Mannia controversa (Meyl.) Schill comb. nov. (Marchantiidae, Aytoniaceae), a long-forgotten European taxon, is fully redescribed and a lectotype selected. It is reported from its original localities in the Swiss Alps and new sites in the Austrian and French Alps. A series of specimens from eastern Asia are closely related and are described as Mannia controversa subsp. asiatica Schill & D.G.Long. For the species, differences with other Mannia species are summarised and for its two subspecies, descriptions, illustrations (including SEM images) and a key are provided along with notes on ecology and distribution maps.
