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We describe a new species of Osteocephalus Fitzinger, 1843 using morphological traits of adult frogs and its larvae, as well as molecular evidence. The new species occurs in the premontane forest of the Cordillera del Yanachaga in the Andes of central Peru, at elevations between 1000 and 1150 m a.s.l. It belongs to the Osteocephalus mimeticus species group and is the sister species of O. mimeticus. It is most similar to three species with predominantly dark irises, tuberculate dorsal skin, and brown dorsal coloration: O. festae Peracca, 1904, O. mimeticus Melin, 1941, and O. verruciger Werner, 1901. Of these three species, the most similar is O. mimeticus. However, the new species can be easily distinguished from O. mimeticus by having a cream or creamy-tan venter with a well-defined pattern of brown chocolate blotches and flecks (venter cream, tan, or brown without marks in O. mimeticus). The tadpoles of O. vasquezi sp. nov. are strikingly different from the tadpoles of O. mimeticus by having a larger oral disk with nine lower labial tooth rows (only six in O. mimeticus). Tadpoles of the new species and those of O. festae are unique among Osteocephalus by belonging to the suctorial ecomorphological guild as shown by their large oral disks. Our time tree suggest that the new species diverged from its sister species at the beginning of the Pleistocene, ~2.5 million years ago.

Stenocercus nigrocaudatus sp. nov. Figures 6–7 Holotype. CORBIDI 19768, an adult male from San Lorenzo, San José de Lourdes (5º4’33.16”S, 78º52’53.749”W, 1,892 m), San Ignacio Province, Cajamarca Department, Peru, collected by P.J. Venegas on 5 September 2018. Paratypes (8): CAJAMARCA DEPARTMENT: San Ignacio Province: CORBIDI 4387, an adult male from Tabaconas (5°14’8.16”S, 79°5’56.58”W, 1,716 m) collected by Maik Dobiey in August 2008; CORBIDI 4388-90, adult females, from Namballe (5°11’40.139”S, 79°4’49.738”W, 1,716 m) collected by M. Dobiey in August 2008; CORBIDI 19765-66, adult females, and CORBIDI 19767 and 19769, adult males, from San Lorenzo, San José de Lourdes (5°4’33.16”S, 78°52’53.749”W, 1,892 m), collected by P.J. Venegas on 5 September 2018. Diagnosis. Among the 80 species of Stenocercus (including the four species described herein), S. nigrocaudatus sp. nov. is only similar to species with granular scales on posterior surface of thighs, relatively short tail, caudal scales spinose, and two caudal whorls per autotomic segment; such as S. asenlignus sp. nov., S. arndti, S. qalaywasi sp. nov., S. flagracanthus, S. leybachi sp. nov., S. bolivarensis, S. carrioni, S. chlorostictus, S. crassicaudatus, S. empetrus, S. eunetopsis, S. torquatus and S. simonsii. Adult males of S. nigrocaudatus can be easily distinguished from the aforementioned species by a contrasting black tail with scattered turquoise flecks (Fig. 7C). Moreover, S. nigrocaudatus can be readily distinguished from S. qalaywasi, S. leybachi, S. bolivarensis, S. carrioni, S. chlorostictus, and S. eunetopsis by having granular scales on dorsal surface of neck (keeled in the compared species).Furthermore, S. leybachi possesses a distinct serrate low crest on neck (absent in S. nigrocaudatus), S. bolivarensis strongly keeled scales on flanks (granular), S. qalaywasi a distinct complete middorsally black antehumeral collar and two black nuchal bands (incomplete and absent, respectively), S. carrioni and S. chlorostictus by having strongly keeled dorsal scales on body (smooth and feebly keeled), and S. eunetopsis by having a longer tail with 62–66% of total length (50–55%). In addition, S. nigrocaudatus possesses more vertebrals (96–108) than S. carrioni (55–72), S. chlorostictus (63–73), and S. eunetopsis (59–80). Stenocercus nigrocaudatus shares with S. asenlignus, S. arndti, S. flagracanthus, S. crassicaudatus, S. empetrus, S. torquatus, and S. simonsii the presence of granular scales on neck. Nevertheless, the new species can be differentiated from these species by the coloration pattern, number of scales, or the length of tail. Adult males of S. arndti are easily distinguished from S. nigrocaudatus (state of character in parentheses) by having a bold black transverse band at midbody that extends ventrolaterally (bands on body absent); adult males of S. empetrus have the belly black (cream); S. simonsii has distinct black bands on body in both sexes (absent). Additionally, S. nigrocaudatus has a greater number of vertebrals (96–108) than S. arndti (74–94), more subdigitals (26–31) than S. empetrus (17–24), and a shorter tail in relation to the total length (50–55%) than S. simonsii (57–63%). Stenocercus asenlignus and S. flagracanthus differ from S. nigrocaudatus in having dorsal scales on the posterior half of body strongly keeled and mucronate (feebly keeled in S. nigrocaudatus). Moreover, adult males of S. asenlignus and S. flagracanthus have black bands on the body (absent in S. nigrocaudatus). Stenocercus crassicaudatus has a longer tail (57–62% of total length) than S. nigrocaudatus (50–55%). Adult males of S. torquatus differ from S. nigrocaudatus in having the antehumeral black collar complete middorsally and two distinct black nuchal transverse bands, whereas the new species has the antehumeral collar incomplete middorsally and lacks nuchal bands. Characterization. (1) Maximum SVL in males 72 mm (n = 4); (2) maximum SVL in females 76 mm (n = 5); (3) vertebrals 96–108; (4) paravertebrals 110–128; (5) scales around midbody 99–117; (6) supraoculars 5–7; (7) internasals 4–5; (8) postrostrals 5–6; (9) loreals 3–7; (10) gulars 48–59; (11) lamellae on Finger IV 26–31; (12) lamellae on Toe IV 30–36; (13) posthumeral mite pocket present as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)]; (14) postfemoral mite pocket distinct with slit-like opening [Type 2 of Torres-Carvajal (2007b)]; (15) parietal eye absent; (16) occipital scales small, smooth, juxtaposed; (17) projecting angulate temporal absent; (18) row of enlarged supraoculars occupying most of supraocular region absent; (19) scales on frontonasal region juxtaposed and smooth, not imbricate; (20) preauricular fringe short; (21) antegular, antehumeral, gular, longitudinal, oblique, postauricular, and supra-auricular neck folds present; (22) lateral nuchals and dorsals similar in size; (23) lateral body scales smaller than dorsals; (24) vertebrals enlarged, forming a distinct row of scales from forelimbs to hindlimbs; (25) dorsolateral crest absent; (26) paravertebrals and adjacent scales from midbody, smooth or feebly keeled, becoming keeled on the second half of body and mucronate between hindlimbs; (27) ventral scales smooth, imbricate; (28) scales on posterior surface of thighs granular; (29) prefemoral fold present; (30) inguinal fold present; (31) preanals not projected; (32) tail not compressed laterally; (33) tail relatively short (tail length 50–55% of total length); (34) caudal whorls per autotomic segment two; (35) tail spinose; (36) postocular stripe present; (37) dark patch on gular region in males absent; (38) dark patch on gular region in females absent; (39) black patch on ventral surface of neck in adult males absent; (40) dark midventral stripe in adult males absent; (41) dark patch on ventral surface of thighs, vent and tail in adult males absent; (42) background color of dorsum green, dark brown or olive green in both sexes; (43) postxiphisternal inscriptional ribs not examined. Description of holotype. Male (Fig. 6); SVL 57 mm; TL 114 mm; maximum head width 12.3 mm; head length 16.3 mm; head height 10.1 mm; scales on parietal and occipital regions small, smooth, juxtaposed, subequal in size; parietal eye not visible: supraoculars six, smooth, juxtaposed; circumorbitals absent; canthals two; loreals one; postrostrals four; internasals four; supralabials five; infralabials five; lorilabials in one row; preocular divided into two scales, most dorsal in contact with posterior canthal; lateral temporals granular; gulars in 55 rows between tympanic openings; all gulars cycloid, smooth, imbricate; second infralabial in contact with first, second and third sublabials; first pair of postmentals in contact; mental not separated from the infralabials by the first pair of postmentals; dorsal and lateral scales of neck and body granular; scales around midbody 107; vertebrals 104 moderately enlarged, keeled, imbricate, forming distinct vertebral row; paravertebrals and adjacent scales slightly smaller than vertebrals, smooth, subimbricate, becoming feebly keeled from the posterior half of dorsum and strongly keeled near hindlimbs insertion; paravertebrals 127; scales on flanks granulars; ventrals smooth, imbricate, more than twice the size of dorsals, only paravertebrals on the second half of body, nearly equal in size or slightly longer than ventrals; preauricular fringe short composed of three enlarged scales with round edge; suprauricular, antehumeral, gular, longitudinal, oblique, antegular, postauricular and rictal neck folds present; dorsolateral, ventrolateral and prefemoral folds present; dorsal scales of forelimbs imbricate, keeled; dorsal scales of hindlimbs imbricate, strongly keeled and mucronate; ventral humeral scales granular; ventral scales of fore- and hindlimbs smooth, imbricate; palmar scales imbricate, keeled and minutely mucronate; plantar scales imbricate, smooth or strongly keeled and mucronate; lamellae on Finger IV 28; lamellae on Toe IV 35; tail rounded (tail length 50% of total length); caudal scales strongly keeled, mucronate, imbricate; basal subcaudal scales smooth, imbricate; posthumeral mite pocket present as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)]; postfemoral mite pocket distinct with slit-like opening [Type 2 of Torres-Carvajal (2007b)]. Color in life (Fig. 7 A-C): head and neck brownish gray with white flecks on head and white dots on neck; labials white with dark brown bars; postocular stripes dark brown, extending through the temporal and edge of occipital region to a black rhomboid blotch in the nuchal region; antehumeral collar black, distinct; dorsal surface of body green covered by bright green dots; forelimbs green with scattered bright green dots; hindlimbs brown with scattered white flecks and dots on posterior surface of thighs; tail black with scattered turquoise flecks on the basal half. Ventrally, gular region grayish white with white dots and black flecks; neck gray with few scattered black flecks; chest and belly cream with an orange hue on the posterior half; thighs, cloacal region, and tail dull orange. Iris dark brown. Color in ethanol 70% (Fig. 6 D-E): the dorsal surface turns dark brownish gray; postocular stripes and the nuchal blotch remain black; the white dots on the neck and the scattered white flecks on hindlimbs are dirty white; the bright green dots on the body and forelimbs are pale gray; tail turns dark brown. Ventrally, the gular region and neck is pale gray with dirty white dots and scattered black flecks, and chest, belly, limbs and base of tail are grayish white; the two distal thirds of the tail are dark brown with grayish white bars. Intraspecific variation. Measurements and scutellation of Stenocercus nigrocaudatus are presented in Table 1. Supralabials 4–5; infralabials 5–6; no specimens showed the second infralabials in contact with third sublabial; first pair of postmentals in contact medially in eight specimens (88.8%). Females larger than males (see Table 1), and both sexes are able to change color from green to dark brown or grayish brown. Sexual dimorphism in coloration is evident in the tail, which is black with scattered turquoise speckles in males (Fig. 7C) and brown with black and gray speckles in the proximal half and dark brown with gray rings in the distal half in females (Fig. 7J). The antehumeral collar is bold black in males and faint black or dark gray in females. Ventrally, the gular region in females is gray with scattered black flecks and speckles, the chest has a greenish hue, the belly is grayish white, and the ventral surface of hindlimbs, cloacal region and tail are tannish cream (Fig. 7I). The single female juvenile specimen (CORBIDI 19766) is dorsally identical to the adult female, but the gular region and chest possess a green hue. Distribution and natural history. Stenocercus nigrocaudatus is known from both sides of the inter-Andean valley of the Chinchipe River in the Cajamarca Department of northeastern Peru, between elevations of 1,700 and 1,892 m (Fig. 3). The two known localities of this species lie at the Yungas (500–2,300 m) ecoregion according to Brack-Egg (1986) and Peñaherrera del Águila (1989), and Eastern Cordillera Real montane forest following Olson et al. (2001). The general landscape in Alto Ihuamaca is composed of humid montane forest covering the steepest slopes and open areas with croplands for corn (Zea mays), coffee (Coffea sp.), and pastures for cattle ranching. In San José de Lourdes, the general landscape includes pastures for cattle ranching and small croplands for coffee, mango (Mangifera indica), and oranges (Citrus sp.), with some scattered patches of secondary forest and fringes of forest bordering ravines and along streams. Several individuals of S. nigrocaudatus were observed basking during sunny days between 900 and 1,500 hours. In small villages and single houses in the field, we observed individuals of S. nigrocaudatus basking on the walls at heights between 2 and 3 m (Fig. 7L), and one individual was observed at 7 m in the wall of a small building. This species also was common in open areas for cattle ranching basking on big tree trunks between 1 and 8 m above ground (Fig. 7K). Up to five individuals, a pair of adults and three juveniles, were observed in the same tree. All individuals observed basking showed a green dorsal coloration that changed to brownish gray to the moment of be captured. Sympatric squamate reptiles collected with S. nigrocaudatus were Alopoglossus buckleyi, Atractus gigas, Enyalioides anisolepis, and Potamites strangulatus; and in San José de Lourdes only Varzea altamazonica. Etymology. The specific epithet nigrocaudatus is a noun in apposition that derives from the Latin word “ nigrum ” that means black and “cauda” that means tail, with the suffix “ tus ” that means provided with. It refers to the black tail that is characteristic of the adult males of this new species.

Stenocercus asenlignus sp. nov. Figures 1–2 & 10 Holotype. CORBIDI 20219, an adult male, from Omia (6°28’12.702”S, 77°23’45.187”W, 1,381 m), Rodríguez de Mendoza Province, Amazonas Department, Peru, collected by P.J. Venegas and L.A. García-Ayachi on 5 December 2018. Paratypes (24): PERU: SAN MARTÍN DEPARTMENT: Mariscal Cáceres Province: MUSM 23034, adult male, MUSM 23035–38, adult females, and MUSM 23039, a juvenile, from El Dorado (06°46’00”S, 77°32’42”W, 1,600 m), collected by P.J. Venegas between 6 and 8 December 2003; CORBIDI 00622 adult female from Los Chilchos (06°42’28.7”S, 77°34’0.9”W, 1,800 m), collected by P.J. Venegas on 28 January 2008; CORBIDI 14780, adult male from Río Lejía (06° 50’11.6”S, 77°29’09.7”W, 1,500 m), collected by M. Salas on 14 June 2012; AMAZONAS DEPARTMENT: Rodríguez de Mendoza Province: CORBIDI 15658, juvenile, from Omia village (6°27’58.5”S, 77°23’50.9”W, 1,390 m), collected by A. García-Bravo on 11 November 2014; CORBIDI 20215–16, 20218, and 20221, adult males, CORBIDI 20214, 20217, and 20220, adult females, and CORBIDI 20222, a juvenile male, from Omia (6°28’12.702”S, 77°23’45.187”W, 1,381 m), collected by P.J. Venegas and L.A. García-Ayachi on 5 December 2018; CORBIDI 20135, adult female, from Santo Toribio village (6°1’55.179”S, 77°19’45.308”W, 1,622 m), collected by P.J. Venegas and A. García-Ayachi on 11 November 2018; CORBIDI 20198, juvenile female, CORBIDI 20199, juvenile male, and CORBIDI 20200–01, adult females, from Fundo Playas del Inca, Santo Toribio, Vista Alegre (6°1’56.356”S, 77°21’6.385”W, 1,682 m), collected by P.J. Venegas and L.A. García-Ayachi on 17 November 2018; CORBIDI 23003, a juvenile, from Limabamba (6°37’53.98”S, 77°26’22.33”W, 2,036 m), collected by Ivan Wong on 30 July 2019; HUÁNUCO DEPARTMENT: Marañón Province: CORBIDI 19549, adult female, from Nuevo Cajhán village, Cholón (8°52’8.076”S, 76°28’44.688”W, 1,625 m), collected by L.A. García-Ayachi on 23 June 2017. Diagnosis. From the 76 previously known species Stenocercus and the new species described herein, only S. arndti, S. leybachi sp. nov., S. bolivarensis Castro & Ayala, 1982, S. carrioni Parker, 1934, S. chlorostictus Cadle, 1991, S. crassicaudatus, S. empetrus, S. eunetopsis, S. flagracanthus, S. nigrocaudatus sp. nov., S. qalaywasi sp. nov., S. torquatus and S. simonsii Boulenger, 1901, share with S. asenlignus granular scales on posterior surface of thighs, relatively short tail, caudals spinose, and two caudal whorls per autotomic segment. However, S. torquatus and S. qalaywasi, are easily distinguished from S. asenlignus (state of character between parentheses) by having transverse black nuchal bands (absent), a middorsally complete antehumeral black collar (incomplete) and, only in the case of S. torquatus (Fig. 10A), the dorsum is emerald green without bands (green with black bands in males). Moreover, S. qalaywasi possesses a longer tail with 57–60 % of the total length versus 49–57% in S. asenlignus. Live male individuals of S. nigrocaudatus can be readily distinguished from S. asenlignus by having the tail black with scattered turquoise spots (tail light brown or grayish brown with dark gray spots or bands) and the body without dorsal black bands (present). In addition, in S. asenlignus the dorsal scales of the body are keeled, becoming gradually strongly keeled and mucronate toward the hindlimb insertion and in S. nigrocaudatus dorsal scales are smooth and feebly keeled becoming strongly keeled but not mucronate close to the hindlimbs insertion. Stenocercus leybachi can be readily distinguished from S. asenlignus by having a distinct, low, serrate crest on the neck that can reach or not to the middle of dorsum, while in S. asenlignus, vertebrals form an indistinct row of enlarged scales along the body. Moreover, S. asenlignus has more vertebrals than S. leybachi (71–106, = 89.8 versus 63–73, = 68.6, respectively). Stenocercus torquatus has more scales around midbody than S. asenlignus (102 to 137, = 116.9 versus 78 to 111, = 96.4, respectively). The recently described S. flagracanthus differs from S. asenlignus in having a tail strongly armed with projected mucronate scales that are less developed in S. asenlignus. In the distal half of the tail of S. flagracanthus the spines are conspicuously alternating in size, with large spines followed by small spines per each caudal whorl, and in S. asenlignus, the alternation in size of spines is undistinguishable. Dorsal scales between the posterior half of body and hindlimbs insertion become enlarged and strongly keeled with strongly projected mucronate scales in S. flagracanthus, while in S. asenlignus, they are keeled and, in some specimens, slightly mucronate. Furthermore, the dorsal and gular pattern is different in both species (state of characters in S. flagracanthus between parentheses): usually adult males of S. asenlignus possess a “zig-zag” pattern of black dorsal bars on dorsum (bold black bars; see Fig. 11 in Venegas et al. 2020a), antehumeral collar bordered by cream spots (cream line), and preserved specimens have the gular region gray with scattered black flecks (gray with cream dots). The other species such as S. carrioni, S. chlorostictus and S. eunetopsis differ from S. anselignus by having dorsal scales of neck keeled and imbricate (granular in S. asenlignus). Stenocercus eunetopsis has a considerably longer tail than S. asenlignus (64–66% of total length vs. 49–57%, respectively), and S. chlorostictus has a strong sexual dichromatism, with the dorsal background color bright green in males and brown in females (males and females gray, brown or green in S. asenlignus). Stenocercus bolivarensis differs from S. asenlignus by having strongly keeled and imbricate lateral body scales (Torres-Carvajal 2007b), which are granular or smooth in S. asenlignus. Stenocercus asenlignus differs from S. crassicaudatus by having fewer paravertebrals (92 to 118, = 105.8 versus 107 to 166, = 126.6), and a shorter tail (49 to 57% of total length versus 57 to 62%). Males of S. arndti are easily distinguished from S. asenlignus by having a bold black transverse band at midbody that extends ventrolaterally (absent in S. asenlignus) and dorsal scales of neck slightly keeled and subimbricate (granular in S. asenlignus). Stenocercus simonsii differs from S. asenlignus (character states in parentheses) by having dorsals imbricate, moderately keeled, but not mucronate (dorsals granular in the anterior half of body, getting gradually enlarged and keeled from the posterior half of body to strongly keeled and mucronate near to the hindlimbs insertion). Stenocercus empetrus differs from S. asenlignus by having the venter yellowish-orange with black reticulations, or completely black, whereas in the new species the venter is gray without reticulations. In addition, S. simonsii and S. empetrus are larger than S. asenlignus (maximum SVL = 88 mm in males and 79 mm in females of S. simonsii, SVL = 103 mm in males and 90 mm in females of S. empetrus, and maximum SVL = 73 mm in males and 70 mm in females of S. asenlignus). Characterization. (1) Maximum SVL in males 73 mm (n = 9); (2) maximum SVL in females 70 mm (n = 14); (3) vertebrals 71–106; (4) paravertebrals 92–118; (5) scales around midbody 78–111; (6) supraoculars 5–8; (7) internasals 4–5; (8) postrostrals 4–6; (9) loreals 2–6; (10) gulars 47–60; (11) lamellae on Finger IV 23–30; (12) lamellae on Toe IV 28–34; (13) posthumeral mite pocket present as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)]; (14) postfemoral mite pocket distinct with slit-like opening [Type 2 of Torres-Carvajal (2007b)]; (15) parietal eye absent; (16) occipital scales small, smooth, juxtaposed; (17) projecting angulate temporal absent; (18) row of enlarged supraoculars occupying most of supraocular region absent; (19) scales on frontonasal region juxtaposed, smooth, not imbricate; (20) preauricular fringe short; (21) antehumeral, gular, longitudinal, oblique, postauricular, supra-auricular, antegular neck folds present; (22) lateral nuchals and dorsals similar in size; (23) lateral body scales smaller than dorsals; (24) vertebrals slightly enlarged, forming a distinct row of scales from forelimbs to hindlimbs; (25) dorsolateral crest absent; (26) paravertebrals and adjacent scales from midbody keeled, becoming strongly keeled and mucronate at the posterior half of body; (27) ventral scales smooth, imbricate; (28) scales on posterior surface of thighs granular; (29) prefemoral fold present; (30) inguinal fold present, weakly defined; (31) preanals not projected; (32) tail not compressed laterally; (33) tail relatively short (tail length 49–57% of total length); (34) caudal whorls per autotomic segment two; (35) tail spinose; (36) postocular stripe absent or present; (37) gular region in males dark gray with black dots; (38) gular region in females grayish yellow with light green dots; (39) black patch on ventral surface of neck in adult males absent; (40) dark midventral stripe in adult males absent; (41) dark patch on ventral surface of thighs, vent and tail in adult males absent; (42) background color of dorsum green, brown or grayish in both males and females, with a “zig-zag” pattern of black transversal bands in adult males; (43) two long postxiphisternal pairs of inscriptional ribs not in contact midventrally (pattern 4A of Torres-Carvajal, 2004). Description of holotype. Male (Fig. 1); SVL 69 mm; TL 88 mm; maximum head width 14.61 mm; head length 17.93 mm; head height 11.20 mm; scales on parietal and occipital regions small, smooth, juxtaposed, subequal in size; parietal eye not visible: supraoculars seven, smooth, juxtaposed; circumorbitals absent; canthals two; loreals three; postrostrals four; internasals four; supralabials five; infralabials five; lorilabials in one row; preocular divided into three scales, most dorsal in contact with posterior canthal; lateral temporals granular; gulars in 57 rows between tympanic openings; all gulars cycloid, smooth, imbricate; second infralabial in contact with first, second and third sublabials; first pair of postmentals in contact; mental not separated from the infralabials by the first pair of postmentals; dorsal and lateral scales of neck and body granular; scales around midbody 97; vertebrals 90 enlarged, keeled, imbricate, forming distinct vertebral row; paravertebrals and adjacent scales slightly smaller than vertebral row, keeled, imbricate, becoming mucronate from midbody to hindlimb insertion; paravertebrals 100; ventrals smooth, imbricate, more than twice the size of dorsals, except for paravertebrals at the second half of body, which are nearly equal in size or slightly longer than ventrals; preauricular fringe short, composed of four enlarged, granular scales; suprauricular, antehumeral, gular, longitudinal, oblique, antegular, postauricular and rictal neck folds present; dorsolateral, ventrolateral and prefemoral folds present; dorsal scales of forelimbs imbricate, keeled; dorsal scales of hindlimbs imbricate, strongly keeled and mucronate; ventral humeral scales granular; ventral scales of fore and hindlimbs smooth, imbricate; palmar scales imbricate, keeled; plantar scales imbricate, strongly keeled, mucronate; lamellae on Finger IV 23; lamellae on Toe IV 29; tail rounded (tail length 55% of total length); caudal scales strongly keeled, mucronate, imbricate; basal subcaudal scales smooth, imbricate; posthumeral mite pocket present as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)]; postfemoral mite pocket distinct with slit-like opening [Type 2 of Torres-Carvajal (2007b)]. Color in life of holotype: dorsally green (from head to the anterior half of body, including forelimbs) speckled with dark gray flecks and with transverse rows of light green dots; posterior half of body and hindlimbs pale brown with the same pattern of flecks and dots scattered of the green half but the light green dots are faint on hindlimbs; tail light brown with black speckles and black bands on the distal third; incomplete middorsal black collar at antehumeral fold and a dorsal “zig-zag” pattern of black bands on vertebral line. Ventrally, the gular region is dark gray with scattered black flecks, chest pale green and venter grayish white. Once captured, it quickly changes its dorsal color from green to brownish gray, with scattered black flecks and cream dots (Fig. 2A). Limbs change from green with black flecks to gray with scattered black flecks and pale cream dots. Distal portion of tail remains light brown with black bands. Iris dark brown. Color in preservative (Fig. 1 D-E): dorsal surface dark gray with scattered black and pale dots, dorsal “zig-zag” bands pattern remains evident. Gular region dark gray with black dots and venter gray. Intraspecific variation. Measurements, scutellation, and other morphological characters of Stenocercus asenlignus are presented in Table 1. Supralabials 4–7; infralabials 4–7; second infralabials in contact with third sublabials in all specimens, except in MUSM 23035; first pair of postmentals in contact medially only in the specimen MUSM 23039. In two dissected specimens, the pattern was three xiphisternal and two long postxiphisternal pairs of inscriptional ribs not in contact midventrally (Pattern 4A; Torres-Carvajal 2004). Sexual dimorphism in size is slightly noticeable (Table 1). The head of adult males looks more robust than the females, and both sexes are able to change color from green to brownish gray or bluish gray in males (Fig. 2) and green to dark gray or pale brown in females. Black collar and “zig-zag” bands dorsal pattern are distinct only in males (Fig. 2A, C & L) and absent or faint in females (Fig. 2D, F & H) and juveniles (Fig. 2I). In adult females throat can be cream with gray flecks and the chest dirty cream (Fig. 2E) or throat grayish green with light green dots and chest green (Fig. 2G), and the venter is gray with a pink tone (Fig. 2E). Juveniles have the throat yellowish with light yellow flecks (Fig. 2J) or green with light green flecks, and the chest and ventral surface of forelimbs pale green. Some males possess transverse rows of yellow or light green dots on body surface and the throat and chest yellowish when basking (Figs. 2K & 10B). Distribution and natural history observations. Stenocercus asenlignus is known from five localities along the Amazon slope of the northern portion of the Central Andes, along the Huallabamba River basin in the departments of Amazonas and San Martín, at elevations between 1500 and 2036 m (Fig. 3). According to Olson et al. (2001), the distribution of S. asenlignus lies inside the Peruvian Yungas ecoregion. At the localities of El Dorado and Río Lejía the habitat is characterized by dense primary forests with some coffee and yuca plots. In Los Chilchos the habitat was secondary forest with open areas for pasture. The general landscape in Playa Los Incas was open areas for cattle ranching near the rivers and slopes covered by primary montane forest. Omia is a small village surrounded by crops of coffee (Coffea sp.), cacao (Theobroma cacao) and mango (Mangifera indica). Most specimens were found on tree trunks inside the forest or at the edge of crop areas, between 2 and 3 m above ground; however, several uncollected individuals were observed at heights between 5 and 10 m. A couple of adult individuals were observed on the rocky slope of a cliff at 5 m height. One adult male (MUSM 23034) was collected on a wall of a “tambo,” a rural house made of logs. When disturbed it hid in a carpenter bee hole. Hatchlings and juveniles were observed basking on tambo walls and fallen trees around crops and near the base of large trees. In Omia village Stenocercus asenlignus is a common species and several individuals were observed basking on house walls and using the holes and crevices between bricks as retreats (Fig. 2L). Individuals observed basking on trees and house walls were found with green dorsum and at the moment of capture this changed abruptly to dark gray or brownish gray color. However, individuals observed on trees and rock walls in the shadow were also found with a grayish brown dorsum. Female CORBIDI 0622 (SVL = 61) collected in the rainy season (January 2008) had 2 and 4 follicles, in the left and right ovary, respectively. Female MUSM 23038 (SVL = 62 mm) had two underdeveloped eggs (pale yellow) that were 9.6–10.3 mm long, 8– 7.8 mm wide, and 156.82–172.57 mm 3 in volume. Female MUSM 23036 (SVL = 70 mm) had two fully developed eggs with white, hard shell (22–22.1 mm long, 8.5–8.6 mm wide and 393.42–396.25 mm 3 of volume); it was found digging a hole in a cavity between roots, this behavior suggests that it was building a nest to deposit the eggs. Also, the presence of hatchlings and juveniles around buttress roots suggests that S. asenlignus deposits their eggs between them. Both gravid females (MUSM 23036, 23038) and a juvenile (MUSM 23039, SVL = 37) were collected at the beginning of the rainy season (December, 2003). Stenocercus asenlignus is not sympatric with other Stenocercus or Tropiduridae species. The only known lizard species sympatric with S. asenlignus are Alopoglossus buckleyi, Anolis fuscoauratus, Cercosaura doanae, and Enyalioides sophiarothschildae. Etymology. The specific epithet asenlignus is a noun in apposition and derives from the Latin words “ asen ” (= climb or ascend) and “ lignus ” (= trunk). It refers to the arboreal habitus of the new species. Remarks. Stenocercus crassicaudatus was reported by Fritts (1974) for San Martín and Loreto departments, based on a neonate (AMNH 57176) and a subadult male (AMNH 57173), respectively, that were examined later by Torres-Carvajal et al. (2005). According to Torres-Carvajal et al. (2005), both specimens are more similar morphologically to S. torquatus; they concluded that S. crassicaudatus is restricted to Cusco Department. While in the absence of a major sample from Loreto and San Martín, they also concluded that S. torquatus is restricted to the Chanchamayo Valley and adjacent areas in Junín and Pasco departments in Central Peru (Torres-Carvajal et al. 2005). Although we did not review the specimens reported by Fritts (1974), we cons

Stenocercus qalaywasi sp. nov. Figures 8–9 Holotype. CORBIDI 20567, adult male from Lampa Pariahuanca, Pariahuanca district, Huancayo province, Junín Department, Peru (11°58’51.9”S, 74°53’47.6”O, 2,587 m), collected by Luis A. García-Ayachi on 19 June 2019. Paratype. CORBIDI 20568, an adult female collected with the holotype. Diagnosis. From all currently known species of Stenocercus (including the new species described herein), S. qalaywasi sp. nov. is only similar to thirteen species (e.g., S. asenlignus sp. nov., S. arndti, S. flagracanthus, S. leybachi sp. nov., S. bolivarensis, S. carrioni, S. chlorostictus, S. crassicaudatus, S. empetrus, S. eunetopsis, S. nigrocaudatus sp. nov., S. torquatus and S. simonsii) in sharing the following characters: granular scales on posterior surface of thighs, relatively short tail, caudals spinose, and two caudal whorls per autotomic segment. From these species, S. qalaywasi possesses a smaller number of vertebrals than S. nigrocaudatus and S. torquatus (77–79 in S. qalaywasi versus 96–108 in S. nigrocaudatus and 83–115 in S. torquatus), scales on dorsal surface of neck keeled (granular in S. asenlignus, S. nigrocaudatus and S. torquatus), a longer tail than S. asenlignus, S. nigrocaudatus and S. torquatus (tail length 57–60% of total length in S. qalaywasi, 51–55% in S. asenlignus, 50–55% in S. nigrocaudatus, and 47–54% in S. torquatus). Stenocercus leybachi is easily distinguished from S. qalaywasi by having a distinct, serrate, low crest on neck (absent in S. qalaywasi) and by lacking a distinct, black antehumeral collar (complete middorsally in S. qalaywasi). Stenocercus arndti, S. crassicaudatus, S. empetrus, S. flagracanthus, and S. simonsii can also be easily distinguished from S. qalaywasi by having the scales on dorsal surface of neck granular, while in the new species they are keeled. Furthermore, S. crassicaudatus and S. flagracanthus possess more vertebrals (83–97) than S. qalaywasi (77–79). In the case of S. flagracanthus, the tail is shorter (50–54% of total length) than S. qalaywasi (57–60%). Species such as S. bolivarensis, S. carrioni, S. chlorostictus, and S. eunetopsis possess keeled scales on the dorsal surface of neck, like S. qalaywasi, and preserved specimens can be confused. However, these species can be distinguished by the following features: from S. arndti, S. carrioni, S. chlorostictus, S. empetrus, and S. simonsii by having a distinct black, middorsally complete, antehumeral collar and two nuchal bands (antehumeral collar incomplete middorsally and nuchal bands absent in the aforementioned species); from S. carrioni and S. chlorostictus by having more vertebral scales (55–72 in S. carrioni, 63–73 in S. chlorostictus and 77–79 in S. qalaywasi); from S. bolivarensis by having the lateral scales of body granular (strongly keeled in S. bolivarensis); and from S. eunetopsis by having more scales around midbody (60–80 in S. eunetopsis and 87–92 in S. qalaywasi) and a shorter tail (57–60% of total length vs. 62–66% in S. eunetopsis). Characterization. (1) Maximum SVL in males 88 mm (n = 1); (2) maximum SVL in females 95 mm (n = 1); (3) vertebrals 77–79; (4) paravertebrals 104–108; (5) scales around midbody 87–92; (6) supraoculars six; (7) internasals four; (8) postrostrals six; (9) loreals five; (10) gulars 44; (11) subdigitals on Finger IV 26–29; (12) subdigitals on Toe IV 33–34; (13) posthumeral mite pocket present as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)]; (14) postfemoral mite pocket distinct with slit-like opening [Type 2 of Torres-Carvajal (2007b)]; (15) parietal eye not visible; (16) scales on occipitoparietal region small, rugose, juxtaposed; (17) projecting angulate temporal absent; (18) row of enlarged supraoculars occupying most of supraocular region absent; (19) scales on frontonasal region juxtaposed, rugose; (20) preauricular fringe present; (21) antegular, antehumeral, gular, longitudinal, and postauricular neck folds present; (22) lateral and dorsal nuchals similar in size; (23) posterior gulars cycloid, smooth, slightly imbricate, not notched; (24) lateral body scales smaller than dorsals, reduced in size, approximately one third of the size of dorsal body scales closer to vertebral line; (25) vertebrals larger than adjacent paravertebrals forming a distinct vertebral row; (26) dorsolateral crest absent; (27) ventrals smooth, imbricate; (28) scales on posterior surface of thighs granular; (29) prefemoral fold present; (30) inguinal groove present; (31) preanals not projected; (32) tail not compressed laterally in adult males; (33) tail relatively short (tail length 57–60% of total length); (34) two caudal whorls per autotomic segment; (35) caudals spinose; (36) dark stripe extending anterodorsally from subocular region to supraciliaries absent; (37) dark patch extensively covering gular region of females absent; (38) dark patch extensively covering gular region of adult males absent; (39) black patch on ventral surface of neck in adult males absent; (40) dark midventral longitudinal mark, such as faint line, conspicuous stripe, or extensive patch in adult males absent; (41) black patches on ventral surfaces of thighs in adult males absent; (42) background color of dorsum green or dark gray, with distinct black bands in adults individuals of both sexes; (43) postxiphisternal inscriptional ribs not examined. Description of the holotype. Male (Fig. 8); SVL 88 mm; TL 136 mm; maximum head width 16.8 mm; head length 21.4 mm; head height 13.2 mm; posterior dorsal head scales small, smooth, juxtaposed; parietal eye not visible; supraoculars in six rows, smooth, juxtaposed, with the most lateral two rows less than half the size of the medial adjacent rows; distinct circumorbitals absent; canthals two; internasals four; postrostrals five, two lateral ones larger; supralabials six; infralabials six; loreals four; lorilabials in one row; preoculars two, the dorsal-most in contact with posterior canthal; lateral temporals granular; gulars in 44 rows between tympanic openings; all gulars cycloid, smooth, imbricate, not notched; second infralabial in contact with first two sublabials; first pair of postmentals partially in contact medially; mental in contact with first pair of infralabials but not with the first pair of postmentals; dorsal scales of neck small, weakly keeled, slightly imbricate, and slightly larger than granular laterals; dorsal scales of body imbricate, keeled, becoming smaller, slightly keeled or smooth towards flanks; scales around midbody 87; vertebrals 77, enlarged, keeled, imbricate, forming a distinct vertebral row; paravertebrals adjacent to vertebral row 104, same size or slightly smaller than vertebrals; ventrals smooth, imbricate, larger than dorsals; preauricular fringe short, composed by two enlarged, projected scales; antegular, antehumeral, gular, longitudinal, and postauricular neck folds present; ventrolateral fold present; humeral dorsal scales imbricate, weakly keeled; dorsal scales of forelimbs imbricate, keeled; dorsal scales of hindlimbs imbricate, keeled, mucronate; ventral humeral scales imbricate; ventral scales of forearms keeled, imbricate, and ventral scales of hindlimbs imbricate, smooth; palmars imbricate, keeled; plantars imbricate, keeled, mucronate; lamellae on Finger IV 26; lamellae on Toe IV 33; tail rounded; caudals strongly keeled, mucronate, imbricate dorsally; two caudal whorls per autotomic segment; basal subcaudals strongly keeled, imbricate; posthumeral mite pocket present as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)]; postfemoral mite pocket distinct with slit-like opening; [Type 2 of Torres-Carvajal (2007b)]. Color in life of holotype (Fig. 9 A-C): Head bright green with a narrow gray postocular stripe and two gray stripes below it; dorsal surface of neck with two pale gray transverse bands and a distinct, middorsally complete black antehumeral collar; dorsum, limbs and tail with a green hue and scattered dark gray flecks; dorsum and forelimbs also covered by bright green specks; gular region dark gray, spotted with light gray blotches, and bearing a pale gray medial patch posteriorly; ventral surface of neck pale gray; chest greenish gray; belly light pink; ventral surface of hips and hindlimbs cream; cloacal region and ventral surface of base of tail cream with a light pink hue; ventral surface of tail gray becoming dark gray towards tip. Iris brown. Color in preservative (Fig. 8): dorsal surface dark gray; the postorbital gray stripe black; bands on neck and antehumeral collar black; dorsum with short irregular black bands along the vertebral region and covered with light gray specks; forelimbs covered with light gray specks and hindlimbs with darker bands than the gray background; fingers and toes light gray with black spots. Ventral surface similar as in life, but without the pink and green hues. Intraspecific variation. Scale counts and measurements for Stenocercus qalaywasi are presented in Table 1. Loreals 4–5; postrostrals 4–5; second infralabial not in contact with third sublabial in all specimens; first pair of postmentals in contact in both specimens. Sexual dimorphism is not evident in S. qalaywasi; the single female paratype (CORBIDI 20568) differs from the male holotype only in having the antehumeral black collar incomplete (Fig. 9E). Ventrally, the gular coloration is greenish cream with cream spots laterally in the female paratype (Fig. 9F), and dark gray with light gray spots in the male holotype. With a low sample of two specimens, the female is larger (95 mm) than the male (88 mm SVL). Distribution and natural history. Stenocercus qalaywasi is known only from the village of Lampa Pariahuanca in the inter-Andean valley of the Mantaro River in central Peru (Fig. 3). It occurs at an elevation of 2,587 m in the department of Junín. The type locality lies within the Peruvian Yungas ecoregion following Olson et al. (2001) and Yungas ecoregion according to Brack-Egg (1986) and Peñaherrera del Águila (1989). Six individuals of S. qalaywasi were observed basking on sunny days at 0900 hours on the rooftops of Lampa Pariahuanca village houses. When disturbed, they hid under the roof tiles, in holes between bricks or in the slit between roof and wall. The surrounded areas of the village are croplands of corn (Zea mays), potato (Solanum tuberosum), carrot (Daucus carota), and barley (Hordeum vulgare), with a few scattered patches of secondary montane forest on the steepest slopes. No other species of lizards or snakes were recorded at this locality. When the adult individuals of S. qalaywasi are basking, they possess the head bright green and the dorsal surface of body and tail with a green hue bearing conspicuous light green specks on back (Fig 9G). At the moment of capture the single male collected changed dramatically in coloration to dark gray with the dorsum containing light gray specks (Fig. 9A). The single collected female specimen did not show a dramatic change of coloration becoming simply dull green (Fig. 9D). Etymology. The specific epithet “ qalaywasi ” is a noun in apposition derived from two words in Quechua, “ qalaywa ” that means lizard and “ wasi ” that means home or house. The specific name refers to the habitus of this species of living in the houses of Lampa Pariahuanca village.

Stenocercus leybachi sp. nov. Figures 4–5 Holotype. CORBIDI 16397, an adult male, from Comunidad Saria, Chaglla (9°43’27.7”S, 75°48’35.9”W, 1,082 m), Huánuco Province, Huánuco Department, Peru, collected by D. Vásquez on 11 October 2015. Paratypes (22). PERU: HUÁNUCO DEPARTMENT: Huánuco Province: CORBIDI 9323, adult female, from Chinchavito (9° 33’ 27.2”S, 75° 55’ 07.1”W, 824 m), collected by P.J. Venegas on 16 June 2011; CORBIDI 13659, juvenile male, from Miraflores (9°41’0.11”S, 75°50’33.44”W, 1,270 m), collected by V. Duran and L. Lujan on 11 October 2013; CORBIDI 16390, a juvenile, CORBIDI 16394–95 and 16398, males, CORBIDI 16399–16400, females, from Saria, Chaglla (9°42’55.4”S, 75°49’3”W, 1,151 m), collected by D. Vásquez on 24 August 2015 and 10 October 2015; CORBIDI 16412 juvenile, CORBIDI 16428–29, 16431, females, CORBIDI 16432, juvenile, CORBIDI 16437, female, from Agua Nueva, Chinchao (9°41’59.82”S, 75°49’55.39”W, 1,115 m), collected by J. C. Chávez-Arribasplata within 24 to 28 September 2015 and 1 to 4 October 2015; CORBIDI 16525–26, a juvenile and female, CORBIDI 16532–33, male and juvenile, CORBIDI 16539, female, and CORBIDI 16594, juvenile, also from Agua Nueva, Chinchao (9°43’6.67”S, 75°48’56.1”W, 1,185 m), collected by A.C. Barboza within 10 to 15 November 2015; Pachitea Province: CORBIDI 13333, male, from Casa de Máquinas, Chaglla (9°42’17.81”S, 75°49’47.96”W, 928 m), collected by V. Duran and L. Luján on August 2013; CORBIDI 13334, male, from El Waro, Chaglla (9°41’55.87”S, 75°49’46.56”W, 927 m), collected by V. Duran and L. Luján on August 2013. Diagnosis. Stenocercus leybachi differs from all other Stenocercus species, except S. arndti, S. asenlignus sp. nov., S. bolivarensis, S. carrioni, S. chlorostictus, S. crassicaudatus, S. empetrus, S. eunetopsis, S. flagracanthus, S. nigrocaudatus sp. nov., S. qalaywasi sp. nov., S. torquatus, and S. simonsii, by having granular scales on posterior surface of thighs, relatively short tail, caudals spinose and two caudal whorls per autotomic segment. Nevertheless, S. leybachi can be easily distinguished from all aforementioned species by having a distinct serrate low crest on neck, that in some specimens reach to the middle of the dorsum. We found the arboreal S. chinchaoensis, a species known from the Upper Huallaga Basin at Huánuco Department (Venegas et al. 2013), sympatric with S. leybachi in the locality of Agua Nueva, Chinchao district, at elevations of 1,115 to 1,200 m. This species also has the ability to change color between green and gray, however this has a longer tail (tail length 61–64% of total length versus 52–58% of total length, respectively) and caudal scales not spinose. Stenocercus boettgeri is another green species distributed in the Amazon slope of central Peru from Huánuco, Pasco and Junín departments, at elevations between 2900 and 3250 m (Torres-Carvajal 2007b). Although this species can be confused with S. leybachi, the former species can be readily distinguished by having the lateral neck scales less than half the size of dorsal neck scales (dorsal and lateral neck scales similar in size in S. leybachi) and lacking a spinose tail. Characterization. (1) Maximum SVL in males 84mm (n=6); (2) maximum SVL in females 82mm (n=7); (3) vertebrals 63–73; (4) paravertebrals 100–112; (5) scales around midbody 74–97; (6) supraoculars 7–9; (7) internasals 4; (8) postrostrals 4–6; (9) loreals 3–5; (10) gulars 42–61; (11) subdigitals on Finger IV 21–28; (12) subdigitals on Toe IV 28–32; (13) posthumeral mite pocket present as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)]; (14) postfemoral mite pocket distinct with slit-like opening [Type 2 of Torres-Carvajal (2007b)]; (15) parietal eye not visible; (16) scales on occipitoparietal region small, some rugose and other smooth, juxtaposed; (17) projecting angulate temporal absent; (18) row of enlarged supraoculars occupying most of supraocular region absent; (19) scales on frontonasal region juxtaposed, smooth, slightly imbricate; (20) preauricular fringe present; (21) antegular, antehumeral, gular, longitudinal, and postauricular neck folds present; (22) lateral and dorsal nuchals similar in size; (23) posterior gulars cycloid, smooth, slightly imbricate, not notched; (24) lateral body scales smaller than dorsals, reduced in size, approximately one third of the size of dorsal body scales closer to vertebral line; (25) vertebrals larger than adjacent paravertebrals forming a conspicuous vertebral row and a distinct low serrate crest on neck that in some specimens comes to the middle of dorsum; (26) dorsolateral crest absent; (27) ventrals smooth, imbricate; (28) scales on posterior surface of thighs granular; (29) prefemoral fold present; (30) inguinal groove present; (31) preanals not projected; (32) tail not compressed laterally in adult males; (33) tail relatively short (tail length 52–58 % of total length); (34) two caudal whorls per autotomic segment; (35) caudals spinose; (36) dark stripe extending anterodorsally from subocular region to supraciliaries absent; (37) dark patch extensively covering gular region of females absent; (38) dark patch extensively covering gular region of adult males absent; (39) black patch on ventral surface of neck in adult males absent; (40) dark midventral longitudinal mark, such as faint line, conspicuous stripe, or extensive patch in adult males absent; (41) black patches on ventral surfaces of thighs in adult males absent; (42) background color of dorsum green, dark brown or gray and without distinct black bands in adult individuals of both sexes; (43) postxiphisternal inscriptional ribs not in contact midventrally [Pattern 4A of Torres-Carvajal 2004)]. Description of the holotype. Male (Fig. 4); SVL 83 mm; TL 117 mm; maximum head width 16.5 mm; head length 20.1 mm; head height 12.7 mm; posterior dorsal head scales small, smooth, slightly imbricate, juxtaposed; parietal eye not visible; supraoculars in seven rows, smooth, slightly imbricate, with the most lateral two rows less than half the size of the medial adjacent rows; distinct circumorbitals absent; canthals two; internasals four; postrostrals four, two median ones larger; supralabials six; infralabials five; loreals four; lorilabials in two rows; preoculars three, the middle one tiny, the dorsal-most in contact with posterior canthal; lateral temporals granular; gulars in 47 rows between tympanic openings; all gulars cycloid, smooth, slightly imbricate, not notched; second infralabial in contact with first three sublabials; first pair of postmentals not in contact medially; mental in contact with first pair of infralabials and first pair of postmentals; dorsal scales of neck keeled and lateral scales of neck granular; dorsal scales of body imbricate, keeled, feebly mucronate becoming smaller and slightly keeled to smooth towards flanks; scales around midbody 86; vertebrals enlarged, keeled, imbricate, in 73 rows, forming distinct vertebral row and a low serrate crest from the neck to the middle of dorsum; paravertebrals adjacent to vertebral row same size as dorsals, keeled, and imbricate; paravertebrals 107; ventrals smooth, imbricate, one third larger than dorsals; preauricular fringe short, composed of two enlarged, posteriorly projected scales; antegular, antehumeral, gular, longitudinal, and postauricular neck folds present; ventrolateral fold present; dorsal humeral scales imbricate, weakly keeled; scales of forearms imbricate, keeled; dorsal scales of hindlimbs imbricate, strongly keeled, mucronate; ventral humeral scales imbricate, weakly keeled; ventral scales of forearms and hindlimbs imbricate, smooth; palmars imbricate, weakly keeled; plantars imbricate, smooth; lamellae on Finger IV 24; lamellae on Toe IV 29; tail rounded (tail length 58% of total length); caudals strongly keeled, mucronate, imbricate dorsally; two caudal whorls per autotomic segment; basal subcaudals slightly keeled, imbricate; posthumeral mite pocket present as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)]; postfemoral mite pocket distinct with slit-like opening; [Type 2 of Torres-Carvajal (2007b)]. Color in life of holotype (Fig. 5 A-C): dorsum emerald green with whitish and turquoise spots on head and neck, and pale greenish yellow spots on dorsum; pelvic region, hindlimbs and tail pale brown covered by dark gray reticulations and pale greenish yellow spots; throat brownish gray with pale gray spots; ventral surface including base of tail dirty cream and rest of tail darker than the base. Once captured it quickly changes its dorsal color from green to dark brown, sprinkled with dirty cream spots on head and neck, and yellowish cream spots on dorsum; forelimbs, hindlimbs and tail dark grayish brown, darker on tail and with a greenish tone on forelimbs; some dirty cream spots are present on hindlimbs. Iris pale brown. Color in preservative (Fig. 4 D-E): head, forelimbs and dorsum to pelvic region greenish gray, sprinkled with cream spots; anterior surface of thighs greenish gray and the rest of hindlimbs, pelvic region and tail grayish brown with scattered dark gray flecks and reticulations. The last one third of tail is black. The throat is greenish gray without spots, the rest of ventral surface of body grayish cream. Intraspecific variation. Measurements,scutellation, and other morphological characters of Stenocercus leybachi are presented in Table 1. Supralabials 4–6; infralabials 5–6; second infralabials not in contact with third sublabials in sixteen specimens (69.5%); first pair of postmentals in contact medially only in four specimens (17.3%). In two dissected specimens, the rib pattern was three xiphisternal and two long postxiphisternal pairs of inscriptional ribs not in contact midventrally, [Pattern 4A of Torres-Carvajal (2004)]. Females are smaller than males (Table 1) and both sexes are able to change color from green to dark brown or grayish brown (see Fig. 5). The seven adult males in the type series lack a black antehumeral collar and of the seven adult females, one (CORBIDI 16429) possesses a middorsally complete collar. Complete black antehumeral collar is present in eight of nine juveniles, only one specimen (CORBIDI 16431) has an incomplete black collar. Adult specimens of both sexes and juveniles possess pale spots on dorsum and some specimens also have scattered black flecks. The throat in adult females can be brownish green with pale green spots, chest with a greenish tone and the belly is dirty cream with or without a pinkish hue on the belly and base of tail. Juveniles have throat and venter yellowish green. Distribution and natural history. Stenocercus leybachi is known from five close localities in the Amazon foothills of the Río Huallaga basin, at elevations between 824–1,270 m, in central Peru (Fig. 3). The known localities of this species lie in the Huánuco Department within the Yungas (500–2,300 m) ecoregion according to Brack–Egg (1986) and Peñaherrera del Aguila (1989), and Peruvian Yungas following Olson et al. (2001). The general habitat where the new species was collected is composed of croplands of coca (Erythroxylum coca), coffee (Coffea sp.), cacao (Theobroma cacao), corn (Zea mays), orange (Citrus sp.) and pastures for cattle ranching with scattered patches of secondary montane forest, especially on the steepest slopes. Individuals of S. leybachi were observed active during sunny days basking on tree trunks at 1.5–6 m above ground. When these individuals felt disturbed, they climbed the tree trunk finding refuge up high. Some individuals were observed and collected with a fishing rod while basking on fallen trees. The individuals found basking were light green and at the moment of capture suddenly changed to brown or brownish gray. Most specimens were collected in the forest canopy, during a flood for the construction of a hydroelectric dam. The specimens were collected by hand on the branches of high trees (5 to 10 m) from a boat, and some individuals tried to escape by hiding in tree holes (Fig. 5 K-L) and cracks in the bark of the trees. Stenocercus leybachi was syntopic in the area of the flood with other arboreal lizards such as Anolis punctatus, Euspondylus excelsum, and S. chinchaoensis. Other sympatric species of squamate reptiles collected with S. leybachi were: A. ortonii, Bothrops chloromelas, Dipsas catesbyi, D. indica, D. schunkii, Drymoluber dichrous, Enyalioides feiruzae, Micrurus annelatus, Oxyrhopus leucomelas, Phrynonax polylepis, Proctoporus sp., and S. prionotus. Etymology. The specific name leybachi is a patronym for Achim Leybach of Marktsteft, Germany, in recognition of his financial support for the taxonomic work and biodiversity research through the BIOPAT-Programme.

We provide information on the distribution, natural history, and conservation status of Nymphargus mixomaculatus (Guayasamin, Lehr, Rodriguez & Aguilar, 2006), a species from central Peru which is currently considered as Critically Endangered. We report four new localities and extend the altitudinal distribution by 430 m and the geographic range by 513 km in a straight line northwest of the previous, only known locality. Furthermore, based on our new data and following the criteria and categories of the International Union for Conservation of Nature, we suggest that N. mixomaculatus should be recategorized as Vulnerable.

Venegas, Pablo J., Echevarría, Lourdes Y., García-Ayachi, Luis A., Landauro, Caroll Z. (2020): Two new sympatric species of Stenocercus (Squamata: Iguania) from the inter- Andean valley of the Mantaro River, Peru. Zootaxa 4858 (4): 555-575, DOI: https://doi.org/10.11646/zootaxa.4858.4.5

Stenocercus nigrobarbatus sp. nov. Figures 6–10, Table 1. Holotype. CORBIDI 13725, adult male from Fundición (12°17’36.41”S, 74°39’39.67” W) at 2,158 m asl, Tayacaja Province, Huancavelica Region, Peru, collected on January 31, 2014 by L. Y. Echevarría. Paratypes. Peru: Huancavelica Department: Tayacaja Province: CORBIDI 13637 a juvenile female from Jatuspata (12°15’14.617’’ S, 74°41’ 16.93’’ W) at 2,972 m asl, collected on September 3, 2013 by C. Landauro; CORBIDI 13638 a juvenile female from Pichiu (12°19’11.815’’ S, 74°39’3.588’’ W) at 2,036 m asl, collected on September 13, 2013 by C. Landauro; CORBIDI 13640 juvenile female from Pichiu, collected on September 12, 2013 by C. Landauro; CORBIDI 13641 adult female from Barropata (12°17’21.943’’ S, 74°41’19.035’’ W) at 1,725 m asl, collected on October 2, 2013 by C. Landauro; CORBIDI 13639 and CORBIDI 13642 female juveniles from Fundición (12°17’32.347’’ S, 74°39’45.433’’ W), at 2,169 m asl, collected on September 28, 2013 by C. Landauro; CORBIDI 13718 adult male from Chupto (12°19’52.96” S, 74°39’13” W) at 2,058 m asl, collected on January 23, 2014 by L. Y. Echevarría; CORBIDI 13719 adult male from Chupto (12°18’22.19” S, 74°39’18.42” W) at 2,314 m asl, on January 24, 2014 by L. Y. Echevarría; CORBIDI 13722 adult female from Chupto (12°19’52.96” S, 74°39’13” W) at 2,058 m asl, collected on January 21, 2014 by L. Y. Echevarría; CORBIDI 13728 adult female from Barropata (12°17’34.95” S, 74°41’34.08” W) at 1,704 m asl, collected on February 2, 2014 by L. Y. Echevarría; CORBIDI 13729 adult female from Barropata (12°17’22.11” S, 74°41’19.07” W) at 1,783 m asl, collected on February 3, 2014 by L. Y. Echevarría; CORBIDI 14669 adult female from Chupto (12°18’48.18” S, 74°39’1.83” W) at 2,345 m asl, collected on July, 1 2014 by L. Y. Echevarría; CORBIDI 14674 adult female from type locality, collected on July 6, 2014 by L. Y. Echevarría; CORBIDI 14676 juvenile female and CORBIDI 14677 adult male from Barropata (12°17’37.66” S, 74°41’39.18” W) at 1,693 m asl, collected on July 7, 2014 by L. Y. Echevarría; CORBIDI 15765–66 (adult male and female, respectively) and CORBIDI 15767 (juvenile male) from Pichiu (12°15’31.57” S, 75°6’3.6” W) at 2,206 m asl, collected on January 14, 2015 by L. Lujan; CORBIDI 16033 adult male from Pichiu (12°19’50” S, 74°39’13.07” W) at 2,090 m asl, collected on July 9, 2015 by J. Malqui; CORBIDI 20546–47 two adult males from San Luis de Estanque (12º19’8.62” S, 74º44’24.19” W) at 2,636 m asl., collected on Jun 17, 2019 by L.A. García-Ayachi. Diagnosis. Adult males of Stenocercus nigrobarbatus can be easily distinguished from all species of Stenocercus by having a continuous black patch covering the infralabials, throat, chest, ventral surfaces of forelimbs, belly (as a black midventral line), ventral surfaces of hind limbs, and pelvic region (Figs. 6B, 8B, 9B and 9C). However, among the 69 currently described species of Stenocercus, S. nigrobarbatus resembles S. frittsi Torres-Carvajal, 2005, and S. variabilis Boulenger, 1901, by the following combinations of characters: (1) granular scales on the posterior surface of thighs, (2) imbricate and keeled lateral body scales, (3) a distinct row of enlarged vertebral scales, (4) unnotched gular scales, (5) three caudal whorls per autotomic segment, (6) brown dorsal ground color, and (7) distinct oblique neck fold, and antegular fold not continuous medially. Stenocercus nigrobarbatus differs from the geographically close S. frittsi (character state of latter in parenthesis) by having a postfemoral mite pocket composed by one or more vertical folds or ridges, Type 1 of Torres-Carvajal (2007a) (postfemoral pocket absent in S. frittsi), 2–4 postrostrals (5–7), and two pairs of postxiphisternal inscriptional ribs, long, not in contact midventrally, pattern 1A of Torres-Carvajal (2004) (three pairs of postxiphisternal inscriptional ribs, two pairs long and the last pair short, not in contact midventrally; pattern 2B of Torres-Carvajal 2004). Stenocercus nigrobarbatus can be distinguished from S. variabilis (character state in parenthesis) by having 2–4 postrostrals (6), postfemoral pocket composed by one or more vertical folds or ridges, Type 1 of Torres-Carvajal (2007a) (slit-like opening, Type 2 of Torres-Carvajal 2007a), and inguinal groove absent (present). In addition, lateral body scales in S. nigrobarbatus are slightly smaller than dorsals, while S. frittsi and S. variabilis have lateral body scales approximately half the size of dorsals. Characterization. (1) Maximum SVL in males 67.73 mm (n = 4); (2) maximum SVL in females 62.29 mm (n = 5); (3) vertebrals 47–73; (4) paravertebrals 69–87; (5) scales around midbody 57–74; (6) supraoculars 5–7; (7) internasals 3–5; (8) postrostrals 2–4; (9) loreals 3–7; (10) gulars 19–30; (11) lamellae on Finger IV 18–23; (12) lamellae on Toe IV 27–34; (13) posthumeral pocket as one or more vertical folds or ridges, Type 1 of Torres-Carvajal (2007a); (14) postfemoral pocket composed by one or more vertical folds or ridges, Type 1 of Torres-Carvajal (2007a); (15) parietal eye not visible; (16) occipital scales small, smooth, juxtaposed; (17) no projecting angulate temporals; (18) supraoculars of varying sizes; (19) scales in frontonasal region slightly imbricate anteriorly; (20) short preauricular fringe present; (21) antehumeral, antegular, gular, oblique, suprauricular and postauricular neck folds present; (22) nuchal mite pocket absent; (23) lateral nuchals less than half size of dorsal nuchals; (24) posterior gulars in adults smooth, imbricate, not mucronate; (25) lateral scales slightly smaller than dorsal body scales; (26) vertebrals larger than adjacent paravertebrals; (27) dorsolateral crest absent; (28) ventrals in adults smooth, imbricate, not mucronate; (29) scales on posterior surfaces of thighs granular; (30) inguinal granular pocket absent; (31) inguinal groove absent; (32) preanals not projecting; (33) tail not compressed laterally in adult males; (34) tail length 62–70% of total length; (35) three caudal whorls per autotomic segment; (36) caudals not spinose; (37) dark stripe extending anterodorsally from subocular region to supraciliaries present; (38) gular region of adult females dark or densely pigmented in all specimens; (39) gular region of adult males dark or densely pigmented in all specimens; (40) black blotch on ventral surface of neck in adult males absent; (41) bold black midventral line present in males; (42) black patch on ventral surface of thighs present in males; (43) dorsal ground color brown, in females and males; and (44) postxiphisternal inscriptional ribs not articulating midventrally, both pairs long, Pattern 1A of Torres-Carvajal (2004). Description of holotype. Male (Fig. 6-8); SVL= 66.02 mm; TL = 130.0 mm; maximum head width = 12.24; head length = 15.87; head height = 8.63; scales on parietal and occipital regions small, smooth, juxtaposed; parietal eye not visible; supraoculars in six rows, smooth, slightly imbricate, of varying sizes; canthals two; anterior most canthal separated from nasal by one minute scale; scales in frontonasal region slightly imbricate; internasals four; postrostrals three, subequal in size, wider than long; supralabials seven; infralabials seven; loreals six; lorilabials in one row; preocular not divided, in contact with posterior canthal; lateral temporals imbricate, weakly keeled; gulars in 29 rows between tympanic openings; all gulars smooth, imbricate; second infralabial in contact with first two sublabials; mental in contact with first pair of infralabials and first pair of postmentals; lateral and dorsal scales of body and dorsal scales of neck keeled, imbricate; lateral scales of neck granular; scales around midbody 63; vertebrals large, in 68 rows, not forming a prominent serrate vertebral crest; paravertebrals 86; ventrals smooth, imbricate; preauricular fringe short, composed of two enlarged scales, both same size; antehumeral, antegular, gular, oblique, suprauricular, postauricular neck folds and ventrolateral body fold present; limb scales keeled, imbricate; ventral scales of hind limbs and upper arms smooth; lamellae on Finger IV 23; lamellae on Toe IV 31; tail not compressed laterally; caudals keeled, imbricate; basal subcaudals smooth, imbricate; vertebral crest extending more than half length of tail; tail length 1.9 times SVL; posthumeral pocket shallow (Type 1 Torres-Carvajal 2007a) with vertically oriented fold approximately 2.57 mm long; postfemoral pocket composed by one vertical fold (type 1 of Torres-Carvajal 2007a); postfemoral region composed of imbricate, smooth scales, becoming smaller toward insertion of hind limbs (Fig. 10A). Color in life of the holotype. Dorsal surfaces of head and neck cinnamon brown with yellow spots, denser on neck; lorilabials and supralabials yellow; infralabials black; ventrolateral regions of head and neck black; dorsal surfaces of body, limbs and tail dusty brown with pale yellow spots; flanks light blue, densely covered with cream spots; limbs and tail with thin dark brown marks on dorsal surfaces (Fig. 8A). Ventral surface of head, throat, chest black; ventral surfaces of forelimbs black, although pigmentation is faint at elbow joint; a bold black midventral line, continuous with chest pigmentation, flanked by pink; ventral surfaces of hind limbs, and pelvic region black, except by the cloaca; posterior surfaces of thighs pink; pre-cloacal region dark yellow and post post-cloacal region pink; ventral surface of tail pink, with a yellow blotch and blackish speckles at the base (Fig. 8B). All black pigmentation on ventral surfaces constitutes a continuous patch, except black pigmentation on tail. Coloration of holotype in ethanol 70%. Dorsally, all yellow spots turned to pale yellow. Dorsal surfaces of head and neck turned brown. Ventrally, pink and yellow pigmentation turned to a less vivid (pale) shade, almost vanished on cloaca. Variation. Scale counts and measurements for Stenocercus nigrobarbatus are presented in Table 1. Loreals 3–7; supralabials 6–8; infralabials 5–8; postrostrals 2–4; second infralabial not in contact third sublabial in all specimens; first pair of postmentals in contact in all specimens. Dorsal coloration in adult males of Stenocercus nigrobarbatus is the same in all adult male paratypes (n = 5) (Fig. 9A). The black coloration on ventral surfaces as a continuous patch is exclusive to adult males (Fig. 9 B– C). The juvenile specimen CORBIDI 13718 has a faint black midventral line on the belly (Fig. 9 D–E). Another juvenile specimen (CORBIDI 13719) has the gular region and ventral surface of neck covered by a dark gray patch and the midventral region of the belly has scattered dark gray dots (Fig. 9 F–G). These immature males (CORBIDI 13718 and 13719) have the pelvic region and the base of tail yellow and the ventral surface of forelimbs cream (Fig. 9 D–G). In both specimens the pink coloration on the flanks of the belly is also less intense than in the holotype. In the adult male paratype (CORBIDI 20547) the base of the tail has a black blotch and the pre-cloacal region is yellow with black speckles (Fig. 9C). Sexual dimorphism is evident in coloration and size (maximum SVL in males 67.0 mm versus 62.0 mm in females). Dorsal coloration in adult females can be gray or brown with irregular dark brown blotches over the vertebral line and a light brown dorsolateral stripe from the temporal region to the base of tail (Fig. 9H); dorsal surface of limbs has dark brown or gray transversal bars; sides of head brown or gray with a thin postocular stripe and some scattered dark brown dots; sides of neck yellowish brown with light yellow flecks; jaw and ventrolateral region of neck black or dark gray; body flanks covered by a dark brown reticulation. Ventrally all adult females have the gular region and neck dark gray, belly and limbs are light cream, and the tail is light orange (Fig. 9I). Juvenile females, between 43.0–51.0 mm of SVL, have the same dorsal and ventral pattern than adult females, only two specimens (CORBIDI 13637 and 13642) have the gular region gray with dark gray speckles, and chest and belly light cream with gray speckles. The smallest juvenile female (CORBIDI 14676) has the gular region covered by gray flecks. The juvenile male CORBIDI 13640 (SVL = 43.0 mm) has the dorsum with dark brown dorsal marks as adult and juvenile females, however, the gular region and chest are gray and the belly is grayish cream. The juvenile male CORBIDI 15767 (SVL = 53.0 mm) has the same dorsal coloration as adult males but ventrally the gular region and chest are gray, and has a faint gray midventral line on belly flanked by a weak pink hue; pelvic region, ventral surface of hindlimbs and tail are light cream. Distribution and natural history observations. Stenocercus nigrobarbatus is known from four localities in SDF of the Mantaro River Valley at elevations between 1,693 and 2,345 m asl, Huancavelica Department, Peru (Fig. 5). Stenocercus nigrobarbatus inhabits a seasonal dry forest, according to classification of Linares-Palomino (2004), and Central Andean Yungas according to Olson et al. (2001). In most localities the habitat has been modified by crops of Zea mays, Opuntia, and Persea sp., roads and the construction of a hydroelectric plant. However, this species is very conspicuous in most localities. Specimens of Stenocercus nigrobarbatus were found inactive under rocks during cloudy days and active, basking or running, during warm days, among rocks, cacti or shrubs. Other species of Squamate reptiles collected at the same localities of S. nigrobarbatus include Ameiva reticulata, Epictia sp., Mastigodryas boddaerti, Micrurus sp., and Oxyrhopus cf. erdisii, and Stenocercus diploauris. Etymology. The specific epithet “ nigrobarbatus ” is a noun derived from the Latin words “ nigro ” (= black) and “ barbatus ” (= bearded). It refers to the black patch covering the gular region and ventral surface of neck, including the jaw angle, of adult males which resembles a black beard.

Stenocercus diploauris sp. nov. Figures 1–4, Table 1. Holotype. CORBIDI 13643, adult male from Limonal (12°13’55.097’’ S, 74°41’27.487’’ W), at 1,678 m asl, Surcubamba District, Tayacaja Province, Huancavelica Department, Peru, collected on September 1, 2013 by A. Escobar. Paratypes. Peru: Huancavelica Department: Tayacaja Province: CORBIDI 9913 (adult female), CORBIDI 9914 (juvenile male), CORBIDI 9915 (adult female), CORBIDI 9916 (adult male) from Jatuspata (12°15’1.2’’ S, 74°41’33.6’’ W), at 2,609 m asl, collected on April 7, 2011 by D. Amaya; CORBIDI 14672 adult female from Chupto (12°18’42.56’’ S, 74°39’13.23’’ W) at 2,328 m asl, collected on July 2, 2014 by L. Y. Echevarría; COR- BIDI 14901 adult female from Jatuspata (12°15’28.83’’ S, 74°41’28.74’’ W) at 2,816 m asl, collected on July 2, 2014 by C. Landauro; CORBIDI 14902 and CORBIDI 14903 adult females from Jatuspata (12°15’35.31’’ S, 74°41’31.74’’ W) at 2,835 m asl, collected on July 3, 2014 by C. Landauro; CORBIDI 14904 adult male from Jatuspata (12°15’34.23’’ S, 74°41’25.12’’ W) at 2,920 m asl, collected on July 3, 2014 by C. Landauro; CORBIDI 14906 adult male from Limonal (12°13’58.82’’ S, 74°41’23.09’’ W) at 1,753 m asl, collected on July 8, 2014 by C. Landauro; CORBIDI 16036 adult female from Pichiu (12°19’50’’ S, 74°39’13.07’’ W) at 2090 m asl, collected on July 12, 2015 by J. Malqui. Diagnosis. Adult specimens of Stenocercus diploauris can be easily distinguished from all known species of Stenocercus by having a C-shaped nuchal mite pocket around the oblique fold, posteriorly limited by the antehumeral fold (Fig. 4). However, among the 69 currently known species of Stenocercus, S. diploauris resembles S. formosus Tschudi, 1845, and S. ochoai Fritts, 1972, by the combination of the following characters: (1) imbricate scales on the posterior surface of thighs, (2) well developed postfemoral mite pocket, (3) antehumeral and oblique neck folds, and (4) absence of posthumeral mite pocket. The new species can be distinguished from S. ochoai and S. formosus by having dorsal and lateral nuchals similar in size and the presence of longitudinal neck fold, in the former species lateral nuchals are smaller than dorsal nuchals and the longitudinal neck fold is absent. Furthermore, S. diploauris differs from S. formosus (character state of latter in parenthesis) by having three whorls per autotomic segment (four), smooth dorsal head scales (keeled), and fewer scales, 50–61, around midbody (74–82). Characterization. (1) Maximum SVL in males 94.82 mm (n = 5); (2) maximum SVL in females 76.06 mm (n = 5); (3) vertebrals 40–50; (4) paravertebrals 63–78; (5) scales around midbody 50–61; (6) supraoculars 5–7; (7) internasals 3–4; (8) postrostrals 2–4; 9) loreals 4–8; (10) gulars 17–24; (11) lamellae on Finger IV 17–21; (12) lamellae on Toe IV 24–30; (13) posthumeral pocket absent; (14) postfemoral pocket distinct with slit-like opening, Type 2 of Torres-Carvajal (2007a); (15) parietal eye not visible; (16) occipital scales large, smooth, imbricate; (17) projecting angulate temporals absent; (18) enlarged supraoculars occupying most of supraocular region in one row; (19) scales on frontonasal region weakly imbricate anteriorly; (20) preauricular fringe present; (21) antehumeral, longitudinal and oblique neck folds present; (22) C-shaped nuchal mite pocket around the oblique neck fold, posteriorly limited by the antehumeral neck fold; (23) lateral nuchals slightly smaller than dorsal nuchals; (24) posterior gulars in adults smooth, imbricate, not mucronate, not notched; (25) lateral and dorsal body scales similar in size; (26) vertebral crest prominent; (27) dorsolateral crest absent; (28) ventrals in adults smooth, imbricate, mucronate; (29) scales on posterior surfaces of thighs keeled, imbricate, mucronate; (30) prefemoral fold absent; (31) inguinal groove absent; (32) preanals projected; (33) tail not strongly compressed laterally in adult males; (34) tail length 50–70% of total length; (35) three caudal whorls per autotomic segment; (36) caudals not spinose; (37) dark stripe extending anterodorsally from subocular region to supraciliaries present in most specimens; (38) gular region of adult females black or densely pigmented; (39) gular region of adult males gray or reddish; (40) black blotch on ventral surface of neck in adult males absent; (41) light gray or cream midventral line present; (42) black patch on ventral surface of thighs absent; (43) background color of dorsum, in females and males, brown; (44) two xiphisternal, and two long postxiphisternal pairs of inscriptional ribs that do not articulate midventrally (Pattern 1A of Torres-Carvajal 2004). Description of holotype. Male; SVL 94.82 mm; TL 217.5 mm; maximum head width 19.18 mm; head length 21.99 mm; head height 13.69 mm; occipitals, parietals, interparietal, and postparietals large, smooth, slightly imbricate (Fig. 2); parietal eye not visible; supraoculars in six rows, smooth, slightly imbricate, with one row two times larger than adjacent rows; anterior and posterior circumorbitals smooth, imbricate; canthals two; anteriormost canthal in contact with nasal; scales in frontonasal region not imbricate; internasals four; postrostrals four, wider than long, median ones smaller; supralabials six; infralabials six; loreals eight; lorilabials in one row; preocular not divid- ed, in contact with posterior canthal; lateral temporals imbricate, keeled; gulars in 22 rows between tympanic openings; all gulars smooth, imbricate; second infralabial in contact with first three sublabials; mental in contact with first pair of infralabials and first pair of postmentals; dorsal and lateral scales of body and neck keeled, imbricate; scales around midbody 53; vertebrals large, in 48 rows, forming a distinct serrate vertebral crest; paravertebrals 77; ventrals smooth, imbricate; preauricular fringe short, composed of two enlarged scales, of similar size; antehumeral, longitudinal and oblique neck folds present; a C-shaped nuchal mite pocket around the oblique fold, posteriorly limited by the antehumeral fold (Fig. 4); limb scales keeled, imbricate; ventral scales of hind limbs smooth; lamellae on Finger IV 20; lamellae on Toe IV 30; tail slightly compressed laterally; caudals keeled, imbricate; basal subcaudals keeled, imbricate; vertebral crest extending two thirds of tail length; tail length 2.3 times SVL; posthumeral pocket absent; postfemoral pocket shallow with slit-like opening (Type 2 of Torres-Carvajal 2007a). Color in life of the holotype. Dorsal surface dusty brown with light cream chevrons over the vertebral line, irregular light cream transversal bars on limbs and a reddish hue on tail; flanks cinnamon, dotted with yellowish cream scales; dorsal surface of head darker than dorsum and with some scattered cream dots; temporal surface of head dark brown, with scattered reddish pigmentation and white dots; loreal region and canthus rostralis dark brown and subocular region, supralabials and infralabials bright cream; sublabials forming a thin black stripe along the lower jaw; superciliaries cream with transversal brown bars; dark brown stripe from postocular region to supratemporals; sides of neck dusty brown with reddish pigmentation; a black blotch covers the nuchal mite pocket; black line below antehumeral fold. Gular region and throat cream with reddish pigmentation on the sides and a faint pink blotch over the throat; chest and ventral surfaces of forelimbs dirty cream; first portion of venter, immediately after forelimb insertion, yellow; belly dirty cream flanked by pink pigmentation; pelvic region and ventral surfaces of thighs yellow; tail pale pink, with yellow pigmentation on the base (Fig. 11B). Irises light brown. Color of the holotype in ethanol 70%. Similar to coloration in life. However, flanks turned dusty brown as dorsum and the reddish coloration to the sides of gular region and ventral surface of neck turned brown (Fig. 1). Variation. Scale counts and measurements for Stenocercus diploauris are presented in Table 1. Loreals 4–8; supralabials 5–6; infralabials 5–6; postrostrals 2–4; second infralabial not in contact with third sublabial in 91% of specimens; first pair of postmentals in contact in 91% of specimens (n = 11). The nuchal mite pocket is conspicuous only in adult specimens, after preservation it becomes less defined. The type series of S. diploauris contains three adult males (CORBIDI 9916, 14904 and 14906) of 68.0 mm to 78.0 mm of SVL, and one juvenile male (CORBIDI 9914) with 61.0 mm of SVL. Two adult males (CORBIDI 9916 and 14906) are identical in dorsal coloration to the holotype. However, ventrally both specimens differ from the holotype by having the posterior portion of the gular region and ventral surface of neck gray and a gray midventral line on the belly. The dorsal coloration of one adult male (CORBIDI 14904) is similar to the holotype differing only by having the flanks dusty brown as the dorsum and not cinnamon as the holotype (Fig. 3A). Ventrally this specimen differs from the holotype by having the gular region cream and the ventral surface of neck gray, the chest and belly are cream with an indistinct light gray midventral line and a dark cream patch covering the pelvic region and the ventral surface of thighs (Fig. 3B). A juvenile male (CORBIDI 9914), has the dorsum grayish and the flanks dusty brown (Fig. 3C). Ventrally this specimen has the gular region, ventral surfaces of neck and chest cream with gray reticulations, and the belly cream with a faint gray midventral line (Fig. 3D). Sexual dimorphism is conspicuous with respect to size (maximum SVL in males 94.82 mm versus 76.0 mm in females) and coloration. Females have brown dorsal surfaces with a gray dorsolateral stripe, and pairs of dark brown triangular blotches along the vertebral line becoming chevrons on the tail (Fig. 3E); flanks are brown as dorsum or cinnamon (CORBIDI 14901) without marks; sides of head brown with a dark brown subocular stripe; jaw, ventrolateral region of head and sides of neck black (Fig. 3E). Ventral surfaces in adult females are brownish cream with a black patch covering the gular region and ventral surface of neck (Fig. 3F). One specimen (CORBIDI 14902) has the gular region and ventral surface of neck black with a cream blotch on the middle. One of the five female paratypes (CORBIDI 14672) has a dusty brown dorsum with dark brown chevrons along the vertebral line and the loreal and subocular regions bright cream like adult males. One juvenile female (CORBIDI 9913) differs from the adult females by having a light cream dorsolateral stripe (gray in adult females). Distribution and natural history observations. Stenocercus diploauris is known from four localities in the SDF of the Mantaro River Valley at elevations between 1,678 to 2,920 m asl, Huancavelica Department, Peru (Fig. 5). Stenocercus diploauris inhabits a seasonal dry forest, according to Linares-Palomino (2004) classification, and Central Andean Yungas according to Olson et al. (2001). Limonal (1,678 m asl), corresponds to the locality with the lowest elevation record of S. diploauris, its general landscape is that of a typical dry forest but with scattered crop lands with plantations of corn Zea mays, avocado pear Persea sp., citrus fruit trees and several other species of fruit trees. The agriculture is more intensive in the surrounding areas of Pichiu village (2,090 m asl); however, the remnants of native vegetation are dominated by shrubs, Opuntia and other cacti species. Chupto, at 2,328 m asl, is a very steep area dominated by shrubs and grasses. The locality of Jatuspata is located within an evergreen forest at elevations between 2,609 m and 2,920 m asl. The holotype of Stenocercus diploauris was collected by chance, it was found dead but not decomposed in a Sherman trap. Most paratypes were collected inactive under rocks, among cacti and shrubs, during cloudy days. Only CORBIDI 14672 was collected while active and moving among shrubs. Stenocercus diploauris and S. nigrobarbatus are known to co-occur at Chupto and Pichiu. Other species of Squamate reptiles collected at the same localities of S. diploauris include Ameiva reticulata, Mastigodryas boddaerti, Micrurus sp., and Wilsonosaura josyi. Etymology. The specific epithet “ diploauris ” is a noun (in apposition) in the nominative singular and derives from the Greek word diploos (= double) and the Latin word auris (= ear). It refers to the depression on both sides of the neck of the new species, appearing like a second tympanic opening.