The Taxonomy Committee completed its annual review of the official Society for Marine Mammalogy list of marine mammal species and subspecies for 2024. A few major changes to the list were made. The genus of the sea mink (extinct) is now recognized as Neogale Gray, 1865 following Patterson et al. (2021). Based on phylogenomic findings reported in Lopes et al. (2021), a subspecies of Arctocephalus was elevated to species: Arctocephalus townsendi (Merriam, 1897), the Guadalupe fur seal. The updated list also includes the addition of three killer whale subspecies: Orcinus orca ater (resident killer whale) and O. orca rectipinnus (Bigg’s killer whale), with O. orca orca (common killer whale) as the nominate subspecies. Resident and Bigg’s killer whales have been recognized in the past as un-named subspecies, and were listed in previous versions of the List of Proposed Un-named Species and Subspecies. Although Morin et al. (2024) proposed their recognition as distinct species of killer whales, such proposal was not followed by the Taxonomy Committee because there were concerns whether this represents a species- or subspecies-level designation. The reasons were mainly due to (1) a possible episodic gene flow among the ecotypes, and (2) the need to conduct a more comprehensive comparative analysis on a global scale to better understand how distinct these ecotypes are from other Orcinus orca clades. Therefore, pending further investigation to better evaluate the taxonomy of the eastern North Pacific killer whales, the two ecotypes are considered provisionally as distinct subspecies of Orcinus orca and named following Morin et al. (2024). Recently, there was also a taxonomic change proposal to elevate the common dolphin subspecies Delphinus delphis bairdii to species (Jefferson et al. 2024). However, a 2/3 majority of voting members was not reached to accept such taxonomic change, mainly due to the lack of nuclear DNA evidence, which is considered by some members of the Committee to be essential to better understand male-mediated gene flow, especially when considering the convergent character of the long-beaked form. Further studies focusing on nuclear DNA are needed to resolve the remaining uncertainties in some relationships between both common dolphin forms within the Pacific Ocean, as well as at the global scale. Therefore, the long-beaked form in the eastern North Pacific is still considered provisionally as a subspecies of Delphinus delphis (D. d. bairdii). The list now recognizes 139 species of marine mammals, 5 of which are extinct or thought to be extinct.

Jefferson, T. A., F. I. Archer and K. M. Robertson. 2024. The long-beaked common dolphin of the eastern Pacific Ocean: Taxonomic status and redescription of Delphinus bairdii. Marine Mammal Science e13133.

Lopes, F., L. R. Oliveira, A. Kessler, Y. Beux, E. Crespo, S. Cárdenas-Alayza, P. Majluf, M. Sepúlveda, R. L. Brownell Jr., V. Franco-Trecu, D. Páez-Rosas, J. Chaves, C. Loch, B. C. Robertson, K. Acevedo-Whitehouse, F. R. Elorriaga-Verplancken, S. P. Kirkman, C. R. Peart, J. B. W. Wolf and S. L. Bonatto. 2021. Phylogenomic discordance in the eared seals is best explained by incomplete lineage sorting following explosive radiation in the Southern Hemisphere. Systematic Biology 70:786-802.

Morin, P. A., M. L. McCarthy, C. W. Fung, J. W. Durban, K. M. Parsons, W. F. Perrin, B. L. Taylor, T. A. Jefferson and F. I. Archer. 2024. Revised taxonomy of eastern North Pacific killer whales (Orcinus orca): Bigg’s and resident ecotypes deserve species status. Royal Society Open Science 11:231368.

Patterson, B. D., H. E. Ramírez Chavez, J. F. Vilela, A. E. R. Soares and F. Grewe. 2021. On the nomenclature of the American clade of weasels (Carnivora: Mustelidae). Journal of Animal Diversity 3:1-8.