Notes on the Diaphananthe bidens Complex (Orchidaceae, Angraecinae), Including a New Species from Western Central Africa

Diaphananthe vespicincta Farminhão & Stévart (Orchidaceae) is described from Equatorial Guinea (Río Muni) and Gabon, as part of a first reappraisal of the unresolved D. bidens (Afzel ex Sw.) Schltr. complex. It differs from D. bidens s.l., wide­spread in the Guineo-Congolian region, by the dark green leaves (vs. pale green to yellow-brown), the wider main longitudinal leaf veins (typically ≥ 0.35 mm vs. 0.18–0.35 mm), and the longer (9.2–13.8 mm vs. 3–7.3 mm) ampullaceous spur with a longer waist. All het­erotypic synonyms of D. bidens were re-examined, in­cluding Mystacidium productum Kraenzl. and Listro­stachys mystacidioides Kraenzl., which are neotypified, and D. trigonopetala Schltr., which is lectotypified. Diaphananthe acuta (Ridl.) Schltr., endemic to São Tomé Island, is excluded from the synonymy of D. bidens, along with D. papagayi (Rchb. f.) Schltr., en­demic to Príncipe Island. Diaphananthe acuta and D. vespicincta are assessed as Endangered and D. papa­gayi as Critically Endangered (possibly Extinct) ac­cording to the IUCN Red List Categories.