The Taxonomy of Podostemaceae Subfamily Tristichoideae in Laos, with Descriptions of Seven New Species

Abstract

This study, based on comparative morphology reinforced by phylogenetic relationships deduced from matK sequences, records 15 species in three genera of Podostemaceae subfamily Tristichoideae from Laos. The species new to science are Dalzellia attapeuensis, D. microphylla, D. pseudoangustissima, Terniopsis microstigma, T. savannaketensis, T. sesadensis, and T. vapyensis. Cussetia diversifolia is excluded from the flora, although it has been reported as being in Laos. Floristic comparison by country shows a significant overlap between the Lao and Thai floras. Given not only the large number of species but also the high incidence of endemism, where seven of the 15 species are known only from within the country, Laos, together with Thailand, represents a center of diversity for Tristichoideae in Asia.