Reassignment of six Polyalthia species to the new genus Maasia (Annonaceae): molecular and morphological congruence

Recently published molecular phylogenies of the Annonaceae have confirmed the long-held hypothesis that the large paleotropical genus Polyalthia is polyphyletic. Species previously assigned to Polyalthia are now known to belong to up to six distinct, generally well-supported clades. Three members of a group of six species previously referred to as the Polyalthia hypoleuca complex form a monophyletic group (with 99% bootstrap support) that is only distantly related to the other species of Polyalthia sampled. Putative morphological synapomorphies are assessed, and justification provided for validating a new generic name, Maasia. Six species names in the Polyalthia hypoleuca complex are accordingly transferred to Maasia: M. discolor, M. glauca, M. hypoleuca, M. multinervis, M. ovalifolia, and M. sumatrana.