[MARMAM] New publication: Offshore and coastal bottlenose dolphins of the western South Atlantic and evidence for a new subspecies

Ana Costa costa.aninha at gmail.com
Thu Jul 28 06:51:55 PDT 2016

Dear MARMAM members,

We would like to announce the following new paper recently published in
Marine Mammal Science (early view):

Costa, A.P.B., Rosel, P.E., Daura-Jorge, F.G., and Simoes-Lopes, P.C.
Offshore and coastal common bottlenose dolphins of the western South
Atlantic face-to-face: What the skull and the spine can tell us. Marine
Mammal Science (early view): <

The taxonomy of *Tursiops truncatus* in the western South Atlantic is not
resolved. Two different hypotheses have been proposed: (1) offshore and
coastal ecotypes with a parapatric distribution, and (2) two species, *T.
truncatus* and *T. gephyreus*, living in sympatry. To test these
hypotheses, we examined a total of 100 physically mature skulls and 35
vertebral columns from the suggested overlap zone in southern Brazil. In
all skulls, 24 measurements, four alveoli counts and two categorical
variables were analyzed. Vertebral formula was determined and five
measurements were taken from selected vertebrae. Multivariate analyses were
conducted for skull and vertebral data. Results revealed the presence of
two well-separated groups. Specimens of Group1 had smaller skulls and
shorter body lengths, but more vertebrae, than Group2. The morphological
characteristics of each group corresponded well with two ecotypes of common
bottlenose dolphins reported in other ocean basins. Therefore, we assigned
the specimens of Group1 to the offshore ecotype, and Group2 to the coastal
ecotype. Differences in the geographic locations and ratio of strandings
supported the parapatric hypothesis. The significant morphological
differentiation observed suggests the presence of different subspecies, but
an additional independent line of evidence is needed to hypothesize whether
they represent different species.

The publication is available online <
http://onlinelibrary.wiley.com/doi/10.1111/mms.12342/abstract> or by
request <abc2978 at louisiana.edu>

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