Phylogenetic relationships in the Primulales inferred from rbcL sequence data

A cladistic analysis of phylogenetic relationships in the Primulales has been conducted, based on nucleotide sequence data from the chloroplast DNA gene rbcL. The analysis included 16 taxa representing all three families in the order, and also six genera from other orders, viz. Magnolia (Magnoliaceae), Caltha (Ranunculaceae), Geranium (Geraniacene), Nicotiana (Solanaceae), Diospyros (Ebenaceae), and Manilkara (Sapotaceae). Previous cladistic analyses of morphological data have indicated that the Theophrastaceae are monophyletic, and that the Myrsinaceae are paraphyletic if including the genus Maesa. The results of the present work corroborate this conclusion, but also indicate that the Primulaceae are paraphyletic. Maesa is part of an unresolved clade that also include the Theophrastaceae and the Primulaceae, and the Myrsinaceae s. str. The latter is part of a monophyletic group also comprising the Primulaceae-Lysimachiinae and Cyclamen. It is concluded that dramatic changes in family circumscriptions are needed in order for taxonomy to reflect strictly monophyletic groups in the Primulales.