Description: Thallus crustose, episubstratic, sorediate or not, rather thin, continuous or more or less cracked, pale grey, to pale grey-brown, often with a characteristic lilac tinge (which disappears in the herbarium), sometimes delimited by a grey-black prothallus, several thalli often merging to cover very large surfaces. Soralia, when present, at first punctiform, then rapidly confluent, concolourous with or slightly paler than thallus, the farinose soredia often abundant and giving the thallus a subleprose appearance. Apothecia very rare in sorediate forms, common in the fertile forms corresponding to S. albocinctum, elongate to almost circular, sessile to immersed, not constricted at base, (0.5-)0.8-1.3 mm wide, with a convex, persistently white-pruinose disc and a thin, finally sometimes excluded thalline margin. Proper exciple thin, of anticlinally arranged hyphae; epithecium brown; hymenium colourless, I+ blue; paraphysoids branched and anastomosing, 1-2 µm thick; hypothecium dark brown to carbonaceous black. Asci clavate, bitunicate, thickened at apex, with an internal K/I+ blue ring. Ascospores 1-septate, hyaline, fusiform, curved, (25-)30-37 x 4-5 µm. Pycnidia rare, black, immersed. Conidia bacilliform, straight or slightly curved, 1-septate, hyaline to pale brown, 6-7 x c. 2 µm. Photobiont trentepohlioid. Spot tests: K-, C-, KC-, P-, UV-. 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)