Atractus pyroni, Arteaga, Alejandro, Mebert, Konrad, Valencia, Jorge H., Cisneros-Heredia, Diego F., Penafiel, Nicolas, Reyes-Puig, Carolina, Vieira-Fernandes, Jose L. & Guayasamin, Juan M., 2017

Arteaga, Alejandro, Mebert, Konrad, Valencia, Jorge H., Cisneros-Heredia, Diego F., Penafiel, Nicolas, Reyes-Puig, Carolina, Vieira-Fernandes, Jose L. & Guayasamin, Juan M., 2017, Molecular phylogeny of Atractus (Serpentes, Dipsadidae), with emphasis on Ecuadorian species and the description of three new taxa, ZooKeys 661, pp. 91-123 : 105-106

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scientific name

Atractus pyroni

sp. n.

Atractus pyroni sp. n.

Proposed standard English name.

Pyron’s Groundsnake

Proposed standard Spanish name.

Tierrera de Pyron


MZUTI 5107 (Fig. 7), adult male collected by José L. Vieira-Fernandes and Carlos Durán on May 23, 2016 between Balzapamba and Bilován, province of Bolívar, Ecuador (S1.83601, W79.13322; 2026 m).


Atractus pyroni is placed in the genus Atractus as diagnosed by Savage (1960), based on phylogenetic (Fig. 1) and morphological (Table 3) evidence. It is included in the Atractus roulei group due to its 15/15/15 dorsal scale rows and its phylogenetic position (Fig. 1). The species is diagnosed based on the following combination of characters: (1) 15/15/15 smooth dorsals; (2) one postocular; (3) loreal long; (4) temporals 1+2; (5) six supralabials, third and fourth contacting orbit; (6) five infralabials, first four contacting chinshields (7) eight maxillary teeth; (8) 3 gular scale rows; (9) 2 preventrals; (10) 143 ventrals; (11) 16 subcaudals; (12) dorsal ground color dark brown with a series of light golden brown paravertebral scales running along the entire dorsum (Fig. 7); (13) venter dark brown with scattered scales of a lighter color; (14) 443 mm SVL; (15) 34 mm TL.


Atractus pyroni is compared to members of the Atractus roulei species group: Atractus carrioni , Atractus lehmanni , and Atractus roulei (Fig. 2). From Atractus carrioni , it differs by having a loreal. From Atractus lehmanni and Atractus roulei , it differs in size and color pattern. Atractus pyroni is 443 mm in SVL; whereas Atractus lehmanni is 262-321 in SVL, and Atractus roulei is 230-396. Both Atractus lehmanni and Atractus roulei have uniform dorsal ground color, whereas Atractus pyroni has a distinct dorsal bicolored pattern (Fig. 7). Finally, in life, Atractus pyroni is darker than the remaining members of the Atractus roulei species group and has a ventral pattern that, instead of having fine speckles, has conspicuous scattered blotches of a contrasting color.

Color pattern.

The dorsal ground color is blackish with a dark vertebral (mid-dorsal) scale row flanked by a dark yellow scale row on either side (the 7th dorsal scale row), irregularly adjoined by one to few additional yellow scales on the 6th dorsal scale row, rendering an appearance of an irregularly edged mid-dorsal striped pattern (Fig. 7). The dorsal and lateral surfaces of the head are dark grayish brown and the labials are dark mustard yellow. All ventral surfaces are glossy grayish black except for the throat and some scattered blotches, which are dark mustard yellow.

Description of holotype.

Adult female, SVL 443 mm, tail length 34 mm (7.7% SVL); body diameter 11.6 mm; head length 14.4 mm (3.3% SVL); head width 9.8 mm (2.2% SVL); interocular distance 5.1 mm; head slightly distinct from body; snout–orbit distance 5.7 mm; rostral 2.8 mm wide, about two times broader than high; internasals 1.5 mm wide; internasal suture sinistral relative to prefrontal suture; prefrontals 2.8 mm wide; frontal 3.5 mm wide, with a curvilinear triangle shape in dorsal view; parietals 4.0 mm wide, about twice as long as wide; nasal divided; loreal 3.7 mm long, about 3 times longer than high; eye diameter 1.8 mm; pupil round; supraoculars 2.1 mm wide; one postocular; temporals 1+2, upper posterior temporal elongate, about five times longer than high, and twice as long as first temporal; six supralabials, 3 rd– 4th contacting orbit; symphisial 2.4 mm wide, separated from chin shields by first pair of infralabials; five infralabials, 1 st– 4th contacting chin shields; anterior chin shields about three times as long as broad, posterior chin shields absent; three series of gular scales; dorsal scales 15/15/15 rows, smooth without apical pits; preventrals 2; ventrals 143; anal plate single; paired subcaudals 16.

Natural history.

The only known specimen of Atractus pyroni was found dead on a dirt road surrounded by silvopastures and remnants of native montane cloudforest.


Known only from the type locality, between Balzapamba and Bilován, in the Ecuadorian province of Bolívar at 2026 m (Fig. 7).


Named after R. Alexander Pyron, one of the most prolific contemporary herpetologists, in recognition of his invaluable contribution to systematics and evolution of the world’s reptiles.

Conservation status.

We consider Atractus pyroni to be to be Data Deficient following IUCN because there is inadequate information to make a direct, or indirect, assessment of its extinction risk based on its scarce distribution data.