Browsing by Author "Dludlu, Meshack N"

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    Cyperaceae tribe Cyperae : phylogenetic relationships and evolutionary patterns of diagnostic characters
    (2007) Dludlu, Meshack N; Muasya, A Muthama
    Phylogenetic relationships in Cyperus and allied genera in the tribe Cypereae (family Cyperaceae) have been reconstructed using parsimony and Bayesian analyses of a combined data matrix, which consisted of plastid DNA (rbcL, trnL-F intergenic spacer, and rps16), nuclear ribosomal DNA (internal transcribed spacer ITS) sequences and morphological data. From both analyses, tribe Cypereae were resolved into a very strongly supported clade (Posterior probability =98%; Bootstrap= 100%) characterised by the Cyperus-type of embryo and the absence of perianth segments. Cyperus sensu stricto is not monophyletic as currently resolved as several cyperoid genera are embedded within it. The Cyperoid clade splits into two distinct clades which are diagnosed by the Eucyperoid (C₃) and Chlorocyperoid (C₄) anatomy. The evolution of key morphological characters used to diagnose genera is discussed and genera whose classification needs to be revisited are highlighted.
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    Phylogenetic position of Cyperus clandestinus (Cypereae, Cyperaceae) clarified by morphological and molecular evidence
    (Wiley, 2014) Muthama, Muasya A; Viljoen, Jan-Adriaan; Dludlu, Meshack N; Demissew, Sebsebe
    Extreme morphological reduction and convergent evolution can obscure taxonomic relationships. Th is phenomenon is frequently encountered in Cyperaceae, where characters traditionally used to diagnose genera have been shown to have evolved independently multiple times. Th e Ethiopian high-altitude perennial fi rst described as Cyperus clandestinus was subsequently moved to Ficinia because it has spiral glume arrangement, unlike typical Cyperus species, which have distichous glume arrangement. However, this position has remained uncertain as no nutlets have previously been studied to establish the presence or absence of the gynophore – the synapomorphy for Ficinia. We resolve this 140-year-old puzzle by describing the morphology of the nutlet, which lacks a gynophore, and use DNA sequence data to resolve the taxon within Cyperus. Cyperus clandestinus was found to be closely related to Remirea maritima and Cyperus cyperoides in the C 4 Cyperus clade, whose members predominantly have distichously arranged glumes. Th is provides further evidence for the unreliability of glume arrangement as a character to distinguish between members of the Cyperus and Ficinia clades, whereas gynophore presence is more congruent with molecular data.