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| Stenocercus canastra
Avila-Pires, Nogueira & Martins, 2019
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Abstract
A new species of the lizard genus Stenocercus Duméril & Bibron, 1837 is described based on six specimens from Serra da Canastra, Minas Gerais, southeastern Brazil. Similar to S. tricristatus (Duméril, 1851), S. dumerilii (Steindachner, 1867), S. quinarius Nogueira & Rodrigues, 2006, and S. squarrosus Nogueira & Rodrigues, 2006, the new species has a pyramidal head and an enlarged, dorsally projected post-supraciliary scale, like a small horn. It is most similar to S. tricristatus, from which it differs in having a more elongated head in ventral view; a larger number of scales around midbody; a distinctly enlarged, smooth preauricular scale; and probably a larger body size. Moreover, the new species has distinctly keeled scales, with phylloid and mucronate dorsals; no enlarged supraoculars; no neck folds; a vertebral, and a pair of dorsolateral and (weak) lateral crests. A redescription of S. tricristatus is presented for comparison with the new species.
Key words: Minas Gerais, new species, Serra da Canastra, Squamata, taxonomy
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| Figures 1–3. (1) Drawing of Stenocercus tricristatus from Plate XXII in Duméril (1851); (2) photograph (by O.A.V. Marques) of a live adult specimen of Stenocercus canastra sp. nov. (holotype, MZUSP 88873); (3) photograph (by CCN) of a live juvenile specimen of S. canatra sp. nov. (MZUSP 94456). |
Stenocercus canastra sp. nov.
Stenocercus cf. tricristatus; Teixeira et al. 2016: 411, 413.
Diagnosis: Stenocercus canastra sp. nov. is characterized by the following combination of features: (1) Dorsal head scales keeled. (2) Interparietal distinct, moderately enlarged; parietals about as large as, or smaller than interparietal; postparietals large, with a prominent keel; other posterior head scales variable in size. (3) Internasals six. (4) No distinctly enlarged supraoculars, but medial ones larger than lateral ones; all with pronounced keels. (5) An enlarged canthal on each side, in contact anteriorly with two elongate scales that form a double canthal ridge. (6) An enlarged, prominent, pointed scale immediately posterior to supraciliaries; no projecting, blade-like, angulate temporal scales. (7) Gulars and ventrals distinctly keeled. (8) Parietal eye distinct. (9) Neck folds absent. (10) Dorsals phylloid, keeled, mucronate, and imbricate; scales on flanks similar to dorsals. (11) A prominent serrate vertebral crest, a slightly less prominent dorsolateral crest, and an even less prominent lateral crest. (12) Mite pockets absent. (13) Scales on posterior surface of thighs imbricate, keeled. (14) Tail nearly cylindrical to moderately compressed, verticils absent. (15) Dorsal coloration with numerous, bold, dark brown rhomboid marks forming a longitudinal series on back, and dark brown vertical bands on flanks; head with at least a dark brown spot between nostrils, and a large, rhomboid spot between eyes; no sexual dimorphism in color pattern. (16) Scales around midbody 39–41, ventrals between anterior margin of forelimbs and anterior margin of hind limbs 25–28. (17) Ear opening bordered anteriorly by a distinctly enlarged, smooth scale. Stenocercus canastra sp. nov. is distinguished from all other Stenocercus except S. dumerilii, S. tricristatus, S. quinarius and S. squarrosus by the presence of an enlarged, prominent post-supraciliary scale (Figs 5–9); from all others except S. tricristatus, S. quinarius and S. squarrosus by a moderately enlarged interparietal (although not as large as in the Tropidurini; Figs 10–11). It is distinguished from S. dumerilii, S. quinarius and S. squarrosus (character states in parentheses) by the presence of a prominent, serrate vertebral crest (in contrast to a low vertebral crest); two, rarely 3, supraciliaries (4, rarely 3); ear-opening bordered anteriorly by a distinctly enlarged scale projecting over tympanum (no enlarged scale projecting over tympanum; Figs 12–17); dorsals distinctly keeled and mucronate (dorsals with a low keel, not or hardly mucronate); 9–10 scales across midbody from one dorsolateral row to the other (11–13 in S. dumerilii, 13–15 in S. quinarius and S. squarrosus); ventrals between anterior level of fore- and hind limbs 24–28 (28–32 in S. dumerilii, 30–34 in S. quinarius, 28–34 in S. squarrosus); scales on chin subequal and imbricate, or only most anterior ones smaller and subimbricate (scales on chin smaller, polygonal, and subimbricate anteriorly, grading into larger, pointed, and imbricate posteriorly; Figs 18–22); tail 1.4–1.8 times SVL (1.2–1.4 times in S. dumerilii, 1.0–1.1 in S. quinarius and 0.8–0.9 in S. squarrosus); and color pattern (Table 1). From S. tricristatus it differs in presenting head width 0.78–0.89 times head length (0.96); 39–41 scales around midbody (33); and ear-opening bordered anteriorly by a distinctly enlarged, smooth scale (scale not larger than adjacent temporal scales, keeled). Moreover, it probably reaches a larger body size (adult males ≥ 70 mm in S. canastra sp. nov. versus 58 mm in the holotype of S. tricristatus).
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Distribution: Stenocercus canastra sp. nov. is only known from Serra da Canastra National Park, Minas Gerais, Brazil (Figs 23–24). Besides the type series, two additional individuals of S. canastra sp. nov. were observed, but not collected, in an area very close to (less than 1 km N) the type-locality (O. Marini, pers. comm.).
Etymology: The specific epithet canastra is a noun in apposition and refers to the mountains (‘Serra da Canastra') where all specimens were collected.
Teresa C. Avila-Pires, Cristiano de C. Nogueira and Marcio Martins. 2019. A New ‘horned' Stenocercus from the Highlands of southeastern Brazil, and Redescription of Stenocercus tricristatus (Reptilia: Tropiduridae). Zoologia. 36: 1-16. DOI: 10.3897/zoologia.36.e22909
