Atractus caxiuana

distribution

Distribution. Known from Brazil and Colombia (Plt. 157 A). In Brazil, recorded by scattered records in Amazonia (Plt. 157 A), at low elevations (Plt. 157 B). No detailed field data on habitat use are available for this species.

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

materials_examined

Type locality. EstaÇão Ecológica Ferreira Penna, Floresta Nacional de Caxiuanã, MelgaÇo, state of Pará, Brazil.

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

description

Description. Head twice as long as wide, slightly arched in lateral view, round in dorsal view; cervical constriction barely distinct; snout truncate in lateral view, round in dorsal view; rostral subtriangular in frontal view, wider than high, barely visible in dorsal view; internasal about twice as wide as long; posterior portion of internasal usually contacting loreal; occasionally postnasal preventing internasal / loreal contact; suture dextral or sinister with respect to prefrontal midline suture; prefrontal as wide as long; supraocular subtrapezoidal, slightly longer than wide; frontal subtriangular, as long as wide; parietal twice as long as wide; nasal completely divided; nostril situated between prenasal and postnasal; prenasal twice as high as postnasal; postnasal slightly higher than long, as long as prenasal; loreal moderately long, contacting second and third supralabials ventrally and internasal anteriorly; pupil round; usually two postoculars slightly higher than long; upper postocular generally higher and longer than lower postocular; temporals 1 + 2; first temporal three times as long as high; upper posterior temporals fused, about four times as long as wide; seven

Morphological variation and affinities of the poorly known snake Atractus caxiuana (Serpentes: Dipsadidae)

diagnosis

Diagnosis. Atractus caxiuana is distinguished from all other congeners by the following combination of characters: loreal contacting the internasal (but see below); 17 / 17 / 17 dorsal scale rows with paired apical pits in both sexes and supra-anal tubercles present only in males; one or two postoculars; loreal moderately long; temporals 1 + 2; seven supralabials, third and fourth contacting orbit; seven infralabials, first three contacting chinshields; five or six maxillary teeth; four gular scale rows; four preventrals; 171 – 184 ventrals in females, 160 – 162 in males; 18 – 24 subcaudals in females, 25 – 30 in males; dorsum mostly dark brown, except for dispersed beige blotches on snout, a creamy incomplete collar covering the parietal, occipital and temporal regions of the head, and two pale brown longitudinal stripes covering the centre of first two dorsal scale rows of the body; belly creamy with lateral portion of the ventral scales dark brown, forming paraventral stripes; small body size, females reaching 265 mm SVL, males 261 mm SVL; small tail length in females (9.0 – 9.2 % SVL), moderately long in males (9.2 – 13.2 % SVL); hemipenis slightly bilobed, non-capitate and non

Morphological variation and affinities of the poorly known snake Atractus caxiuana (Serpentes: Dipsadidae)