Pristimantis stipa, Venegas, Pablo J. & Duellman, William E., 2012

Venegas, Pablo J. & Duellman, William E., 2012, Two syntopic new species of the Pristimantis orestes Group (Anura: Strabomantidae) from northwestern Peru, Zootaxa 3249, pp. 47-59 : 55-57

Pristimantis stipa new species

Figs. 1 (C & D), 6(A–D), 7

Holotype: CORBIDI 0 2833, an adult female, from Cañaris, Provincia de Ferreñafe, Región Lambayeque, Perú (6˚7'14.4" S, 79˚18'4.43" W; 3596 m.a.s.l.) obtained on 16 June 2007 by Pablo J. Venegas.

Paratypes: CORBIDI 02834–37, four adult males, collected with the holotype by Pablo J. Venegas.

Diagnosis. This member of the Pristimantis (Pristimantis) orestes Group has: (1) skin on dorsum areolate; that on flanks and venter coarsely areolate; discoidal fold only present as a prominent thoracic fold; dorsolateral fold prominent, discontinuous; (2) tympanic annulus present, weakly defined; tympanic membrane distinct; (3) snout bluntly rounded in dorsal view and in lateral view; (4) upper eyelid tubercles absent; upper eyelid nearly as wide as, or equal to IOD; cranial crests absent; (5) dentigerous processes of vomers prominent, oblique, narrowly separated; (6) vocal slits absent; spinous nuptial pads absent; (7) Finger I shorter than Finger II; discs on fingers narrow, rounded, without marginal grooves; (8) lateral fringes on fingers absent; (9) ulnar tubercles present, coalesced into a low fold; (10) heel and outer edge of tarsus lacking tubercles; inner tarsal fold present; (11) inner metatarsal tubercle prominent, elevated, elliptical, twice as large as lower oval outer metatarsal tubercle; plantar surface areolate; (12) lateral fringes on toes and webbing absent; Toe V slightly shorter than Toe III; toe discs narrow, rounded, without marginal grooves; (13) dorsum entirely brown without markings; groin, posterior surface of thigh, and concealed surfaces of shank and foot dark brown with or without white marks; ventral surfaces dark brown with white spots or mottling; (14) SVL in adult males 15.6–24.4 mm (x = 18.8; n = 4), in one adults female 35.1 mm.

Pristimantis stipa differs from all other species of Pristimantis , including the 15 species currently assigned to the P. o re s t e s Group, except P. s i m o n s i i, by the following combination of characters: dorsum areolate; discs on fingers and toes narrow without discernable marginal grooves; and ulnar tubercles coalesced into low fold. However, it is easily distinguished from P. s i m o n s i i by having dentigerous processes of vomers prominent (absent in P. simonsii ); tympanic annulus and membrane distinct (absent); and Toe V slightly shorter than Toe III (Toes III and V about equal in length). In lacking well-defined marginal grooves on the discs on the fingers and toes, P. stipa can be confused with Phrynopus . The only species of Phrynopus known from the Cordillera Occidental is P. thompsoni from farther south in Región La Libertad. This species of Phrynopus differs from Pristimantis stipa by having longitudinal rows of pustules on the dorsum, tympanic annulus and membrane absent, Fingers I and II equal in length, and venter tan with brown spots.

Description of the holotype. Adult female with robust body; head narrow, not as wide than body, wider than long; head width 37.6% of SVL; head length 30.4% of SVL; snout short lacking terminal tubercle, bluntly rounded in dorsal and lateral views; eye–nostril distance 69.2% of eye diameter; nostrils rounded, directed dorsolaterally; canthus rostralis straight in dorsal view, slightly curved in profile; loreal region concave; lips rounded; upper eyelid lacking tubercles; upper eyelid width 96.7% of IOD; tympanic annulus present, weakly defined, with the posterodorsal margin obscured by supratympanic fold, tympanum diameter 35.8% of eye diameter, tympanum–eye distance about 1.5 times tympanum diameter; one enlarged postrictal tubercle on left side and two different-sized postrictal tubercles on right side. Choanae small, ovoid, not concealed by palatal shelf of maxilla; dentigerous processes of vomers prominent, oblique, narrowly separated, situated posteromedial to choanae, each bearing three teeth; tongue twice as long as wide, notched behind, free posteriorly for two thirds of its length.

Skin on dorsum areolate; dorsolateral fold prominent, fleshy, and discontinuous; skin on flanks, ventral surfaces of thighs, belly, chest, and throat coarsely areolate; discoidal fold only present as prominent thoracic fold; cloacal sheath short; cloacal region tuberculate. Ulnar tubercles coalesced into low fold; palmar tubercles fleshy, elevated, outer palmar tubercle bifid, approximately twice size of ovoid, thenar tubercle; distal subarticular tubercles weakly defined, except proximally, round in ventral and lateral views; supernumerary tubercle sat bases of Fingers II and III distinct; fingers lacking lateral fringes; Finger I shorter than Finger II; discs on fingers narrow with rounded tips; pads on fingers lacking circumferential grooves ( Fig. 1 C).

Hind limbs slender, tibia length 34.1% of SVL; foot length 39.6% of SVL; upper surfaces of hind limbs areolate; posterior and ventral surfaces of thighs areolate; heel lacking tubercles; outer surface of tarsus lacking tubercles; short inner tarsal fold present; inner metatarsal tubercle prominent, elliptical, twice size of low, oval outer metatarsal tubercle; plantar surface areolate; subarticular tubercles well defined, round in ventral and lateral views; toes lacking lateral fringes; webbing absent; discs on toes narrow with rounded tips, like those on fingers; toes lacking circumferential grooves; relative lengths of toes: 1<2<3>5<4 ( Fig. 1 D); Toe III slightly longer than Toe V (disc on Toe V reaching to third subarticular tubercle on Toe IV, tip of the disc on Toe III extending to distal edge of distal subarticular tubercle on Toe IV).

Measurements of the holotype (in mm): SVL 35.1; tibia length 12.0; foot length 13.9; head length 10.7; head width 13.2; eye diameter 3.9; tympanum diameter 1.4; interorbital distance 3.1; upper eyelid width 3.0; internarial distance 2.9; eye–nostril distance 2.7.

Color of holotype in life: The dorsum was brown ( Fig. 6 A); the groin, posterior and anterior surface of thighs, concealed surface of shanks and dorsal surface of feet were blackish brown with irregular dirty white blotches, and the venter dark brown with white spots ( Fig. 6 B). The iris was grayish white with brown mottling.

Color of holotype in preservative ( Fig. 7 ): In ethanol, the coloration is as described above, except that the blackish brown is brown, and the dirty white blotches are white; iris greenish is gray with a fine brown mottling.

Variation. The morphology and coloration of the paratypes are identical to the holotype ( Fig. 6 : C & D). Males are smaller than females, lack vocal slits, and have white nuptial pads on the dorsal and medial surfaces of thumb. The mottling on the throats of males is brownish cream ( Fig. 6 D). See Table 1 for measurements and proportions of the type series.

Distribution and natural history. Pristimantis stipa is known only from the type locality in a humid puna above tree line, at an elevation of 3596 m.a.s.l., on the eastern slope of the Cordillera Occidental in northwestern Peru ( Fig. 5 ). There it occurs syntopically with P. mariaelenae .

Etymology. The specific name is a noun in apposition. It is the generic name of the feather grass ( Pooideae ) that is common at the type locality and in most areas above tree line and below snow line in Peru.

Remarks. The type locality, Cañaris, has been poorly explored herpetologically. It is located in the northeastern corner of the Región Lambayeque at the right margin of the Río Huancabamba (2500–3800 m.a.s.l.). The general landscape is a humid puna with scattered patches of elfin forest and cloud forest partially cleared for cattle ranching and cropland. The destruction of the natural habitats in Cañaris by the local people has been continuous since the 1970s; however, the general area is currently under new human pressure because of mineral exploration. Other surveys by the senior author in Cañaris and the nearby locality of Incahuasi recorded more species of strabomantid frogs, including Lynchius sp., P. chimu , P. petrobardus , P. phoxocephalus , and three species of Prisitmantis. Inasmuch as the unidentified species of strabomantids might be new species, probably all of the recorded species, except for P. phoxocephalus , are restricted to the northern portion of the Cordillera Occidental in Peru. It is well known that most members of the Pristimantis orestes Group have limited distributional ranges (Lehr 2007). Although some large patches of cloud forest still remain, the humid puna is strongly overgrazed by cattle and is frequently burned ( Fig. 8 ); a high probability of future mining activity is a significant new potential threat.

Figures

FIGURE 1. (A, B) Hand and foot of Pristimantis mariaelenae. (C, D) Hand and foot of Pristimantis stipa. Scale bars = 3 mm. Photos by L. Alza.

FIGURE 5. Distribution of Pristimantis mariaelenae and P. stipa in Peru. The red dot indicates the type locality of both species, the only locality where these species are known to date. White circles are major cities for reference.

FIGURE 6. Living adults of Pristimantis stipa. (A, B) Dorsolateral and ventral views of the female holotype, CORBIDI 2833, 35.1 mm SVL. (C, D) Dorsolateral and lateral views of a male paratype, CORBIDI 2834, 24.4 mm SVL. Photos by PJV.

FIGURE 7. Preserved Pristimantis stipa (holotype) in dorsal (left), and ventral (rigth) views. Photos by PJV.

FIGURE 8. Habitat at the type locality of Pristimantis mariaelenae and P. stipa on May 2007. The bunch grass is Stipa sp. Photo by PJV.