A potential third Manta Ray species near the Yucatán Peninsula? Evidence for a recently diverged and novel geneticMantagroup from the Gulf of Mexico

Abstract

We present genetic and morphometric support for a third, distinct, and recently diverged group of Manta ray that appears resident to the Yucatán coastal waters of the Gulf of Mexico. Individuals of the genusMantafrom Isla Holbox are markedly different from the other described manta rays in their morphology, habitat preference, and genetic makeup. Herein referred to as the Yucatán Manta Ray, these individuals form two genetically distinct groups: (1) a group of mtDNA haplotypes divergent (0.78%) from the currently recognizedManta birostrisandM. alfredispecies, and (2) a group possessing mtDNA haplotypes ofM. birostrisand highly similar haplotypes. The latter suggests the potential for either introgressive hybridization between Yucatán Manta Rays andM. birostris, or the retention of ancestralM. birostrissignatures among Yucatán Manta Rays. Divergence of the genetically distinct Yucatán Manta Ray fromM. birostrisappears quite recent (<100,000 YBP) following fit to an Isolation-with-Migration model, with additional support for asymmetrical gene flow fromM. birostrisinto the Yucatán Manta Ray. Formal naming of the Yucatán Manta Ray cannot yet be assigned until an in-depth taxonomic study and further confirmation of the genetic identity of existing type specimens has been performed.