Duthieeae, a new tribe of grasses (Poaceae) identified among the early diverging lineages of subfamily Pooideae: molecular phylogenetics, morphological delineation, cytogenetics and biogeography

The phylogeny of Pooideae, one of the largest subfamilies of grasses, has been intensively studied during the past years. To investigate the early evolutionary splits in Pooideae we used a broad sample of genera with uncertain placement, some of which have not been studied in molecular phylogenetics before, complemented by representatives from other lineages of this subfamily. Morphological, cytogenetic and biogeographical analyses were added to the molecular sequence work on chloroplast matK–3’trnK and nuclear ITS. According to chloroplast DNA data, a new and well-supported lineage was identified among the early branches. It consisted of Phaenosperma and a larger group of genera encompassing Anisopogon, Danthoniastrum, Duthiea, Metcalfia, Pseudodanthonia (inclusion resting on ITS and morphology), Sinochasea and Stephanachne. Based on structural characters we suggest to keep Phaenosperma under the monotypic tribe Phaenospermateae and to accommodate the other genera under a new tribe Duthieeae, which is mo...