Systematic revision of the Mola mola cryptic species complex: Formal description of Mola solis sp. nov. and Mola lunae sp. nov.

The taxonomic framework of the ocean sunfish genus Mola (Tetraodontiformes: Molidae) has historically been confounded by pronounced morphological conservatism, complex ontogenetic trajectories, and the logistical challenges of securing physical vouchers for massive pelagic fishes. While previous molecular assessments (e.g., Bass et al., 2005; Yoshita et al., 2009) revealed deeply divergent cryptic lineages globally distributed within the putative Mola mola species complex (widely referred to in the literature as Mola sp. A and Mola sp. B), the absence of trackable physical holotypes has precluded formal Linnean designation. Here, we resolve this longstanding systematic anomaly by integrating mitochondrial cytochrome c oxidase subunit I (COI) barcoding with the morphological evaluation of newly designated, museum-vouchered specimens. We formally describe two new species: Mola solis sp. nov. (corresponding to the historical Clade A lineage) and Mola lunae sp. nov. (corresponding to the historical Clade B lineage). The holotype for M. solis (Voucher DABFUK/FI/329) was secured off the coast of Kerala, India, whereas the holotype for M. lunae (Voucher SZN) originates from the Tyrrhenian Sea, Italy. Both species exhibit extensive circumglobal distributions across temperate and tropical marine environments and are unambiguously diagnosed by fixed nucleotide substitutions in the COI barcode region. Morphologically, mature adults can be differentiated by clavus edge morphology and cranial profile ontogeny, although molecular diagnosis remains paramount for definitive identification, particularly in juveniles. The formal naming of Mola solis and Mola lunae eradicates decades of nomenclatural ambiguity, providing a stabilized, rigorous taxonomic foundation essential for all future ecological, biogeographical, and conservation studies of these highly migratory taxa.