Margelliantha P.J.Cribb, Kew Bull. 34: 329 (1979).
This genus of pretty little orchids was described in 1979 by the Kew botanist Phillip Cribb. Six species are known to date, all immediately recognizable by the white or pale yellow flowers which are unusual amongst African orchids, many of which have reflexed parts, in remaining partly closed, or almost bell shaped.
Type species:
Margelliantha leedalii P.J.Cribb
All the species grow in montane forests, often on isolated hills, where they are often enveloped in mist or low cloud while the surrounding country may be hot and dry. The plants have their roots embedded in mass and lichens on the branches of trees and shrubs thus occupying a special micro-habitat in places where orchids are rather unexpected.
The name is derived from the Greek words margelis (pearl) and anthos (flower). In Margelliantha leedalii, the type of the genus and the only species that has been recorded from Kenya, the resemblance to a pearl is most marked because all the tepals are a glistening white. The whiteness is accentuated by the bright green anther cap at the apex of the column.
The few people who have tried to grow Margelliantha species have found them not difficult in conditions similar to those that succeed with some of the smaller Diaphananthe species.
EC., E. Trop. & S. Africa
Key to the species of Margelliantha P.J.Cribb

Bibliography and References:
Cribb PJ. 1979 New or little known orchids from East Africa. Kew Bull. 34. (2): 321 - 340 (1979)
Killmann D, Fischer E. 2007 Margelliantha lebelii, a new species of Margelliantha from Nyungwe National Park, Rwanda.
Orchidee 58. (6): 743-750.