Atractus cerberus, 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 : 99-102

publication ID

publication LSID

persistent identifier

taxon LSID

treatment provided by

ZooKeys by Pensoft

scientific name

Atractus cerberus

sp. n.

Atractus cerberus sp. n.

Proposed standard English name.

Cerberus Groundsnake

Proposed standard Spanish name.

Tierrera cancerbera


MZUTI 4330 (Fig. 5a), adult male collected by José L. Vieira-Fernandes and Alejandro Arteaga on November 06, 2015 at Pacoche, province of Manabí, Ecuador (S1.06664, W80.88123; 280 m).


MZUTI 5108 (Fig. 5b), adult male collected by Alejandro Arteaga on September 04, 2016.


Atractus cerberus is placed in the genus Atractus as diagnosed by Savage (1960), based on phylogenetic evidence (Fig. 1). It is included in the Atractus iridescens group due to its brown dorsal ground color (Fig. 5) and its phylogenetic position (Fig. 1). The species is diagnosed based on the following combination of characters: (1) 17/17/17 smooth dorsals; (2) two postoculars; (3) loreal moderate; (4) temporals 1+2; (5) seven supralabials, third and fourth contacting orbit; (6) seven infralabials, first four contacting chinshields (7) seven maxillary teeth; (8) three gular scale rows; (9) three preventrals; (10) 152-157 ventrals; (11) 25-26 subcaudals; (12) dorsal ground color brown with faint black longitudinal bands (Fig. 5); (13) venter light yellow faintly speckled with brownish pigment; (14) 212-309 mm SVL; (15) 23-36 mm TL.


Atractus cerberus is included in the Atractus iridescens species group and compared to other Pacific lowland congeners that have a brownish ground color (Fig. 2): Atractus boulengerii , Atractus dunni , Atractus echidna , Atractus esepe sp. n., Atractus iridescens , Atractus medusa , Atractus microrhynchus , and Atractus occidentalis . From Atractus boulengerii and Atractus medusa , it differs in having a striped pattern as opposed to bold black blotches (Fig. 5). From all others, it differs in having yellow ventral surfaces (as opposed to cream or dingy white) and having more than 150 ventrals in males. Finally, the dorsal pattern of Atractus cerberus is less clearly marked than in the majority of the known specimens of the species included in the Atractus iridescens group. Instead of having conspicuous spots, blotches or lines, Atractus cerberus has a series of feebly visible dashes made of pigment slightly darker than the surrounding ground color.

Color pattern.

The dorsal ground color is brown with five feebly visible dark-brown to black longitudinal lines that are not continuous throughout the length of the body but broken into spots along some sections (Fig. 5). Between the dark longitudinal lines on each side of the body, there are fields of lighter pigment that on some sections of the body correspond to lines. The head is darker than the rest of the dorsal surfaces and is marked by a dark, irregular postocular stripe that reaches the corner of the mouth (Fig. 5). The top of the supralabials is tinged with black. The ventral surfaces are yellowish cream with scattered brownish speckling that becomes more concentrated towards the tail, which is almost completely brown. The iris is carmine and the pupil is black.

Description of holotype.

Adult male, SVL 212 mm, tail length 23 mm (10.8% SVL); body diameter 6.5 mm; head length 7.9 mm (3.7% SVL); head width 4.8 mm (2.3% SVL); interocular distance 3.1 mm; head slightly distinct from body; snout–or bit distance 2.8 mm; rostral 1.6 mm wide, about one time broader than high; internasals 1.0 mm wide; internasal suture sinistral relative to prefrontal suture; prefrontals 1.7 mm wide; frontal 2.3 mm wide, with a curvilinear triangle shape in dorsal view; parietals 2.1 mm wide, about twice as long as wide; nasal divided; loreal 1.5 mm long, about 2 times longer than high; eye diameter 1.4 mm; pupil round; supraoculars 1.4 mm wide; two postoculars; temporals 1+2, upper posterior temporal elongate, about four times longer than high, and three times as long as first temporal; seven supralabials, 3 rd– 4th contacting orbit; symphisial 1.0 mm wide, about twice as broad as long, separated from chin shields by first pair of infralabials; seven 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 17/17/17 rows, smooth without apical pits; preventrals 3; ventrals 157; anal plate single; paired subcaudals 26.

Natural history.

The two known specimens of Atractus cerberus were found in an isolated patch of deciduous lowland forest surrounded by dry lowland shrubland. MZUTI 4330 was found active on leaf litter at 19h29, in 80% closed canopy secondary forest far from streams. The night was warm and there was drizzle the night before. MZUTI 5108 was found crossing a forest trail close to an open area at 10h00 during a sunny morning after a rainy night.


Known only from the type locality, Pacoche, in the Ecuadorian province of Manabí at 280-324 m (Fig. 3). This locality is 3 km airline distance from the shoreline.


The specific epithet " cerberus " is derived from the name of the Greek monster Kérberos. In Greek mythology, Kérberos is a monstrous multi-headed dog that guards the gates of the underworld, preventing the dead from leaving. Here, we use this word in allusion to the type locality, at the gates of the newly formed “Refinería del Pacífico”, a massive industrial oil-processing plant that can easily be likened to the underworld.

Conservation status.

Although Atractus cerberus belongs to a poorly studied genus of snakes and is known only from two specimens collected recently in a single locality, we consider this species to be Critically Endagered following B1a,b(iii) IUCN criteria because: i) its extent of occurrence is estimated to be less than 50 km2 (i.e. total area of continous semideciduous forest in the Refugio de Vida Silvestre Pacoche); ii) it has not been detected in any other locality in the province of Manabí despite numerous surveys ( Almendáriz and Carr 2007, Cisneros-Heredia 2004, MECN et al. 2013); and iii) and its habitat is severely fragmented, isolated from other such habitats and declining in extent and quality due to deforestation.