Stenocercus imitator Cadle, 1991

Torres-Carvajal, Omar, 2007, A TAXONOMIC REVISION OF SOUTH AMERICAN STENOCERCUS (SQUAMATA: IGUANIA) LIZARDS, Herpetological Monographs 21 (1), pp. 76-178 : 127-128

Stenocercus imitator Cadle

( Fig. 18 )

Stenocercus imitator Cadle, 1991:38 . Holotype: FMNH 232634 , a male from ‘‘road above Monte Seco toward Chorro Blanco , approximately 1.5 km (airline) NE Monte Seco, 1450 m, Río Zaña , Departamento Cajamarca, Perú ̕̕.

Diagnosis.— Stenocercus imitator and S. praeornatus are unique among species of Stenocercus with granular scales on the posterior surface of thighs in that adult males have a distinct black transverse band across the ventral surface of neck and a pink or lavender ventral background. S. imitator can be distinguished from S. praeornatus by having fewer vertebrals (49–66, X = 56.87 and 65–71, X = 67.83, respectively), fewer gulars (29–44, X = 34.98 and 38–50, X = 46.50, respectively), and fewer scales around midbody (85–124, X = 102.96 and 99–122, X = 107.67, respectively).

Description.—(1) Maximum SVL in males 100 mm ( Cadle, 1991); (2) maximum SVL in females 87 mm ( Cadle, 1991); (3) vertebrals 49–66; (4) paravertebrals 89–119; (5) scales around midbody 85–124; (6) supraoculars 4–7; (7) internasals 3–5; (8) postrostrals 4–5; (9) loreals 2–3; (10) gulars 29–44; (11) subdigitals on Finger IV 19–26; (12) subdigitals on Toe IV 28–37; (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 or wrinkled, juxtaposed; (17) projecting angulate temporals absent; (18) row of enlarged supraoculars occupying most of supraocular region absent; (19) scales on frontonasal region juxtaposed; (20) preauricular fringe present; (21) antegular (continuous medially), antehumeral, gular, longitudinal, oblique, postauricular, and supra-auricular neck folds present; (22) lateral nuchals less than half the size of dorsal nuchals; (23) posterior gulars cycloid, smooth, slightly imbricate, not notched; (24) lateral scales reduced in size, approximately half the size of dorsal body scales; (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 strongly compressed laterally in adult males; (33) tail length 65–70% 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 in 75% of specimens; (37) dark patch extensively covering gular region in 40% of females; (38) dark patch extensively covering gular region of adult males absent; (39) black patch on ventral surface of neck in adult males present; (40) dark midventral longitudinal mark such as faint line, conspicuous stripe, or extensive patch in adult males always present; (41) dark patches on ventral surface of thighs in adult males absent; (42) postxiphisternal inscriptional ribs not in contact midventrally, Patterns 1A and 2B.

Color in life.—Dorsum brown with dark bars middorsally and bright yellow spots in males; black vertical antehumeral bar bordered posteriorly by yellow line in males; black circular mark on scapular region in males; vertebral crest with some light blue patches in males; infralabials and gular region yellowish; yellow longitudinal line extends posteriorly from eye, over tympanum, to about a third of distance between fore and hind limbs in females; black patch on ventral surface of neck in males; throat and belly bright lavender in males; pectoral region white in females; belly and ventral aspect of hind limbs with orange wash in females; ventral aspect of tail pale orange ( Cadle, 1991). Considerable variation in color patterns has been reported for S. imitator ( Cadle, 1991; Schlüter, 1999 a).

Natural History.—Clutch size in S. imitator is 4–5 eggs; gravid females range in size between 70–83 mm SVL ( Cadle, 1991). Females with enlarged ova (>10 mm) were collected around May–June 1987. This species has been collected mostly on the ground in open areas within the forest, as well as disturbed areas such as agricultural plantations ( Cadle, 1991).

Distribution.— Stenocercus imitator occurs in the western Cordillera of the central Andes in Peru between 7 ° S–5 ° S ( Fig. 19 ). It is known from the upper valleys of Río Zaña, Río Piura (Pacific drainage), and Río Marañón (Atlantic drainage) in Departamentos Cajamarca and Piura at elevations of 1200– 2600 m. S. imitator occurs in sympatry with S. chlorostictus and S. percultus in both Departamentos, and S. eunetopsis in Cajamarca.

Figures

FIG. 18.—Eight species of Stenocercus. (A) S. fimbriatus (JCA); (B) S. formosus (MLU); (C) S. guentheri (LAC); (D) S. humeralis (OTC); (E) S. imitator (PVE); (F) S. iridescens (RWM); (G) S. lache (JMR); (H) S. limitaris (PVE).

FIG. 19.—Distribution of six species of Stenocercus in Ecuador and Peru.