Michael Sabin’s Ground Snake

description

Description of holotype. Adult male, SVL 256 mm, tail length 39 mm (15.2 % SVL); body diameter 7.4 mm; head length 10.7 mm (3.1 % SVL); head width 6.4 mm (2.5 % SVL); interocular distance 3.7 mm; head slightly distinct from body; snout-orbit distance 3.5 mm; rostral 1.9 mm wide, ca. as broad as high; internasals 1.0 mm wide; prefrontals 2.0 mm wide; frontal 3.0 mm wide, with a curvilinear triangular shape in dorsal view; parietals 2.9 mm wide (65 % length); nasal divided; loreal 2.2 mm long, ~ 3 x longer than high; eye diameter 1.4 mm; pupil round; supraoculars 1.3 mm wide; one postocular; temporals 1 + 2; five supralabials, third contacting orbit; symphysial 1.7 mm wide, ~ 3 x as broad as long, separated from chinshields by first pair of infralabials; five infralabials, first three contacting chinshields; chinshields ~ 2 x as long as broad, posterior chinshields absent; dorsal scales arranged in 15 / 15 / 15 rows, smooth without apical pits; no preventrals; ventrals 143; anal plate single; 31 paired subcaudals.

Leaving no stone unturned: three additional new species of Atractus ground snakes (Serpentes, Colubridae) from Ecuador discovered using a biogeographical approach

description

Figs 8, 9, 10 f-h Proposed standard English name: Michael Sabin's Ground Snake. Proposed standard Spanish name: Culebra tierrera de Michael Sabin.

Leaving no stone unturned: three additional new species of Atractus ground snakes (Serpentes, Colubridae) from Ecuador discovered using a biogeographical approach

diagnosis

Diagnosis. Atractus michaelsabini sp. nov. is placed in the genus Atractus, as diagnosed by Savage (1960), based on phylogenetic evidence (Fig. 1). The species is diagnosed based on the following combination of characters: (1) 15 / 15 / 15 smooth dorsals; (2) one postocular; (3) loreal 3 x longer than high; (4) temporals 1 + 2; (5) five or six supralabials, with (usually) third and fourth contacting orbit; (6) five or six infralabials, with (usually) first three contacting chinshields; (7) 9 - 13 maxillary teeth; (8) 1 - 3 rows of gular scales; (9) 1 - 3 preventrals; (10) 143 - 144 ventrals in males and 144 - 153 in females; (11) 24 - 31 subcaudals in males and 17 - 19 in females; (12) dorsal ground color golden yellow (Figs 8, 10 f-g) to dark brown (Fig. 10 h) with each scale outlined in black, forming a reticulation; (13) venter yellowish with various degrees of brown stippling (Fig. 8 b); (14) 256 - 321 mm SVL in males and 201 - 392 mm SVL in females; (15) 35 - 42 mm TL in males and 21 - 37 mm TL in females.

Leaving no stone unturned: three additional new species of Atractus ground snakes (Serpentes, Colubridae) from Ecuador discovered using a biogeographical approach

distribution

Distribution. Atractus michaelsabini sp. nov. is endemic to an estimated 2,530 km 2 area along the Pacific slopes of the Andes in southwestern Ecuador. The species occurs in the xeric inter-Andean valley of the Rio Jubones as well as on the slopes of the Cordillera de Chilla. Atractus michaelsabini sp. nov. is known from provinces Azuay, El Oro, and Loja, and has been recorded at elevations between 927 and 2922 a. s. l. (Fig. 2).

Leaving no stone unturned: three additional new species of Atractus ground snakes (Serpentes, Colubridae) from Ecuador discovered using a biogeographical approach