A giant on the ground: another large-bodied Atractus (Serpentes: Dipsadinae) from Ecuadorian Andes, with comments on the dietary specializations of the goo-eaters snakes

Abstract

Body-size is significantly correlated with the number of vertebrae (pleomerism) in multiple vertebrate lineages, indicating that somitogenesis process is an important factor dictating evolutionary change associated to phyletic allometry and, consequently, species fitness and diversification. However, the role of the evolution of extreme body sizes (dwarfism and gigantism) remains elusive in snakes, mainly with respect to postnatal ontogeny in dietary preferences associated with evolution of gigantism in many lineages. We described herein a new species in the highly diversified and species-rich genus Atractus on the basis of four specimens from the southeastern slopes of the Ecuadorian Andes. The new species is morphologically similar and apparently closely related to two other allopatric giant congeners (A. gigas and A. touzeti), from which it can be distinguished by their distinct dorsal and ventral coloration, the number of supralabial and infralabial scales, the number of maxillary teeth, and relative width of the head. In addition, we discuss on the ontogenetic trajectories hypotheses and dietary specializations related to evolution of gigantism in the goo-eaters genus Atractus.

Systematic review of the polychromatic ground snakesAtractus snethlageaecomplex reveals four new species from threatened environments

“…Furthermore, the specimen referred as Atractus snethlageae without voucher, photographed by Arteaga et al (2017) also is similar to A. pachacamac . Thus, as far we know, A. touzeti is still known only from its type series from the Cordillera de los Guacamayos in northeastern Ecuador (>1800 m asl; see Schargel et al, 2013 and Passos et al, 2019).…”

“…The genus comprises 143 currently recognized species (Uetz et al, 2020). However, many species remain known only from their type series or from geographically restricted regions (Passos et al, 2019). Consequently, some important aspects related to geographic, ontogenetic, sexual dimorphism, and population variation have not yet been properly documented (Passos et al, 2012).…”

Morphology and natural history of Three-lined Snakes, Atractus trilineatus (Squamata, Dipsadidae), in the Eastern Caribbean

“…The genus is primarily South American with some minor representation in Panama (Myers 2003). A comprehensive revision of the genus is lacking, and the alpha taxonomy of the clade is in disarray due to some species being known only from the type material, misidentified specimens, and the extraordinarily large number of species descriptions (Passos and Lynch 2010;Passos et al 2019). Some of these are microendemics and are known only from the holotype or a small series of specimens from restricted ranges (Passos et al 2007), whereas others are relatively widespread (Wallach et al 2014).…”

The Western Amazonian Richness Gradient for Squamate Reptiles: Are There Really Fewer Snakes and Lizards in Southwestern Amazonian Lowlands?

“…For this reason, we have provided a list of vouchered specimens from LABS that can be cross-referenced by future studies. Potentially problematic groups include the following snake genera: (1) Chironius, including the relationship between C. carinatus and C. exoletus in southern Peru (listed as C. exoletus/carinatus in Table A1) as well the potential for cryptic diversity in several other taxa [48,52]; (2) all species in the genus Erythrolamprus ( = Liophis), which appears to consist of five species at LABS, but where-in light of recent taxonomic work [27]-the connections between the taxa we list and Erythrolamprus/Liophis taxa reported for other Amazonian sites is unclear; (3) Atractus, a megadiverse snake genus that contains at least three species at LABS, but which is in need of comprehensive revision for southern Amazonia; species of this genus are frequently misidentified in both museum and field collections [53,54].…”