Two new species of Kaempferia subgenus Protanthium (Zingiberaceae) from Northern Thailand

Kaempferia aurora Noppornch. & Jenjitt., from Tak province near the Thailand-Myanmar border, and K. caespitosa Noppornch. & Jenjitt., from Lampang province, Northern Thailand, are described as new species of subgenus Protanthium (Horan.) Baker. The diagnostic characters are clearly compared with the similar species. Detailed illustrations, photographs of floral dissection, information of phenology, distribution and ecology, and preliminary conservation status are provided for each new taxon. An identification key to the species of Kaempferia subgen. Protanthium in Thailand are also revised and presented.