Elatostema tenuinerve, a new species from Guangxi province China is described and illustrated. Elatostema tenuinerve most closely resembles E. pseudobrachyodontum, but differs in the following characters: margin of the leaves crenate, teeth obtuse; cystoliths 0.15 mm long or less; stipules 1.5–long, subulate, glabrous; pistillate receptacle with cystoliths, bracts in 2 whorls, ca. 13, 0.2–0.5 mm long, apex shortly acuminate, not corniculate; achenes with 7 longitudinal ridges. In the Flora of China, E. tenuinerve would be placed in sect. Elatostema ser. Nanchuanensia.