Distribution: N - VG (Castello 2002, Martellos & Castello 2004), Ven (Lazzarin 2000b), TAA (Knoph & Leuckert 2000), Lomb (Valcuvia & al. 2003), Piem (Isocrono & Falletti 1999, Valcuvia 2002, 2002b, Isocrono & al. 2003), VA (Piervittori & Isocrono 1999, Piervittori & al. 2004), Emil (Fariselli & al. 2020), Lig (Watson 2014). C - Tosc, Sar (Knoph & Leuckert 2000). S - Camp (Ricciardi & al. 2000), Si (Ottonello & Romano 1997, Ottonello & al. 2011).
Description: Thallus crustose, thinly episubstratic, often poorly evident, continuous to indistinctly rimose-areolate or granular, pale to dark green-grey. Apothecia lecideine, black, shiny at least when young, sessile, constricted at base, 0.4-0.8(-1) mm across, with a flat to weakly convex disc and a persistent, glossy, often sinuous proper margin. Proper exciple dark throughout, blackish brown in outer part, brown within, without crystals; epithecium brown, without crystals; hymenium colourless, not inspersed with oil droplets, 40-65 µm high; paraphyses easily made free in K, simple, rarely anastomosing or branched, thickened at apex; hypothecium colourless to very pale brown (sometimes darker red-brown in older apothecia). Asci 8-spored, clavate, with an intensely I+ blue tholus penetrated by a weakly amyloid, broadly cylindrical axial mass, and a poorly developed ocular chamber, Lecidella-type. Ascospores 1-celled, hyaline, broadly ellipsoid to subglobose, 7-15 x 5-9 µm, with a thick, smooth wall, not halonate. Pycnidia globose, black, with a brown wall. Conidia thread-like, curved. Photobiont chlorococcoid. Spot tests: thallus K- or K+ yellow, C-, KC-, P- or P+ pale yellow. Chemistry: atranorin, sometimes in low amounts.
Note: on steeply inclined to slightly underhanging surfaces of hard, acid to base-rich, non-calciferous rocks.