian Ecuador encompasses that observed in all of the types, except that of festae, which has more ventral spotting than any other individual.

The webbing on the hand usually excludes the penultimate phalanges of the fingers, but in some specimens from Amazonian Ecuador the webbing encompasses the proximal parts of the penultimate phalanges of the fingers. In a few of these specimens, the holotype of festae, and one paratype of cabrerai the webbing extends to the middle of the penultimate phalanges of the third and fourth fingers. In the holotype of cabrerai the webbing extends to the middle of the penultimate phalanges of the third and fourth fingers and to the base of the disc of the second finger.

The types of the nominal taxa and series of specimens from Guyana and Amazonian Ecuador display noticeable variation in dorsal coloration. The variety of dorsal patterns of all of the types is included in the variation displayed by the other specimens. All specimens have some amount of dark spotting on the flanks; all have vertically barred lips, on which a pale subocular spot usually is evident. Probably the most unifying physical characteristic of all of the specimens is the nature of the skin on the anterior part of the flank. The skin is elevated amidst an irregular network of depressions. This areolate dermal condition is present in all specimens and does not occur in other species of Osteocephalus. The degree of tubercularity of the skin on the dorsum is variable and sexually dimorphic. All males are tubercular, whereas small females are smooth or have only a few scattered tubercles. Large females usually have pronounced tubercles on the eyelids and supratympanic fold.

In their description of Hyla carri, Cochran and Goin (1970:211) misrepresented the nature of the dentigerous processes of the prevomers, which are angular, not ʌ-shaped. Their suggestion that the Colombian Hyla carri is related to Hyla claresignata in southeastern Brasil is unfounded. The latter species is smaller (40 mm), has a yellow dorsum and venter, dark brown spots dorsolaterally, oblique dentigerous processes of the prevomers, small tympanum, and smooth skin dorsally.

The ventral coloration of the type of Hyla festae resembles that of Osteocephalus verrucigerus, but the type differs from verrucigerus by having areolate skin on the flanks and distinct dark markings on the dorsum. In verrucigerus the skin on the flanks is smooth, and the dorsum is uniform dark brown, except for a tan snout in females.