Distribution: N - Lig (Putortì & al. 1999b). C - Tosc (Putortì & al. 1999, Giralt & al. 2000), Sar (Rizzi & al. 2011, Di Nuzzo & al. 2022).
Description: Thallus crustose, episubstratic, whitish, whitish grey or yellowish green, continuous, granulose or rimose, usually forming wide patches. Apothecia lecideine-biatorine, black, 0.2-0.4 mm across, adnate, sometimes conﬂuent, with a flat to strongly convex disc, and a thin, often finally excluded proper margin. Proper exciple poorly developed, to 20 μm thick; epithecium dark brown; hymenium colourless, without oil droplets, 70-90(-100) μm high; apical cells of paraphyses swollen, (3.5-)4-5 μm wide; hypothecium inspersed with oil droplets, 100-120 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, brown, ellipsoid, (19-)21-24(-29) x 7.5-9.5(-11) μm, thickened at septum when young, uniformly thin-walled at maturity, finely ornamented. Photobiont chlorococcoid. Spot tests: thallus K+ yellow-brown, C-, KC-, P+ orange-red, UV-. Chemistry: with variable, usually low amounts of atranorin, fumarprotocetraric, protocetraric, confumarprotocetraric and convirensic acids.
Note: a species with a mainly western distribution in Europe, found on trunks of old trees, especially Castanea and Quercus, and on lignum. From Toscana, besides the type, there are recent collections from the province of Lucca, on Castanea, by Coppins (in litt.). The species is included in the Italian red list of epiphytic lichens as “Endangered” (Nascimbene & al. 2013c).