Lagenorhynchus

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Lagenorhynchus
Witsnuitdolfijn - Lagenorhynchus albirostris.jpg
Lagenorhynchus albirostris
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Delphinidae
Genus: Lagenorhynchus
Gray, 1846
Species

Lagenorhynchus albirostris
†

Lagenorhynchus is a genus in the infraorder Cetacea, containing only a single extant species as of 2021: the white-beaked dolphin (L. albirostris).[1][2] In addition, the extinct species is also classified in this genus.[3]

Lagenorhynchus is thought to be a rather basal member of the family Delphinidae, with only the Atlantic white-sided dolphin (Leucopleurus acutus) and the subfamily Orcininae (containing the killer whale, Orcinus orca) being more basal.[4]

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.

Taxonomic history[]

The melon-headed whale was once classified in this genus, but was later removed to its own genus, Peponocephala.

Current taxonomy[]

The Atlantic white-sided dolphin, Pacific white-sided dolphin, Peale's dolphin, hourglass dolphin and dusky dolphin were all formerly classified in this genus. However, an analysis of the mitochondrial cytochrome b gene found that the genus Lagenorhynchus, as previously conceived, was not a natural (monophyletic) group. LeDuc, Perrin & Dizon 1999 found that the white-beaked and Atlantic white-sided dolphins were phylogenetically isolated within the Delphinidae, whereas the remaining four species were members of the Lissodelphinae, a predominantly Pacific clade of dolphins also including the right whale dolphins and the Cephalorhynchus dolphins. These findings were somewhat problematic taxonomically, since the white-beaked dolphin is the type species of the genus Lagenorhynchus; if the other species are not closely related to the white-beaked dolphin, then they must be removed from the genus. Accordingly, LeDuc et al. suggested that the Atlantic white-sided dolphin be placed within its own genus, Leucopleurus, and that the remaining species would need taxonomic revision, as well. Leduc proposed Sagmatias as the new genus for the Pacific white-sided dolphin, Peale's dolphin, hourglass dolphin and dusky dolphin.[5] The American Society of Mammalogists has since followed this placement.[6]

Other taxonomies[]

May-Collado & Agnarsson 2006 actually recovered the hourglass and Peale's dolphins as nested phylogenetically among the species of Cephalorhynchus, and they suggest these two species be transferred to that genus. Some acoustic and morphological data support for this arrangement. Both hourglass and Peale's dolphins share with the species of Cephalorhynchus a distinct type of echolocation signal known as a narrow-band, high-frequency signal.[7][8] This signal is shared with porpoises (Phocoenidae) and pygmy sperm whales (Kogiidae), but is not found among other dolphin groups. According to Schevill & Watkins 1971, Peale's dolphin and the Cephalorhynchus species are the only dolphins that do not whistle. Presumably this is the case for hourglass dolphins, as well. Peale's dolphin also shares with several Cephalorhynchus species the possession of a distinct white "armpit" marking behind the pectoral fin.

According to an analysis by May-Collado & Agnarsson 2006, the remaining two species, the dusky and Pacific white-sided dolphins, are closely related to each other and form the sister group to the (expanded) genus Cephalorhynchus. If this placement is accurate, a new genus name will need to be coined to accommodate these two species.

Notes[]

  1. ^ "Explore the Database". www.mammaldiversity.org. Retrieved 2021-07-13.
  2. ^ Vollmer, Nicole L.; Ashe, Erin; Brownell, Robert L.; Cipriano, Frank; Mead, James G.; Reeves, Randall R.; Soldevilla, Melissa S.; Williams, Rob (2019). "Taxonomic revision of the dolphin genus Lagenorhynchus". Marine Mammal Science. 35 (3): 957–1057. doi:10.1111/mms.12573. ISSN 1748-7692.
  3. ^ "Fossilworks: Lagenorhynchus harmatuki". fossilworks.org. Retrieved 17 December 2021.
  4. ^ McGowen, Michael R; Tsagkogeorga, Georgia; Álvarez-Carretero, Sandra; dos Reis, Mario; Struebig, Monika; Deaville, Robert; Jepson, Paul D; Jarman, Simon; Polanowski, Andrea; Morin, Phillip A; Rossiter, Stephen J (2019-10-21). "Phylogenomic Resolution of the Cetacean Tree of Life Using Target Sequence Capture". Systematic Biology. 69 (3): 479–501. doi:10.1093/sysbio/syz068. ISSN 1063-5157. PMC 7164366. PMID 31633766.
  5. ^ LeDuc, Perrin & Dizon 1999
  6. ^ "Explore the Database". www.mammaldiversity.org. Retrieved 2021-07-13.
  7. ^ Tougaard & Kyhn 2010
  8. ^ Kyhn et al. 2010

References[]

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