Taxonomic revision of twelve species of the genus Cynorkis Thouars (Orchidaceae, Habenariinae) from Reunion Island, based on a morphological and ecological approach

Many species, described by Frappier in the genus Hemiperis, now a synonym of Cynorkis, pose a taxonomic problem because the type specimens are considered lost or they were described from living material only. Based on a population-level ecological study, we here conclude that 12 out of the 21 Hemiperis taxa proposed by Frappier should be reduced to two. C. brachycentra (Frapp.) Schltr., C. crispa (Frapp.) Schltr., C. globulosa (Frapp.) Schltr., C. ludens (Frapp.) Schltr. and C. simplex (Frapp.) Hermans & P.J.Cribb are proposed as synonyms of Cynorkis pleiadea (Frapp.) Schltr., whereas C. breviplectra (Frapp.) Schltr., C. clavata (Frapp.) Schltr., C. imbellis (Frapp.) Hermans & P.J.Cribb, C. nitida (Frapp.) Schltr., C. ringens (Frapp.) Schltr. are proposed as synonyms of Cynorkis constellata (Frapp.) Schltr.. A neotype is proposed for C. pleiadea (Frapp.) Schltr., and a lectotype for C. constellata (Frapp.) Schltr. These two remaining taxa can be differentiated on the basis of the presence or absence of glandular hairs and, to a lesser extent, on a difference in their ecological niche. Cynorkis pleiadea (Frapp.) Schltr. usually occurs at a lower altitude than C. constellata (Frapp.) Schltr., the former inhabiting cloud forest between 1000 and 2000 m, whereas the latter prefers highland ericoid vegetation between 1500 and 2500 m. Although the flowering period of both species overlaps, peak flowering in C. constellata (Frapp.) Schltr. occurs earlier (March) than in C. pleiadea (Frapp.) Schltr. (April).