Summary
For a long time, the genus Metaxya was treated as monotypic with a single species, M. rostrata. A second species, M. lanosa, was described in 2001 on the basis of morphological features and rbcL gene sequences with a suggestion that the genus may contain even more species. We have now systematically compared morphological traits in a large number of Metaxya specimens collected in tropical America. We have also carried out phylogenetic analyses of 32 Metaxya and 5 outgroup specimens based on four markers of the plastid genome (rbcL, matK, and rps4 genes, and trnG-trnR intergenic spacer). Based on the morphological variation among the Metaxya specimens, we accept six distinct species, three of which we describe as new in this paper. Molecular phylogenetic analyses resolved five distinct clades. Four of these corresponded with the morphologically delineated species (M. contamanensis sp. nov., M. elongata sp. nov., M. lanosa, and M. parkeri). The fifth clade contained all the individuals of the remaining two species, of which M. rostrata was rendered paraphyletic by M. scalaris sp. nov. being nested within it. Since M. scalaris was resolved as monophyletic, and the two are clearly distinguishable morphologically, we consider them true species despite the incomplete genetic differentiation.
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Acknowledgements
We thank K, SP, US and Z for access to their physical collections, COL, NY, UC and Z for scanning specimens on request and the following herbaria for online access to their collections: AAU, B, CAY, COL, GH, HUEFS, INPA, K, MO, NY, P, SP and UC. We thank Jefferson Prado, Robbin C. Moran, Michael Kessler, Alan R. Smith and Michel Boudrie for information on additional specimens, Alan R. Smith, Maarten Christenhusz, Rafaël Govaerts and Irina Belyaeva for comments on nomenclature and taxonomic literature, Nelly Llerena for making the illustrations, Mirkka Jones for linguistic comments, Mikael Kukkonen for scanning specimens and Servicios de biodiversidad (http://serviciosdebiodiversidad.com/web/) for support. This project was funded by Turun Yliopistosäätiö grant to Glenda Cárdenas and by Academy of Finland grants to Hanna Tuomisto and Samuli Lehtonen.
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An erratum to this article is available at http://dx.doi.org/10.1007/s12225-016-9661-6.
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Cárdenas, G.G., Tuomisto, H. & Lehtonen, S. Newly discovered diversity in the tropical fern genus Metaxya based on morphology and molecular phylogenetic analyses. Kew Bull 71, 5 (2016). https://doi.org/10.1007/s12225-016-9618-9
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DOI: https://doi.org/10.1007/s12225-016-9618-9