Description: Thallus crustose, episubstratic, glaucous white to pale ochre, granulose-verrucose, continuous to finely rimose, usually poorly delimited, sometimes with a whitish prothallus. Apothecia lecanorine, abundant, often crowded and deformed by mutual compression, 0.4-0.8(-1.2) mm across, at first immersed in the thallus warts, then sessile, with a flesh-coloured, olivaceous grey to brown-black, epruinose, mostly flat disc, and a persistent, prominent, crenulate-granulose thalline margin. Thalline exciple with a few large crystals insoluble in K, visible under polarized light; proper exciple colourless, without crystals, 10-15 µm wide; epithecium pale to dark brown, sometimes with an olivaceous tinge. with many small crystals (chlarotera-type); hymenium colourless, 55-75 µm high, I+ blue; paraphyses c. 1.5 µm thick, sparingly branched, coherent, the apical cells up to 2 µm wide; hypothecium colourless or yellowish, 35-50 µm high. Asci 8-spored, clavate to subcylindrical, very thin-walled, with a K/I+ blue, tall tholus penetrated by a faintly amyloid apical cushion, the wall K/I-, surrounded by a blue outer layer, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid to broadly fusiform, straight or rarely slightly curved, 10-13.5 x 4-7 µm, often guttulate, with a 0.5-1 µm thick wall. Photobiont chlorococcoid. Spot tests: thallus K+ yellow, C+ carmine red, KC+ fleeting red, P+ yellow-orange. Chemistry: atranorin, chloroatranorin, 3,5-dichloro-20-O-methylanziaic acid, 3,5-dichloro-20-O-methylnorstenosporic acid, 5-chloro-20-O-methylanziaic acid, 3,5-dichloro-20-O-methylnorhyperlatolic acid.
Note: a Mediterranean lichen found on branches of shrubs in littoral maquis subject to humid maritime winds; mainly Tyrrhenian in Italy. It is included in the Italian red list of epiphytic lichens as “Vulnerable” (Nascimbene & al. 2013c).
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)