Abstract
Based on phylogenetic studies and morphological evidence, we propose the synonymization of Morrenia and Schistogyne under Araujia and Oxypetalum respectively. As a result, eight new combinations are proposed in Araujia (A. brachystephana, A. hassleriana, A. herzogii, A. odorata, A. scalae, A. stuckertiana, A. stuckertiana subsp. grandiflora and A. variegata), and eight in Oxypetalum, including two new names (O. fiebrigii, O. heptalobum, O. karstenianum, O. longipedunculatum, O. pentaseta, O. pubescens, O. sylvestre and O. tucumanense). We provide new synonymies and designate lectotypes for Lagenia megapotamica, Morrenia hassleriana, M. herzogii, M. intermedia, Schistogyne boliviensis, S. longipedunculata and S. sylvestris. We also clarify the typification of Tweedia.