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1 February 2013 Rheophytism in Bornean Schismatoglottideae (Araceae)
Wong Sin Yeng
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Abstract

The Schismatoglottid Alliance (tribes Schismatoglottideae, Cryptocoryneae and Philonotieae: Araceae) has been shown to be monophyletic in a previous study based on two cpDNA regions (matK and trnL-F). Here, ten additional taxa of Schismatoglottideae were sequenced, including two extra-Bornean Piptospatha species, and the type species of Hottarum, unavailable at the time of the previous analyses. Phylogenetic analyses were performed by using parsimony, likelihood (RAxML and likelihood ratchet PAUP*), and Bayesian inference to determine the placement of these additional taxa within Schismatoglottideae. The resulting tree topology supports, 1) a monophyletic West Sarawak clade comprising three genera: Aridarum, Bakoa, and Piptospatha; and 2) a supra-Lupar Line (the boundary between two of the known Bornean biochores) clade comprising the ‘Schismatoglottisjosefii complex. Nineteen morphological, ecological, and geographical characters were coded and mapped using parsimony (unordered model) onto the Bayesian tree to investigate incidents of homoplasy or apomorphic status of morphologies presumed significant in the evolution of rheophytism. The morphologies proposed here as the primary mechanisms adaptive for rheophytism in Bornean Schismatoglottideae are: root/shoot disarticulation; a free ligular sheath; and marcescent senescence of the ligule. Two morphologies formerly used as generic definers, and previously treated as homologous: presence of a micropylar appendage, and thecae horns, are shown to be homoplastic.

© Copyright 2013 by the American Society of Plant Taxonomists
Wong Sin Yeng "Rheophytism in Bornean Schismatoglottideae (Araceae)," Systematic Botany 38(1), 32-45, (1 February 2013). https://doi.org/10.1600/036364413X661908
Published: 1 February 2013
JOURNAL ARTICLE
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KEYWORDS
Araceae
Borneo
character mapping
phylogeny
rheophytic
Schismatoglottideae
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