Gastrochilus balangshanensis (Orchidaceae, Aeridinae), a new subalpine epiphytic orchid from the Mountains of Southwest China

<i>Gastrochilusbalangshanensis</i>, a new orchid species from the Balang Mountain, Sichuan Province, Southwest China, is described and illustrated. It morphologically resembles <i>G.affinis</i>, but differs in having shorter stems, a reniform epichile and a sub-hemispherical hypochile (spur), obtuse-rounded at the apex. The results of molecular phylogenetic analyses based on nuclear ribosome internal transcribed spacer (nrITS) and four chloroplast DNA markers (<i>mat</i>K, <i>psb</i>A-<i>trn</i>H, <i>psb</i>M-<i>trn</i>D and <i>trn</i>L-F) from 50 <i>Gastrochilus</i> species indicate that <i>G.balangshanensis</i> is closely related to <i>G.heminii</i> and <i>G.bernhardtianus</i>, also endemic to the Hengduan Mountains. The novelty is a branch and trunk epiphyte in mixed coniferous forest.