Morphological and mitochondrial DNA divergence validates blackmouth, Galeus melastomus, and Atlantic sawtail catsharks, Galeus atlanticus, as separate species

Authors

  • R. Castilho,

    Corresponding author
    1. * Biodiversity and Conservation Group, CCMAR, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal and Coastal Fisheries Research Group, CCMAR, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
      †BioCon, CCMAR, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal. Tel.: +351 918 397 182; fax: +351 289 800 069; email: rcastil@ualg.pt
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  • M. Freitas,

    1. * Biodiversity and Conservation Group, CCMAR, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal and Coastal Fisheries Research Group, CCMAR, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
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  • G. Silva,

    1. * Biodiversity and Conservation Group, CCMAR, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal and Coastal Fisheries Research Group, CCMAR, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
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  • J. Fernandez-Carvalho,

    1. * Biodiversity and Conservation Group, CCMAR, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal and Coastal Fisheries Research Group, CCMAR, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
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  • R. Coelho

    1. * Biodiversity and Conservation Group, CCMAR, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal and Coastal Fisheries Research Group, CCMAR, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
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†BioCon, CCMAR, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal. Tel.: +351 918 397 182; fax: +351 289 800 069; email: rcastil@ualg.pt

Abstract

A total of 60 morphometric traits and nucleotide sequences of the entire mtDNA NADH dehydrogenase subunit 2 (ND2) gene [1047 base pair (bp)] in 23 individuals of blackmouth, Galeus melastomus, and 13 individuals of sawtail catsharks, Galeus atlanticus, caught in Southern Portugal, were examined to test the validity of these two taxa. These sharks closely resemble each other, have overlapping geographical ranges and are difficult to identify by morphological characters. Non-metric multidimensional scaling of morphometric variables indicates a clear separation between the two species, with 10 characters each contributing 2·12–2·45% of the total variability between species. Maximum likelihood, parsimony and neighbour-joining trees revealed two major mtDNA haplotype clades, corresponding to the two species, with an average corrected sequence divergence between them of 3·39 ± 0·56%. Within species divergences between haplotypes averaged 0·27 ± 0·18% in G. melastomus and 0·12 ± 0·08% in G. atlanticus. A total of 35 diagnostic nucleotide site differences and four restriction fragment length polymorphism recognition sites in the ND2 gene can be used to distinguish the two species.

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