Selaginella magna (Selaginellaceae), a new species in S. subg. Stachygynandrum from Guangxi, Fujian and Hunan, China, is here described and illustrated. It is the largest erect Selaginella species in China, characterized by acropetally shortening branches acropetally. Selaginella magna is most similar to S. willdenowii , but can be differentiated by its erect main stem, rhizophores restricted to rhizomes and stolons, and the absence of auricles at the base of both ventral and axillary leaves. Its triangular frond-like leafy stem with an acuminate apex confers a high degree of distinguishability in its natural habitat.