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Sagmatias obliquidens (Pacific white-sided dolphin)
Taxonomy
Lagenorhynchus obliquidens was named by Gill (1865). It is extant. Its type specimen is USNM 1961, 1962, 1963, a skull ( 3 skulls). Its type locality is San Francisco, which is in a Holocene coastal horizon in California.
It was recombined as Delphinus obliquidens by Scammon and Cope (1869); it was recombined as Sagmatias obliquidens by LeDuc et al. (1999), Perrin et al. (2013) and Vollmer et al. (2019); it was considered an invalid subgroup of Lissodelphinae by Agnarsson and May-Collado (2008).
It was recombined as Delphinus obliquidens by Scammon and Cope (1869); it was recombined as Sagmatias obliquidens by LeDuc et al. (1999), Perrin et al. (2013) and Vollmer et al. (2019); it was considered an invalid subgroup of Lissodelphinae by Agnarsson and May-Collado (2008).
Synonyms
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Synonymy list
| Year | Name and author |
|---|---|
| 1865 | Lagenorhynchus obliquidens Gill |
| 1866 | Delphinus longidens Cope |
| 1869 | Delphinus obliquidens Scammon and Cope p. 22 |
| 1904 | Lagenorhynchus obliquidens Trouessart p. 767 |
| 1955 | Lagenorhynchus ognevi Slensov |
| 1977 | Lagenorhynchus obliquidens Barnes p. 323 figs. Table 1 |
| 1991 | Lagenorhynchus obliquidens Vidal p. 5 |
| 1998 | Lagenorhynchus obliquidens Rice p. 114 |
| 1999 | Sagmatias obliquidens LeDuc et al. p. 639 figs. Figure 2 |
| 2005 | Lagenorhynchus obliquidens Mead and Brownell p. 730 |
| 2013 | Sagmatias obliquidens Perrin et al. p. 571 figs. Table 1 |
| 2019 | Sagmatias obliquidens Vollmer et al. |
| 2021 | Lagenorhynchus obliquidens Jefferson p. 50 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
Sagmatias obliquidens Gill 1865 [Pacific white-sided dolphin]
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Invalid names: Delphinus longidens Cope 1866 [synonym], Lagenorhynchus ognevi Slensov 1955 [synonym]
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| N. L. Vollmer et al. 2019 | Sagmatias obliquidens is the only species of Sagmatias, Leuco- pleurus, Lagenorhynchus, or Cephalorhynchus that inhabits the North Pacific Ocean. Among Sagmatias, Lagenorhynchus, and Leucopleurus species, the pigmentation of S. obliquidens is similar to that of S. obscurus and S. australis, however there is no overlap in distribution between S. obliquidens and either of these two species. Fraser (1966) stated that the pigmentation pattern of S. obliquidens is most similar to that of S. australis, but these two species can be distinguished based on the extent of dark pigmentation on the chin and the pattern of the flank patch at the posterior flipper insertion, and the dorsal fin of S. obliquidens is often lighter with more gray pigmentation than that of S. australis. Additional features of the coloration of S. obliquidens are given under Coloration.
In general, the skull morphology of all four species of Sagmatias is similar, however S. obliquidens and S. obscurus can be distinguished from other Sagmatias species by their greater rostral length, shorter braincase, and lower ramus (Miyazaki and Shikano 1997b). Further- more, S. obliquidens is differentiated from S. obscurus by having a greater preorbital width and a wider rostrum at midlength (Miyazaki and Shikano 1997b). Sagmatias obliquidens also has more vertebrae than S. obscurus (Miyazaki and Shikano 1997b). The distinction between S. obliquidens and the other species of Sag- matias as well as all species in the genera Leucopleurus, Lagenor- hynchus, Lissodelphis, and Cephalorhynchus is also supported by genetic data from both nuclear and mitochondrial DNA markers (Fig. 2, 3). Phylogenetic studies consistently recover a close sister-species relationship between S. obliquidens and S. obscurus, but the relationships between S. obliquidens and S. australis/S. cruciger are less clear and these stud- ies often have included little to no data from the latter two species (Table 2; Harlin-Cognato and Honeycutt 2006, May-Collado and Agnarsson 2006, Agnarsson and May-Collado 2008, McGowen 2011, Banguera- Hinestroza et al. 2014a). Additional analyses may lead to further genus-level taxonomic revision for S. obliquidens. If S. obliquidens and S. obscurus are determined to be significantly differentiated at the genus level from S. australis and S. cruciger, a new genus name will be needed for obliqui- dens and obscurus because S. amblodon Cope, 1866 (= australis) is the type species of Sagmatias and no other synonyms are available for these two species. |