The rediscovery and delimitation of Elatostema setulosum W.T.Wang (Urticaceae).

Of the 280 species of Elatostema documented in China, 189 are known only from a single collection. Elatostema setulosum is one such species, having been known only from the type collection for nearly half a century, until recent field investigations in Guangxi. Due to its morphological similarity to E. huanjiangense and E. tetracephalum, we undertook a critical review of all three species using morphological and molecular evidence. Our results suggest that all three names refer to the same species, which based on priority should be known as Elatostema setulosum. We recognize E. huanjiangense and E. tetracephalum as synonyms. A distribution map of E. setulosum and the extinction risk according to the IUCN criteria is provided. After recircumscription, the taxon must be considered as Least Concern (LC). [ABSTRACT FROM AUTHOR]