Towards a new classification of the giant paraphyletic genus Cyperus ( Cyperaceae): phylogenetic relationships and generic delimitation in C4 Cyperus.

Maximum likelihood and Bayesian inference analyses of nuclear ribosomal DNA ( ETS1f) and plastid DNA ( rpl32-trnL, trn H-psb A) sequence data are presented for ' C₄ Cyperus' ( Cyperaceae). The term ' C₄ Cyperus' encompasses all species of Cyperus s.l. that use C₄ photosynthesis linked with chlorocyperoid vegetative anatomy. Sampling comprises 107 specimens of 104 different taxa, including many of the subdivisions of C₄ Cyperus s.s. and all C₄ segregate genera ( Alinula, Ascolepis, Kyllinga, Lipocarpha, Pycreus, Queenslandiella, Remirea, Sphaerocyperus and Volkiella). According to our results, C₄ Cyperus is a well-supported monophyletic clade nested in C₃ Cyperus. Despite the lack of resolution along the backbone of the C₄ Cyperus clade and for some internal branches, several well-supported clades can be distinguished. The first clade in C₄ Cyperus is formed by Cyperus cuspidatus and C. waterloti. Other recognizable and well-supported clades correspond to segregate genera, i.e. Ascolepis, Lipocarpha including Volkiella, and Kyllinga. Species of C₄ Cyperus s.s. form a core grade in which the C₄ segregate genera are embedded. Pycreus, the largest segregate genus composed of c. 120 species, is not monophyletic as it includes several C₄ species of Cyperus s.s. This study establishes a phylogenetic framework for revising the classification and character evolution in Cyperus s.l. © 2013 The Linnean Society of London [ABSTRACT FROM AUTHOR]