The Defensive Repertoire of New World Coral Snakes: Evolution and Natural History

Felipe José Paiva , Leandro Alves Silva, Fabricius Domingos, Fabio de Lima Muniz, Ricardo Alexandre Kawashita-Ribeiro

The defensive repertoire of New World coral snakes is diverse, but its evolutionary history remains poorly understood. We compiled 280 records of 11 defensive behaviors across 85 species of Micrurus and one species of Micruroides from the literature and contributions by researchers, naturalists, and wildlife photographers. Fifty-seven records represented behaviors not previously documented for the respective species. Using mitochondrial ND4 sequences, we inferred a Bayesian phylogeny, reconstructed ancestral states, and evaluated phylogenetic signal of the defensive behaviors. Tail-raising and coiling, dorsoventral body flattening, erratic movements, and head-hiding were reconstructed in the common ancestor of Micruroides and Micrurus, indicating a broadly conserved ancestral defensive repertoire. Erratic movements and head-hiding showed significant individual phylogenetic signal, and the combined profile of the four widespread behaviors was also phylogenetically structured. Hemipenis eversion was reconstructed as a synapomorphy of the sampled Micrurus frontalis-M. spixii clade, with an independent origin in M. boicora. Ventral exposure, cloacal popping sounds, and other less frequent behaviors also showed independent origins. These findings reveal a defensive repertoire combining deep evolutionary conservation with repeated origins of more restricted behaviors, while highlighting major gaps in behavioral sampling.