Taxonomic revision of the genus Bolusiella (Orchidaceae, Angraecinae) with a new species from Cameroon, Burundi and Rwanda

On basis of morphological analyses and field investigation, a revision of Bolusiella (Angraecinae; Orchidaceae) was undertaken. We examined 302 specimens from several main herbaria, and for each of the six taxa recognized we provide a morphological description, distribution, habitat, phenology and IUCN conservation status assessment. Distribution maps and an identification key are also provided. Detailed examinations of specimens and comparison with nomenclatural types resulted in one novelty, Bolusiella fractiflexa, which is distributed in lowland and montane forests of Cameroon, Burundi and Rwanda. This species is close to Bolusiella maudiae and B. talbotii in general aspect but differs from them in having only a small or absent spur and a basally fractiflex inflorescence. Some taxonomic changes are made: B. alinae is synonymous with B. talbotii, and B. batesii is lectotypified and considered synonymous with B. zenkeri. Two new records are provided: B. maudiae from Nigeria and B. zenkeri from Liberia