Broadhead Ground Snake

description

Redescription of the holotype. Adult male; SVL 227 mm, CL 35.7 mm (15.7 % SVL); head length 12.8 mm (5.6 % SVL), head width 5.4 mm (42 % head length); head height 4.7 mm. Head indistinct from body; head flattened in lateral view and sub-triangular in dorsal view; snout acuminate in lateral view and rounded in dorsal view; rostral large, well visible in dorsal view and rounded in frontal view; internasal as wide as long; internasal suture sinistral with respect to prefrontal suture; prefrontal wider than long; supraocular sub-trapezoidal in dorsal view, about twice longer than wide; frontal sub-pentagonal, longer than wide; parietal about twice longer than wide; nasal divided; nostril almost restricted to prenasal; prenasal and postnasals about twice higher than long; loreal short, about as high as long; loreal contacting second and third supralabials; pupil subelliptical; postocular single, sub-pentagonal, about twice higher than long; temporal 1 + 2; anterior temporal slightly longer than high; upper posterior temporals fused, about twice longer than high; supralabials six, third and fourth contacting orbit; first two supralabials with equivalent height and smaller than third and

Morphological variation and taxonomy of Atractus latifrons (Günther, 1868) (Serpentes: Dipsadidae)

diagnosis

Diagnosis. Atractus latifrons can be distinguished from all its congeners by the following combination of characters: (1) dorsal scale rows 17 / 17 / 17; (2) postocular single; (3) loreal short, eventually fused to postnasal; (4) temporals 1 + 2; (5) supralabials six, third and fourth contacting orbit; (6) infralabials seven (n = 79), first four contacting chinshields (n = 80); (7) maxillary teeth five to six, lacking maxillar diastema; (8) gular scale rows three or four; (9) preventrals three or four; (10) ventrals 145 – 190 in females, 134 – 178 in males; (11) subcaudals 24 – 41 in females, 20 – 42 in males; (12) aposematic coloration, in preservation, with three mainly patterns [bicolor in monads, tricolor in dyads, and tricolor in tetrads] intercalating black and / or white rings separated by red interspaces; (13) ventral coloration, in preservation, similar to dorsum with complete black rings intercalating by red interspaces; (14) body size moderate to large, females reaching 566 mm SVL, males 521 mm SVL; (15) caudal length moderately long in females (10.9 - 14.6 % SVL), moderately long to long in males (13.3 – 20.0 % SVL); (16) hemipenis moderately bilobed, slightly semicapit

Morphological variation and taxonomy of Atractus latifrons (Günther, 1868) (Serpentes: Dipsadidae)

materials_examined

Holotype. Adult male, BMNH 1946.1.6.52 (formally BMNH 67.9.17.207), collected by Hauswell in the municipality of Pebas (= Pevas, 03 º 20 ’ S, 71 º 49 ’ W, ca. 100 m above sea level), department of Loreto, Peru (Figs. 10 – 11).

Morphological variation and taxonomy of Atractus latifrons (Günther, 1868) (Serpentes: Dipsadidae)

distribution

Distribution. Known from Bolivia, Brazil, Colombia, and Peru, in Amazonian forest (Plt. 168 A). In Brazil, widespread in Amazonia and northwestern Cerrado (Plt. 168 A) at low elevations (Plt. 168 B). Observed in the field in primary and secondary forest (Dixon and Soini, 1977, Hoogmoed, 1980, Martins and Oliveira, 1993, Almeida et al., 2014).

Atlas of Brazilian Snakes: Verified Point-Locality Maps to Mitigate the Wallacean Shortfall in a Megadiverse Snake Fauna