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. 2014 Jan 22;9(1):e83623.
doi: 10.1371/journal.pone.0083623. eCollection 2014.

A new species of river dolphin from Brazil or: how little do we know our biodiversity

Tomas Hrbek  1 , Vera Maria Ferreira da Silva  2 , Nicole Dutra  1 , Waleska Gravena  1 , Anthony R Martin  3 , Izeni Pires Farias  1
Affiliations

Affiliations

  • 1 Laboratory of Evolution and Animal Genetics (LEGAL), Department of Biology, Institute of Biological Sciences, Federal University of Amazonas (UFAM), Manaus, AM, Brazil.
  • 2 Laboratory of Aquatic Mammals (LMA), National Research Institute of the Amazon (INPA), Manaus, AM, Brazil.
  • 3 Centre for Remote Environments, University of Dundee, Dundee, United Kingdom.

A new species of river dolphin from Brazil or: how little do we know our biodiversity

Tomas Hrbek et al. PLoS One. .
. 2014 Jan 22;9(1):e83623.
doi: 10.1371/journal.pone.0083623. eCollection 2014.

Authors

Tomas Hrbek  1 , Vera Maria Ferreira da Silva  2 , Nicole Dutra  1 , Waleska Gravena  1 , Anthony R Martin  3 , Izeni Pires Farias  1

Affiliations

  • 1 Laboratory of Evolution and Animal Genetics (LEGAL), Department of Biology, Institute of Biological Sciences, Federal University of Amazonas (UFAM), Manaus, AM, Brazil.
  • 2 Laboratory of Aquatic Mammals (LMA), National Research Institute of the Amazon (INPA), Manaus, AM, Brazil.
  • 3 Centre for Remote Environments, University of Dundee, Dundee, United Kingdom.

Abstract

True river dolphins are some of the rarest and most endangered of all vertebrates. They comprise relict evolutionary lineages of high taxonomic distinctness and conservation value, but are afforded little protection. We report the discovery of a new species of a river dolphin from the Araguaia River basin of Brazil, the first such discovery in nearly 100 years. The species is diagnosable by a series of molecular and morphological characters and diverged from its Amazonian sister taxon 2.08 million years ago. The estimated time of divergence corresponds to the separation of the Araguaia-Tocantins basin from the Amazon basin. This discovery highlights the immensity of the deficit in our knowledge of Neotropical biodiversity, as well as vulnerability of biodiversity to anthropogenic actions in an increasingly threatened landscape. We anticipate that this study will provide an impetus for the taxonomic and conservation reanalysis of other taxa shared between the Araguaia and Amazon aquatic ecosystems, as well as stimulate historical biogeographical analyses of the two basins.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1

Figure 1. Distribution map of all known…

Figure 1. Distribution map of all known species and subspecies of Inia .

Black outline denotes…

Figure 1. Distribution map of all known species and subspecies of Inia.
Black outline denotes the limit of the Amazon basin. Question marks denote uncertainty as to which species occurs in the Tocantins River downstream of the Tucuruí dam which potentially delimits the distributions of I. geoffrensis and I. araguaiaensis sp. nov. Bars on the Madeira River represent a series of rapids that delimit the distribution of I. geoffrensis and I. boliviensis. The single bar on the northern limit of the Amazon basin represents the Casiquiare canal which connects the Amazon and Orinoco basins, and is thought to delimit the I. g. humboldtiana subspecies from I. g. geoffrensis.
Figure 2

Figure 2. Bayesian inference of population structuring…

Figure 2. Bayesian inference of population structuring using STRUCTURE 2.3.3 , .

We analyzed 10…

Figure 2. Bayesian inference of population structuring using STRUCTURE 2.3.3 , .
We analyzed 10 nuclear microsatellite loci sampled from 45 I. boliviensis, 44 I. geoffrensis and 32 I. araguaiaensis sp. nov. individuals. Highest posterior probability is associated with three biological groups; mean LnP(K = 3) = −2041.115.
Figure 3

Figure 3. Principal component analysis of the…

Figure 3. Principal component analysis of the microsatellite data performed in the Ade4 package in…

Figure 3. Principal component analysis of the microsatellite data performed in the Ade4 package in the R vers. 2.14.1 statistical program.
Principal component axes 1 and 2 are plotted on the X and Y axes, respectively, and ellipses denote 67.53% density contours around each sample group.
Figure 4

Figure 4. Correspondence analysis of the microsatellite…

Figure 4. Correspondence analysis of the microsatellite data performed in the Ade4 package in the…

Figure 4. Correspondence analysis of the microsatellite data performed in the Ade4 package in the R vers. 2.14.1 statistical program.
Factors 1 and 2 are plotted on the X and Y axes, respectively, and ellipses denote 67.53% density contours around each sample group.
Figure 5

Figure 5. Bayesian phylogenetic analysis and divergence…

Figure 5. Bayesian phylogenetic analysis and divergence time estimation in BEAST 1.7.1 using the complete…

Figure 5. Bayesian phylogenetic analysis and divergence time estimation in BEAST 1.7.1 using the complete mitochondrial DNA cytochrome b gene.
We used four independent fossil calibration points (indicated as orange bars). Numbers at nodes represent estimates of divergence times with highest posterior probability, while bars around each divergence time estimate represent 95% highest posterior density of the estimate.
Figure 6

Figure 6. The cranium (6a) and the…

Figure 6. The cranium (6a) and the mandible (6b) of the holotype of Inia araguaiaensis …

Figure 6. The cranium (6a) and the mandible (6b) of the holotype of Inia araguaiaensis sp. nov.; 10 cm ruler shown.
See this image and copyright information in PMC

References

    1. Da Silva VMF (1994) Aspects of the biology of the Amazonian dolphins genus Inia and Sotalia fluviatilis Cambridge, UK: The University of Cambridge.
    1. Rossetti D de F, Valeriano MM (2007) Evolution of the lowest Amazon basin modeled from the integration of geological and SRTM topographic data. Catena 70: 253–265 10.1016/j.catena.2006.08.009 - DOI
    1. Goulding M, Barthem RB, Ferreira EJG (2003) The Smithsonian Atlas of the Amazon. Washington, DC: Smithsonian Institution Press.
    1. Banguera-Hinestroza E, Cárdenas H, Ruiz-García M, Marmontel M, Gaitán E, et al. (2002) Molecular identification of evolutionarily significant units in the Amazon River dolphin Inia sp. (Cetacea: Iniidae). J Hered 93: 312–322 10.1093/jhered/93.5.312 - DOI - PubMed
    1. Pilleri G, Gihr M (1977) Observations on the Bolivian, Inia boliviensis, (D’Orbigny, 1834) and the Amazonian bufeo, Inia geoffrensis (Blainville, 1817), with a description of a new subspecies (Inia geoffrensis humboldtiana). In: Pilleri G, editor. Investigations on Cetacea. Bogotá, Colombia, Vol. 8: 11–76.

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