Abstract
A synopsis of Tridactyle Schltr. (Orchidaceae) in São Tomé and Príncipe is presented. We recognize nine species in São Tomé and Príncipe, including four new species. We describe here T. amadorii D’haijère, T. cocophila D’haijère, T. levelevis D’haijère & Stévart, and T. oboensis D’haijère & Stévart. Tridactyle armeniaca (Lindl.) Schltr., recorded by previous studies, is native to West Africa and is not found in São Tomé and Príncipe. Tridactyle exhibits an important diversification in São Tomé and Príncipe, with seven species being endemic (endemism rate > 75%). Here, new records are registered; the natural distribution ranges, habitat, ecology, and conservation status based on IUCN guidelines are detailed for all species; two names are lectotypified; and an identification key is provided.