Reappraisal of Microtropis macrocarpa CY Cheng & TC Kao (Celastraceae), a critically endangered species endemic to Yunnan, China

Microtropis macrocarpa C.Y. Cheng & T.C. Kao has been treated as a synonym of Microtropis macrophylla Merr. & Freeman in most taxonomic reports in China. According to our study, M. macrocarpa is an independent species endemic to Yunnan, China. Microtropis macrophylla and Microtropis pachyphylla Merr. & Freeman should be treated as synonyms of Microtropis longifolia Wall. ex Kurz. M. macrocarpa is also identified as a critically endangered species, CR B I ab (i,ii,iii,v), based on the IUCN Red List Categories and Criteria. The foliar surface, anther and pollen structures were also observed with a scanning electron microscope.