A molecular phylogeny, morphology and classification of genera of Ranunculeae (Ranunculaceae)

Ranunculeae represent a highly diverse and cosmopolitan tribe within Ranunculaceae. Because of the great diversity of morphological features and lack of molecular phylogeny for the tribe, the classification of its genera has always been controversial. We report here molecular phylogenetic analyses based on nuclear and plastid markers (nrITS, matK, trnK, psbJpetA) that provide a framework for understanding relationships and character evolution within the tribe. Maximum parsimony analyses suggest a weakly supported basal dichotomy, while Neighbor Net analysis indicates strong support for five distinct lineages. Both methods revealed several well-supported, small terminal clades which correspond to previously described genera, characterised by unique morphological features and character combinations. Anatomical structures of the achenes suggested relationships with greatest concordance to those in the molecular phylogeny. Macroscopic analysis of achene morphology often indicated parallel evolution of structures related to certain dispersal mechanisms. Characters of perianth, androecium, gynoeceum and pollen are highly homoplasious, but several features characteristic of small terminal clades and terminal branches can be observed. Geographic isolation and adaptions may have triggered the evolution of morphological characters. We conclude that a classification accepting several small genera (Arcteranthis, Beckwithia, Callianthemoides, Ceratocephala, Coptidium, Cyrtorhyncha, Ficaria, Halerpestes, Hamadryas, Krapfia, Kumlienia, Laccopetalum, Myosurus, Oxygraphis, Paroxygraphis, Peltocalathos, Trautvetteria) and a large genus Ranunculus s.str. (including Batrachium, Aphanostemma and Gampsoceras) reflects best the molecular phylogeny and morphological diversity of the tribe.