Erasanthe (Orchidaceae, Epidendroideae, Vandeae, Aerangidinae), a new endemic orchid genus from Madagascar

A new genus, Erasanthe P.J.Cribb, Hermans & D.L.Roberts, is erected for Aeranthes henrici (Schltr.) P.J.Cribb, Hermans & D.L.Roberts, an aberrant species in Aeranthes Lindl. This new genus is morphologically distinct from Aeranthes, having stout roots, oblanceolate leaves with undulate margins and stout inflorescence axes, bearing simultaneously several white to pale green flowers, rather than fibrous roots, linear leaves with flat margins, and wiry inflorescences bearing translucent flowers, usually borne in succession. Its large flower is also distinct for its lacerate lip and very long slender spur, neither feature being present in other Aeranthes. Recent DNA studies, based upon ITS and MatK gene sequences, have indicated that Erasanthe is sister to a clade comprising Beclardia, Cryptopus and Oeonia, that is quite distant from the clade containing the other Aeranthes species which form a clade sister to Jumellea, another predominantly Madagascan genus.