Tursiops truncatus nuuanu, a new subspecies of the common bottlenose dolphin from the eastern tropical Pacific

In the eastern Pacific Ocean, three distinct forms of common bottlenose dolphin ( Tursiops truncatus ) have been identified, with suggestions they may be different species: a southern California/Mexico coastal, a northern temperate offshore, and an eastern tropical Pacific (ETP) offshore form. Curre...

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Bibliographic Details
Published in:Journal of mammalian evolution 2023-03, Vol.30 (1), p.213-229
Main Authors: Costa, A. P. B., Archer, F. I., Rosel, P. E., Perrin, W. F.
Format: Article
Language:English
Subjects:
Animal Genetics and Genomics
Anthropology
Biomedical and Life Sciences
Body size
Cetacea
Dolphins & porpoises
Ecotypes
Environmental conditions
Evolutionary Biology
Human Genetics
Life Sciences
Morphology
New subspecies
Offshore
Original Paper
Skull
Tursiops truncatus
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Summary:In the eastern Pacific Ocean, three distinct forms of common bottlenose dolphin ( Tursiops truncatus ) have been identified, with suggestions they may be different species: a southern California/Mexico coastal, a northern temperate offshore, and an eastern tropical Pacific (ETP) offshore form. Currently, only one species ( T. truncatus ) is recognized in the region, with the first two forms described as distinct ecotypes. The goal of this study was to improve our understanding of the taxonomic status of these previously described forms through a re-examination of their morphological differentiation. We analyzed 135 skulls from the eastern and western Pacific, including the two nominal species, T. gillii and T. nuuanu , previously described for the eastern North Pacific and ETP, respectively. Additionally, we examined the holotypes of two currently recognized species in the genus, T. truncatus and T. aduncus . Our results showed significant morphological differentiation among bottlenose dolphins in the Pacific Ocean. The ETP offshore bottlenose dolphins were smaller in skull and body size and diagnostically distinct from dolphins in the western North Pacific and other regions in the eastern Pacific. Our results also indicated that, while other bottlenose dolphins in the Pacific were more similar to the globally distributed T. truncatus , the ETP offshore dolphins shared similarities with a previously described species in that region. The distinct environmental conditions in the ETP may be driving the evolutionary differentiation of these bottlenose dolphins. Given these results, we here recommend the recognition of ETP offshore bottlenose dolphins as a distinct subspecies, Tursiops truncatus nuuanu .
ISSN:1064-7554
1573-7055
DOI:10.1007/s10914-022-09641-5