Pier Luigi Nimis
Responsible for the apparatus of images: Andrea Moro - Management of the software and databases: Stefano Martellos

This is the first draft of a key to crustose, sterile lichens with green photobionts potentially occurring in Italy (403 infrageneric taxa). Most crustose lichens may occur in the sterile state, especially at the beginning of their life-cycle, and of course it was impossible to include all of them here. The absence of important diagnostic characters related to sexual reproduction renders the key particularly difficult. Chemical characters are of paramount importance: the classical spot-tests and/or the colour appearing under UV-light may provide useful hints on secondary metabolites, but often they may be not clear or may be difficult to observe: in general, it would be best to carry out the spot tests with acetone extracts on filter paper, but in several cases TLC will be indispensable for a correct identification. In some cases, morphological and chemical characters will not be enough, rendering DNA analysis indispensable. Thus, this key should be used with great prudence, although in several cases it could at least help to greatly reduce the number of possible options.
Important keys to sterile lichens in Europe were published by Clauzade & Roux (1985), Smith & al. (2009), Wirth & al. (2013) and, limited to the epiphytic species of Norway, T√łnsberg (1992). Sterile lichens were mostly neglected by Italian lichenologists. Studies like that by Dietrich & Scheidegger (1996), however, show that they are a very important, often overlooked component of the lichen biota.


Clauzade G., Roux C. 1985. Likenoj de Okcidenta Europo. Ilustrita determinlibro. Bull. Soc. Bot. Centre-Ouest, N. Ser., N. Spec. 7. Royan, 893 pp.
Dietrich M., Scheidegger C. 1996. The importance of sorediate crustose lichens in the epiphytic lichen flora of the Swiss Plateau and the Pre-Alps. Lichenologist, 28, 5: 245-256.
Smith C.W., Aptroot A., Coppins B.J., Fletcher A., Gilbert O.L., James PW., Wolseley P.A. (eds.) 2009. The Lichens of Great Britain and Ireland. British Lichen Society, London. 1046 pp.
T√łnsberg T. 1992. The sorediate and isidiate, corticolous, crustose lichens in Norway. Sommerfeltia 14: 1-331.
Wirth V., Hauck M., Schultz M. 2013. Die Flechten Deutschlands. Stuttgart, Ulmer. 2 voll., 1244 pp.

Last modified: January, 9, 2023

Project Dryades, Department of Life Sciences, University of Trieste - CC BY-SA 4.0