Two new species of Litostigma (Gesneriaceae) from the China–Vietnam border area based on morphological and molecular data, adding new stigma characters for the genus

Litostigma is a recently described small genus with two species confined to limestone karsts in southwestern China and adjacent Vietnam. During the course of field works on the limestone karsts of the China–Vietnam border area, two unknown species of Litostigma were collected. Molecular phylogenetic analyses based on nuclear ITS sequences strongly confirm the placements of the two new species in Litostigma. However, these two new species can be distinguished from the previously known species by distinct morphological characters. Thus, Litostigma pingbianense and L. napoense are recognized as two new species. This adds to the morphological variability of the genus. Most importantly, both simple and divided stigmas does occur in this genus.