Sagmatias

Sagmatias was a genus of dolphins, defined in 1866 by Edward Drinker Cope[1] with Peale's dolphin as type species, described as Sagmatias amblodon. It has been proposed to resurrect the genus to include four species of oceanic dolphins currently classified in the genus Lagenorhynchus.[2] Mitochondrial DNA studies have indicated that Pacific white-sided dolphin, Peale's dolphin, dusky dolphin and hourglass dolphin are more closely related to dolphins in the Lissodelphininae subfamily, than to the two other members of the genus: Atlantic white-sided dolphin and white-beaked dolphin.[3] This phylogenetic relationship is further supported by cladistic analysis of morphological characters.[4] However, resurrection of the genus Sagmatias has not been accepted by the Society for Marine Mammalogy's taxonomic Committee, because the finer details of the phylogenetic relationships between the four species in the proposed Sagmatias genus and the four species of dolphins in the genus Cephalorhynchus remains to be resolved.[5] Genetic and bioacoustical evidence suggest that Peale's dolphin and hourglass dolphin are closer related to the Cephalorhynchus species than to the Pacific white-sided dolphin and dusky dolphin,[6][7][8] which, if true, would make the genus Sagmatias paraphyletic.

Examples of different phylogenetic trees
Pichler et al (2001)[9] May-Collardo and Agnarsson (2006)[6]
Lissodelphininae 
 Lissodelphis 

 L. peronii

 L. borealis

 Sagmatias 

 S. obscurus

 S. obliquidens

 S. australis

 S. cruciger

 Cephalorhynchus 

 C. heavisidii

 C. hectori

 C. commersonii

 C. eutropia

Lissodelphininae 
 Lissodelphis 

 L. peronii

 L. borealis

 S. obscurus

 S. obliquidens

 S. australis

 S. cruciger

 Cephalorhynchus 

 C. heavisidii

 C. hectori

 C. commersonii

 C. eutropia

Phylogenetic tree where Sagmatias forms a monophyletic sister group to Cephalorhynchus Phylogenetic tree where Sagmatias does not form a monophyletic group

References

  1. ^ Cope, E.D. (1866). "Third contribution to the history of the Balaenidae and Delphinidae". Proceedings of the Academy of Natural Sciences of Philadelphia: 293–300.
  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. S2CID 92421374.
  3. ^ Leduc, R.; Perrin, W.; Dizon, E. (August 18, 1998). "Phylogenetic Relationships among the Delphinid Cetaceans Based on Full Cytochrome B Sequences". Marine Mammal Science. 15 (3): 619–648. doi:10.1111/j.1748-7692.1999.tb00833.x.
  4. ^ Murakami, Mizuki; Shimada, Chieko; Hikida, Yoshinori; Soeda, Yuhji; Hirano, Hiromichi (2014). "Eodelphis kabatensis, a new name for the oldest true dolphin Stenella kabatensis Horikawa, 1977 (Cetacea, Odontoceti, Delphinidae), from the upper Miocene of Japan, and the phylogeny and paleobiogeography of Delphinoidea"". Journal of Vertebrate Paleontology. 34 (3): 491–511. doi:10.1080/02724634.2013.816720. S2CID 85210375.
  5. ^ "List of marine mammal species and subspecies". Society for Marine Mammalogy.
  6. ^ a b May-Collado, Laura; Agnarsson, Ingi (February 2006). "Cytochrome b and Bayesian inference of whale phylogeny". Molecular Phylogenetics and Evolution. 38 (2): 344–354. doi:10.1016/j.ympev.2005.09.019. PMID 16325433.
  7. ^ Tougaard, J.; Kyhn, L. A. (28 December 2009). "Echolocation sounds of hourglass dolphins (Lagenorhynchus cruciger) are similar to the narrow band high-frequency echolocation sounds of the dolphin genus Cephalorhynchus". Marine Mammal Science. 26 (1): 239–245. doi:10.1111/j.1748-7692.2009.00307.x. ISSN 0824-0469. OCLC 497138903.
  8. ^ Kyhn, L. A.; Jensen, F. H.; Beedholm, K.; Tougaard, J.; Hansen, M.; Madsen, P. T. (1 June 2010). "Echolocation in sympatric Peale's dolphins ( Lagenorhynchus australis ) and Commerson's dolphins ( Cephalorhynchus commersonii ) producing narrow-band high-frequency clicks". Journal of Experimental Biology. 213 (11): 1940–1949. doi:10.1242/jeb.042440. PMID 20472781. S2CID 207169275.
  9. ^ Pichler, F. B.; Robineau, D.; Goodall, R. N. P.; Meyer, M. A.; Olivarria, C.; Baker, C. S. (September 2001). "Origin and radiation of Southern Hemisphere coastal dolphins (genus Cephalorhynchus)". Molecular Ecology. 10 (9): 2215–2223. doi:10.1046/j.0962-1083.2001.01360.x. PMID 11555263. S2CID 24368161.