The Mediterranean False Killer Whale (Pseudorca crassidens rafinesquegiglioliorum subsp. nov.): Transdisciplinary Consilience of Genetic Evidence, Natural History, and Behavioral Ecology in Cryptic Speciation.

The subspecies Pseudorca crassidens rafinesquegiglioliorum subsp. nov. is hereby formally established following a detailed historical, morphometric, and ecological review of false killer whale specimens in the Mediterranean Sea, integrated with recent evidence of molecular isolation. The taxonomic roots of this entity trace back to the 18th century, when it was initially named Delphinus dalippus by the zoologist and naturalist Constantine Samuel Rafinesque (1814). Although this name had chronological priority over Pseudorca crassidens, the rules of the International Commission on Zoological Nomenclature (ICZN) dictate today that it must be classified as a nomen oblitum, favoring the stability of the name defined by Owen in 1846. However, the insights of Rafinesque and, subsequently, of Enrico Hillyer Giglioli (1882) regarding the distinction of the Mediterranean population from the Atlantic one, find full validation today. Through the application of modern paradigms of cryptic speciation, widely documented and accepted for Orcinus orca, and using the resident insular models of the Hawaiian archipelago as an analogical counterpart, this study demonstrates the existence of an autochthonous Mediterranean ecotype. The analysis of osteological specimens reveals a phenotype characterized by clear adaptive dwarfism and the reduction of the dental formula compared to the Atlantic Ocean population. Such morphology is reflected in a trophic specialization focused on the coastal predation of large pelagic fish (Coryphaena hippurus and Thunnus spp.), historically documented in the Adriatic and Sicily, and supported by recent global isotopic analyses. The framework is definitively corroborated by mitochondrial DNA genetic investigations (Manetti, 2024), which reveal the existence of an exclusive haplotype identified through the analysis of historical specimens. The sympatric coexistence in the basin of distinct populations isolated by behavioral barriers is hypothesized.