Dischidia thongphaphumensis (Apocynaceae: Asclepiadoideae), a new species from western Thailand

Dischidia thongphaphumensis is a newly discovered species from Thong Pha Phum National Park, Kanchanaburi province, western Thailand. It is here described, illustrated and compared with its morphologically most similar species, D. rimicola. These two species are similar in sessile inflorescences, creamy white flowers without corolline coronas, lanceolate-triangular corolla lobes with antrorse trichomes and longitudinal ribs on the inner surface, and sagittate staminal corona lobes. However, the new species can be distinguished from D. rimicola by its ovate-lanceolate or lanceolate leaves with papillose adaxial epidermal cells, and by its staminal corona lobes that are characterised by narrowly falcate lateral arms.