Stenocercus asenlignus, 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 : 5-10

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 consider it possible that these specimens may be S. asenlignus due to the distribution and its resemblance with S. torquatus according to Torres-Carvajal et al. (2005).

Figures

FIGURE 1. Stenocercus asenlignus sp. nov. preserved holotype, adult male, SVL 69 mm (CORBIDI 20219): 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 2. Dorsolateral and ventral views of Stenocercus asenlignus sp. nov. in life: (A, B) holotype (CORBIDI 20219); (C) adult male, SVL 73 mm (MUSM 23034); (D, E) adult female, SVL 72 mm (CORBIDI 20220); (F, G) adult female, SVL 59 mm (CORBIDI 20135); (H) adult female, SVL 71 mm (CORBIDI 20217); (I, J) juvenile, SVL 32 mm (CORBIDI 20199); (K) adult male photographed basking in Omia (not collected); (L) adult male photographed in Omia (not collected). Photographs by (A-J) PJV, (K) LAGA, and (L) AGB.

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 10. Spiny-tailed species of Stenocercus in situ. (A) adult male of S. torquatus basking on a branch near Oxapampa town; (B) adult male of S. asenlignus sp. nov. basking in a tree near Omia (type locality); (C, D) adult female of S. torquatus hidden and perched on a roof support of a rural house; (E) an adult male of S. flagracanthus hidden at the base of a wall near Shipasbamba; and (F) an adult male of S. flagracanthus basking in a tree at Suyubamba. Photographs by (A) O. Custodio, (B) T. Mark, (C, D) A. Marchelie, (E) AGB, and (F) E. Calle-Alverca.