Aristolochia phuphathanaphongiana Do sp. nov. from southwestern Thailand is described here. The new species is most similar to A. acuminata and A. kongkandae, but it is distinguished by having a broad-ovate to cordate bracteole that is sessile and 8-15 x 6-12 mm, the entire perianth being dark purple to maroon black, with lanceolate limb and abaxial surface densely covered with long grey hairs, as well as by non-winged seeds. In addition to the description, a key to the species of Aristolochia subsect. Podanthemum from the Himalayan region and Indochina is provided.