Phylogenetic position of Cyperus clandestinus (Cypereae, Cyperaceae) clarified by morphological and molecular evidence

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Nordic Journal of Botany

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University of Cape Town

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.