A new lycophyte species, Selaginella longistrobilina P. S. Wang, X. Y. Wang & Li Bing Zhang (Selaginellaceae), is described and illustrated from limestone hills in central Guizhou, China. Selaginella longistrobilina is most similar to S. prostrata H. S. Kung in the shape of the microphylls and in the arrangement, shape, and size of the sporophylls. However, the new species has longer strobili to 2.5 cm, and the sporophylls are often navicular adaxially, while S. prostrata has strobili only 3–4 mm, and the sporophylls are flattened adaxially. Selaginella longistrobilina is only known from central Guizhou, while S. prostrata is more widely distributed from Hunan, Sichuan to Yunnan in China. A new combination, S. prostrata (H. S. Kung) Li Bing Zhang, based on Lycopodioides prostrata H. S. Kung, is made and lectotypified herein.