Disperis ngeziensis, a New Critically Endangered Orchid from Pemba Island, Tanzania

Disperis ngeziensis sp. nov. (Orchidaceae), a supposed mycoheterotrophic orchid is here newly described from material collected in Ngezi-Vumawimbi Forest Reserve, Pemba Island, Tanzania. The only known population grows in a patch of evergreen coastal forest dominated by Intsia bijuga, Manilkara sansibarensis, Erythrophleum suaveolens and Ficus lutea, in Vumawimbi area. The new species belongs to Disperis subgenus Dryorkis and is related to the species of the “Johnstonii group”. It is most closely related to D. neilgherrensis, the only member of the genus with an Asiatic distribution, from which it can be distinguished by its smaller size, the presence of a single small leaf, and the morphology of the labellum.