Pristimantis leucorrhinus, Boano, Giovanni, Mazzotti, Stefano & Sindaco, Roberto, 2008

Boano, Giovanni, Mazzotti, Stefano & Sindaco, Roberto, 2008, A new peculiar frog species of the genus Pristimantis from Yanachaga-Chemillén National Park, Peru, Zootaxa 1674, pp. 51-57 : 52-53

Pristimantis leucorrhinus sp. nov.

Holotype. MHNSM 19996 ( Fig. 1 ), a single female from the cloud forest surrounding the Refugio El Cedro (10°32.7’S, 75°21.4’W) at m 2500, collected on 11.XI.2006, Distrito de Chontabamba, Provincia de Oxapampa, Departamento de Pasco, Peru, by G. Boano, S. Mazzotti and R. Sindaco.

Diagnosis. A member of the Pristimantis unistrigatus group having: (1) skin on dorsum shagreen, skin on venter areolate (mostly anteriorly), discoidal fold absent, dorsolateral folds in the scapular region only; (2) tympanic membrane and tympanic annulus absent; (3) snout short, rounded in dorsal and lateral views, swollen in the nostril region and slightly depressed between nostrils; (4) upper eyelid with many small tubercles and one large, horn-like tubercle ( Fig. 1 , inset b), eyelid slightly narrower than interorbital distance, cranial crests absent; (5) vomerine teeth small; (6) condition of vocal slits and nuptial excrescences unknown; (7) Finger I shorter than Finger II, discs on outer fingers broadly expanded, rounded; (8) fingers without lateral fringes; (9) ulnar tubercles present; (10) heel with single tubercle ( Fig. 1 , inset a), tarsal tubercles present; inner tarsal fold absent; (11) inner metatarsal tubercle rather large, ovoid, about 3x rounded outer metatarsal tubercle, few supernumerary plantar tubercles, low, diffuse; (12) toes with lateral fringes, webbing absent, Toe V longer than Toe III (condition “C” according to Duellman & Pramuk 1999), discs on toes slightly smaller than those on fingers; (13) dorsum cream and brown with dark brown markings, top of snout creamy white, venter brownish-grey with small black turbercles and a few white spots; black throat, black groin with two irregular white spots on the anterior surfaces of the thighs (Fig. 2); (14) snout to vent length (thereafter SVL) 21.1mm in the only known specimen.

Pristimantis leucorrhinus is readily distinguished from all other species known from Peru by the combination of prominent, horn-like supraocular tubercles, a distinctive black and white pattern of the groin and a brownish iris with darker reticulations. Thirteen other Peruvian species ( P. altamazonicus , colodactylus , coronatus , cruciocularis , flavobracatus , imitatrix , lirellus , martiae , quaquaversus , rhabdocnemus , simonsii , tantanti , and ventrimarmoratus ) lack a differentiated tympanic membrane and annulus. None of these has a hornlike supraocular tubercle, and none has a color pattern like that of P. leucorrhinus . In particular, the very similar P. flavobracatus ( Lehr et al. 2006) differs also by the colour (yellow) and pattern on groin and thighs, and by the colour of the iris, gold with fine black reticulations, with a broad dark-brown horizontal streak across pupil, and a narrow black vertical streak from pupil to lower margin of eye forming a “T”.

Description of the holotype. Head almost as wide as body, slightly wider than longer; head width 39,3 % of SVL; head length 33.2 % SVL; snout short, rounded in dorsal and lateral views, swollen in nostril region with internarial region depressed; distance between eye and nostril 90% of eye diameter; nostrils directed dorsolaterally; canthus rostralis curved downwards in dorsal view, straight in profile; loreal region slightly concave; lips rounded; upper eyelid bearing many tubercles, five of them prominent, apical one more than twice as large as others; upper eyelid width 92% of interorbital distance; supratympanic fold weak, tympanic annulus and tympanic membrane absent; enlarged postrictal tubercles absent. Choanae small, rounded; vomerine teeth small; tongue rounded, 1.14 times as wide as long (length 4.2 mm, width at midlength of tongue 4.8 mm), not notched posteriorly, posterior three-fourths free.

Skin on dorsum shagreen; dorsolateral folds present in the scapular region only; skin on flanks smooth with few, scattered spicules; skin on belly and chest areolate (mostly so anteriorly); discoidal fold absent; large tubercles in cloacal region on proximal half of posterodorsal surfaces of thighs. Forelimbs with low ulnar tubercles; palmar tubercles slightly elevated, outer tubercle approximately twice size of inner one; supernumerary tubercles below Fingers II–IV round, low, subequal in size to subarticular tubercles well defined, round in ventral view and subconical in lateral view, most prominent on base of Finger I; fingers with lateral fringes; relative length of fingers I <II <IV <III; discs on fingers expanded, largest on Fingers III–IV, rounded; all fingers having pads well defined by circumferential grooves ( Fig. 3 a). Hind limbs slender, tibia length 52.6% of SVL; foot length 40.8% of SVL; upper surfaces of hind limbs smooth; posterior and ventral surfaces of thighs areolate; heel bearing single, strongly elevated, flat, subtriangular tubercle (less developed on left leg); tarsus with two small, elongate, low tubercles; tarsal fold absent; inner metatarsal tubercle low, elliptical, about twice size of outer metatarsal tubercle; some low plantar supernumerary tubercles; subarticular tubercles well defined, round in ventral view, subconical in lateral view; toes with lateral fringes, not webbed; discs on toes slightly smaller than those on fingers, most prominent on Toes IV–V, well defined by circumferential grooves; relative length of toes is I = II <III <V <IV; Toe V much longer than Toe III (disc on Toe III not reaching distal subarticular tubercle on Toe IV, tip of the disc on Toe V extending to distal bor- der of distal subarticular tubercle on Toe IV) ( Fig. 3 b).

Figures

FIGURE 1. The holotype of Pristimantis leucorrhinus in dorsolateral view; a) particular of the heel; b) particular of the eye (photo G. Gertosio).

FIGURE 3. Sketch of the tubercles arrangement under hand (A) and foot (B).