Description: Thallus leprose, consisting of a firm mass of soredia-like granules, pale to dirty blue-grey, usually poorly delimited. Medulla not evident. Granules 20-45 μm diam., rather compact, usually without projecting hyphae, well separated from one another, often gathered into up to 120 μm thick consoredia. Photobiont chlorococcoid. Spot tests: K+ yellow, C-, KC-, P+ orange, UV-. Chemistry: atranorin, stictic, constictic and cryptostictic acids, zeorin and very rarely an unidentified fatty acid (major to trace).
Note: a mainly montane species in Italy, requiring humid conditions; it prefers acid bark not colonised by bryophytes, especially at the base of old trunks, but it rarely occurs also on soil, lignum and epiphytic mosses.
Growth form: Leprose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)