Osteocephalus inframaculatus ( Boulenger, 1882 )

Jungfer, Karl-Heinz, 2010, The taxonomic status of some spiny-backed treefrogs, genus Osteocephalus (Amphibia: Anura: Hylidae), Zootaxa 2407, pp. 28-50 : 36-38

Osteocephalus inframaculatus ( Boulenger, 1882) nov. comb.

( Fig. 5 )

Hyla inframaculata Boulenger, 1882 Hyla inframaculata – Nieden 1923 Hyla inframaculata – Duellman 1977 Hyla inframaculata – Frost 2009

This species, known only from the holotype, BM 1947.2.13.10, has only appeared in species lists after its description. Its type locality is “Santarem”, Estado do Para, Brazil. Although there are few characters found in species of Osteocephalus that are not present in other hylid genera ( Jungfer and Hödl 2002), the combination of angular vomers, a bifid ultimate subarticular tubercle of Finger IV and tuberculate dorsal skin characterize Hyla inframaculata as a species of Osteocephalus . The tuberculate dorsal skin in a female specimen together with areolate skin on the flanks, non-uniform coloration of the posterior surfaces of the thighs and a row of tubercles on the tarsus indicate that the species is a member of the buckleyi complex. With only one undissected specimen at hand, neither sex, identified by lack of nuptial excrescences, lack of vocal sac apertures and externally visible vocal sacs, nor adult size can be taken for completely granted.

Redescription of the holotype: Snout rounded in dorsal and lateral view, as long as the diameter of the orbit. Head slightly wider than long, without raised lateral edges of the frontoparietals. Canthus rostralis rounded, indistinct; loreal region slightly concave; interorbital space as broad as the upper eyelid. Dorsal surfaces of head and canthus rostralis covered with small, irregular tubercles; larger tubercles on the orbits. Tympanum distinct, large, about 70% of the diameter of the eye. A heavy tuberculate supratympanic fold from the midlevel of the eye to a point at about 2 h (when tympanum is thought as a clock face), sloping towards the flanks to a point at about midlevel of the tympanum. Tongue circular, vomers angular, almost between the large choanae. Anteriorly, the choanae reach slightly beyond the anterior parts of the vomers, posteriorly it is vice versa.

Dorsum tuberculate. Two dorsal folds not mentioned in the original description, but shown in Plate XXIII ( Boulenger 1882) and still present, are irregular and obviously artefacts of preservation. Anterior two thirds of the flanks areolate. Ventrally granulate. Cloacal opening at about midlevel of the thighs. Anal sheath absent. Circumanal tubercles present, low. Axillary membrane weak. Upper surfaces of limbs weakly tuberculate. A row of irregular tubercles on the outer ventrolateral edge of the lower arm and the tarsus. Hidden surfaces of limbs smooth. When bent forward, the tibiotarsal articulation reaches nearly the tip of the snout.

Finger discs rounded. Disc on Finger III about 70% the diameter of the tympanum. The relative lengths of the adpressed fingers is I <II <IV <III. Finger webbing formula is I basal II 1 ½ — 2 2/3 III 3 – — 2+ IV. Webbing on the inner edge of Finger III reaches halfway between penultimate and ultimate subarticular tubercle. The distal subarticular tubercle on Finger IV is bifid. The relative length of adpressed toes is I <II <III ≤ V <IV. The webbing formula is I 1 + — 2 II 1 + — 2 ½ III 1 1/3 — 2 1/3 IV 2 ½ — 1 V.

Measurements of the holotype (in mm): SVL 41.9; HL 14.2; HW 14.5; TL 22.4; FL 27.6; ED 5.2; TD 3.7; FD 2.2; EN 4.6; IN 3.1; TE 2.2.

Coloration: Dorsally grayish brown, indistinctly marbled with dark brown; Flanks marbled white and brown; throat and chest with bold brown blotches on cream ground; posterior half of abdomen and ventral surfaces of thighs light brown; hidden surfaces of arms and legs boldly marbled with brown and cream. The tibiofibular bones are white.

Comparisons: The only known female is much smaller than both female O. festae (78.9 mm) and O. cabrerai (71.8 mm), and smaller than female O. buckleyi (54.1 mm). Other differences to O. cabrerai include the outer edge of Finger IV, which is tuberculate in its proximal half and smooth in the distal half (with an irregular fringe in O. cabrerai ) and there are no tubercles on the lower jaw (present in O. cabrerai ). It differs from O. festae in the coloration of the posterior surfaces of thighs in preservative, which are tan with light short vermiculation (uniform brown). It differs from O. buckleyi , O. cabrerai and O. festae in having a longer snout. The snout is round in dorsal view, while O. buckleyi usually has a bluntly rounded to truncate snout.

Osteocephalus inframaculatus may be diagnosed as (1) a medium-sized species with sexual dimorphism unknown; (2) skin on dorsum of female tuberculate; (3) anterior two thirds of the flanks areolate; (4) canthus rostralis indistinct, rounded, curved inward; (5) frontoparietal ridges not visible through skin; (6) dentigerous processes of vomers angular; (7) tuberculate supratympanic fold from the midlevel of the eye sloping posterior to the tympanum towards the flanks up to about midlevel of the tympanum; (8) web on inner edge of third finger reaching halfway between penultimate and ultimate subarticular tubercle; (9) distal subarticular tubercle on Finger IV bifid; (10) dorsum grayish brown, indistinctly marbled with dark brown; (11) ventrally anterior half with large brown blotches on cream ground, posterior half light brown; (12) several light markings on the upper lip, the largest one posteroventral to the midlevel of the eye to the tympanum; (13) flanks marbled white and brown; (14) position of vocal sacs unknown; (15) juvenile coloration unknown; (16) tadpole habitat and labial tooth row formula unknown; (17) color of tibiofibular bones white in preservative.

Figures

FIGURE 5. Osteocephalus inframaculatus (holotype): a. dorsolateral, b. ventral view, c. posterior surface of thigh and cloacal area. Not to scale.