Vieira's Snail-eating Snake

description

Description of holotype. Adult male, SVL 515 mm, tail length 199 mm (38.6 % SVL); head length 20.7 mm (4.0 % SVL) from tip of snout to angle of jaw; head width 11.6 mm (55 % head length) taken at broadest point; snout-orbit distance 4.9 mm; head distinct from neck; snout short, blunt in dorsal outline and rounded in profile; rostral 3.8 mm wide, higher than broad; internasals 2.1 mm wide, broader than long; prefrontals 3.4 mm wide, slightly broader than long, entering orbit; supraocular 3.6 mm long, longer than broad; frontal 4.3 mm long, with a rounded triangular shape, in contact with prefrontals, supraoculars, and parietals; parietals 6.4 mm long, longer than broad; nasal divided, in contact with two supralabials, loreal, prefrontal, internasal, and rostral; loreal 2.3 mm long, longer than high, entering the orbit; eye diameter 3.9 mm; pupil semi-elliptical; no preocular; two postoculars; temporals 1 + 2; seven supralabials with 4 th and 5 th contacting orbit; symphysial precluded from contacting chinshields by first pair of infralabials; nine infralabials with 1 st- 6 th contacting chinshields; two pairs of chinshields longer than wide; dorsal scales in 15 / 15 / 15 rows, smoot

A consolidated phylogeny of snail-eating snakes (Serpentes, Dipsadini), with the description of five new species from Colombia, Ecuador, and Panama

description

Figs 4 d, 9, 10 b-d, 11 a, b Proposed standard English name: Vieira's Snail-eating Snake Proposed standard Spanish name: Culebra caracolera de Jose Vieira

A consolidated phylogeny of snail-eating snakes (Serpentes, Dipsadini), with the description of five new species from Colombia, Ecuador, and Panama

diagnosis

Diagnosis. Sibon vieirai sp. nov. is placed in the genus Sibon based on phylogenetic evidence (Fig. 1 a) and on having the penultimate supralabial conspicuously higher than all other supralabials. The species is diagnosed based on the following combination of characters: (1) 15 / 15 / 15 smooth dorsals with enlarged vertebral row (1.4 - 3 x as wide as adjacent rows); (2) loreal and prefrontal in contact with orbit; (3) 7 - 8 supralabials with, usually, 4 th, 5 th, and occasionally 6 th contacting orbit; (4) 9 - 10 infralabials with 1 st to 6 th in contact with chinshields, first pair of infralabials in contact behind symphysial; (5) 183 - 195 ventrals in males, 178 - 189 in females; (6) 95 - 105 divided subcaudals in males, 78 - 92 in females; (7) dorsal background color slate gray to brownish gray with faint blackish blotches or incomplete bands bordered by a series of white dots, fine blackish and white speckling in the interspaces (Figs 4 d, 9 a, 10 b-d), ventral surfaces white with encroachment from the dorsal blackish blotches and with or without fine black speckles in-between the blotches (Fig. 9 b), dorsal aspect of head black with fine white speckles, throat white with vari

A consolidated phylogeny of snail-eating snakes (Serpentes, Dipsadini), with the description of five new species from Colombia, Ecuador, and Panama

distribution

Distribution. Sibon vieirai sp. nov. is known from at least 95 localities (listed in Suppl. material 2) along the Chocoan lowlands and adjacent foothills of the Andes in northwestern Ecuador and southwestern Colombia. Previous records of S. nebulatus from the rainforests of northwestern Ecuador as well as those of the Pacific lowlands of Colombia in Narino department almost surely correspond to this new species. Sibon vieirai sp. nov. occurs over an estimated 58,551 km 2 area and has been recorded at elevations 5 - 1803 m above sea level (Fig. 12).

A consolidated phylogeny of snail-eating snakes (Serpentes, Dipsadini), with the description of five new species from Colombia, Ecuador, and Panama