Pogostemon puerensis (Lamiaceae), a new species from Yunnan of China

Pogostemon is the largest genus in tribe Pogostemoneae (Lamiaceae) and exhibits considerable morphological diversity, which has complicated species delimitation in parts of Southeast Asia. During botanical surveys in Pu’er City, Yunnan Province, China, a distinctive population of Pogostemon resembling P. hainanensis and P. parviflorus was discovered but differs in several stable morphological characters. Its taxonomic status was assessed using comparative morphology and molecular phylogenetic analyses based on five plastid regions ( matK , psbA–trnH , rbcL , rps16 , trnL–trnF ) and the nrITS region. The sampling included 57 accessions representing 35 species of Pogostemon , with representatives of other genera in Pogostemoneae and related tribes as outgroups. Bayesian and maximum likelihood analyses recovered the Pu’er plant as a well-supported lineage within Pogostemon , sister to P. parviflorus in the plastid dataset and to P. cablin in the nuclear dataset. Morphologically, it differs from P. hainanensis , P. parviflorus , and P. cablin by its much shorter bracteoles, distinctly exserted corolla, and longer stigma lobes; it is further distinguished from P. hainanensis and P. parviflorus by the densely hairy upper two-thirds of the inner calyx tube and from P. cablin by its different phenology. It is therefore described as a new species, Pogostemon puerensis X.X.Wu, Z.H.Li & Qiang Wang.