Habenaria diwata(Orchidaceae: Orchidoideae), a new species from Mount Malinao, Albay Province,Luzon Island, Philippines

A new species,Habenaria diwata R.Bustam., J.Collantes & M.R.B.Altamirano(Orchidaceae: Orchidoideae), is described from Mount Malinao, Luzon Island, Philippines.Habenaria diwata most closely resembles the Taiwanese species H. tsaiana T.P.Lin in having bipartite petals with an entire posterior lobe and a tripartite labellum with an entire mid-lobe and subdivided side lobes, but differs by its shorter lateral sepals (9–11 mm long vs 12.5–13.5mm long in H. tsaiana), anterior petal lobes that are mostly entire, with the lower margin lacerate or unequally bifid at the apex (vs subdivided into two segments), shorter labellum base (1 mm vs 1.5–2 mm) and labellum side lobes subdivided into two filiform segments (vs subdivided into three filiform segments). Differences of H. diwata from a similar Philippine species,H. lingulosaAmes, are briefly discussed. This discovery raises the current number of recognised Habenaria species in the Philippines to 22. Illustrations and information on its distribution, habitat, phenology, and proposed conservation status are provided.