The enigmatic moss Fissidens jansenii Sergio & Pursell recorded on Plateau de Millevaches (Limousin, France) with comments on its morphological variability

摘要

The rare Fissidens jansenii Sergio & Pursell is reported on plateau de Millevaches, Limousin (France), nearly 1000 km north of the nearest known population. As a result, F. jansenii is known from the Iberian Peninsula and now from western France. An updated distribution map of the species in Europe is provided. The new material is fully described and illustrated and the ecology in France is outlined. Gametophytically, French specimens of F. jansenii do not deviate significantly from Portuguese material and the variability of characters is discussed. In France, on plateau de Millevaches, F. jansenii is relatively frequent but constitutes rather small populations, with a low number of individuals. Sporophytes were regularly encountered and reproduction is most likely to be by spore dispersal. On plateau de Millevaches, F. pusillus (Wilson) Milde shares a comparable habitat but is easily distinguished from F. jansenii. Morphologically similar species occurring in Western Europe and that could potentially be confused with F. jansenii (F. rivularis and F. rufulus Bruch & Schimp.) are compared.