Phylogenetic analysis ofPotentilla using DNA sequences of nuclear ribosomal internal transcribed spacers (ITS), and implications for the classification ofRosoideae (Rosaceae)

Abstract

The circumscription ofPotentilla has varied widely. To investigate the monophyly ofPotentilla and the phylogenetic relationships of associated genera we used nuclear ribosomal internal transcribed spacer (ITS) DNA sequences. Fourteen species ofPotentilla (sensuWolf 1908) were included, some of which represent proposed segregate genera (such asArgentina, Comarum, Drymocallis, Duchesnea, Pentaphylloides, andSibbaldiopsis), and 17 other genera ofRosoideae, usingPrunus as outgroup. Our most parsimonious tree strongly implies thatPotentilla is not monophyletic. Forcing the monophyly ofPotentilla yields distinctly longer trees. Several morphological features appear to have evolved several times independently, including the swollen receptacle (“strawberry”) and ternate leaves. In order to minimise nomenclatural change and to name only well supported clades,Potentilla should be split into several genera, while other previously recognised genera such asDuchesnea, Horkelia, andIvesia are best included inPotentilla. We suggest, however, that a phylogenetic nomenclature (sensude Queiroz & Gauthier 1994) might be a better solution.