Petrocodon hunanensis (Gesneriaceae), a new species identified by both morphological and molecular evidence from limestone area in Hunan, China

Petrocodon hunanensis, a new species of Gesneriaceae from limestone area in Hunan Province, China, is described and illustrated. The new species is morphologically similar to Petrocodon coriaceifolius, but readily differs from the latter one in the growth form with terrestrial stems and distinct internodes, both surfaces of leaf densely with white pubescence, petiole densely with reddish-purple or white pubescence, zygomorphic corolla white or pale purple and 2-3 cm long, pedicels 0.3-2 (2.8) cm long, 4 stamens and 1 staminodes, ovary and capsule stipitate. Molecular evidences indicate that it is systematically similar to P. hispidus, but the morphologies of two relatives are obviously different.