Dischidia (Apocynaceae, Asclepiadoideae) in Laos and Vietnam

Two new species, Dischidia dohtii Tran & Livsh. and D. cornuta Livsh., are described and illustrated. Dischidia rimicola Kerr is illustrated for the first time. All three species are associated with treenesting ants of the genus Crematogaster. Presentation experiments with seeds of D. rimicola indicate that they are attractive to the ants. The possible affinity between D. dohtii and the enigmatic D. khasiana Hook.f. from north-eastern India is discussed; D. khasiana is lectotypified. A key to the 14 species of Dischidia documented from Vietnam and Laos and a list of exsiccatae are provided.