Polyalthia khaosokense (Annonaceae), a new species from Peninsular Thailand with a key to the Polyalthia evecta species complex

Polyalthia khaosokense, a new species from southern Thailand is described, and photographs and illustrations are provided. Additionally, the key to the species in the Polyalthia evecta complex has been updated to include the new species. Currently, the complex comprises 12 species, whereas the genus now includes 22 species in Thailand.