Stenocercus arndti, Venegas, Pablo J., Echevarria, Lourdes Y. & Alvarez, Silvana C., 2014

Venegas, Pablo J., Echevarria, Lourdes Y. & Alvarez, Silvana C., 2014, A new species of spiny-tailed iguanid lizard (Iguania: Stenocercus) from northwestern Peru, Zootaxa 3753 (1), pp. 47-58 : 48-56

publication ID	https://doi.org/ 10.11646/zootaxa.3753.1.4
publication LSID	lsid:zoobank.org:pub:80782116-E419-4D5F-9286-AFA07C369291
DOI	https://doi.org/10.5281/zenodo.6133032
persistent identifier	https://treatment.plazi.org/id/03B4A569-FF9A-FF84-FF0B-FB8DCEDF1AB7
treatment provided by	Plazi
scientific name	Stenocercus arndti
status	sp. nov.

Treatment

Stenocercus arndti sp. nov.

( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Proposed standard English name: La Granja whorltail lizard Proposed standard Spanish name: Capón de La Granja

Holotype. CORBIDI 0 1680 ( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 ), an adult male from Quebrada Checos (6°21´12.63´´ S, 79°06´41.15´´ W), at 1997 m elevation, La Granja District, Chota Province, Cajamarca Region, Peru, collected by P.J. Venegas on 22 August 2008.

Paratypes. CORBIDI 0 1681 and 0 1685, an adult male and adult female, respectively, collected with the holotype; CORBIDI 0 1682 and 0 1688, adult males; CORBIDI 0 1692, adult female; CORBIDI 0 1686, 0 1687, and 0 1690, subadult males; CORBIDI 0 1683 and 0 1689, subadult females; CORBIDI 0 1691, a juvenile male; CORBIDI 0 1684, a hatchling, all from Quebrada La Iraca, (6°22´09.9´´ S, 79°08´04.61´´ W), at 2213 m elevation, La Granja District, Chota Province, Cajamarca Region, Peru, collected by P.J. Venegas on 9 August 2008.

Referred specimens (photo vouchers). Two adult females from Kañaris (6°03´26.18´´ S, 79°16´00.35´´ W), at 2318 m elevation, Ferreñafe Province, Lambayeque Region, Peru, captured and released by P. J. Venegas on 25 May 2007.

Diagnosis. Stenocercus arndti differs from all other species of Stenocercus , except for S. bolivarensis Castro & Ayala 1982 , S. carrion Parker 1934 , S. chlorostictus Cadle 1991 , S. crassicaudatus Tschudi 1845 , S. empetrus Fritts 1972 , S. eunetopsis Calde 1991 , S. simonsii Boulenger 1885 , and S. torquatus Boulenger 1885 , in having granular scales on the posterior surface of the thighs, two caudal whorls per autotomic segment, mucronate caudal scales, and a distinct longitudinal row of enlarged vertebral scales. However, the new species is easily distinguished from these species in having a bold black transverse band at midbody that extends ventrolaterally in adult males. Furthermore, S. carrioni , S. chlorostichus and S. euneptopsis differ from S. arndti (in parentheses) in having the dorsal scales of the neck keeled and imbricate (slightly keeled and subimbricate) and the dorsal scales of the trunk keeled (feebly keeled). Additionally, S. carrioni and S. euneptopsis have fewer scales at midbody (66–96, x =82.43 ± 8.13 in S. carrioni and 60–80, x =70.62± 5.38 in S. euneptopsis , versus 85–100, x =91.54 ± 6.32 in the new species), and S. chlorostichus has a strong sexual dichromatism, with the dorsal background color green in males and brown in females (males and females gray or brown). Stenocercus empetrus differs from S. arndti in having a venter of yellowish-orange with black reticulations (white, pale gray, or pale orange without reticulations), caudal scales without strongly projected mucrons (strongly projected mucrons present), and attaining a larger size, with a maximum SVL= 103 mm in males and 90 mm in females (maximum SVL= 90 mm in males and 77 mm in females). Stenocercus simonsii differs from S. arndti in having the dorsal scales of the neck almost coarsely granular, while in the new species these scales are slightly keeled and subimbricate. Stenocercus crassicaudatus and S. torquatus differ from the new species in having the dorsal scales of the neck granular (slightly keeled and subimbricate) and more scales around the midbody (97–121, x =108.87 ± 5.99 in S. crassicaudatus and 102–137, x =116.96 ± 8.21 in S. torquatus , versus 85–100, x =91.54 ± 6.32 in S. arndti ). Moreover, S. torquatus differs from S. arndti in having a black antehumeral collar complete middorsally in adult males (incomplete), as well as two transverse bands anterior to the antehumeral collar (absent), and the ability to change color between emerald green and dark brown or gray (unable to change color). Stenocercus bolivarensis has strongly keeled and imbricate lateral body scales (Torres-Carvajal 2007b), which are smooth in the new species, and fewer scales around the midbody (67–82, x =73.08 ± 4.63 in S. bolivarensis , versus 85–100, x =91.54 ± 6.32 in S. arndti ).

Characterization. (1) Maximum total length in males 90 mm (n = 7); (2) maximum total length in females 77 mm (n = 3); (3) vertebrals 74–94; (4) paravertebrals 87–108; (5) scales around midbody 85–100; (6) supraoculars 5–7; (7) internasals 3–4; (8) postrostrals 4; (9) loreals 2; (10) gulars 49–60; (11) lamellae on Finger IV 22–28; (12) lamellae on Toe IV 23–30; (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 a distinct pocket slightly depth with a posteroventrally oriented slit-like opening [Type 2 of Torres-Carvajal (2007b)]; (15) parietal eye absent; (16) occipital scales small, smooth, juxtaposed; (17) projecting angulate temporals absent; (18) enlarged supraoculars occupying most of supraocular region in one row absent; (19) scales on frontonasal region smooth, juxtaposed; (20) preauricular fringe absent; (21) antegular, antehumeral, gular, longitudinal, oblique, postauricular, supraauricular, and transverse antegular neck folds present; (22) lateral nuchals slightly smaller than dorsal nuchals; (23) posterior gulars smooth, imbricate, apical pit absent; (24) lateral body scales smaller than dorsal body scales; (25) vertebrals same size as dorsals, 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 compressed laterally in adult males; (33) tail length 53–64 % of total length; (34) two caudal whorls per autotomic segment; (35) caudals spinose; (36) dark stripe that extends anterodorsally from subocular region to supraciliaries absent; (37) color pattern of gular region in adult females with clear marks, similar to ventral color pattern; (38) color pattern of gular region in adult males with clear marks; (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 or brown; (43) postxiphisternal inscriptional ribs not in contact midventrally (Pattern 2B and 4A of Torres-Carvajal 2004).

Description of the holotype. Male ( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 ); SVL 79 mm; TL 101 mm; maximum head width 15.3 mm; head length 18.9 mm; head height 11.5 mm; scales on parietal and occipital regions small, slightly wrinkled, juxtaposed ( Fig. 2 View FIGURE 2 ); parietal eye not visible; supraoculars in five rows, smooth, with the lateral most three rows less than half the size of the medial adjacent rows; distinct circumorbitals present; canthals two; anterior-most canthal in contact with nasal; internasals four; postrostrals four, approximately as wide as long; supralabials seven; infralabials six; loreals three; lorilabials in one row; preocular divided into four scales, the two dorsals in contact with posterior canthal; lateral temporals granular; gulars in 49 rows between tympanic openings; all gulars cycloid, smooth, imbricate, apical pit absent; second infralabial in contact with the second and third sublabials; first pair of postmentals in contact medially; mental separated from the infralabials by the first pair of postmentals; dorsal and lateral scales of neck granular; lateral scales of body conspicuously smaller than dorsals, but not granular, slightly imbricate; scales around midbody 88; vertebrals enlarged, keeled, imbricate, in 74 rows, forming distinct vertebral row; paravertebrals adjacent to vertebral row slightly enlarged, keeled, and imbricate; paravertebrals 92; ventrals smooth, imbricate, more than twice the size of dorsals; preauricular fringe absent; 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, smooth; dorsal scales of hind limbs imbricate, keeled, mucronate; ventral humeral scales smooth and imbricate, about one third the size of the dorsal humeral scales; ventral scales of forearms and hind limbs imbricate, smooth; palmars and plantars imbricate, keeled; lamellae on Finger IV 26; lamellae on Toe IV 26; tail rounded; caudals strongly keeled, mucronate, imbricate; basal subcaudals smooth, imbricate; posthumeral mite pocket present as one or more vertical folds [Type 1 of Torres-Carvajal (2007b)]; postfemoral mite pocket present as a distinct pocket slightly depth with a posteroventrally oriented slit-like opening [Type 2 of Torres-Carvajal (2007b)].

Color in life of holotype ( Fig. 3 View FIGURE 3 ): head dorsal surface green, loreal region and snout bright green, temporal region and sides of head behind the eyes brown with white spots, thin dark brown temporal and two postocular stripes present; dorsum brown with several pale green spots, diffuse dark brown bands, and a bold black transversal band at midbody that extends ventrolaterally and is incomplete middorsally; black antehumeral collar present, incomplete middorsally; flanks brown with several white spots on sides of neck and pale green flecks on sides of trunk; tail brown; arms greenish brown and legs brown, both with dark brown flecks; throat greenish-white with diffuse brown spots, chest and belly white with brown borders and gray flecks; ventral surface of thighs and cloacal region cream.

Variation. Measurements, scutellation, and other morphological characters of Stenocercus arndti are presented in Table 1. Loreals 1–5; supralabials 6–7; infralabials 5–7; second infralabials not in contact with third sublabials in 58% of specimens; first pair of postmentals not in contact medially in 25% of specimens. In two dissected specimens the postxiphisternal pairs of inscriptional ribs were two in one specimen (both pairs long), and in the other specimen (the first and second pair were long and the third pair short) (Pattern 2B and 4A of Torres-Carvajal 2004).

CHARACTERS n =13

Scales around midbody 85–100 (91.54 ± 6.32) Vertebrals 74–94 (83.23 ± 6.77) Paravertebrals 87–108 (100.23 ± 5.83) Gulars 49–60 (52.92 ± 3.65) Supraoculars 5–7 (6)

Internasals 3–4 (4)

Subdigitals Finger IV 22–28 (24.15 ± 2.03) Subdigitals Toe IV 23–30 (25.54 ± 1.94) Tail length/total length 0.53–0.64 (0.58 ± 0.08) Maximum SVL males 90

Maximum SVL females 77

Sexual dimorphism is evident in adult individuals. Males differ from females in having a conspicuous anthehumeral black collar and a bold black transversal band at midbody, whereas females only have several diffuse dark brown short transversal bands along the back. The other two collected adult males (CORBIDI 01681-82 and 01688) and one subadult male (CORBIDI 01690) differ from the holotype only by having the head completely brown and the throat brown with white spots ( Fig. 4 View FIGURE 4 : A & B). Subadult males (CORBIDI 01686-87) and a juvenile male (CORBIDI 01691) differ from the aforementioned males in having the diagnostic mark on the dorsum dark brown, while is conspicuous black in adult males.

In life, the adult female (CORBIDI 01692; Fig. 4 View FIGURE 4 : C & D) has a gray dorsum, while in the other collected females the dorsum was brown as in the males ( Fig. 4 View FIGURE 4 : E & G). The throat of females was gray with white spots (CORBIDI 01692; Fig. 4 View FIGURE 4 D), yellowish-green with gray spots (CORBIDI 01685; Fig. 4 View FIGURE 4 F), or yellow with white spots (CORBIDI 01689; Fig. 4 View FIGURE 4 H). The two referred specimens, two adult females from Kañaris ( Fig. 4 View FIGURE 4 : I–L), differ from the adult females from the type locality only in having the throat and chest yellow without white or gray spots on the throat ( Fig. 4 View FIGURE 4 : J & L). Subadult females and the single hatchling collected have the transverse bands on the dorsum more evident than in the adult female, especially the anthehumeral black collar.

Natural history observations. The habitat at the type locality and in the vicinity of Kañaris are croplands with scattered large boulders and bushes. Croplands are embedded in a matrix of shorter-stature and drier forest. However, the forest has been almost removed and only some small patches of secondary forest remain close to ravines. All individuals of Stenocercus arndti were observed active on sunny days at between 10:00 and 15:00 h basking on large rocks, fallen tree trunks, and fences of rock or wood. Stenocercus arndti is sympatric with S. huancabambae and S. stigmosus in Quebrada La Iraca, and with only S. huancabambae in Quebrada Checos. Other sympatric species of squamate reptiles collected with the new species in the type locality were Chironius monticola, Dipsas peruana, Epictia teaguei, Liophis taeniurus, Micrurus peruvianus, and Pholidobolus sp. In the vicinity of Kañaris, S. arndti was found sympatric only with Pholidobolus sp.

Distribution. Stenocercus arndti is known only from two adjacent localities close to La Granja village in the interandean valley of the Río Chotano and from one locality in the vicinity of Kañaris village in the interandean valley of the Río Huancabamba on the Amazonian slope of the northern portion of the Cordillera Occidental in northwestern Peru ( Fig. 5 View FIGURE 5 ). It occurs at elevations from 1997–2318 m in the regions of Cajamarca and Lambayeque. The type locality lies within the Yungas (500–2300 m) ecoregions according to Brack (1986) and Peñaherrera del Águila (1989).

Etymology. The specific name is a patronym for Dr. Rudolf G. Arndt of Pomona, New Jersey, USA, in recognition of his financial support for the improvement of the herpetological collection of CORBIDI through the BIOPAT-Programme.