Description: Thallus crustose, rather thin, more or less cracked, sometimes delimited by a grey-black prothallus, several thalli often merging to cover very large surfaces, pale grey, to pale grey-brown, often with a characteristic violet or lilac tinge (which disappears in herbarium). Soralia first punctiform, then rapidly confluent, concolourous with or slightly paler than thallus, the farinose soredia often abuindant and giving the thallus a subleprose appearance. Apothecia very rare, elongate to almost circular, 0.8-1.3 mm wide, with a convex, persistently pruinose disc. Epithecium brown; hymenium colourless; hamathecium of branched and anastomosing paraphysoids; hypothecium dark brown. Asci clavate, bitunicate, thickened at apex, with an internal K/I+ blue ring. Ascospores 1-septate, hyaline, fusiform, curved, 30-37 x 4-5 µm. Pycnidia rare, black, immersed. Conidia bacilliform, straight o slightly curved, 1-septate, hyaline to pale brown, 6-7 x c. 2 µm. Photobiont trentepohlioid. Spot tests: K-, C-, KC-, P-. Chemistry: unidentified fatty acids.
Note: a mild-temperate, mostly western species found on ancient oaks in northern Italy, but most abundant in Tyrrhenian Italy (e.g. on orange-trees along the Amalfi coast). The fertile, non-sorediate morph previously called Schismatomma albocinctum is genetically identical to the sorediate morph (Ertz & Tehler 2011); it has a Mediterranean-Atlantic distribution, and is found on bark of Pinus, Juniperus, Pistacia and other shrubs in maritime, very humid situations, being much rarer than the typical, sorediate form.
Growth form: Crustose
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)