Lagenorhynchus

Lagenorhynchus is a genus of oceanic dolphins in the infraorder Cetacea, that formerly contained six extant species.<ref>Template:Cite web</ref> However, there was consistent molecular evidence that the genus is polyphyletic<ref name="leduc">Template:Harvnb</ref> and several of the species moved to other genera, leaving only the white-beaked dolphin in this genus among extant species.<ref name=marine2025/> In addition, the extinct species Lagenorhynchus harmatuki is also classified in this genus.<ref>Template:Cite web</ref>

Etymology

The name Lagenorhynchus derives from the Greek lagenos meaning "bottle" and rhynchus meaning "beak". Indeed, the "bottle-nose" is a characteristic of this genus. However, the dolphins popularly called bottlenose dolphins belong in the genus Tursiops.

Taxonomy

For a long time there was compelling phylogenetic molecular evidence that the genus Lagenorhynchus is polyphyletic, in that it contained several species that are not closely related.<ref name="Vollmer">Template:Cite journal</ref> Template:Harvnb found that white-beaked and Atlantic white-sided dolphins are phylogenetically isolated within the Delphinidae, where they are believed to be rather basal members of the family, along with the orca (subfamily Orcininae).<ref>Template:Cite journal</ref> This was confirmed in 2025 by Galatius, et al.<ref>Template:Cite journal</ref>

As a result, in 2025 most of the species previously placed in Lagenorhynchus were moved to other genera, leaving it as a monotypic genus containing only the white-beaked dolphin.<ref name=marine2025>Template:Cite web</ref> Other species previously included in Lagenorhynchus were moved to:<ref name=marine2025/>

• Atlantic white-sided dolphin Leucopleurus acutus
• Pacific white-sided dolphin Aethalodelphis obliquidens
• Dusky dolphin Aethalodelphis obscurus
• Peale's dolphin Cephalorhynchus australis
• Hourglass dolphin Cephalorhynchus cruciger

This phylogeny is supported by acoustic and morphological data; both the hourglass and Peale's dolphins share, with the other species of Cephalorhynchus, a distinctive type of echolocation signal known as a narrow-band/high-frequency signal.<ref>Template:Harvnb</ref><ref>Template:Harvnb</ref> This signal is also used by porpoises (Phocoenidae) and the pygmy sperm whales (Kogiidae), but is not found among other dolphins. According to Template:Harvnb, Peale's dolphin, and the other Cephalorhynchus species, are the only dolphins that do not "whistle"; presumably, this would be the case for hourglass dolphins, as well. Peale's dolphin also shares with several Cephalorhynchus species the possession of a distinct white marking behind the pectoral (“armpit”) fin.Template:Citation needed

The melon-headed whale was first classified as member of the genus Lagenorhynchus, but was later moved to its own genus, Peponocephala.<ref>Template:Cite journal</ref>

References

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