Reassessing the systematics of Leptodeira (Serpentes, Dipsadidae) with emphasis in the South American species

Abstract

Within the diverse subfamily Dipsadinae, Imantodini represents one of the few groups distributed in North, Central and South America. The tribe comprises the genera Leptodeira and Imantodes, from which Leptodeira is the most diverse, including 15 species and 11 subspecies, distributed from southern USA to central Argentina. Taxonomy and affinities among these taxa are poorly resolved, and the phylogenetic relationships among the South American diversity were never properly assessed before. Here, we investigate the phylogenetic relationships and the taxonomic status of Leptodeira spp. based on a comprehensive multilocus dataset with emphasis in the South American radiation. Besides assessing the phylogenetic relationship and species cohesion, we also evaluate the morphological variation among the South American diversity of Leptodeira. Our results support the monophyly of Imatodini and Leptodeira, while indicating that several individuals classified as Leptodeira annulata and L. septentrionalis do not cluster together within their respective species. Moreover, specimens identified as belonging to the subspecies L. a. annulata, L. a. cussiliris, L. s. ornata and L. s. polysticta do not group together suggesting the current classification includes non-natural groups. The analysis of morphological evidence also supports the phylogenetics results, indicating that several clades can be recognized as evolutionary units presenting distinct phenotypes. To equate the taxonomy to our results, we propose a new taxonomic arrangement for Leptodeira in which we are: (1) redefining the composition of L. annulata and L. septentrionalis; (2) elevating five subspecies to species level; (3) revalidating one species; (4) recognizing four species complexes; and (5) indicating the presence of hidden diversity (probably four undescribed species). Finally, we describe a new species (Leptodeira tarairiu sp. nov.) from the open formations of South America (Cerrado and Caatinga), and we provide detailed redescriptions for all South American species of Leptodeira.