Abstract: Four new species of Orchidaceae from China, Heminium lijiangense, Peristylus fasciculatus, Platanthera milinensis, and Ponerorchis gongshanensis, together with a new country record, Peristylus tenuicallus, are described and illustrated based on morphological and/or phylogenetic analyses. Heminium lijiangense is closely related to H. elisabethae but differs from it by having the dorsal sepal ovate-orbicular and lip mid-lobe distinctly shorter than lateral lobes. P. fasciculatus is close to Peristylus tradescantifolius but is distinguished from it by having several fascicled and straight, root-like tubers (vs. one or two oblongoid tubers), old stems usually persistent, middle lobe of lip narrowly ligulate-lanceolate and half as long as the lateral lobes (vs. middle lobe deltoid, about a third as long as the lateral lobes or less), a raised callus at the base of each lateral lobe (vs. callus absent), spur gradually attenuate toward the apex (vs. spur clavate). Platanthera milinensis is similar to P. stenochila by sharing small green flowers and lip without a spur, but differs in having a creeping rhizome, a corymbose inflorescence, and a broadly ovate and slightly 3-lobed lip. Ponerochis gongshanensis is similar to P. faberi in its small flowers, but differs in having a linear leaf c. 3 mm wide (vs. leaf 5-13 mm wide), in the lip having collar-like raised margins on the sides of the spur entrance, and a mid-lobe which is notched at the apex but not divided into two divergent lobules that are nearly as large as the lateral lobes, as in P. faberi. All the proposed species obtained high support in phylogenetic analysis as new species. The recently described genus Apetalanthe is reduced to synonymy of Ponerorchis and a new combination is made.

Key words: Orchidaceae, Herminium, Ponerorchis, Peristylus, Platanthera, China