Talk:Lagenorhynchus

Taxonomic revision of Lagenorhynchus

I found the only available genus for the clade containing the Hourglass and Peale's Dolphins is Sagmatias Cope, 1866. [1] Therefore, Lagenorhynchus cruciger, L. australis, L. obliquidens, and L. obscurus should be changed to Sagmatias cruciger, S. australis, S. obliquidens, and S. obscurus respectively.

[1] http://www.ubio.org/apps/Hershkovitz/index.php?func=s&ID=48&t=s —The preceding unsigned comment was added by 72.194.116.63 (talk) 03:29, 8 January 2007 (UTC).

I would like to open a discussion on the systematics of the genus Lagenorhynchus. While there is little doubt that the genus is polyphyletic and a reorganisation is needed, there is not yet consensus on how this should be done. The de facto authority on cetacean taxonomy, the Society for Marine Mammalogy's Taxonomic Comittee still include six species in the genus in the list of marine mammal species:

• Lagenorhynchus acutus (Gray, 1828). Atlantic white-sided dolphin
• Lagenorhynchus albirostris (Gray, 1846). White-beaked dolphin
• Lagenorhynchus australis (Peale, 1848). Peale’s dolphin
• Lagenorhynchus cruciger (Quoy and Gaimard, 1824). Hourglass dolphin
• Lagenorhynchus obliquidens Gill, 1865. Pacific white-sided dolphin
• Lagenorhynchus obscurus (Gray, 1828). Dusky dolphin

Currently the organisation of pages on these species follows a recent publication: Vollmer, et al. (2019) Taxonomic revision of the dolphin genus Lagenorhynchus. Marine Mammal Science., which inclues resurrection of the geni Leucopleurus and Sagmatias. The main problem with the genus Sagmatias as proposed by Vollmer, et al. (2019), is that it may be paraphyletic, because the authors do not address the possibility that hourglass dolphin and Peale's dolphin may be closer related to the genus Cephalorhynchus than to dusky dolphin and Pacific white-sided dolphin. Thus, as long as this has not been settled by the taxonomic committee, the nomenclature should follow the traditional inclusion of all six species in Lagenorhynchus, with approriate description of the taxonomic issues on the relevant pages. JakobT (talk) 19:27, 16 December 2021 (UTC)

As I did not hear any protests after two weeks, I have changed the systematics so it follows the traditional and still valid classification, with all six species included in Lagenorhynchus. Note that the American Society of Mammalogists is not the authority on cetacean taxonomy. If you disagree with the changes, please discuss here before reverting. Thanks, JakobT (talk) 23:30, 2 January 2022 (UTC)

• "We find continued support for three species at the base of Delphinidae (Leucopleurus acutus, O. orca, and Lagenorhynchus albirostris; Fig. 2), although their configuration differs from an earlier large-scale analysis of the group, which places O. orca as sister to the remaining delphinids to the exclusion of both L. acutus and L. albirostris (McGowen 2011). Neither L. acutus nor L. albirostris is closely related to the other former members of Lagenorhynchus, now included within the genus Sagmatias (sensu Leduc et al. 1999; Vollmer et al. 2019; Fig. 2)" – Michael R McGowen, Georgia Tsagkogeorga, Sandra Álvarez-Carretero, Mario dos Reis, Monika Struebig, Robert Deaville, Paul D Jepson, Simon Jarman, Andrea Polanowski, Phillip A Morin, Stephen J Rossiter, Phylogenomic Resolution of the Cetacean Tree of Life Using Target Sequence Capture, Systematic Biology, Volume 69, Issue 3, May 2020, Pages 479–501, https://doi.org/10.1093/sysbio/syz068 ~ cygnis insignis 17:08, 7 February 2022 (UTC)

• The quote above is the opinion of the authors of the paper, but this does not mean that the community as a whole recognizes the proposed changes. Quote from the de facto authority on cetacean taxonomics, the Society for Marine Mammalogy taxonomic committee: "The genus Lagenorhynchus is widely considered a polyphyletic taxon containing morphologically convergent species (Cipriano 1997, LeDuc et al. 1999, McGowen 2011, Banguera-Hinestroza et al. 2014, Vollmer et al. 2019). Vollmer et al. (2019) provided a detailed review of the relationships among members of the genus Lagenorhynchus and their relationship to Cephalorhynchus and Lissodelphis. Results continue to support the polyphyletic nature of the genus Lagenorhynchus and multiple morphological and genetic analyses indicate that L. albirostris and L. acutus are evolutionarily distinct from the other members of all three genera. Vollmer et al. (2019) recommended revision of the genus sensu Leduc et al. (1999), placing L. obscurus, L. obliquidens, L. australis and L. cruciger into the genus Sagmatias, L. acutus into the genus Leucopleurus and leaving L. albirostris in a monotypic genus Lagenorhynchus. While a majority of committee members supported the changes proposed by Vollmer et al. (2019), a 2/3 majority of voting members was not reached. Primary objection to the changes focused on remaining uncertainties in some relationships and the potential confusion that may be created if the proposed changes require further revision in the near future. At issue are 1) the conflicting support among data sets for a sister-taxa relationship between L. albirostris and L. acutus (which would obviate the need for Leucopleurus), and 2) evidence that australis and cruciger should be included in Cephalorhynchus (which would necessitate a new genus for obliquidens and obscurus, as australis is the type species for the genus Sagmatias). Therefore, the taxonomy list retains all species in Lagenorhynchus, recognizing that the current taxonomy does not reflect the evolutionary distinctiveness of L. albirostris and L. acutus. Next steps in unraveling the taxonomy of these dolphins will need to involve robust datasets that include all Lagenorhynchus and Cephalorhynchus species". https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/. Eventually, Lagenorhynchus will be split, but not before more conclusive evidence about the relationship within the Lissodelphininae has been provided. JakobT (talk) 19:44, 7 February 2022 (UTC)

Merger proposal: Sagmatias

@Geekgecko, JakobT, and Cygnis insignis: Until there is a well-established idea of what kind of genera Lagenorhynchus should be divided into, I suggest making Sagmatias and Leucopleurus redirects to this page. All information about these genera so far can be presented here. HFoxii (talk) 03:11, 23 August 2022 (UTC)

Agree, good proposal. JakobT (talk) 13:53, 27 November 2022 (UTC)

Oppose; the Sagmatias article as it currently stands focusses on the retired genus name, which seems to reflect the current status. The lede is quite clear on this. The Leucopleurus page is a redirect, and that seems to be appropriately pointing to Atlantic white-sided dolphin (Lagenorhynchus acutus) which does seem to be a better target than Lagenorhynchus. So, readers seem to be best served by the current structure, awaiting future consensus in the field. Klbrain (talk) 08:18, 11 April 2023 (UTC)

Closing with no merge given the stale discussion and uncotested objection; not yet might be appropriate too. Klbrain (talk) 16:00, 11 July 2023 (UTC)