Distribution: C - Tosc (Bungartz & al. 2004). Sar (Giralt & al. 2011). S - Camp (TSB 32280), Si (Bungartz & al. 2004)
Description: Thallus crustose, episubstratic, from thin and poorly developed to areolate or even bullate-subsquamulose, whitish to grey, sometimes delimited by a grey prothallus. Cortex with small crystals dissolving in K; medulla white, with crystals insoluble in K, I-. Apothecia lecideine, black, initially adnate but soon becoming sessile, crowded, often coalescing, to 0.5-0.6(-0.7) mm across, with a flat to strongly convex, epruinose disc, and an initially thick, then thinner and finally excluded proper margin. Proper exciple well developed, brown throughout, N-, up to 80 μm thick, of radially arranged hyphae, the inner part of long-celled, parallel, strongly agglutinated and thick-walled hyphae, the outer part of short-celled, isodiametric hyphae without intercellular spaces; epithecium brown, N-; hymenium colourless, 70-90 μm high, inspersed with numerous oil droplets; paraphyses strongly coherent, the apical cells 3-4(-5) μm wide, with a brown cap; hypothecium brown, up to 150 μm high. Asci 8-spored, clavate to cylindrical-clavate, the apical dome K/I+ dark blue with a pale, conical-pointed apical cushion (axial mass), the wall I-, but the thin outer gel I+ blue, Bacidia-type. Ascospores 1-septate, not constricted at septum. brown, ellipsoid with usually pointed ends, (11-)13-15(-18) x (5-)6-7(-8) μm; young ascospores slightly thickened at apex and strongly thickened at septum (Dirinaria-type) or usually only thickened at septum (Physconia-type), the thickenings almost disappearing in mature ascospores (Buellia-type), the wall smooth, the ontogeny of type B (apical inner wall-thickenings produced before septum formation). Pycnidia dark, immersed. Conidia bacilliform, 4-5 x 1-1.2 μm. Photobiont chlorococcoid. Spot tests: thallus K+ yellow, C-, KC-, P-. Chemistry: atranorin, chloroatranorin and diploicin, usually with additional isofulgidin.
Note: a mild-temperate, mainly Mediterranean-Atlantic, much misunderstood species (see Giralt & al. 2011) found on siliceous rocks in the Mediterranean area.
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)