A New Infrageneric Classification of Gastrochilus (orchidaceae: Epidendroideae) Based on Molecular and Morphological Data

Gastrochilus is an orchid genus containing 73 species of mainly epiphytic on trees or rocks in mountain forests of tropical and subtropical Asia. Previous phylogenetic analyses and morphological assessments have failed to produce a well-resolved phylogeny at the infrageneric level. In the present study, a new infrageneric classification of Gastrochilus is proposed based on thoroughly morphological and phylogenetic analyses based on 52 species. Our phylogenetic analysis divided the genus into six sections including three new sections, G. sect. Pseudodistichi, G. sect. Brachycaules and G. sect. Acinacifolii. We also re-instate G. suavis to the specific rank. Furthermore, two new species, G. armeniacus Jun Y. Zhang, B. Xu & Yue H. Cheng and G. minjiangensis Jun Y. Zhang, B. Xu & Yue H. Cheng, are described and illustrated. A key to six sections of the genus is presented.