Based on morphological observations, molecular phylogenetic analyses, and literature consultations, a new species of Gesneriaceae, Petrocodon mirus, is described and illustrated here. This new species exhibits morphological similarity with P. pulchriflorus and P. hechiensis, but is easily distinguished from the latter two by its slightly leathery leaf blade, liner to ligulate-oblong lip lobes, and shorter tube with constriction at middle. In addition, the new species differs from P. pulchriflorus by its reflexed adaxial lip lobes, and from P. hechiensis by its included stamen and pistil. However, the stigma of P. mirus is very similar to the chiritoid stigma diagnostic for Chirita Buch.-Ham. ex Don (now mostly included in Primulina); based on this observation a new hypothesis for the evolution of the chiritoid stigma is proposed.