Atractus medusa

description

Description of holotype: Adult male, 325 mm SVL; 60 mm CL (18.4 % of SVL); head length 10.5 mm (3.2 % of SVL); head width 4.9 mm (47 % of head length); head arched in lateral view, rounded in dorsal view; snout slightly acuminate in lateral view, rounded in dorsal view; cervical constriction barely distinct; rostral sub-triangular, 1.8 mm broad, 0.7 mm high, poorly visible in dorsal view; internasal 0.8 mm long, 0.3 mm wide; internasal suture sinistral with respect to prefrontal suture; prefrontal 2.2 mm long, 2.0 mm wide; supraocular sub-trapezoidal, 1.3 mm long, 0.6 mm wide; frontal sub-pentagonal, 2.6 mm long, 2.5 mm wide; parietal 4.1 mm long, 2.4 mm wide; nasal divided; nostril located between prenasal and postnasal; prenasal 0.6 mm long, twice as high as long; postnasal 0.3 mm high, as high as long; loreal 2.2 mm long, 0.5 mm high, contacting second and third supralabials; eye diameter 1.4 mm; pupil round; two postoculars with similar size; upper postocular 0.6 mm high, 0.4 mm long, slightly longer than lower postocular; temporals 1 + 2; first temporal 1.5 mm, slightly longer than high; upper posterior temporals elongate, 3.3 mm long, 0.8 mm wide; seven supralabials, third an

Pacific lowland snakes of the genus Atractus (Serpentes: Dipsadidae), with description of three new species

diagnosis

Diagnosis: Atractus medusa is distinguished from all congeners by the combination of the following characters: (1) 17 / 17 / 17 smooth dorsal scale rows; (2) two postoculars; (3) loreal long; (4) temporals 1 + 2; (5) seven supralabials, third and fourth contacting orbit; (6) seven infralabials, first four contacting chinshields; (7) five maxillary teeth; (8) three gular scale rows; (9) two preventrals; (10) 133 ventrals in the single male; (11) 46 subcaudal; (12) dorsum beige with light occipital band and round dark brown blotches, decreasing in size posteriorly; (13) venter cream with diffuse dark brown dots concentrated posteriorly; (14) moderate body size, male with 325 mm SVL; (15) long tail (18.4 % SVL); (16) hemipenis strongly bilobed, semicapitate, and semicalyculate. Comparisons: Atractus medusa is distinguished from all congeners by having lobes twice as long as the hemipenial body. Additionally, A. medusa shares exclusively with A. boulengerii 17 dorsal scale rows, five or six maxillary teeth, large black band on neck, and rounded dorsal blotches decreasing in size posteriorly. Atractus medusa differs from A. boulengerii by having 133 ventrals in male, single postdiastema

Pacific lowland snakes of the genus Atractus (Serpentes: Dipsadidae), with description of three new species

discussion

Remarks: Despite the fact that A. medusa is described on the basis of a single specimen, it is apparently abundant on Gorgona Island (M. Rada, pers. commun.). The island is a national park of Colombia and, as a consequence, collecting is limited.

Pacific lowland snakes of the genus Atractus (Serpentes: Dipsadidae), with description of three new species

distribution

Distribution: Known only from the continental Gorgona Island, municipality of Guapi, department of Cauca, Pacific region of Colombia (Fig. 2).

Pacific lowland snakes of the genus Atractus (Serpentes: Dipsadidae), with description of three new species