Premna vietnamensis (Lamiaceae, Premnoideae), a distinct new species from the Central Highlands of Vietnam.

Premna vietnamensis, a distinct new species which is endemic to Gia Lai Province in Central Highlands of Vietnam, is described and illustrated. It is characterized by its calyx tube bearing a semi-globose fleshy appendage, which has not been reported before from all known congeneric taxa, as well as from the Lamiaceae. A phylogenetic analysis of the whole Lamiaceae based on a sampling including representatives from all 12 currently recognized subfamilies confirmed the placement of this new species within Premna of the Premnoideae. Morphologically and geographically, P. vietnamensis is most similar to P. stenobotrys, but differs significantly in many aspects.