The role of the American continent on the diversification of the stingrays' genus Hypanus Rafinesque, 1818 (Myliobatiformes, Dasyatidae)

PETEAN, FLÁVIA F.; YANG, LEI; CORRIGAN, SHANNON; LIMA, SERGIO M. Q.; NAYLOR, GAVIN J. P.

Congreso; Evolution; 2021

The stingrays of the resurrected genus Hypanus Rafinesque, 1818 currently encompass eight valid species (previously considered as Dasyatis) distributed both in the Atlantic and Pacific oceans. However, the phylogenetic relationships amongst some of them were based on a single mitochondrial gene and did not involve all putative Hypanus species, lacking H. marianae and H. rudis. To address the monophyly of the genus and evaluate their divergence times and possible routes of dispersion, we sequenced the whole mitochondrial genomes of all valid species using the gene capture methodology and performed Maximum Likelihood analyses and Bayesian Inferences. In addition to the monophyly of the genus, we found that H. longus from the Pacific coast of the American continent is a sister-group to the clade H. berthalutzae + H. rudis. This sister relationship is the result of a cladogenetic event derived from the vicariant closure of Isthmus of Panama. Another clade regards the species complex H. guttatus (Bloch & Schneider, 1801), with one lineage in Central and another in South America, which were produced by a speciation event probably related to the Amazon barrier. Another species complex concerns H. say (Lesueur 1817), with one lineage at the Eastern coast of the United States and another in the Gulf of Mexico, separated by the Florida Peninsula. Hypanus marianae (Gomes, Rosa & Gadig, 2000), endemic to Northeastern Brazil, whose phylogenetic relationships within the genus were unknown, is a sister-group to the clade composed by H. americanus species complex, H. berthalutzae, H. longus, and H. rudis. We also identified the species Fontitrygon geijskesi as more closely related to H. guttatus than to other Fontitrygon species, thus it should be allocated to Hypanus as H. geijskesi. The genus originated 33.97 Ma [26.13-36.09 HPD] and its subsequent diversification was probably related to a world cooling event in which these stingrays were restricted to tropical waters in Western Atlantic. Oceanic geophysical changes are consistent with the divergence times of lineages within this group of stingrays, which harbors a hidden diversity that might affect the conservation status of some species.