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The taxonomic status of butterfly rays within the genus Gymnura remains a subject of ongoing debate among researchers. Some authors recognize up to five valid species for the Americas, while others considered several to be synonyms, which has posed a persistent challenge. We aimed to shed light on this complexity by employing molecular operational taxonomic units (MOTUs) based on the mitochondrial gene cytochrome oxidase I (COI). Genetic sequences were obtained from fresh muscle tissue collected in the marine ecoregions corresponding to the type locality from all the nominal butterfly ray species distributed along the Eastern Tropical Pacific (ETP). Our results unveiled compelling findings; all the species delimitation models used consistently identified seven MOTUs for the American continent and an extra G. altavela MOTU restricted to Africa. In addition, our results and models exceeded the worldwide accepted interspecific threshold of 2.0%. Remarkably, our results support the taxonomic reinstatement of Gymnura afuerae (Hildebrand, 1946) as a valid species, with a range expanding into the ETP in the Southern Hemisphere. Similarly, our data support the recent suggestion of resurrecting Gymnura valenciennii (Duméril, 1865) as a valid species in the western Atlantic. These findings urge a reassessment of the conservation status and a comprehensive taxonomic revision of American butterfly rays. Full article

Elasmobranchii are relatively well-studied. However, numerous phylogenetic uncertainties about their relationships remain. Here, we revisit the phylogenetic evidence based on a detailed morphological re-evaluation of all the major extant batomorph clades (skates and rays), including several holomorphic fossil taxa from the Palaeozoic, Mesozoic and Cenozoic, and an extensive outgroup sampling, which includes sharks, chimaeras and several other fossil chondrichthyans. The parsimony and maximum-likelihood analyses found more resolved but contrasting topologies, with the Bayesian inference tree neither supporting nor disfavouring any of them. Overall, the analyses result in similar clade compositions and topologies, with the Jurassic batomorphs forming the sister clade to all the other batomorphs, whilst all the Cretaceous batomorphs are nested within the remaining main clades. The disparate arrangements recovered under the different criteria suggest that a detailed study of Jurassic taxa is of utmost importance to present a more consistent topology in the deeper nodes, as issues continue to be present when analysing those clades previously recognized only by molecular analyses (e.g., Rhinopristiformes and Torpediniformes). The consistent placement of fossil taxa within specific groups by the different phylogenetic criteria is promising and indicates that the inclusion of more fossil taxa in the present matrix will likely not cause loss of resolution, therefore suggesting that a strong phylogenetic signal can be recovered from fossil taxa. Full article