Despax's Ground Snake

description

Description: Head twice as long as wide, arched in lateral view, rounded in dorsal view; snout truncate in lateral view, rounded in dorsal view; cervical constriction indistinct; rostral subtriangular in frontal view, broader than high, little visible in dorsal view; internasal as long as wide; internasal suture sinistral with respect to prefrontal suture; prefrontal as long as wide; supraocular sub-trapezoidal, slightly longer than wide; frontal sub-triangular, as long as wide; parietal twice as long as wide; nasal divided; nostril located between prenasal and postnasal; prenasal about three times as high as long; postnasal smaller than prenasal, about twice as high as long; loreal long, contacting second and third supralabials; small preocular (as long as high) ocasionally present, preventing orbit / loreal contact; pupil subelliptical; two postoculars; upper postocular slightly longer than lower and lower slightly higher than upper postocular; temporals 1 + 2; first temporal twice as long as high; upper posterior temporal elongate, four times as long as wide; generally seven supralabials, third and forth contacting orbit; second and third supralabials of similar size and slightl

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

diagnosis

Diagnosis: Atractus paucidens is distinguished from all congeners by the following combination of characters: (1) 17 / 17 / 17 smooth dorsals; (2) two postoculars; (3) loreal long; (4) temporals generally 1 + 2; (5) generally seven supralabials, third and fourth contacting orbit; (6) seven infralabials, first four contacting chinshields; (7) five or six maxillary teeth; (8) generally four gular scale rows; (9) four preventrals; (10) 169 – 190 ventrals in females, 169 – 175 in males; (11) 31 – 38 subcaudals in females, 43 – 45 in males; (12) dorsal ground colour black with narrow cream bands on the flanks; (13) venter beige, heavily scattered with black dots to uniformly black; (14) moderate body size in females 419 mm SVL and small in males 263 mm SVL; (15) tail long in females (15.1 – 16.0 % SVL) and males (18.6 – 21.3 % SVL); (16) hemipenis moderately bilobed. Comparisons: Among all congeners, Atractus paucidens shares the occasional occurrence of preoculars and long tail length in both sexes only with A. favae. Atractus paucidens differs from A. favae in having the first pair of infralabials preventing symphisial / chinshields contact, loreal long, 31 – 38 subcaudals in females

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

discussion

Remarks: Despax (1910) described Atractus (Atractopsis) paucidens, new subgenus and species distinguishing it from remaining Atractus by having a reduced maxillary bone with only four large teeth decreasing in size posteriorly. In a subsequent paper, Despaux (1911) figured the maxilla of Atractopsis paucidens. Savage (1960) did not recognize Atractopsis, pointing out that the maxilla illustrated by Despax (1911) was apparently broken and for that reason lacked posterior teeth. Savage (1960) advocated that this taxon was concordant with other Atractus species with regard to maxillary dentition and also agreed in other morphological features, and therefore allocated it tentatively to the A. trilineatus species group. Savage (1960) reported the second individual of A. paucidens from Pitzara River at province of Pichincha. We report herein seven (four males and three females) additional A. paucidens, all topotypes. Although the study of maxillary bones of these specimens does not corroborate Savage’s suspicion of a broken element (the species displays low number of maxillary teeth, see above), there is no reason to recognize the subgenus Atractopsis according to the actual Atractus con

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

distribution

Distribution: Pacific coast of Ecuador from the mouth of the Pitzara River (02 º 00 ’ N, 79 º 09 ’ W) to Santo Domingo de Los Colorados (00 º 15 ’ S, 79 º 09 ’ W) in the province of Pichincha. Atractus paucidens inhabits rainforest at elevations of 200 – 600 m (Fig. 6).

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