Synophis bicolor Peracca, 1896

Pyron, R. Alexander, Guayasamin, Juan M., Penafiel, Nicolas, Bustamante, Lucas & Arteaga, Alejandro, 2015, Systematics of Nothopsini (Serpentes, Dipsadidae), with a new species of Synophis from the Pacific Andean slopes of southwestern Ecuador, ZooKeys 541, pp. 109-147 : 121

Taxon classification Animalia Squamata Colubridae

Synophis bicolor Peracca, 1896

Holotype.

MZUT 257, locality given only as "South America."

Etymology.

None given by Peracca (1896); presumably from the Greek bi-color for "two colors," referring to the dark dorsum and light venter.

Description.

Small-sized (~200-400mm SVL) dipsadine snakes of the Andes and Chocó of Colombia and Ecuador, diagnosable by 16-27 maxillary teeth, 9-12 infralabials, 8 or 9 supralabials, fused prefrontals, loreal present, 2 postoculars, 152-193 ventrals, 96-143 subcaudals, dorsal scales in (19 –21)-(17–19)-(17– 18) weakly keeled rows, neural spine expanded and flattened, laterally expanded zygapophyses, and hemipenes slightly bilobed, semicalyculate, and semicapitate, relatively stout and bulbous, covered in large spines or hooks. Populations of this species are found in both lowland Chocóan rainforest and Andean cloud forests. Individuals are often found in leaf litter or in bushes, active at night. One collection from the Pacific Andean slopes of Ecuador (UMMZ 185886-185891) represents clutches of 2, 2, and 8 eggs, with hatchlings 125-132mm SVL. Nothing is known of diet.

Notes.

This is a species complex comprising at least three species-level taxa, which are distinct genetically, geographically, and morphologically (Figs 1, 3D, 4, 7, 9; Tables 1-3).

First are the Ecuadorean Andean highlands populations ( Synophis aff. bicolor ), which occur both on both the Pacific and Andean versants (~800-1700m). These are diagnosable by number of ventrals (152-166), subcaudals (96-122), infralabials (10 or 11), and supralabials (8 or 9), in combination. One individual (UMMZ 91550) has 24/27 maxillary teeth. The southernmost individual we examined (MZUTI 4180) has a very low number of ventral scales (152) compared to the remaining populations (160-166). Populations east and west of the Andes may also be a distinct species (O. Torres-Carvajal, pers. comm.), and are presented separately here. Most records from the Pacific versant north of the Río Toachi appear to represent Synophis calamitus (see below); one specimen reported from north of the river (BMNH 1940.2.30.31) may be mis-labeled, mis-identified, or the locality mis-referenced, or the species may be sympatric at some localities north of the river.

Second are the Chocóan populations from NW Ecuador, and presumably SW Colombia (~200-300m). These match the holotype in having 174-183 ventrals, 129-138 subcaudals, 8 supralabials, and typically 9 infralabials, though one specimen from further south (MZUTI 4175) has 11. We revise the type locality of Synophis bicolor by subsequent restriction (sensu Smith 1953) to Tobar Donoso, Carchi Province, Ecuador (1.19, -78.50), locality of several specimens examined here (Tables 1, 2; Figs 1, 4, 7, 9), to cement this association. Thus, this population represents Synophis bicolor sensu stricto in the case of future revision.

Third are the Colombian Andean highland populations (~1400-1500m; see Nicéforo-Maria 1970), which differ from the holotype in having 184-193 ventrals (versus 180), 127-131 subcaudals (versus 136), and 10-12 infralabials (versus 9). This group likely represents a third species, Synophis cf. bicolor . While we refrain from describing these additional Synophis bicolor -group species here based on limited current sampling, the populations described above likely represent at least two (Ecuadorean Andean highland and Colombian Andean Highland) if not three (E and W Ecuadorean and Colombian Andean highland) species.