Phylogenetic insights into New World Cyperus (Cyperaceae) using nuclear ITS sequences

Abstract

We analyzed nuclear ITS sequences of 95 samples representing 85 taxa of Cyperus sensu lato under maximum likelihood and Bayesian frameworks. This work is exploratory in nature with the objectives of gaining insight into relationships among New World Cyperus and targeting problematic clades for future research. In our resulting phylogenetic hypothesis, the genera Cyperus, Kyllinga, Oxycaryum, Pycreus, and Queenslandiella were intermixed, confirming the paraphyletic nature of Cyperus as reported by other researchers. We recovered a strongly-supported clade whose members possess C4 photosynthesis. The C3/C4 split has also been previously reported based on research employing different methods of phylogenetic estimation and different molecular markers. We provide preliminary evidence that Cyperus sections Haspani, Laxiglumi, Strigosi, Thunbergiani, and Umbellati are not monophyletic. Cyperus subgenus Diclidium, which is characterized by a unique mode of spikelet shattering, is monophyletic and highly derived in our analysis, but additional taxa are needed for a more robust assessment. We discuss hypothesized relationships and taxonomic implications for several other species and species complexes.