Description: Thallus foliose, rather loosely attached, sorediate, forming orbicular rosettes 3-5(-8) cm in diam. Lobes flat to slightly concave, 0.5-1(-1.3) mm wide, grey to brownish grey, usually darker towards the margins. slightly pruinose at tips, with a distinct network of laminal, linear pseudocyphellae contrasting with the dark lobe margins. Soralia initially marginal, fissural, later laminal, orbicular, convex, with dark grey granulose soredia. Lower surface black in center, paler at margins, with black, furcate rhizines. Upper cortex paraplectenchymatous; medulla lemon-yellow at least in upper part; lower cortex prosoplectenchymatous. Apothecia lecideine, very rare (not seen in Italian material), laminal, 0.3-1.5 mm across, with a black, epruinose disc, without a distinct thalline margin. Internal stipe distinct, brownish-red and K+ purple in upper part, white and K- in lower part; proper exciple blackened; epithecium bluish black, K+ purple; hymenium colourless; paraphyses capitate; hypothecium brown. Asci 8-spored, clavate, -type. Ascospores 1-septate, brown, ellipsoid, 13-19 x 6-8 µm. Pycnidia black, immersed. Conidia bacilliform, 3-4 x c. 1 µm. Photobiont chlorococcoid. Spot tests: upper cortex and medulla K- (upper cortex sometimes K+ yellow), C-, KC-, P-, UV-. Chemistry: upper cortex with atranorin; medulla with terpenes and an unknown pigment.
Note: a subtropical species occurring both on bark (rarely) and on siliceous rocks. The species, which was considered as a pre-glacial relict in Europe by Masson (2008), is certainly very rare in Italy.
Growth form: Foliose, narrow lobed
Substrata: bark and rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)