Part 5

Distribution.--The periphery of the Amazon Basin, in the Guianas and the upper part of the basin in southern Colombia, Ecuador, Peru, and extreme western Brasil (Fig. 9). Most localities are at elevations of less than 500 m, but the species ascends the lower Andean slopes to elevations of 1100 m. 265 specimens from 31 localities.

Remarks.--Most adults of leprieurii have distinct transverse markings on the back; these are variable in width, extent, and arrangement. In some specimens, such as USNM 166557, some of the transverse bars are fragmented into spots; in a few specimens the dorsal pattern consists solely of small dark spots arranged in transverse rows. Such specimens have a dorsal pattern resembling that of some taurinus. The transverse nature of the dorsal markings is further modified in some specimens, such as USNM 166555, in which the dark bars are fragmented and oblique.

Extreme ontogenetic change in color pattern is exhibited by this species (Fig. 10). Juveniles having snout-vent lengths of less than 28 mm have an olive-brown dorsum with a pale cream stripe across the head and broad, cream, dorsolateral stripes; transverse dark bars are absent on the body and limbs. Individuals having snout-vent lengths of 30-35 mm have dark brown transverse bars on the back and limbs but still retain the light dorsolateral stripes, whereas the stripes are lost in larger individuals.

Coloration in life of specimens from Lago Agrio, Ecuador: "In males the dorsal ground color varies from dark brown to ochre-tan; dorsal markings uniformly dark brown. Most specimens have dark brown and cream anal stripes; labial area cream-colored. Flanks vary from tan to white. Ventral coloration varies from salmon to tan to white. The iris is bronze with a greenish cast and black reticulations. In females the dorsal coloration is the same as in males, except that dark marks tend to be outlined with cream; venter tannish salmon." (W. E. Duellman, field notes, 12 May 1969).

=Osteocephalus pearsoni= (Gaige)

Hyla pearsoni Gaige, 1929:3 [Holotype.--UMMZ 57548 from the upper Rio Beni, below mouth of Rio Mapiri, Departamento El Beni, Bolivia; N. E. Pearson collector].

Osteocephalus pearsoni--Goin, 1961:13.

Justification of Synonymy.--Goin (1961:13) suggested that Hyla pearsoni Gaige was an Osteocephalus, but Cochran and Goin (1970:217) considered pearsoni to be a Hyla. The presence of exostosed dermal roofing bones, angulate prevomerine dentigerous processes, and the structure of the vocal sacs are characters which place the species in Osteocephalus.

Diagnosis.--1) Size moderate, sexual dimorphism evident; maximum observed snout-vent length in males 46.2 mm, in females 54.7 mm; 2) skin on dorsum in males bearing a few, small, scattered non-spinous tubercles; 3) skin on flanks smooth; 4) web extending to base of antepenultimate phalange on inner edge of third finger; 5) dorsum tan with irregular brown blotches; 6) venter cream with fine brown reticulations; 7) lips dark with pale vertical bar below eye; 8) flanks pale tan with round, brown spots; 9) dermal roofing bones of skull slightly exostosed; 10) dermal sphenethmoid absent; 11) nasals narrowly separated medially; 12) anteromedial margin of frontoparietal between mid- and anterior levels of orbit; 13) frontoparietal fontanelle covered; 14) palatine not serrate; 15) parasphenoid lacking odontoids; 16) zygomatic ramus of squamosal extending about one-half distance to maxillary arch; 17) transverse processes of third presacral vertebra approximately equal in width to sacral diapophyses; transverse processes of presacral vertebrae 3-8 subequal in width; 18) intermandibularis and submentalis muscles connected; 19) supramandibular portion of interhyoideus extensively developed; associated skin forming broad loose fold.

Osteocephalus pearsoni can be distinguished most readily from other members of the genus by the brown reticulate pattern on the venter, round brown spots on the flanks, and smooth skin on the flanks. Also, it is the least tuberculate species in the genus.

Distribution.--Upper Amazon Basin and Amazonian slopes of the Andes in central Peru (1620 m in Rio Ucayali drainage) and northern Bolivia (less than 500 m in Rio Beni drainage) (Fig. 8). 6 specimens from 3 localities.

Remarks.--The specimen from Yaupi, Peru (KU 136312) is a subadult female having a snout-vent length of 39.8 mm. In life the coloration was: "Dorsum light pinkish brown with large rich chocolate brown blotch from eyes to anterior tips of ilia; numerous small chocolate blotches on flanks; dorsal surfaces of thighs and shanks, canthus, and supraorbital region to insertion of forearm chocolate brown; supralabial border and short bar from eye to lip bronze-white; venter bronze-white with numerous tiny chocolate brown flecks [tending to form reticulations on throat and chest]; anterior and posterior surfaces of thighs light olive-brown; iris largely black with gold flecks." (Thomas H. Fritts, field notes, 23 March 1970.) On the basis of this one subadult, it seems likely that reticulations on the venter develop with age.

=Osteocephalus taurinus= Steindachner

Osteocephalus taurinus Steindachner, 1862:77 [Holotype.--NHMW 16492 from Barra do Rio Negro, Manaus, Territorio do Amazonas, Brasil; Johann Natterer collector].

Osteocephalus flavolineatus Steindachner, 1862:80 [Holotype.--NHMW 16495 from Cucui, Territorio do Amazonas, Brasil; Johann Natterer collector].

Trachycephalus (Osteocephalus) taurinus Steindachner, 1867:64.

Osteocephalus planiceps Cope. 1874:122 [Holotype.--ANSP 11399 from Nauta, Departamento de Loreto, Peru; James Orton collector]. New synonymy.

Hyla taurina--Boulenger, 1882:363 [synonymized Osteocephalus flavolineatus Steindachner, 1862, with O. taurinus Steindachner, 1862].

Hyla planiceps--Boulenger, 1882:364.

Hyla (Trachycephalus) vilarsi Melin, 1941:40 [Holotype.--NHMG 488 from Taracua, Rio Uaupes, Territorio do Amazonas, Brasil; Douglas Melin collector]. (fide Bokermann, 1966:64.)

Hyla depressa Andersson, 1945:73 [Holotype.--NHRM 1966 from the Rio Pastaza watershed (? Provincia Pastaza), Ecuador; William Clarke-MacIntyre collector]. New synonymy.

Justification of Synonymy.--The holotype of Osteocephalus taurinus is a female having a snout-vent length of 103.9 mm. The diameter of the tympanum is 6.8 mm, 77.3 percent of the diameter of the eye. The skull is strongly exostosed, and the lateral edges of the frontoparietals are elevated so as to form distinct ridges. The skin on the dorsum is smooth. When we examined the type on 5 August 1969, the specimen was soft and badly faded to a pale creamy tan with pale brown transverse bars on the hind limbs and spots on the flanks. Steindachner (1862:79) described the coloration of the type: "In the preserved specimen the dorsum of the entire body, including fore and hind limbs, is a light yellow-brown color, which becomes lighter towards the venter. The belly is whitish, as are the undersides of the arms and legs. The throat is indistinctly marbled with brown. Roundish dark brown flecks are randomly distributed in a considerable number along the side of the body up to the eye; the tympanum is more or less fully surrounded by brown. A few discrete spots, always more or less drawn out in length, on the sides of the body, are also found on the posterior part of the back. The dorsal surfaces of the fore and hind feet are marked with somewhat obliquely arranged brown transverse bands, which are more intensively colored near the margin than in the middle of the band." (free translation from German.)

The holotype of Osteocephalus flavolineatus is a female having a snout-vent length of 81.8 mm. The diameter of the tympanum is 6.0 mm, 71.4 percent of the diameter of the eye. The skull is strongly exostosed, and the lateral edges of the frontoparietals are elevated so as to form a ridge on each side. The skin on the dorsum is very weakly tuberculate. We examined the type on 9 August 1969 and found it to be in excellent condition. The color pattern is unchanged from that described by Steindachner (1862:81). The dorsum is tan with irregular brown blotches on the back, spots on the flanks, and transverse bars on the limbs. A narrow creamy white, middorsal stripe extends from the snout to the vent. The subocular area is creamy tan, and the venter is tan. Boulenger (1882:363) questionably synonymized flavolineatus with taurinus. We have observed that a middorsal cream stripe occurs in about 10 percent of the specimens of taurinus and in some specimens of buckleyi. This is a common color morph in many species of Eleutherodactylus. In the absence of distinguishing morphological characteristics we can only conclude that the middorsal stripe is a pattern variant and that Boulenger was correct in synonymizing flavolineatus with taurinus.

The holotype of Osteocephalus planiceps is a male having a snout-vent length of 58.5 mm. The diameter of the tympanum is 4.9 mm, 77.8 percent of the diameter of the eye. The skull is moderately exostosed, and the lateral edges of the frontoparietals are distinctly elevated. The skin on the dorsum is tuberculate. Cope (1874:122) described the coloration of the type as follows: "Color above uniform dark brown, concealed surfaces on the limbs similar and without any markings. Sides a little varied with the white of the belt. A light border to the upper lip, and lighter line from the orbit to the angle of the mouth; dermal scapular fold pale edged. Femur and tibia with dark crossbands on the exposed surfaces." We examined the holotype on 25 September 1969, and found it to be soft and rubbed. The coloration remains much the same as described by Cope, who provided no means of distinguishing planiceps from taurinus. The coloration and morphometric and structural characters of the type of planiceps all fall within the range of variation displayed by series of O. taurinus from the upper Amazon Basin.

The type of Hyla vilarsi is a gravid female having a snout-vent length of 62.7 mm. The diameter of the tympanum is 4.8 mm, 73.8 percent of the diameter of the eye. The dorsal roofing bones of the skull are moderately exostosed, and the lateral edges of the frontoparietals are distinctly elevated. The skin on the dorsum is smooth. Melin (1941:42) described the coloration of the holotype as follows: "Above uniform reddish brown; upper eyelids and sides of head darkish brown; below the rostral edge a narrow dark band, continuing as a broader light-edged one through the eye and tympanum towards the base of the forelimb and then farther on continuing along the sides as a line of black spots; sides of upper jaw whitish with traces of dark cross bars (one distinct under the eye); sides of body darkish with black spots and marble, often on a whitish ground; thighs, tibiae, and tarsi each with two broad light-edged, dark cross bars on a brownish ground (less distinct on thighs); sides of thighs finely mottled with brown; beneath whitish with small, sparse spots along jaw, on the chest and sides." We examined the type on 17 February 1969, at which time the specimen was somewhat desiccated, especially the hands and feet. The coloration remains much the same as described by Melin, except that he failed to note the presence of four elongate spots on the back.

The status of the names Osteocephalus planiceps Cope and Hyla vilarsi Melin was confused by Cochran and Goin (1970:322), who assigned these names to the synonymy of O. leprieurii. Bokermann (1966:64) placed Hyla vilarsi in the synonymy of Osteocephalus taurinus without justification. The type specimens of both planiceps and vilarsi have moderately exostosed dermal roofing bones and distinct cranial ridges. The type of planiceps has moderately large tubercles on the dorsum, and the type of vilarsi has spots on the throat, chest, and flanks and longitudinal markings on the back. All of these features are characteristic of taurinus and not of leprieurii, which lacks exostosis and cranial ridges and has transverse markings on the back, no spots on the throat, chest, and flanks, and in males has small dorsal tubercles.

The type of Hyla depressa is a male having a snout-vent length of 69.8 mm. The diameter of the tympanum is 5.2 mm, 77.6 percent of the diameter of the eye. The dorsal roofing bones of the skull are moderately exostosed, and the lateral edges of the frontoparietals are elevated. The skin on the dorsum is tuberculate. The dorsum is dull brown with a broad darker brown longitudinal mark having indistinct lateral edges from the snout to the post-sacral area. A narrow cream middorsal line extends from the snout to the vent. The side of the head is dark brown, palest posteroventral to the orbit. The posterior surfaces of the thighs are dull brown; the flanks are pale brown, and the ventral surfaces are pale creamy tan. Dark brown transverse bars are present on the limbs. When we examined the type on 3 January 1969, it was in excellent condition. Andersson (1945:75) contrasted the type of Hyla depressa with leprieurii and buckleyi, but he did not compare his specimen with taurinus, from which it exhibits no distinguishing features.

Osteocephalus taurinus is a widespread and variable species, and it has received several specific names. We are convinced that Osteocephalus taurinus Steindachner, 1862, is the oldest available name for this large Amazonian species. The following names are junior synonyms: Osteocephalus flavolineatus Steindachner, 1862; Osteocephalus planiceps Cope, 1874; Hyla (Trachycephalus) vilarsi Melin, 1941; Hyla depressa Andersson, 1945.