Stenocercus azureus (Müller)

(Fig. 7)

Tropidocephalus azureus Müller, 1880:45. Holotype: NMB 3601 from ‘‘ Uruguay ̕̕; Müller, 1885:107.

Liolaemus azureus Boulenger, 1885 b:192.

Saccodeira azurea Boulenger, 1885 a:160; Koslowsky, 1898:183.

Proctotretus azureus Amaral, 1937:180; Burt and Burt, 1930:21; Burt and Burt, 1931:286; Burt and Burt, 1933:41; Peters and Donoso-Barros, 1970:241.

Stenocercus azureus Frost, 1992:43; Cei, 1993:304.

Diagnosis.—Among species of Stenocercus that lack posthumeral and postfemoral mite pockets, and have imbricate scales on the posterior surface of thighs (i.e., S. azureus, S. doellojuradoi, S. dumerilii, S. pectinatus, S. quinarius, S. sinesaccus, S. squarrosus, and S. tricristatus), those species formerly assigned to ‘‘ Proctotretus ̕̕ (i.e., S. azureus, S. doellojuradoi and S. pectinatus) are unique in having posteriorly projected preanals that form a denticulate border, and two longitudinal rows of lorilabials between the anterior portion of the subocular and the corresponding supralabials. S. azureus can be distinguished from S. doellojuradoi and S. pectinatus (character states in parentheses) by having unnotched, strongly keeled ventrals and gulars (smooth ventrals and gulars, with caudal notch).

Description.—(1) Maximum SVL in males 59 mm (n = 2); (2) maximum SVL in females 83 mm (n = 4); (3) vertebrals 30–37; (4) paravertebrals 34–42; (5) scales around midbody 33–39; (6) supraoculars five; (7) internasals 4–5; (8) postrostrals four; (9) loreals two; (10) gulars 13–19; (11) subdigitals on Finger IV 10–14; (12) subdigitals on Toe IV 16–23; (13) posthumeral mite pocket absent; (14) postfemoral mite pocket absent; (15) parietal eye always visible through interparietal cornea; (16) scales on occipitoparietal region small, keeled, imbricate (17) projecting angulate temporals absent; (18) row of enlarged supraoculars occupying most of supraocular region absent; (19) scales on frontonasal region imbricate anteriorly; (20) preauricular fringe present; (21) antehumeral fold present; (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 strongly keeled, imbricate, mucronate; (28) scales on posterior surfaces of thighs keeled, imbricate, mucronate; (29) inguinal granular pocket absent; (30) inguinal groove absent; (31) preanals projected; (32) tail not compressed laterally in adult males; (33) tail length 64% of total length; (34) caudal whorls per autotomic segment two; (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 adult males absent; (41) dark patches on ventral surface of thighs in adult males absent; (42) postxiphisternal inscriptional ribs not in contact midventrally, Patterns 1C, 2C, and 2D.

Color in life.—Background with green and chestnut tones, occasionally with an iridescent blue tint; dorsum with one pair of dorsolateral cream stripes extending posteriorly above tympania from each eye to base of tail, as well as a longitudinal series of three semicircular marks between dorsolateral stripes; flanks with a ventrolateral stripe usually extending between head and hind limbs; dorsum of head with a V or M-shaped interorbital bar and another mark anterior to it; distal portion of tail with dark rings; ventral surfaces homogeneous and lighter than dorsal surfaces (Carreira et al., 2005).

Natural History.—Eggs are laid around January; females ranging between 67– 80.2 mm SVL contained 6–9 oviductal eggs (Carreira and Baletta, 2004; Torres-Carvajal, 2004 b).

Distribution.— Stenocercus azureus is known from the lowlands (150–250 m) of southeastern South America between 34 ° S– 24 ° S (Fig. 11). This species occurs in Estados Paraná, Rio Grande do Sul, and São Paulo in southern Brazil, as well as Departamentos Artigas, Canelones, Cerro Largo, Lavalleja, Rivera, Salto, Soriano, and Tacuarembó in Uruguay (Carreira et al., 2005; Nogueira and Rodrigues, 2006).

Remarks.—Although small sample size did not allow me to study intraspecific variation in S. azureus in more detail, there are some observations worth mentioning. Similar to S. doellojuradoi and S. pectinatus, S. azureus has a small antehumeral mite pocket. However, two female specimens (AMNH 131858 and MCZ 133257) from Estados Paraná and Rio Grande do Sul in southern Brazil lack this structure, suggesting that there is variation in the presence of the antehumeral mite pocket, or that the two specimens in question represent a new species similar to S. azureus. Furthermore, R. Etheridge (personal communication) has examined specimens from Uruguay that seem to be hybrids between S. azureus and S. pectinatus based on several morphological characters.