Revision and phylogeny of Acalypha (Euphorbiaceae) in Malesia

Twenty-eight species of Acalypha are recognized in Malesia. Acalypha paniculata is the sole member of subgenus Linostachys in Malesia and the rest of the species belong to subgenus Acalypha. Four previously synonymized species are resurrected as distinct species, namely A. angatensis, A. cardiophylla var. cardiophylla, A. grandis, and A. wilkesiana. Four species names are newly reduced to synonymy. The molecular phylogenetic analyses indicate that Acalypha is monophyletic, as is the subgenus Acalypha. The early-diverging lineages in the genus, and its closest outgroup, consist of African species. The Malesian species do not form a monophyletic group although the molecular data strongly support two small clades within the region that are morphologically homogeneous. The classification system that Pax and Hoffmann applied to subgenus Acalypha, which is based primarily on inflorescence morphology, appears to be unsatisfactory and incongruent with the phylogenetic analyses.