<i>Hymenophyllum bifurcatum</i> (Hymenophyllaceae, Polypodiidae), a new Chinese Himalayan fern species

A new fern species was discovered in Motuo County (Tibet, China) in the context of the taxonomic revision of Chinese <i>Hymenophyllum</i> (Hymenophyllaceae). This species shows diagnostic features of <i>Hymenophyllum</i> subg. <i>Mecodium</i>, and is clearly morphologically distinct from all known Asian <i>Hymenophyllum</i> species by its bifid segment apices with acute tips. In addition, based on phylogenetic analyses using three chloroplast DNA markers (<i>rbc</i>L, <i>rbc</i>L-<i>acc</i>D, and <i>rps</i>4-<i>trn</i>S), we show that the species forms a distinct lineage within <i>Hymenophyllum</i> subg. <i>Mecodium</i>. This new species, named <i>H. bifurcatum</i>, apparently endemic to Tibet (Xizang Province), is discussed and described here.