Six new species of Friesodielsia (Annonaceae) are described and illustrated; seven species are documented for Thailand for the first
time, with a lectotype designated for the name Oxymitra latifolia. Oxymitra fornicata var. glabra is raised to species rank as
Friesodielsia glabra. These additions bring the species diversity of Friesodielsia in Thailand to 16 species. A key to the Thai species
is provided.