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.