Taxonomy without borders: Revision of the genus Atractus (Serpentes: Dipsadidae) from the Andes between Colombia and Venezuela

Abstract

We review the taxonomy of Atractus species distributed continuously along northeastern portions of the Andes of Colombia (= Eastern Cordillera), Sierra of Perijá on the Colombia-Venezuela border, and Cordillera of Mérida in northwestern Venezuela. We assess the taxonomic status of 29 species names on the basis of congruence between quantitative and qualitative phenotypic characters (pholidosis, morphometrics, color patterns, scales micro-or-namentations, male genitalia, and osteological features) along their entire distribution. Our results support the recognition of 23 species, 6 of which are new to science (5 described herein), through unique morphological diagnostic characters or unique combinations. We propose the synonymy of 14 old and even recently presented names based on the widespread overlap of all morphological character systems analyzed. Taxonomic decisions were made on the light of examination of available type series, geographically representative samples, anatomical preparations or observations, and careful literature review for all taxa recorded in the study area. We provide a dichotomous key for all recognized species along northeastern Andes of Colombia to northwestern Andes of Venezuela. We compare the geographic variation, morphological cohesion, and distribution limits of highland Atractus and contrast them with lowland species. Finally, we discuss the ultimate implication of taxonomic studies delimited by political boundaries or based on geographically restricted samples, especially when such approaches rely extensively on online datasets without critical examination of specimens.