Description: Thallus crustose, superficial, usually rather thick (c.1.5 mm), smooth to cracked-areolate or rarely tuberculate, whitish-grey or pale grey, rarely pale straw, delimited by a zoned, white to pinkish brown prothallus. Isidia of two types: a) soft isidia resembling soredia, matt and with an uneven, apparently weakly corticated surface, white to grey, b) true isidia with a shiny, corticate surface, grey or brownish-grey; the soft isidia may form groups which strongly resemble soralia. Apothecia very rare, lecanorine, to 3.5(-5) mm wide, rounded or irregular, with a flesh-coloured, flat to concave, white-pruinose disc and a more or less farinose thalline margin with small papillae or isidia. Proper exciple prominent, visible as a ring around thalline margin; hymenium colourless, up to 200 μm tall; hypothecium yellowish. Asci 4-8-spored, with thick, amyloid walls, Pertusaria-type. Ascospores 1-celled, hyaline, thin walled, (30-)42-68 x 25-35 μm. Photobiont chlorococcoid. Spot tests: K- C+red, KC+ red, P-, UV+ glaucous. Chemistry: gyrophoric acid (major). lecanoric acid (trace to minor) plus other accessory substances.
Note: a mild-temperate lichen found on old, isolated deciduous trees in humid areas; certainly more widespread, especially in northern Italy.
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)