Isoetes yunguiensis (Isoetaceae), a new basic diploid quillwort from China

Isoetes yunguiensis, a basic diploid species with a chromosome number of 2n = 22, is described and illustrated. This species occurs on the Yunnan-Guizhou Plateau in southwest China. It is similar to L japonica in its appearance and emergent aquatic habit. Herbarium specimens of L yunguiensis previously have been misidentified as L japonica. Isoetes yunguiensis differs from L japonica in megaspore and microspore morphology and chromosome number.