Stenocercus torquatus Boulenger, 1885

Torres-Carvajal, Omar, 2007, A TAXONOMIC REVISION OF SOUTH AMERICAN STENOCERCUS (SQUAMATA: IGUANIA) LIZARDS, Herpetological Monographs 21 (1), pp. 76-178 : 158-160

Stenocercus torquatus Boulenger

( Fig. 22 )

Stenocercus torquatus Boulenger, 1885 a:133 . Holotype: BMNH 61.5.22.4 , a male from ‘‘Peru̕̕ (restricted to María Teresa, 19 km on road Oxapampa-Llaupi , 10 ° 42'05"S, 75 ° 27'22"W, 1470 m, Departamento Pasco, Peru by Torres-Carvajal et al. [2005]); Torres-Carvajal et al., 2005.

Stenocercus crassicaudatus (part) Burt and Burt, 1931:287; Etheridge, in Peters and Donoso-Barros, 1970; Fritts, 1974:45. Synonymy fide Burt and Burt, 1930:22.

Diagnosis.— Stenocercus torquatus differs from all other species of Stenocercus except S. bolivarensis , S. carrioni , S. chlorostictus , S. crassicaudatus , S. empetrus , S. eunetopsis , and S. simonsii in having granular scales on the posterior surface of thighs, two caudal whorls per autotomic segment, mucronate caudal scales, and a distinct longitudinal row of enlarged vertebral scales. Of these species, only S. crassicaudatus , S. simonsii , and S. torquatus have granular dorsal scales on neck (imbricate, and smooth or keeled in remaining species). S. torquatus is distinguished from S. crassicaudatus and S. simonsii by having a black antehumeral collar complete middorsally in adult males, subadult females, and juveniles, as well as two black transverse bands anterior to the antehumeral collar and the ability to change colors between emerald green and dark brown or gray. An antehumeral collar also is present in all species mentioned above except S. crassicaudatus ; however, in those species the collar is usually incomplete middorsally. Additionally, two black transverse bands anterior to the antehumeral collar have been reported in S. eunetopsis ( Cadle, 1991) , but they are not as distinct as in S. torquatus .

Description.—(1) Maximum total length in males 84 mm (n = 27); (2) maximum total length in females 74 mm (n = 16); (3) vertebrals 83–115; (4) paravertebrals 103– 151; (5) scales around midbody 102–137; (6) supraoculars 6–8; (7) internasals 4–6; (8) postrostrals 6–8; (9) loreals 2–5; (10) gulars 47–67; (11) subdigitals on Finger IV 22–29; (12) subdigitals on Toe IV 26–32; (13) posthumeral mite pocket present as one or more vertical folds or ridges; (14) postfemoral mite pocket distinct with slit-like opening; (15) parietal eye not visible through interparietal cornea; (16) scales on occipitoparietal region small, smooth, juxtaposed; (17) projecting angulate temporals absent; (18) row of enlarged supraoculars occupying most of supraocular region absent; (19) scales on frontonasal region juxtaposed anteriorly; (20) preauricular fringe present; (21) antegular (continuous medially), antehumeral, gular, longitudinal, oblique, postauricular, and supra-auricular neck folds present; (22) lateral and dorsal nuchals similar in size; (23) posterior gulars cycloid, smooth, slightly imbricate, not notched; (24) lateral scales reduced in size, approximately half the size of dorsal body scales closer to vertebral line; (25) vertebrals larger than adjacent paravertebrals; (26) dorsolateral crest absent; (27) ventrals smooth, imbricate; (28) scales on posterior surfaces of thighs granular; (29) inguinal granular pocket present; (30) inguinal groove present; (31) preanals not projected; (32) tail not compressed laterally in adult males; (33) tail length 47–54% of total length; (34) caudal whorls per autotomic segment two; (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 surface of thighs in adult males absent; (42) postxiphisternal inscriptional ribs not in contact midventrally (AMNH 23132, 23143–44, 23146 and MCZ 29303, 45882, misidentified as S. crassicaudatus in Torres-Carvajal [2004 a], correspond to S. torquatus .)

Color in life.—Dorsum emerald green, dark brown, or gray with yellow, black, or white scattered spots in some specimens; upper and lower eyelids light yellow in some specimens; black longitudinal stripe extending posterodorsally from preocular region to anterodorsal aspect of neck; black antehumeral collar in males bordered with yellow bands anteriorly and posteriorly; two short, black transverse bands anterior to antehumeral collar; ventral surface of body cream or light grey; pectoral and gular regions yellowish grey with light spots laterally in males; preanal region purple in some males and white in some females; tail gray, purple, or green. The dark antehumeral collar and short transverse bands anterior to it are present in juveniles of both sexes; they are retained in adult males, whereas females seem to gradually lose them with age. Both sexes of S. torquatus have the ability to change their dorsal background color from emerald green to dark brown or grey ( Torres-Carvajal et al., 2005).

Natural History.—Clutch size in S. torquatus is two eggs; the smallest individual was collected on July 2004 and had a total length of 71 mm (SVL = 35 mm, TL = 36 mm). This species is arboreal, with individuals collected at 1–4 m on tree trunks or seen at higher distances. Color change has been observed immediately after capture suggesting that it occurs as a response to stressful situations. The green coloration blends into the color of the mosses and ferns where this species has been found, whereas the dark coloration might provide camouflage against dark backgrounds.

Distribution.— Stenocercus torquatus is known from the central Andes (12 ° S–10 ° S) in the eastern Cordillera of Peru ( Fig. 10 ). This species occurs in Departamentos Junín and Pasco at elevations between 800–1800 m. S. torquatus is sympatric with S. boettgeri , S. formosus , and S. scapularis at María Teresa, 10 ° 42'05"S, 75 ° 27'22"W, 1470 m, Departamento Pasco ( Torres-Carvajal et al., 2005). S. variabilis occurs allopatrically at higher elevations (>2500 m) in Departamento Junín ( Fritts, 1974).

Figures

FIG. 22.—Six species of Stenocercus. (A) S. stigmosus (PVE); (B) S. torquatus (MLU); (C) S. trachŋcephalus (JMR); (D) S. tricristatus (illustration from plate XXII in Duméril, 1856); (E) S. Ʋariabilis (MLU); (F) S. Ʋarius (LAC).

FIG. 10.—Distribution of six species of Stenocercus in Peru.