Gastrochilus jiuzhaigouensis (Orchidaceae, Epidendroideae), a new epiphytic orchid from Jiuzhaigou World Heritage Site, China

<i>Gastrochilus jiuzhaigouensis</i> (Orchidaceae), a new orchid species epiphytic on tree branches on the bank of an alpine lake at the famous Jiuzhaigou National Park in China, is described and illustrated. It differs from its morphologically similar species, <i>G. bernhardtianus</i>, by its shorter stems, obliquely linear-lanceolate leaves, reniform and revolute epichile without ornamentation, and the absence of a middle ridge at central callus of the epichile. To test its species status, sequences of the nuclear ribosomal internal transcribed spacer (nrITS) and four chloroplast DNA markers (<i>matK</i>, <i>psbA-trnH</i>, <i>psbM-trnD</i>, and <i>trnL-F</i>) were newly generated. Molecular phylogenetic analyses including 53 accessions of <i>Gastrochilus</i> species resolved it within the same clade as <i>G. bernhardtianus</i>, but with distinct boundary. Both morphological differences and phylogenetic evidence supported it a species new to science.