2021 年 47 巻 3 号 p. 119-130
The recent discovery in Hong Kong of plants matching the description of Tropidia nipponica, a rhizomatous, leafy geophyte native to southwest Japan, Taiwan and parts of southern China, fomented a taxonomic investigation of this and morphologically similar members of Tropidia in subtropical East Asia. Following critical analysis of type specimens and other authentic fresh and preserved material from throughout the range of all relevant names, as well as consultation of protologues and all relevant literature, the Japanese endemic T. nipponica var. hachijoensis and two Taiwanese endemics T. angustifolia and T. sui are found to fall within the range of variation of T. nipponica, and are thus newly synonymised. The morphological characters previously used to distinguish these endemic taxa—in particular, plant stature, leaf shape, prominence of the sterile bract and stem sheaths, floral rachis length, synsepal outline and labellum epichile shape and ornamentation—are shown to vary continuously and thus be ineffective at separating them. A lectotype is designated to stabilise T. nipponica, and an amended description, as well as notes on phenology, ecology, global range, taxonomy and conservation status, are provided. The species is assessed as Vulnerable following IUCN Red List guidelines, due to small population size.
