Stenocercus angulifer (Werner)

Torres-Carvajal, Omar, 2007, A TAXONOMIC REVISION OF SOUTH AMERICAN STENOCERCUS (SQUAMATA: IGUANIA) LIZARDS, Herpetological Monographs 21 (1), pp. 76-178 : 85-87

Stenocercus angulifer (Werner) ( Fig. 7 )

Leiocephalus angulifer Werner, 1901 a:595 . Holotype: ZMB 16594 , from ‘‘ Ecuador.̕̕

Leiocephalus aculeatus O̕ Shaughnessy, 1881: 243 .

Leiocephalus iridescens aculeatus (part) Burt and Burt, 1931:269; Burt and Burt, 1933:27; Burt and Myers, 1942:302; Cunha, 1961:85.

Ophryoessoides aculeatus (part) Etheridge, 1966:88; Peters, 1967:28; Etheridge, in Peters and Donoso-Barros, 1970:213.

Stenocercus aculeatus (part) Frost, 1992:43; Torres-Carvajal, 2000:5; Cadle, 2001:184.

Diagnosis.—Among species of Stenocercus with strongly keeled ventrals and laterally oriented nostrils, S. angulifer is similar to S. aculeatus , S. caducus , S. fimbriatus , S. prionotus , and S. scapularis in having a distinct posthumeral mite pocket. It differs from S. caducus , S. fimbriatus , and S. prionotus by having a distinct postfemoral mite pocket. From S. scapularis (character states in parenthesis) it differs by having a laterally compressed tail in adults (cross-section shape of tail rounded), caudal fractures planes (fracture planes absent), smooth infralabials and sublabials (infralabials and sublabials keeled), and postxiphisternal inscriptional ribs continuous medially (postxiphisternal inscriptional ribs not in contact medially). S. angulifer can be distinguished from S. aculeatus by having a shallower postfemoral mite pocket, a narrower opening of the posthumeral mite pocket, and a higher tail in adult males. The strongly laterally compressed tail in adult males of S. angulifer is more than twice as high as the tail in males of S. aculeatus of similar size. Although sample size for S. aculeatus is small (n = 5), S. angulifer has more vertebrals (37–47, X = 41.63), more scales around midbody (38–50, X = 42.10), and fewer subdigitals on Toe IV (19–25, X = 22.84) than S. aculeatus (31–39, X = 35.20, 32–37, X = 35.00, and 23–27, X = 25.00, respectively).

Description.—(1) Maximum SVL in males 96 mm (n = 15); (2) maximum SVL in females 82 mm (n = 9); (3) vertebrals 37–47; (4) paravertebrals 37–57; (5) scales around midbody 38–50; (6) supraoculars 4–5; (7) internasals 4–8; (8) postrostrals 4–6; (9) loreals 2–3; (10) gulars 16–20; (11) subdigitals on Finger IV 15–19; (12) subdigitals on Toe IV 19–25; (13) posthumeral mite pocket present as a deep depression; (14) postfemoral mite pocket distinct with slit-like opening; (15) parietal eye not visible through interparietal cornea; (16) scales on occipitoparietal region large, wrinkled, subimbricate; (17) projecting angulate temporals two; (18) row of enlarged supraoculars occupying most of supraocular region present; (19) scales on frontonasal region imbricate anteriorly; (20) preauricular fringe inconspicuous or absent; (21) neck folds absent; (22) lateral and dorsal nuchals similar in size; (23) posterior gulars rhomboidal, projected posteriorly, strongly keeled and imbricate, not notched; (24) lateral and dorsal body scales similar in size; (25) vertebrals larger than adjacent paravertebrals; (26) dorsolateral crest present; (27) ventrals keeled, imbricate, mucronate; (28) scales on posterior surfaces of thighs keeled, imbricate; (29) inguinal granular pocket absent; (30) inguinal groove absent; (31) preanals projected; (32) tail strongly compressed laterally in adult males; (33) tail length 68–73% 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 present; (37) dark patch extensively covering gular region of females absent; (38) dark patch extensively covering gular region in adult males present; (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) dark patches on ventral surface of thighs in adult males absent; (42) postxiphisternal inscriptional ribs continuous midventrally, Pattern 6B (KU 121093, identified as S. aculeatus in Torres-Carvajal [2004 a], corresponds to S. angulifer .)

Description of holotype.—Juvenile male; SVL = 44 mm; TL = 91 mm; maximum head width = 9.53 mm; head length = 11.58 mm; head height = 8.14 mm; scales on parietal and occipital regions large, wrinkled, subimbricate; parietal eye not visible; supraoculars in five rows, wrinkled, imbricate, one row occupying most of supraocular region; canthal single; scales in frontonasal region imbricate; internasals four; lorilabials in one row; lateral temporals imbricate, keeled; gulars in 19 rows between tympanic openings; all gulars keeled, imbricate; lateral and dorsal scales of neck, body, and limbs keeled, imbricate; scales around midbody 41; vertebrals large, in 38 rows, forming serrate vertebral crest; one dorsolateral crest on each side; paravertebrals 45; ventrals strongly keeled, imbricate, mucronate; preauricular fringe absent; neck folds absent; subdigitals on Finger IV 15; subdigitals on Toe IV 21; tail slightly compressed laterally; caudals keeled, imbricate; tail length 2.1 times SVL; posthumeral mite pocket deep with narrow opening; postfemoral mite pocket present with slit-like opening.

Color in preservative of holotype.—Dorsum yellowish brown with seven posteriorly-oriented dark triangular transverse marks arranged middorsally between occiput and vent; throat and flanks of body dark brown; venter bronze; antehumeral fold whitish ( Werner, 1901 a). The ‘‘antehumeral fold̕̕ of Werner (1901 a) corresponds to a weak vertical crest between the insertion of the fore limb and the dorsolateral crest.

Color in life (males only).—Background dark brown; dorsal aspect of head and flanks darker than dorsum; six faint, dark chevrons longitudinally arranged on dorsum between fore and hind limbs; faint creamish-brown vertical line from insertion of fore limb to dorsolateral crest; some scales on sides of neck cream; sides of head dark gray; gular region black; mental and infralabials gray; a reddish-brown to pink tint extends midventrally from pectoral region and ventral aspect of fore limbs to pelvic region and ventral aspect of thighs; tail with alternating wide, dark brown rings and narrow, light brown rings; white, small, irregular marks on ventral aspect of tail (based on photographs of QCAZ 6761 taken by F. Ayala.)

Natural History.—Clutch size in S. angulifer is two eggs; the smallest individual was collected in May 1993 and had a total length of 112 mm (SVL = 39 mm, TL = 73 mm; Torres-Carvajal, 2000).

Distribution.— Stenocercus angulifer occurs on the eastern slopes of the northern Andes in central Ecuador (2 ° S–1 ° S). This species is known from Provincias Morona-Santiago, Pastaza, and Tungurahua at elevations of 266–1200 m ( Fig. 9 ).

Remarks.— Cadle (2001) was the first author to note some differences between Ecuadorian and Peruvian populations of ‘‘ Stenocercus aculeatus ̕̕. Here I conclude that they represent different species and resurrect S. angulifer from synonymy with S. aculeatus .

Figures

FIG. 7.—Eight species of Stenocercus. (A) S. angel (LAC); (B) S. angulifer (FAY); (C) S. apurimacus (WED); (D) S. azureus (SCA); (E) S. boettgeri (MLU); (F) S. boliƲarensis (FCA); (G) S. caducus (LSI); (H) S. chlorostictus (MLU).

FIG. 9.—Distribution of six species of Stenocercus in Ecuador.