Aerangis (Orchidaceae) in Madagascar, the Mascarenes, and the Comoro Islands.

The genus Schltr. (Orchidaceae, subfamily Epidendroideae, tribe Vandeae, subtribe Angraecinae) in Madagascar and adjacent archipelagos is revised. Twenty-seven species have been recorded from the region, all of them endemic. Twenty of these are endemic to Madagascar, three to the Comoros only, three to the Comoros and Madagascar and one to Madagascar and Réunion. A third of all in the area were assessed to be immediately endangered with 15% Critically Endangered (CR) and 18.5% Endangered (EN). 37% are considered Vulnerable (VU), 15% Near Threatened (NT) and 11% are of Least Concern (LC). Section (Schltr.) Hermans is newly established. All the species are described and their typification, history, identification, pollination, distribution and habitat are discussed. The nomenclature and identity of (Thouars) Schltr., (Rchb.f.) Schltr., (B.S.Williams) Schltr., (Rchb.f.) P.J.Cribb & Carlsward, Schltr., (Hook.f.) Schltr., Schltr., (Sander ex Mast.) Hermans and (Rchb.f.) H.Perrier, are reassessed. Conservation assessments, illustrations and distribution maps are included for all the species. A checklist of the sections, species and a key to their identification are provided. Hermans is described from the Comoros for the first time.