Psychrophrynella usurpator, Riva, Ignacio De La, Chaparro, Juan C. & Padial, José M., 2008

Riva, Ignacio De La, Chaparro, Juan C. & Padial, José M., 2008, A new, long-standing misidentified species of Psychrophrynella Hedges, Duellman & Heinicke from Departamento Cusco, Peru (Anura: Strabomantidae), Zootaxa 1823, pp. 42-50 : 44-47

Psychrophrynella usurpator , new species

( Figs. 1–3 )

Holotype. KU 138939, adult female, one of a series collected by W. E. Duellman, T. H. Fritts, I. Ceballos, and O. Ochoa on 16 January 1971 at N slope of Abra Acjanacu, 29 km NNE Paucartambo (13º12’S, 71º37’W), Departamento Cusco, Peru, 3400 m.

Paratypes. KU 138937–8, 138940–9, and 138951–62, same data as holotype; MHNC (Museo de Historia Natural de Cusco) 4642–3, collected by J. C. Chaparro on 19 February 2003 at Pantillacocha, Kosñipata Valley, Provincia Paucartambo (13º12’S, 71º33’W), Departamento Cusco, Peru, 3539 m.

Diagnosis. (1) Medium size (maximum SVL 24.1 mm in females), body moderately robust; legs moderately long (TL + FL 78–87% SVL in females); (2) tympanic membrane absent; tympanic annulus visible through the skin; (3) first finger slightly shorter than second ( Fig. 2 ); (4) tips of digits barely swollen, not expanded laterally; (5) webbing of toes and lateral fringes absent; (6) two metatarsal tubercles; an oblique, prominent, elongate inner tarsal tubercle, clearly separated from inner metatarsal tubercle; tarsal fold absent ( Fig. 2 ); (7) dorsal skin and ventral skin smooth; (8) snout rounded in dorsal view and in profile; (9) dorsum gray to brown; (10) venter brown flecked with cream.

At the type locality, P. usurpator is syntopic with Bryophryne cophites , which is distinguished from P. usurpator by being more robust, lacking a visible tympanic annulus, having Finger I shorter than Finger II, and having dorsal and ventral skin areolate (see Fig. 96 in Hedges et al., 2008, and Fig. 1 in Lehr & Catenazzi, 2008). Within Psychrophrynella , P. usurpator is unique in having a prominent, elongate, oblique tarsal tubercle. For Pristimantis, Lynch & Duellman (1997) described a tarsal fold as "a more or less clearly defined ridge extending a variable distance proximal to the inner metatarsal tubercle", and distinguished it from a tarsal tubercle when it is within one length of the inner metatarsal tubercle and if it appears to be connected to it. In P. usurpator , the tarsal tubercle is usually clearly separated from the inner metatarsal tubercle and it is not a simple dermal structure but a true tubercle; however, it may be prolongated as a fine rim toward the inner side of the tarsus, forming a structure similar to a tarsal fold (but perhaps not homologous to it). Another species, P. bagrecito (Lynch) , from Río Marcapata below Marcapata, ca. 2740 m, Departamento Cusco (approximately 90 km airline SE of Abra Acjanacu), also has a tarsal tubercle, but it is smaller and sickle-shaped; in addition, P. bagrecito is smaller (maximum SVL of males 16.3 mm, females 18.6; Lynch, 1986) than P. usurpator (20.3 and 24.1 mm, respectively). The second geographically closest species, P. boettgeri Lehr occurs in Departamento Puno, approximately 220 km (airline) SE of Abra Acjanacu. Psychrophrynella usurpator differs from P. boettgeri in having smooth ventral skin (areolate in P. b o e t t g e r i), a tarsal tubercle (absent), larger size (maximum SVL 24.1 in P. usurpator , 18.4 in P. boettgeri ), and lacking dorsolateral folds (present). Seventeen species of Psychrophrynella are known from Bolivia ( De la Riva 2007; Hedges et al. 2008); besides some morphological and color pattern differences, none has a tarsal tubercle, as in P. usurpator .

Description of the holotype. Body moderately robust; dorsal skin smooth with some scattered minute tubercles; ventral skin smooth; no dorsolateral or pectoral folds; head wider than long, its width 30% of SVL; head length 29% of SVL; head length 94% of head width; snout rounded in dorsal view and in profile; nostrils not protuberant, directed laterally, closer to snout than to eyes; canthus rostralis moderately sharp, slightly concave in dorsal view, convex in profile; eye-nostril distance 81% of eye length; loreal region barely concave, interorbital region flat, lacking cranial crests; no tubercles on upper eyelid; tympanic membrane absent; tympanic annulus visible through skin; supratympanic fold weak; three conical postrictal tubercles on left side, two on right side; tongue large, oval, not notched; choanae round, small, widely spaced; vomerine odontophores absent. Limbs moderately long; tips of digits barely swollen, not expanded laterally; ulnar tubercles and fold absent; thenar tubercle single, oval, flattened, smaller than round palmar tubercle; fingers moderately long, not fringed; subarticular tubercles round, those at the bases of proximal phalanges swollen; first finger slightly shorter than second, relative length of fingers 1<2<4<3; tibia length 41% of SVL; an inner, oblique tarsal tubercle; no tarsal fold; two metatarsal tubercles, the oval inner one approximately same size as conical outer one; supernumerary tubercles small, poorly defined; subarticular tubercles of toes round, moderately large; toes not webbed, lateral folds absent; relative length of toes 1<2<5<3<4; foot length 46% of SVL.

Measurements (in mm) of the holotype. Snout-vent length, 24.1; head length (from rictus to tip of snout), 7.0; head width (at level of rictus), 7.4; internarial distance, 2.8; eye-nostril distance (straight line distance between anterior corner of orbital opening and posterior margin of external nares), 2.6; eye diameter, 3.1; tibia length, 10.0; foot length (from proximal margin of inner metatarsal tubercle to tip of fourth toe), 11.0.

Color and variation. In preservative, the holotype has dorsum, head, extremities, and groin uniformly chocolate brown; throat and venter brown, paler than dorsum, with beige flecks; ventral surfaces of thighs uniformly brown; dark brown stripe from tip of snout to above insertion of hind limb, outlined by fine cream line; pale cream transversal line above the vent. Overall, color in life is similar, but no particular data are available on the color of the living holotype.

Living specimens have “venter bluish-gray with brown reticulations; throats in males dull grayish-brown; iris dark brown with gold flecks; dorsal coloration highly variable but predominately dark brown with orange and dull red markings; some have tan and/or gray markings” (W. E. Duellman’s field notes on the series KU 138937–64). Lynch (1975) stated that, in life, the dorsal ground color varies from dull brown, tan, tannishorange, to reddish; if dorsal markings are present, they are dull red, tan, or gray; also, there may be an orange or yellow middorsal stripe ( Fig. 3 ; see also Fig. 100 in Hedges et al., 2008); the venter is bluish-gray with brown reticulations, and males have dull grayish-brown throats; the iris is dark brown with gold flecks. Males have vocal sacs and vocal slits, but no nuptial pads. For morphometric variation, see Table 1 .

Distribution and ecology. The species is known only from elevations of 3270–3539 m in the vicinity of the type locality ( Fig. 4 ). Abra Acjanacu is a high pass in the Cordillera de Paucartambo, which is the easternmost Andean range facing the Amazonian lowlands in Departamento Cusco. Duellman (1978) described the locality and provided a detailed map of the area.

Individuals are commonly found under rocks in humid puna. Psychrophrynella usurpator was found syntopically with Bryophryne cophites (Lynch) , Gastrotheca excubitor Duellman & Fritts , G. marsupiata (Duméril & Bibron) , and Telmatobius timens De la Riva, Aparicio & Ríos (W. E. Duellman, pers. comm.). Etymology. The specific name is a sustantive in apposition and it is the Latin word for usurper. The name refers to the fact that this species has been using a name that actually belongs to frogs of another genus. Remarks. Calls of Psychrophrynella usurpator have not been analyzed. Individuals were heard calling in mid-afternoon, and the call is a series of short, quickly repeated, moderately high notes (W. E. Duellman’s field notes). No data are available on life history.

Figures

FIGURE 1. Living specimen of Psychrophrynella usurpator sp. nov. (MHNC 4642, paratype) from Pantillacocha, N slope of Abra Acjanacu, Departamento Cusco, Peru. Photograph by JCC.

FIGURE 2. Palmar and plantar surfaces of holotype (KU 138939) of Psychrophrynella usurpator sp. nov. The arrow points the prominent, oblique tarsal tubercle. Photograph by JMP.

FIGURE 3. Specimen of Psychrophrynella usurpator sp. nov. (KU 173323) with yellow middorsal stripe. Photograph by WED.

FIGURE 4. Map of western South America showing the type locality of Psychrophrynella usurpator sp. nov. in southern Peru.

Tables

TABLE 1. Morphometrics of Psychrophrynella usurpator sp. nov. Means followed by ranges in parentheses. For abbreviations, see text.

	Females (n = 7)	Males (n = 8)
SVL	23.4 (22.7–24.1)	20.0 (19.5–20.3)
HL	8.0 (7.0–8.7)	7.5 (7.3–7.8)
HW	7.7 (7.4–7.9)	7.2 (7.1–7.2)
IND	2.7 (2.7–2.8)	2.0 (1.9–2.1)
END	2.5 (2.4–2.6)	2.1 (1.9–2.1)
ED	3.1 (3.1–3.2)	3.0 (2.9–3.0)
TL	9.8 (9.5–10.1)	8.6 (8.5–8.8)
FL	10.3 (9.8–11.1)	9.3 (9.2–9.3)
HL/SVL	0.3 (0.3–0.4)	0.4 (0.4–0.4)
HW/SVL	0.3 (0.3–0.3)	0.4 (0.4–0.4)
END/ED	0.8 (0.8–0.8)	0.7 (0.6–0.7)
TL/SVL	0.4 (0.4–0.4)	0.4 (0.4–0.4)
FL/SVL	0.4 (0.4–0.5)	0.5 (0.5–0.5)