Stenocercus chinchaoensis, Venegas, Pablo J., Duran, Vilma & Garcia-Burneo, Karla, 2013

Venegas, Pablo J., Duran, Vilma & Garcia-Burneo, Karla, 2013, A new species of arboreal iguanid lizard, genus Stenocercus (Squamata: Iguania), from central Peru, Zootaxa 3609 (3), pp. 291-301 : 292-300

Stenocercus chinchaoensis sp. nov.

( Figs. 1–5 )

Proposed standard English name: Chinchao whorltail lizard Proposed standard Spanish name: capón de Chinchao

Holotype. CORBIDI 0 9024 ( Figs. 1 , 2 ), an adult male from Dos Aguas (9°48´30´´ S, 75°49´59.1´´ W), 1879 m, Distrito de Chinchao, Provincia de Huánuco, Región de Huánuco, Perú, collected by K. García-Burneo on 17 March 2011.

Paratypes. CORBIDI 0 9023 and 0 9025, two adult males from Rinconada (9°48´50.1´´ S 75°47´18.2´´ W), 1766 m, Distrito de Chaglla, Provincia de Pachitea, Región de Huánuco, Peru, collected by K. García-Burneo on 29 March 2011; CORBIDI 09320-22, an adult female, adult male, and juvenile female, respectively, collected from the same area as the holotype by P. J. Venegas and V. Duran on 8 July 2011.

Diagnosis. Stenocercus chinchaoensis is distinguished from other species of Stenocercus (except S. boettgeri , S. haenschi , S. humeralis , and S. varius ) by having granular scales on the posterior surface of the thighs, enlarged vertebrals, three caudal whorls per autotomic segment, a medially complete antegular fold, non-spinose caudals, and by males lacking a black transverse band on the ventral surface of the neck. In life, Stenocercus chinchaoensis is distinguished from these species by lacking yellow or pale green spots on the dorsum ( Fig. 3 ), with the exception of S. haenschi , and with the ability to change colors between green or water green and grey. Furthermore, S. chinchaoensis has more scales around the midbody (104–107, x =105.66) than S. boettgeri (79–104, x = 88.61), S. haenschi (57–64, x =60.50), and S. varius (74–88, x =82.35) (Torres-Carvajal 2007b); S. chinchaoensis has lateral and dorsal nuchals similar in size (lateral nuchals less than half the size of dorsal nuchals in S. boettgeri , S.

haenschi , and S. varius ); S. chinchaoensis has the dorsal scales of the neck granular (keeled and imbricate in S. boettgeri , S. haenschi , and S. varius ). In addition, males and females of S. boettgeri are larger (maximum SVL =108 and 94 mm, respectively) than S. chinchaoensis (maximum SVL= 86 mm in males and 71 mm in females). Although S. chinchaoensis is similar in scutellation to S. humeralis , the new species can be easily distinguished from the latter by having the scales in the frontonasal region nearly equal in size to the scales in the occipitoparietal region, while in S. humeralis the scales on the frontonasal region are twice or three times longer than the scales on the occipitoparietal region. Another useful character to distinguish between S. humeralis and the new species is the type of postfemoral mite pocket: present in S. chinchaoensis as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)], but present as a slitlike opening in S. humeralis [Type 2 of Torres-Carvajal (2007b)]. Finally, S. humeralis differs in coloration from the new species by presenting black spots on the gular region in both males and females, however, the spots are diffuse gray or white in the new species.

Characterization. (1) Maximum total length in males 86 mm (n=4); (2) maximum total length in females 71 mm (n =2); (3) vertebrals 79–90; (4) paravertebrals 117–139; (5) scales around midbody 104–107; (6) supraoculars 6; (7) internasals 4; (8) postrostrals 6; (9) loreals 3–5; (10) gulars 43–50; (11) lamellae on Finger IV 23–30; (12) lamellae on Toe IV 32 –34; (13) posthumeral mite pocket present as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)]; (14) postfemoral mite pocket present as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)]; (15) parietal eye absent; (16) occipital scales small, smooth, juxtaposed; (17) projecting angulate temporal absent; (18) enlarged supraoculars occupying most of supraocular region in one row absent; (19) scales on frontonasal region juxtaposed; (20) preauricular fringe short; (21) antegular, antehumeral, gular, longitudinal, oblique, postauricular, supra-auricular, and transverse antegular neck folds present; (22) lateral and dorsal nuchals similar in size; (23) posterior gulars cycloid, smooth, slightly inbricate, not notched; (24) lateral scales reduced in size, approximately half the size of dorsal body scales; (25) vertebrals slightly enlarged, forming inconspicuous longitudinal row between fore and hind limbs; (26) dorsolateral crests absent; (27) ventrals smooth, imbricate; (28) scales on posterior surfaces of thighs granular; (29) prefemoral fold present; (30) inguinal groove present; (31) preanals not projected; (32) tail not strongly compressed laterally in adult males; (33) tail length 61–64% of total length; (34) three caudal whorls per autotomic segment; (35) caudals not spinose; (36) dark stripe extending anterodorsally from subocular region to supraciliaries absent; (37) color pattern of gular region in adult females with dark gray flecks and white spots, similar to ventral color pattern; (38) color pattern of gular region in adult males with gray flecks and white spots, similar to ventral color pattern; (39) black blotch on ventral surface of neck in adult males absent; (40) dark midventral stripe in adult males absent; (41) black patches on ventral surface of thighs in adult males absent; (42) background color of dorsum grey, turquoise or green; (43) postxiphisternal inscriptional ribs not in contact midventrally (Pattern 1A, 1B, and 2C of Torres-Carvajal 2004).

Description of holotype. Male ( Figs. 1–2 ); SVL 73.2 mm; TL 130 mm; maximum head width 14.8 mm; head length 19.7 mm; head height 10.7 mm; posterior dorsal head scales small, smooth, juxtaposed; parietal eye not visible; supraoculars in six rows, smooth, slightly imbricate, with the most lateral three rows less than half the size of the medial adjacent rows; distinct circumorbitals absent; canthals two; internasals four; postrostrals six, approximately as wide as long; supralabials five; infralabials six; loreals three; lorilabials in one row; preocular divided into three scales, the dorsal-most in contact with posterior canthal; lateral temporals granular; gulars in 49 rows between tympanic openings; all gulars cycloid, smooth, slightly imbricate, not notched; second infralabial in contact with first two sublabials; first pair of postmentals in contact medially; mental without contact with first pair of infralabials but in contact with first pair of postmentals; dorsal and lateral scales of neck granular; dorsal scales of body imbricate, slightly keeled, becoming gradually granular toward flanks; scales around midbody 106; vertebrals enlarged, slightly keeled, imbricate, in 90 rows, forming distinct vertebral row; paravertebrals adjacent to vertebral row slightly enlarged, slightly keeled, and imbricate; paravertebrals 139; ventrals smooth, imbricate, more than twice the size of dorsals; preauricular fringe short, composed of three enlarged, posteriorly projected granular scales; antegular, antehumeral, gular, longitudinal, oblique, postauricular, supra-auricular, and transverse antegular neck folds present; ventrolateral and prefemoral folds present; dorsal scales of fore limbs imbricate, keeled; dorsal scales of hind limbs imbricate, strongly keeled, not mucronate; ventral humeral scales granular; ventral scales of forearms and hind limbs imbricate, smooth; palmars and plantars imbricate, keeled; lamellae on Finger IV 28; lamellae on Toe IV 33; tail rounded; caudals strongly keeled, slightly mucronate, imbricate dorsally; basal subcaudals smooth, imbricate; posthumeral mite pocket present as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)]; postfemoral mite pocket present as one or more vertical folds or ridges [Type 1 of Torres-Carvajal (2007b)].

Color in life of holotype (based on digital photograph): Head and dorsum grey with a bold black mantle on the vertebral line becoming a zig-zag bold stripe from midbody to the base of tail; black antehumeral collar present; thin black postocular stripe present; venter white with pale gray spots in the throat.

Variation. Measurements, scutellation, and other morphological characters of Stenocercus chinchaoensis are presented in Table 1 . Loreals 3–5; supralabials 5–6; infralabials 5–6; second infralabials not in contact with third sublabials in all specimens; first pair of postmentals not in contact medially in 50% of specimens. In three dissected specimens the postxiphisternal pairs of inscriptional ribs were two in two specimens (one with two long pairs and the second specimen with the first pair long and the second pair short) and three in one specimen (the first pair long and the two following pairs short) (Pattern 1A, 1B, and 2C of Torres-Carvajal 2004, respectively).

An adult male CORBIDI 0 9321 ( Fig. 4 ) had the following coloration in life: head greenish brown with a thin black postocular stripe present; dorsum green, but mostly covered by wide transverse bold black marks arranged longitudinally over vertebral line; black antehumeral collar present; first third of tail sky blue; flanks and limbs green with scattered black flecks; throat white with pale grey spots; chest and belly white; ventral surface of thighs, pelvic region, vent, and base of tail brownish cream. This individual changed its coloration immediately after it was caught, replacing the green coloration by grey tones ( Fig. 4 A).

An adult female CORBIDI 0 9320 ( Fig. 3 A–B) had the same dorsal color as the males, but with a grayish green tail dorsally. However, it had a diffuse middorsal black mantle with a pale vertebral stripe and tranverse black bars on the tail, and the flanks and dorsal surface of the limbs were sprinkled by dark and light flecks. After the change of coloration, the head of this individual turned green ( Fig. 3 A).

A juvenile female CORBIDI 0 9322 ( Fig. 3 C–D) had a dorsal pattern of middorsal transverse bold black marks arranged longitudinally over the vertebral line and transverse black bars on the tail.

Both sexes of Stenocercus chinchaoensis have the ability to change their dorsal background color from green or water green to grey. This ability was reported previously only in S. torquatus (Torres-Carvajal et al. 2005) . Color change was observed immediately after capture, suggesting that it occurs as a response to stress as occurs in S. torquatus according to Torres-Carvajal et al. (2005). The green or water green coloration matches the color of the mosses than cover the tree trunks where the individuals were found ( Fig. 5 ).

Natural history. In a field trip to the type locality by PJV and VD, six individuals of Stenocercus chinchaoensis were observed active on sunny days between 1000 and 1400 h. Of these, three were found basking on house walls from 2–4 m above the ground, and three were basking on broad tree trunks between approximately 1–8 m above ground. These observations suggest that this species is mainly arboreal. The habitats at the type locality on both sides of the Huallaga River (villages of Dos Aguas and Rinconada) contain second-growth vegetation, coffee and citric plantations, and cattle pasture. S. chinchaoensis is sympatric with S. cupreus ; S. prionotus occurs allopatrically at lower elevations (900 m) in the same region. Other sympatric species of squamate reptiles collected with S. chinchaoensis were Bothriopsis chloromelas, Dipsas peruana, Liophis janaleeae, Micrurus annellatus, and Philodryas sp. One adult female (CORBIDI 0 9320, SVL = 71mm) collected on 8 July contained two oviductal eggs, in the right oviduct, and four follicles.

Distribution. Stenocercus chinchaoensis is known only from two adjacent localities (Dos Aguas and Rinconada) in the upper valley of the Río Huallaga on the Amazonian slope of the Andes in central Peru ( Fig. 6 ). It occurs at elevations of 1700–1900 m in the Región Huánuco. The type locality lies within the Yungas (500–2300 m) ecoregion according to Brack (1986) and Peñaherrera del Águila (1989).

Etymology. The specific name refers to the District of Chinchao in which the type locality is situated.

Figures

FIGURE 1. Stenocercus chinchaoensis sp. n., holotype CORBIDI 0 9024, male, 73.2 mm SVL. The absence of complete antegular fold in the ventral view is an artifact of fixation. Photographs by P. J. Venegas.

FIGURE 2. Dorsal (top), lateral (middle), and ventral (bottom) views of the head of Stenocercus chinchaoensis sp. n. Holotype, CORBIDI 0 9024, male. Scale bar = 5 mm. The absence of complete antegular fold in the ventral view of the head (bottom) is an artifact of fixation. Photographs by P. J. Venegas.

FIGURE 3. Three species of Stenocercus from Perú. (A, B) Adult female of S. chinchaoensis sp. n. (CORBIDI 0 9320, 71 mm SVL). (C, D) Juvenile of S. chinchaoensis (CORBIDI 0 9322, 58 mm SVL). (E) Adult male of S. boettgeri (CORBIDI 03823). (F) Adult female of S. humeralis (CORBIDI 00934). Photographs by P. J. Venegas (A – D and F) and G. Chavez (E).

FIGURE 4. Dorsolateral (A) and ventral views (B) of adult male paratype of Stenocercus chinchaoensis sp. n. (CORBIDI 0 9321, 84 mm SVL). Photographs by P. J. Venegas.

FIGURE 5. Stenocercus chinchaoensis sp. n. on a tree trunk showing its aqua green coloration (individual not collected). Photograph by P. J. Venegas.

FIGURE 6. Distribution map of Stenocercus chinchaoensis sp. n. (circle), S. boettgeri (crosses), S. humeralis (diamonds), S. haenschi (triangle), and S. varius (stars).

Tables

TABLE 1. Sexual variation in scutellation and measurements (mm) of Stenocercus chinchaoensis sp. n. Range followed by mean ± standard deviation is given for quantitative characters if applicable.

CHARACTER	Males (n = 4)	Females (n = 2)
Scales around midbody	104–107 (105.7 ± 1.6)	104–107 (105.5)
Vertebrals	79–90 (84.5 ± 5.8)	81–85 (83)
Paravertebrals	117–139 (125 ± 10.7)	124–126 (125)
Gulars	46–50 (47.7 ± 2.6)	43–46 (44.5)
Supraoculars	6	6
Internasals	4	4
Subdigitals finger IV	25–30 (27.5 ± 2.8)	23–27 (25)
Subdigitals toe IV	33–34 (33.5 ± 0.5)	32–33 (32.5)
Tail length/total length	0.64	0.61–0.62 (0.61)
Maximum SVL	86	71