For 185 years, the genus Eumachia (Rubiaceae) was considered to include one species from Tonga. Since 2015, 94 more names have been added to it, expanding Eumachia into a pantropical genus of shrubby plants, most of whose members were originally described in Psychotria. Four Psychotria species from Southeast Asia that were identified as potentially belonging in Margaritopsis (now a synonym of Eumachia) have not yet had combinations made in Eumachia. They are considered here, and new combinations are made for Psychotria extensa Miq., P. montana Blume and P. rostrata Blume. The fourth name, Psychotria expansa Blume, is considered a synonym. The identities of Chassalia sangiana Miq. and Psychotria rhodocarpa Teijsm. & Binn. are also discussed. Lectotypes are designated for several names.
