Osteocephalus cabrerai ( Cochran and Goin, 1970 )

Jungfer, Karl-Heinz, 2010, The taxonomic status of some spiny-backed treefrogs, genus Osteocephalus (Amphibia: Anura: Hylidae), Zootaxa 2407, pp. 28-50 : 29-33

Osteocephalus cabrerai ( Cochran and Goin, 1970)

( Figs. 1 , 2 , 8 a)

Hyla cabrerai Cochran and Goin, 1970

Osteocephalus buckleyi – Trueb and Duellman 1971 (synonymized cabrerai with buckleyi ) Osteocephalus cabrerai – Duellman and Mendelson 1995 (revalidated cabrerai , nov. comb.) Osteocephalus cabrerai – Lynch 2002

Osteocephalus cabrerai – Frost 2009

The holotype of O. cabrerai (USNM 152759) is from the Caño Guacayá, a tributary of the lower Río Apaporis, Departamento Amazonas, Colombia. Cochran and Goin (1970) described it in detail and differentiated it from O. buckleyi by chest and throat coloration, a variable character in O. buckleyi , and by more webbing. Trueb and Duellman (1971) synonymized O. cabrerai with O. buckleyi stating that its morphological characters were within the variation of the latter. Duellman and Mendelson (1995) revalidated O. cabrerai on the basis of a green male with nuptial excrescences from San Jacinto, Departamento Loreto, Peru. Subsequently, most authors dealing with O. buckleyi -like frogs that were predominantly green called them O. cabrerai (Gorzula and Señaris 1998, Lescure and Marty 2000, Lynch 2002). I was able to examine the holotype and also the specimen from San Jacinto (KU 221927), among others, and identified the latter as O. buckleyi . Nonetheless, O. cabrerai is considered a valid species here. I have seen Colombian and Peruvian material and concur with Lynch (2002) that frogs he collected near Leticia, Departamento Amazonas, Colombia, are O. cabrerai . Figure 1 in Lynch (2002) lower right (not as stated upper left) depicts a specimen.

Cochran and Goin (1970), Trueb and Duellman (1971) and Duellman and Mendelson (1997) provide details of the morphology of the holotype, so no detailed description is given here. These authors all agree that O. cabrerai has more webbing and is much more tuberculate than O. buckleyi .

Comparisons: The holotype and additional material is compared with O. buckleyi from northwestern Amazonia ( Colombia, Ecuador, northern Peru) (see Appendix for specimens examined). Females of O. cabrerai (SVL up to 71.4 mm) from Colombia and Peru are much larger than those of O. buckleyi (SVL up to 54.2 mm). Males are up to 54.8 mm (up to 46.7 in O. buckleyi ).

There are several tubercles ventrally on the posterior part of the lower jaw (absent in O. buckleyi ). The webbing ( Fig. 8 a) between Finger I and II of O. cabrerai reaches beyond the subarticular tubercle on Finger I and is continued to the disc as a smooth fringe. It reaches the subarticular tubercle on Finger II and is continued to the disc as a smooth fringe. In O. buckleyi ( Fig. 8 b) it is basal (i. e. considerably lower than the only subarticular tubercle on Finger I and the proximal subarticular tubercle on Finger II). In O. cabrerai webbing on the inner side of Finger III reaches the proximal part of the ultimate subarticular tubercle and continues as a fringe to the finger disc. In O. buckleyi webbing on the inner side of Finger III varies. It reaches the penultimate subarticular tubercle or less than half way between the penultimate and the ultimate subarticular tubercle. In O. cabrerai , the outer edge of Finger IV is irregularly fringed (either smooth, tuberculate, a smooth fringe, or a fringe with a few slightly raised tubercles in O. buckleyi ) and the ulna bears several large tubercles posteriorly (several low tubercles in O. buckleyi ). A row of tubercles along the posteroventral margin of the tarsus is very prominent in O. cabrerai (variable, i.e. low to prominent, in O. buckleyi ). Only the disc is free of webbing on Toe I, while the intercalary tubercle is free in O. buckleyi . An axillary membrane extends for about one third or slightly more the length of the upper arm (one fourth in O. buckleyi ). The tympanum is elliptical (its height about 90% its width in the holotype) to round (same as in O. buckleyi ). Both species can be predominantly green, but while this is almost exclusively so in O. cabrerai , O. buckleyi may have dorsal and lateral colorations of all shades of brown, grey and green.

The iris color of O. cabrerai is whitish to light golden with dark venation that varies with light from fine to wide. There is a dark brown horizontal bar and a dark brown vertical streak in the lower half of the iris ( Fig. 2 ).The iris coloration varies in O. buckleyi . There are specimens with almost clear golden or yellow irises, but also darker ones (golden tan), with irregular venation, some with a hue of radiating dark lines. There is usually a dark horizontal mid-eye bar varying in intensity, and often a dark vertical streak in the lower half of the iris ( Fig. 3 ).

The posterior surfaces of the thighs of O. cabrerai are light tan with dark tan spots or irregular tan markings in preservative. In life, they are bright blue with tan spots or irregular tan markings. The hidden surfaces of tibia, tarsus, parts of Toe I and II, axillary membrane and posterior part of upper arm are bright blue. In O. buckleyi the posterior surfaces of the thighs are variable: in preservative tan with or without dark brown and/or light marbling or irregular crossbars. In life they are tan to dark purple with or without black and/or green marbling or ill-defined crossbars. Breeding males of O. cabrerai with well-developed nuptial excrescences found in amplexus lack keratinized tips on dorsal tubercles (present in O. buckleyi ).

The tibiofibular bones are green in life in both species. Bones of some preserved specimens of O. buckleyi are pale with no green visible.

Snout-to-vent lengths are similar in O. festae (males up to 48.1 mm, females up to 78.9 mm) and O. cabrerai (males up to 54.8 mm SVL, females up to 71.4 mm), but the latter differs from O. festae (in parentheses) in a truncate snout in dorsal and lateral aspect (rounded), in a larger tympanum in females of O. cabrerai with TD/HL = 0.20–0.22 and TD/FD = 1.11–1.31 (TD/HL = 0.16–0.19 and TD/FD = 0.87–1.08 in females of O. festae ), tubercles ventrally on the posterior part of the lower jaw (smooth), a tuberculate supratympanic fold (smooth) and more extensive webbing. On the hand the webbing reaches at least the proximal end of the ultimate subarticular tubercle on the inner side of Finger III (the penultimate subarticular tubercle). The outer edge of Finger IV is irregularly fringed (a row of low tubercles). The tibiofibular bones are green (white).

Reaching an SVL of 71.4 mm in females, O. cabrerai appears to be a much larger species than O. inframaculatus (41.9 mm in the only known female specimen). The latter species also lacks tubercles ventrally on the posterior part of the lower jaw. The posterior surfaces of the thighs are tan with light short vermiculation (light with tan spots or irregular tan markings in O. cabrerai ). Webbing of O. inframaculatus (see below) is similar to that of O. buckleyi , i. e. considerably less extensive than in O. cabrerai .

Osteocephalus cabrerai may be diagnosed as (1) a medium to large-sized species with considerable sexual dimorphism in SVL (71.4 mm in females, 54.8 mm in males) and minor differences in dorsal tuberculation; (2) skin on dorsum granulate in females, tuberculate in males; tubercles lacking keratinized tips in breeding males; (3) skin on flanks areolate; (4) canthus rostralis weakly angular, strongly curved inward; (5) frontoparietal ridges not visible from outside; (6) dentigerous processes of vomers angular; (7) a tuberculate supratympanic fold from midlevel of eye to midlevel of tympanum posteriorly, sloping towards arm insertion up to lower tympanum level; (8) web on inner edge of third finger reaching proximal part of ultimate subarticular tubercle or beyond, continued as a fringe to finger disc; (9) distal subarticular tubercle on Finger IV broad-edged to bifid; (10) dorsum variable in shades of green with tan and brown blotches, streaks, or a reticulate pattern; (11) venter creamy white with or without tan spots; (12) a pale supralabial mark posteroventrally from eye to mid-tympanum; (13) flanks light with or without tan blotches; (14) position of vocal sacs paired, protruding posteroventral to angles of jaws; (15) juvenile coloration unknown; (16) tadpoles in streams, labial tooth row formula unknown; (17) color of tibiofibular bones green in preservative.

Distribution: Osteocephalus cabrerai is known from several lowland sites below 250 m a.s.l. in Amazonian Colombia (Departamento Amazonas) and Peru (Departamentos Loreto and Ucayali). There are also specimens from the Guiana Shield and the Orinoco Delta in Venezuela (Gorzula and Señaris 1998, Lescure and Marty 2000, Lima et al. 2005 [as O. buckleyi ]) that I refrain from including in the present study.

Figures

FIGURE 1. Osteocephalus cabrerai (holotype): a. dorsal, b. ventral, c. lateral view of the head. Not to scale.

FIGURE 2. Amplecting pair of Osteocephalus cabrerai from Quebrada Negra, Río Iauasiyacu, Loreto, Peru.

FIGURE 3 Amplecting pair of Osteocephalus buckleyi from Jatun Sacha, Napo, Ecuador.

FIGURE 8. Hand and foot of a. Osteocephalus cabrerai (female holotype), b. O. buckleyi (SMNS 13713, female from Jatun Sacha, Napo, Ecuador), c. O. festae (female holotype). Some fingers and toes are spread with needles (not entirely shown), that may cover parts of the discs or intercalary tubercles. Not to scale.