Hypanus brevis: a newly resurrected Eastern South Pacific stingray lineage revealed by integrative taxonomy

Abstract

Hypanus brevis (Garman, 1880) and Hypanus dipterurus (Jordan & Gilbert, 1880) are currently considered as a conspecific lineage of the Eastern Pacific "diamond stingray". This group has been the subject of nomenclatural disputes for about 145 years, with H. brevis accepted as the junior synonym. To clarify the historical confusion surrounding this lineage, we employed an integrative taxonomic approach using specimens from the Eastern North and Eastern South Pacific (ENP and ESP). Both single (COI) and multilocus (COI - 16S rRNA) genetic analyses revealed a distinct evolutionary unit in the ESP. While morphological analyses detected subtle differences between ENP and ESP specimens (e.g., disc length and internostril width), most characters exhibited significant overlap, suggesting low evolutionary divergence. A Bayesian molecular clock analysis estimated this divergence at approximately 5.6 Ma. In accordance with Garmans (1880) original description based on specimens from Paita (northern Peru), we formally resurrect H. brevis from synonymy with H. dipterurus. Our findings suggest an anti-tropical speciation pathway, with core populations of H. brevis and H. dipterurus restricted to the temperate waters of the ESP and ENP, respectively. Notably, a single, fixed COI haplotype was detected in all H. brevis specimens from the north-central Peruvian coast. This result may indicate a severe bottleneck event, raising concerns about the genetic health and long-term viability of this vulnerable species. Finally, we analyzed historical fishery data of H. brevis to infer its current population status, suggesting targeted conservation measures and precautionary management to prevent further loss of genetic diversity.