Leptochilus mengsongensis (Polypodiaceae), a new species of fern from SW China

Leptochilus mengsongensis (Polypodiaceae), a new species of fern from Bulong Nature Reserve, Xishuangbanna, Yunnan, southwestern China, is described and illustrated. The main characters of morphological close relatives Leptochilus pedunculatus and Leptochilus axillaris were compared, results showed that it differs from L. axillaris mainly by its separate oblongrhomboid acrostichoid patched sori, and densely set roots; meanwhile, it differs from L. pedunculatus mainly in its narrowly lanceolate fertile fronds, thinly leathery lamina and vague zigzag veins, and shorter stipe. Analysis of rbcL gene fragments of L. mengsongensis revealed that 20 of 663 sites differed from L. pedunculatus, thereby providing further evidence for its recognition as a distinct species.