Aristolochia ferox, a new species of subg. Siphisia (Aristolochiaceae) from Guangxi, China

Aristolochia ferox is described as a new species endemic to the Jiuwanshan Mountains, northern Guangxi, China. It is morphologically similar to A. championii, A. quangbinhensis, I. haimingii and A. fangchi in vegetative characters but is readily distinguished by its floral traits, particularly the adaxial calyx limb, which is wholly dark purple and muricate with coarse, fleshy, conical outgrowths. The new species is restricted to a very small geographic range.

Field surveys indicate that it is extremely rare, with very small extant populations, and is potentially threatened by ethnobotanical harvesting. Accordingly, it is preliminarily assessed as Critically Endangered (CR C 2 a (i), D) under the IUCN Red List criteria.