Synonyms: Buellia lauri-cassiae auct. eur. non (Fée) Müll. Arg.; Buellia triphragmia auct. non (Nyl.) Arnold
Distribution: N - TAA (Nascimbene & al. 2007b), Piem, Lig (Watson 2014). S - Camp, Bas (Ravera & al. 2015d).
Description: Thallus crustose, episubstratic, of variable thickness, continuous to rimose-areolate, whitish, whitish-grey to greyish green, with a smooth to irregular surface, rarely granulose-verrucose. Cortex with numerous crystals of atranorin, sometimes overlain with a thin epinecral layer; medulla white, I-. Apothecia lecideine, at first immersed, later adnate to sessile, up to 0.7 mm across, with a black, epruinose, flat to slightly convex disc (strongly convex only in overmature apothecia), and a thin, entire, slightly prominent proper margin. Proper exciple dark reddish brown, more or less uniformly pigmented, sometimes paler in inner part, K-, N-; epithecium dark brown; hymenium colourless, 70-90 µm high, not inspersed with oil droplets; paraphyses 1.5(-2) µm thick in lower part, the apical cells (3-)5-6(-7) µm wide, with a brown cap; hypothecium dark reddish brown. Asci 8-spored, Bacidia-type. Ascospores 3-septate, brown, mostly curved, ellipsoid with rounded to rarely slightly pointed ends, the middle septum thickened in young spores, (14-)16-19(-22) x 5.5-7(-9) µm, with ontogeny of type A (apical wall thickenings produced after septum formation). Pycnidia rare, black, immersed. Conidia bacilliform, 4-6.3 x c. 1 µm. Photobiont chlorococcoid. Spot tests: thallus K+ yellow, C-, KC-, P+ faintly yellow. Chemistry: atranorin.
Note: mainly lignicolous, more rarely on the bark of conifers in upland areas: a critical taxon, which needs further study (see Nimis 1993: 145). The species is included in the Italian red list of epiphytic lichens as “Critically Endangered” (Nascimbene & al. 2013c).