How to kill two genera with one tree: clarifying generic circumscriptions in an endemic Malagasy clade of Sapindaceae

Authors

  • SVEN BUERKI,

    Corresponding author
    1. Department of Biodiversity and Conservation, Real Jardin Botánico, CSIC, Plaza de Murillo 2, 28014 Madrid, Spain
    2. Molecular Systematics Section, Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK
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  • PORTER P. LOWRY II,

    1. Missouri Botanical Garden, P.O. Box 299, St Louis, MO 63166-0299, USA
    2. Muséum National d'Histoire Naturelle, Case Postale 39, 57 rue Cuvier, 75231 05 CEDEX, Paris, France
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  • SYLVIE ANDRIAMBOLOLONERA,

    1. Missouri Botanical Garden, Madagascar Research and Conservation Program, B.P. 3391, Antananarivo 101, Madagascar
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  • PETER B. PHILLIPSON,

    1. Missouri Botanical Garden, P.O. Box 299, St Louis, MO 63166-0299, USA
    2. Muséum National d'Histoire Naturelle, Case Postale 39, 57 rue Cuvier, 75231 05 CEDEX, Paris, France
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  • LAURA VARY,

    1. Department of Ecology and Evolutionary Biology, University of California-Irvine, 321 Steinhaus Hall, Irvine, CA 92697, USA
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  • MARTIN W. CALLMANDER

    1. Missouri Botanical Garden, P.O. Box 299, St Louis, MO 63166-0299, USA
    2. Conservatoire et Jardin botaniques de la Ville de Genève, ch. de l'Impératrice 1, CH-1292 Chambésy, Switzerland
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E-mail: s.buerki@kew.org

Abstract

Phylogenetic relationships in a Malagasy clade of Sapindaceae, encompassing Molinaea (with members also in the Mascarene Islands), Neotina, Tina and Tinopsis, were inferred by expanding a previous nuclear and plastid DNA data set for the family. The circumscription of these morphologically similar genera has remained problematic since the first family-wide treatment. To investigate this situation, representative taxa were analysed to: (1) test the monophyly of the genera; (2) investigate their phylogenetic relationships; and (3) explore alternative circumscriptions that reflect phylogeny and yield genera that are morphologically coherent and easily characterized. Phylogenetic inferences supported the monophyly of the group and its subdivision into three clades. All species of Molinaea sampled belong to a clade (Clade I) that is sister to a clade comprising Neotina, Tina and Tinopsis, within which one clade (Clade II) encompasses Tinopsis and Neotina (with the latter nested within the former) and another (Clade III) comprises all taxa of Tina. These three genera can be easily distinguished from Molinaea by having two rather than three carpels, which represents an unambiguous synapomorphy. Given the paraphyly of Tinopsis with regard to Neotina and the strong support for the monophyly of Tina, two potentially viable options are available for the generic delimitation of the taxa in this clade: (1) to recognize two genera corresponding, respectively, to Clades II and III; or (2) to place all of the taxa in a single genus encompassing both clades. Based on a review of morphological evidence the second option is favoured and consequently a broad generic concept is applied. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165, 223–234.

Ancillary