Stenocercus diploauris, Venegas & Echevarría & García-Ayachi & Landauro, 2020

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), pp. 555-575 : 557-562

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.

Figures

FIGURE 1. Stenocercus diploauris sp. nov., holotype CORBIDI 13643, male, 94.82 mm SVL. Dorsal (A) and ventral (B) views. Photographs by P.J. Venegas. Scale bar = 10 mm.

FIGURE 2. Dorsal (A), lateral (B), and ventral (C) views of the head of Stenocercus diploauris sp. nov. holotype, CORBIDI 13643, male. Photographs by P.J. Venegas. Scale bar = 10 mm.

FIGURE 3. Paratypes of Stenocercus diploauris sp. nov.: (A, B) Dorsolateral and ventral view of an adult male paratype (CORBIDI 14904); (C, D) Dorsolateral and ventral views of a subadult male (CORBIDI 9914); (E, F) Dorsolateral and ventral views of an adult female (CORBIDI 14901). Photographs by C.Z. Landauro.

FIGURE 4. Lateral view of the nuchal mite pocket of freshly dead holotype of S. diploauris sp. nov. (CORBIDI 13643). Yellow arrow: oblique neck fold; blue arrow: nuchal mite pocket as a C-shaped depression around the oblique neck fold; red arrow: antehumeral fold; green arrow: longitudinal neck fold. Scale bar = 10 mm.

FIGURE 5. Distribution map of six species of Stenocercus from Peru. S. diploauris sp. nov. (pentagons), S. formosus (squares), S. frittsi (crosses), S. nigrobarbatus sp. nov. (triangles), S. ochoai (circles), and S. variabilis (diamonds). Symbols with a dot in the middle correspond to type localities.

FIGURE 11. Ventral views of adult males of Stenocercus from the Anatomegalepis clade in life: (A) S. apurimacus, (B) S. diploauris sp. nov. (holotype), (C) S. formosus (MTD 44698), (D) S. ochoai, and (E) S. scapularis (CORBIBI 17739). Photographs by: (A) P.J. Venegas, (B) C.Z. Landauro, (C) M. Lundberg, (D) L. Mamani; and (E) L. Luján.