Argostemmaehuangzhangense (Rubiaceae), a new species from Guangdong, China.

Argostemmaehuangzhangense , a new Rubiaceae species from E'huangzhang Nature Reserve, Guangdong Province, China, is here described and illustrated. A morphological comparison between the new species and its putative relatives, A.lamxayanum , A.laotica and A.verticillatum , is presented. The new species is mostly similar to A.laotica , but they can be distinguished from each other since Argostemmaehuangzhangense presents solitary flower (vs. 2-flowered inflorescences), flower lobes 4 (vs. 5) and anthers opening by longitudinal slits (vs. apical pores). In a preliminary IUCN Red List status of Argostemmaehuangzhangense this species is assigned as Vulnerable (VU).