Stenocercus aculeatus (O̕Shaughnessy)

Torres-Carvajal, Omar, 2007, A TAXONOMIC REVISION OF SOUTH AMERICAN STENOCERCUS (SQUAMATA: IGUANIA) LIZARDS, Herpetological Monographs 21 (1), pp. 76-178 : 81-82

Stenocercus aculeatus (O̕Shaughnessy)

Leiocephalus aculeatus O̕Shaughnessy, 1879: 303 . Syntypes: BM 1946.8.12.33–36 , from ‘‘ Moyobamba , [Departamento San Martín], Peru ̕̕; BM 1946.8.12.34 herein designated as lectotype.

Liocephalus aculeatus (part) Boulenger, 1885 a:167.

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. aculeatus is similar to S. angulifer , 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. aculeatus can be distinguished from S. angulifer by having a much deeper postfemoral mite pocket, a wider opening of the posthumeral mite pocket, and a lower 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), this species has fewer vertebrals (31–39, X = 35.20), fewer scales around midbody (32–37, X = 35.00), and more subdigitals on Toe IV (23–27, X = 25.00) than S. angulifer (37–47, X = 41.63, 38–50, X = 42.10, and 19–25, X = 22.84, respectively).

Description.—(1) Maximum SVL in males 103 mm (n = 3); (2) maximum SVL in females 91 mm (n = 2); (3) vertebrals 31–39; (4) paravertebrals 41–48; (5) scales around midbody 32–37; (6) supraoculars four; (7) internasals 4–5; (8) postrostrals 5–6; (9) loreals four; (10) gulars 15–18; (11) subdigitals on Finger IV 18–19; (12) subdigitals on Toe IV 23–27; (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 not strongly compressed laterally in adult males; (33) tail length 70– 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, Patterns 6A and 7, with the posteriormost pair not articulating with corresponding dorsal ribs (specimens of Stenocercus aculeatus in Torres-Carvajal [2004 a] correspond to S. angulifer , S. fimbriatus , and S. prionotus .)

Color in life.—Although no descriptions of color in life are available for S. aculeatus , when described the type specimens still retained a vertical white line on the shoulder between fore limb insertion and dorsolateral crest, as well as two longitudinal white lines between tympanum and shoulder (O̕ shaughnessy, 1879).

Distribution.— Stenocercus aculeatus occurs on the eastern slopes of the central Andes in northern Peru (8 ° S–5 ° S). This species is known from Departamentos La Libertad, Loreto, and San Martín at elevations of 723–1311 m ( Fig. 6 ). It is possible that S. aculeatus occurs in sympatry with S. prionotus ( Cadle, 2001) .

Remarks.— Torres-Carvajal (2000) described syntype BM 1946.8.12.34, which is herein designated as lectotype of S. aculeatus . The tail in this specimen is subelliptical, but not ‘‘strongly compressed̕̕ as mentioned by Torres-Carvajal (2000). In fact, one of the main characters that distinguish S. aculeatus from the herein resurrected S. angulifer is that adult males of the latter species have strongly compressed tails.

Figures

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