Diferenciação morfológica e ampliação geográfica de espécies de cobras corais-verdadeiras do complexo Micrurus ibiboboca (Merrem, 1820): diferentes abordagens

Abstract

Snakes of the family Elapidae include globally renowned representatives such as the black mamba, green mamba, king cobra, and cobras of the genus Naja, known for their high toxicity and significant medical relevance. In the New World, this family is represented by the true coral snakes, notable for their striking coloration, reclusive behavior, and potent neurotoxic venom. Due to the extensive overlap of diagnostic characteristics, comprehensive taxonomic revisions often involving the redescription and description of new species are frequently carried out using both morphological and molecular traits, as these snakes also exhibit substantial cryptic diversity. Recent studies have revised the Micrurus ibiboboca complex, redescribing the taxon and describing three new species: Micrurus anibal, Micrurus bonita, and Micrurus janisrozei. However, these species exhibit considerable overlap in morphological characters, making the use of complementary tools, such as geometric morphometrics, particularly valuable for identifying new distinguishing features. As these recently described species were previously treated under the same name throughout their distribution, it is essential to investigate intraspecific morphological variation using multiple approaches, including geographic variation and/or sexual dimorphism, to enhance our understanding of their biology. In this context, the present study aimed to investigate inter- and intrapopulational differences in M. bonita, M. ibiboboca, and M. janisrozei specifically along a latitudinal gradient for M. bonita and M. ibiboboca, and across different Morphoclimatic Domains for M. bonita and M. janisrozei. Sexual dimorphism and species delimitation within the group were also tested using geometric morphometric techniques. Morphological variation was detected along the latitudinal gradient in M. bonita and M. ibiboboca, and morphological differences related to the number of body triads were observed in M. bonita and M. janisrozei across distinct Morphoclimatic Domains. This study also expands the known geographic distribution of M. ibiboboca and M. janisrozei. Additionally, it demonstrates that the four species exhibit significant differences in head shape, with sympatric species such as M. ibiboboca and M. janisrozei being more similar to each other. Only M. bonita showed sexual dimorphism in both head size and shape, while M. janisrozei exhibited dimorphism in head shape only. The results suggest that ecomorphological studies in Micrurus species should be encouraged, as this approach provides relevant insights into the biology of these organisms. Finally, this study highlights the utility of alternative tools such as geometric morphometrics in identifying traits that are undetectable through traditional methods, contributing not only to ecomorphological research but also to taxonomic studies.