A new ‘horned’ Stenocercus from the highlands of southeastern Brazil, and redescription of Stenocercus tricristatus (Reptilia: Tropiduridae)

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.

摘要：基于采自巴西东南部米纳斯吉拉斯州卡斯特拉山脉（Serra da Canastra）的6号标本，记述了钝趾蜥属（Stenocercus Duméril & Bibron, 1837）1新种。该新种与S. tricristatus（Duméril, 1851）、S. dumerilii（Steindachner, 1867）、S. quinarius Nogueira & Rodrigues, 2006以及S. squarrosus Nogueira & Rodrigues, 2006形态近似，均具备金字塔形头部，以及一枚膨大且向背部凸起的眶后上鳞，外形酷似小型角突。该新种与S. tricristatus的亲缘关系最为接近，二者的区别特征包括：腹面观下头部更为修长；体中部环体鳞片数量更多；前耳鳞明显膨大且表面光滑；且推测体型更大。此外，该新种的鳞片均具明显棱脊，背鳞呈叶状且具锐尖；无膨大的眶上鳞；无颈褶；具1条椎嵴、1对背外侧嵴以及（微弱的）侧嵴。为便于与本新种进行对比研究，本文同时对S. tricristatus进行了重新记述。