Stenocercus leybachi, Venegas & García-Ayachi & Chávez-Arribasplata & García-Bravo, 2022

Venegas, Pablo J., García-Ayachi, Luis A., Chávez-Arribasplata, Juan C. & García-Bravo, Antonio, 2022, Four new species of polychromatic spiny-tailed iguanian lizards, genus Stenocercus (Iguania: Tropiduridae), from Peru, Zootaxa 5115 (1), pp. 1-28 : 11-15

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.

Figures

FIGURE 3. Distribution map of Stenocercus asenlignus sp. nov., Stenocercus leybachi sp. nov., S. nigrocaudatus sp. nov., and S. qalaywasi sp. nov., and the similar species: S. arndti, S. carrioni, S. chlorostictus, S. crassicaudatus, S. empetrus, S. eunetopsis, S. flagracanthus, S. simonsii, and S. torquatus. The symbols of species with a black spot in the centre correspond to type localities. Black dots correspond to important cities for reference.

FIGURE 4. Stenocercus leybachi sp. nov. preserved holotype, adult male, SVL 83 mm (CORBIDI 16397): dorsal (A), lateral (B), and ventral (C) views of the head; dorsal (D) and ventral (E) views of the entire specimen. Photographs by LAGA. Scale bar = 10 mm.

FIGURE 5. Dorsolateral and ventral views of Stenocercus leybachi sp. nov. in life: (A-C) holotype, SVL 83 mm (CORBIDI 16397); (D, E) adult male, SVL 84 mm (CORBIDI 16532); (F, G) adult male, SVL 81 mm (CORBIDI 13333); (H) adult female, SVL 82 mm (CORBIDI 16400); (I, J) adult female, SVL 80 mm (CORBIDI 16429); (K) adult male hidden in a tree hole (not collected); (L) adult female photographed hidden in a hollow branch (not collected). Photographs by (A-C, & H) D. Vásquez, (D, E, & I-L) JCCA, and (F, G) V. Duran.