DNA Barcoding Reveals Novel Evolutionary Lineages: Revision of the Dactylopterus volitans Complex and Description of Four New Endemic Species, Dactylopterus siculus sp. nov., Dactylopterus mediterraneus sp. nov., Dactylopterus naabensis sp. nov., and Dactylopterus brasilianus sp. nov.

Historically, the benthic teleost Dactylopterus volitans (Linnaeus, 1758) has been regarded as a single panmictic taxon, broadly distributed across the northern and southern Atlantic Ocean and the Mediterranean Sea basin. However, the pronounced morphological conservatism characteristic of the family Dactylopteridae has long obscured a complex and profound evolutionary fragmentation within this geographic range. The present study addresses this systematic anomaly by employing a rigorous molecular genetics approach based on DNA barcoding of the mitochondrial COI (Cytochrome c oxidase subunit I) locus from vouchered museum specimens. Molecular alignment results definitively dismantle the monospecific paradigm, revealing an unexpectedly high degree of genetic divergence and exposing the existence of an extensive cryptic species complex.The genetic identity of the nominal species, Dactylopterus volitans (sensu stricto), is herein formally restricted to the eastern Atlantic clade. Concurrently, four novel species are described: Dactylopterus siculus sp. nov., an isolated endemic in the central Mediterranean (Sicily, Italy); Dactylopterus mediterraneus sp. nov., a broadly distributed taxon spanning the entire Mediterranean basin; Dactylopterus naabensis sp. nov., an isolated lineage in the Gulf of Mexico; and Dactylopterus brasilianus sp. nov., endemic to the South American continental shelf.Analysis of the Miocene fossil record (†Dactylopterus decrozi) corroborates the hypothesis of extreme morphological stasis in the cranial architecture of the genus, elucidating the phenotypic latency of these ancient evolutionary divergences. Allopatric radiation within the complex was demonstrably driven by severe vicariance events and stringent oceanographic filters (e.g., salinity gradients, thermal fluctuations, and oceanic currents) rather than overt physical barriers. This taxonomic revision necessitates a drastic re-evaluation of the ecology, biogeography, and historical phenotypic data assignment for the genus Dactylopterus.