A New Argyreia Lour. (Convolvulaceae) from Northern Thailand

Argyreia elegans Traiperm, Tetsana & Chitchak, sp. nov., from northern Thailand is described and illustrated. The new species resembles A. kerrii Craib but differs in terms of having lanceolate to oblong leaves, up to two inflorescences (each bearing 1–3 flowers emerging from an axillary bud), and outer sepals that are densely velvety-pubescent on the abaxial side. A detailed description, an updated key to the species for the Flora of Thailand, as well as anatomical, micromorphological, and taxonomic notes are provided.