A taxonomic revision of Pseudodracontium (Araceae-Aroideae-Thomsonieae)

The Indochinese genus Pseudodracontium N.E. Br. (Araceae) is revised. Seven species are recognized; a key is given. Four new species from Vietnam and Thailand are described: P. fallax, P. kuznetsovii, P. lanceolatum, and P. latifolium. Distributions of all the species are mapped. Pseudodracontium macrophyllum Gagnep. ex Serebryanyi is validly published here for the first time. Two taxa are reduced to synonymy: P. anomalum N.E. Br. is reduced to P. lacourii; P. flotoi S.Y. Hu is reduced to P. harmandii. Three species (P. kerrii, P. laoticum, and P. siamense) invalidly published by Gagnepain are mentioned under the species to which they actually belong. Ecological and taxonomic notes are provided.