Pristimantis spectabilis, Duellman, William E. & Chaparro, Juan Carlos, 2008

Duellman, William E. & Chaparro, Juan Carlos, 2008, Two distinctive new species of Pristimantis (Anura: Strabomantidae) from the Cordillera Oriental with a distributional synopsis of strabomantids in Central Peru, Zootaxa 1918, pp. 13-25 : 19-21

Pristimantis spectabilis new species

Holotype: MHNC 7073, a subadult female, from Santa Bárbara, 3300 m, Distrito Huancabamba, Provincia Oxapampa, Departamento Pasco, Peru (10°20' 14.71" S, 75°38' 27.73" W), obtained on 5 May 2008 by Amanda J. Delgado.

Diagnosis. The new species is placed in the Pristimantis (Pristimantis) unistrigatus Group (as defined by Hedges et al., 2008a) because it has expanded digital discs supported by T-shaped terminal phalanges, Finger I shorter than Finger II, and Toe V much longer than Toe III. It has: (1) skin on dorsum smooth; that on venter smooth with scattered small tubercles; discoidal fold absent; dorsolateral folds absent; (2) tympanic membrane differentiated; tympanic annulus distinct, its length about 56% length of eye; (3) snout rounded in dorsal view and in profile; (4) upper eyelid lacking tubercles, much narrower than IOD; cranial crests absent; (5) dentigerous processes of vomers absent; (6) condition of vocal slits and nuptial pads unknown; (7) Finger I much shorter than Finger II; discs expanded, elliptical, about 1.5 times width of digit proximal to disc; (8) fingers lacking lateral fringes; (9) row of low subconical ulnar tubercles; (10) heel lacking tubercles; outer edge of tarsus bearing row of low, rounded tubercles; distinct inner tarsal fold; (11) inner metatarsal tubercle ovoid, elevated, about 3 × subconical outer metatarsal tubercle; supernumerary plantar tubercles few, low on proximal segments; (12) toes lacking lateral fringes; webbing absent; Toe V much longer than Toe III; discs slightly smaller than those on fingers; (13) dorsum mottled brown and black with discrete white spots and white interorbital bar; venter tan with dark gray spots and midventral line; (14) SVL unknown in males, 22.7 mm in single female.

The coloration alone distinguishes Pristimantis spectabilis from all other Peruvian members of the genus. The only other Peruvian member of the Pristimantis unistrigatus Group with smooth skin on the venter is P. diadematus Jiménez de la Espada, a much larger species (females up to 44.5 mm SVL) in the Amazon Basin. It differs from P. s p e c t a b i l i s by having fringes on the fingers and toes, lacking ulnar tubercles, having a narrower IOD (upper eyelid about 75% IOD, contrasted to 39% in P. s p e c t a b i l i s), and by having an entirely different color pattern. Among Peruvian Pristimantis , the pale interorbital bar is essentially unique to P. spectabilis . Some individuals of an Amazonian species, P. luscombei Duellman and Mendelson , have a cream or tan interorbital bar that is expanded anterior to the snout or posteriorly to the occipital region.

Description of holotype. A subadult female with head narrower than body, head width 29.5% of SVL; head length 35.2% of SVL; snout short, rounded in dorsal view and in profile, barely protruding beyond margin of lower jaw; eye-nostril distance 74% of diameter of eye; nostrils slightly protuberant, directed laterally at level just behind anterior margin of lower lip. Canthus rostralis nearly straight, rounded in profile, not elevated; loreal region noticeably concave; lips slightly flared; internarial region not depressed; top of head flat; upper eyelid lacking tubercles; its width 38.6% of IOD; cranial crests absent; supratympanic fold thin, extending from posterior edge of orbit, angling ventrally at point posterodorsal to tympanum, barely obscuring upper edge of tympanum; tympanic annulus distinct, smooth; tympanic membrane differentiated, smooth; tympanum round, 55.5% of diameter of eye, separated from eye by distance slightly greater than diameter of tympanum; one slightly enlarged postrictal tubercle. Choanae small, ovoid, not obscured by palatal shelf; dentigerous processes of vomers not evident; tongue about twice as long as wide, shallowly notched behind, posterior two thirds not adherent to floor of mouth.

Skin on all surfaces smooth; discoid fold not evident; dorsolateral folds absent; cloacal sheath short, no tubercles in cloacal region. Ulnar tubercles low, subconical; thenar tubercle elliptical, elevated; palmar tubercle deeply bifid, elevated; subarticular tubercles large, rounded, none bifid; supernumerary tubercles absent; fingers rather short, lacking lateral fringes; relative lengths of fingers I <II <IV <III; Finger I much shorter than Finger II; discs on Fingers III and IV elliptical, about 1.5 times width of digit proximal to disc; all fingers having terminal ventral pads weakly defined by circumferential grooves ( Fig. 1 C). Hind limbs slender; when hind limbs flexed perpendicular to axis of body heels overlap by about one fourth length of shank; tibia length 50.7% of SVL; foot length 48.9% of SVL; heel lacking tubercles; outer edge of tarsus bearing row of low, rounded tubercles; distinct inner tarsal fold on distal three-fourths of tarsus; inner metatarsal tubercle ovoid, elevated, about three times size of subconical outer metatarsal tubercle; toes slender, lacking lateral fringes, bearing elliptical terminal discs slightly smaller than those on fingers; webbing absent; relative lengths of toes I <II <III <V <IV; Toe III much shorter than Toe V; Toe III not extending to antepenultimate subarticular tubercle on Toe IV; Toe V extending nearly to proximal base of penultimate subarticular tubercle on Toe IV; subarticular tubercles large, rounded; supernumerary tubercles few, only on proximal segments of toes IV and V ( Fig. 1 D).

Coloration in preservative: Dorsum of body and limbs brown with conspicuous white interocular bar and small spots on body and shanks; flanks tan with two broad diagonal marks on each side; limbs brown with darker brown transverse bars—one each on wrist, forearm, and tarsus, two each on thigh and shank. Head markings consisting of three dark brown labial bars on dull tan lips and dark brown postorbital bar; canthal stripe absent. Posterior surfaces of thighs tan except for large, triangular, black subcloacal patch. Venter dull tan with black markings—diffuse spots, narrow midventral line from throat to posterior edge of abdomen, and narrow diagonal marks laterally on throat; palmar and plantar surfaces black with tan tubercles and toe pads.

Coloration in life: Dorsum dull brown with chocolate brown markings narrowly outlined in cream; narrow irregular dorsolateral tan area confluent with ground color on dorsal aspects of flanks, becoming reddish orange ventrally ( Fig. 3 ). Markings on head consisting of dark brown labial bars on reddish brown upper lips, dark brown postorbital stripe, pair of dark brown oval spots outlined with cream anterior to level of orbits, and broad greenish white interocular bar on anterior parts of upper eyelids; small greenish white spots on dorsum of body and shanks. Posterior surfaces of thighs reddish brown; ventral surfaces reddish orange with scattered black flecks, irregular, narrow black line from throat to posterior part of abdomen, and diagonal bars laterally on throat; palmar and plantar surfaces mostly black with orange tubercles.

Measurements of holotype in mm: SVL 22.7, tibia length 11.5, foot length 11.1, head length 8.0, head width 6.7, IOD 4.4, internarial distance 2.2, width of upper eyelid 1.7, diameter of eye 2.7, eye-nostril distance 2.0; diameter of tympanum 1.5.

Distribution and ecology. This species is known only from the type locality at an elevation of 3300 m at the upper limits of the elfin forest or “ceja de montaña,” where the terrestrial Phrynopus miroslawae Chaparro, Padial , and De la Riva was found under moss. The single specimen of Pristimantis spectabilis was perched on a leaf about 60 cm above the ground at night in the dry season.

Etymology. The specific name is a Latin adjective meaning showy or notable and refers to the rather gaudy color pattern of this species.

Remarks. Persons unfamiliar with the diversity of strabomantid frogs, especially Pristimantis in the Andes, might look askance at the act of describing a species based on a single specimen. However, the type specimen of P. spectabilis is so strikingly different from any other species known from the region that we do not hesitate to name it as a new species.

We tentatively place this species in the unistrigatus Group of the subgenus Pristimantis . As noted by Hedges et al. (2008a), this group is a catch-all and certainly is not monophyletic. We anticipate that molecular data will aid in the placement of this species, which is like members of the Pristimantis unistrigatus Group in having Toe V much longer than Toe III, but it differs from most members of the group in having smooth skin on all surfaces and weak circumferential grooves on the digits.

Figures

FIGURE 3. Pristimantis spectabilis— A and B. Dorsal and ventral views of the holotype, MHNC 7073, subadult female, 22.7 mm SVL. Photographed prior to preservation.

FIGURE 1. A and B. Hand and foot of Pristimantis lucasi. C and D. Hand and foot of Pristimantis spectabilis. Scale bars = 3 mm.