Usnea intermedia (A. Massal.) Jatta

Usnea intermedia currently includes European pendent fertile taxa without vegetative propagules from the U. barbata group. However, it requires a detailed molecular revision as the morphologically defined species do not correspond to the known phylogeny (Clerc & Naciri 2021).

In Europe, it grows on various trees in humid mountain forests of the temperate zone. The lichen is absent from Scandinavia (Westberg et al. 2021). In the past, it was recorded under various names, e.g., U. faginea, U. glauca or U. rigida (Černohorský et al. 1956). Its historical distribution requires a revision of the herbarium material because of possible confusion with underdeveloped or non-pendent forms of U. florida. The material that has already been revised suggests that the species used to be more abundant also at lower elevations (Šoun 2015, Šoun & Němec 2015). Currently, it is a rare species, which is not spreading as many other Usnea species do. It is more abundant only in the Šumava Mts, where it probably survived during the period of acid rain.

Literature: Černohorský Z., Nádvorník J. & Servít M. (1956): Klíč k určování lišejníků ČSR. I. díl. – Nakladatelství ČSAV, Praha. Clerc P. & Naciri Y. (2021): Usnea dasopoga (Ach.) Nyl. and U. barbata (L.) F. H. Wigg. (Ascomycetes, Parmeliaceae) are two different species: A plea for reliable identifications in molecular studies. – Lichenologist 53: 221–230. Šoun J. (2015): Revize herbáře lišejníků Josefa Uličného. ‒ Bryonora 56: 81‒87. Šoun J. & Němec R. (2015): Lišejníky rodu Usnea na Znojemsku. – Thayensia 12: 65–78. Westberg M., Moberg R., Myrdal M., Nordin A. & Ekman S. (2021): Santesson’s chec­klist of Fennoscandian lichen-forming and lichenicolous fungi. – Uppsala University: Museum of Evolution.

Ascomycota → Lecanoromycetes → Lecanorales → Parmeliaceae → Usnea