Aethalodelphis

Aethalodelphis is a genus of oceanic dolphins erected in 2025 for two species, the Pacific white-sided dolphin (Aethalodelphis obliquidens) and the dusky dolphin (Aethalodelphis obscurus), which are its only members. Both species were formerly included in the genus Lagenorhynchus, but several studies demonstrated that Lagenorhynchus as previously constituted was polyphyletic, meaning that it grouped dolphins that were not each other's closest relatives. As a result the Pacific white-sided dolphin and the dusky dolphin were reclassified into the new genus in 2025. The Pacific white-sided dolphin lives in the cool and temperate waters of the North Pacific, the morphologically similar dusky dolphin lives in the South Pacific, and genetic analysis suggests that the two diverged around two million years ago.