Stenocercus melanopygus Boulenger, 1900

Torres-Carvajal, Omar, 2007, A TAXONOMIC REVISION OF SOUTH AMERICAN STENOCERCUS (SQUAMATA: IGUANIA) LIZARDS, Herpetological Monographs 21 (1), pp. 76-178 : 135-136

Stenocercus melanopygus Boulenger

( Fig. 20 )

Stenocercus melanopygus Boulenger, 1900: 182 . Syntypes: BMNH 1900.3.30.6–8 (RR 1946.8.11.85–88), BMNH 1900.3.30.6–9 ( MCZ 126133 ), 1900.3.30.10–13 (RR 1946.8.11.78–81) from ‘‘ Baños , 9000 ft, [Departamento] Cajamarca, Peru ̕̕; Burt and Burt, 1933:43; Etheridge, in Peters and Donoso-Barros, 1970:257; Fritts, 1974: 57.

Diagnosis.— Stenocercus melanopygus is distinguished from all species of Stenocercus except S. stigmosus in having granular scales on the posterior surface of thighs, vertebral and paravertebrals similar in size (i.e., no vertebral crest), three caudal whorls per autotomic segment, and imbricate or subimbricate smooth scales on the lateral surface of neck that are approximately less than half the size of dorsal neck scales. S. melanopygus differs from S. stigmosus (character states in parentheses) by lacking a posthumeral mite pocket (posthumeral mite pocket present as one or more vertical folds or ridges) and an oblique neck fold (oblique neck fold present). In addition, adult males of S. melanopygus lack the ventral black spots characteristic of S. stigmosus .

Description.—(1) Maximum SVL in males 85 mm (n = 23); (2) maximum SVL in females 63 mm (n = 21); (3) vertebrals 45–59; (4) paravertebrals 45–58; (5) scales around midbody 47–56; (6) supraoculars 5–6; (7) internasals 4–5; (8) postrostrals 4–8; (9) loreals 1–3; (10) gulars 20–25; (11) subdigitals on Finger IV 15–19; (12) subdigitals on Toe IV 21–28; (13) posthumeral mite pocket absent; (14) postfemoral mite pocket distinct with slit-like opening; (15) parietal eye always 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) antehumeral and longitudinal neck folds present; (22) lateral and dorsal nuchals similar in size; (23) posterior gulars cycloid, smooth, slightly imbricate, notched; (24) lateral and dorsal body scales similar in size; (25) vertebrals and adjacent paravertebrals similar in size; (26) dorsolateral crest absent; (27) ventrals smooth, imbricate; (28) scales on posterior surfaces of thighs granular; (29) inguinal granular pocket absent; (30) inguinal groove absent; (31) preanals not projected; (32) tail not compressed laterally in adult males; (33) tail length 61–66% of total length; (34) caudal whorls per autotomic segment three; (35) caudals not spinose; (36) dark brown 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 4% of adult males; (41) dark patches on ventral surface of thighs in 52% of adult males; (42) postxiphisternal inscriptional ribs not in contact midventrally, Patterns 1A, 2B.

Color in life.— Schlüter (2004) describes seven patterns to summarize color variation among males of S. melanopygus , which have a characteristic black or yellow patch covering at least the ventral surfaces of the pelvic region, base of tail, and hind limbs ( Fritts, 1974; Schlüter, 1999 d, 2004). Females have the following color features: dorsum light brown to grayish brown; whitish dorsolateral stripe from face to base of tail (this stripe also present in juveniles of both sexes); venter white or cream, sometimes with pink tint; ventral aspect of tail yellowish-brown ( Schlüter, 1999 d, 2004).

Natural History.—A female laid seven eggs in captivity in October 1998 ( Schlüter, 1999 d). Incubation time was 98–100 days at a temperature of 22–25 C. This species has been observed on the ground, blades of Agave plants, small rocks, and large rock piles ( Fritts, 1974).

Distribution.— Stenocercus melanopygus occurs in the western Cordillera of the central Andes in northern Peru ( Fig. 6 ). This species is known from the upper valley of Río Marañón (Atlantic drainage) at elevations between 2700– 3250 m in Departamentos Cajamarca and La Libertad (8 ° S–7 ° S). It is sympatric with S. empetrus at several localities.

Figures

FIG. 20.—Eight species of Stenocercus. (A) S. marmoratus (AMU); (B) S. melanopŋgus (PVE); (C) S. modestus (MLU); (D) S. nigromaculatus (WED); (E) S. nubicola (PVE); (F) S. ochoai (WED); (G) S. orientalis (PVE); (H) S. ornatissimus (MLU).

FIG. 6.—Distribution of five species of Stenocercus in Peru.