Distribution: N - Piem, Emil (Ravera & al. 2022b), Lig (Ravera & al. 2022b). C - Tosc (Benesperi & al. 2007), Laz (TSB 6354), Sar. S - Cal (Puntillo 1996).
Description: Thallus foliose, heteromerous and dorsiventral, usually closely appressed, fragmented or forming up to 3-4(-10) cm wide rosettes, pale grey-brown to deep brown-black. Lobes 2-6 mm wide, fragile, thin, the upper surface , pale grey-brown to deep brown-black, smooth or slightly wrinkled, with scattered, crenulate, 1-2 mm wide laminal phyllidia with swollen tips, which sometimes are densely crowded in older thallus parts; lobe margins entire, often ascending and crisped. Lower surface pale at margins, brown-black in central parts, matt, smooth to ridged-undulate, without a tomentum. Upper and lower cortex pseudoparenchymatous; medulla ochre yellow to yellow-orange, the hyphae encrusted with acicular, pale yellow crystals. Apothecia rare, developing on the underside of lobes, ear- to kidney-shaped, up to 3 mm across, with a brown-black disc and an entire margin. Epithecium brownish; hymenium colourless, c. 70 μm high; paraphyses simple, coherent; hypothecium colourless to yellowish. Asci 8-spored, fissitunicate, the thickened apex with a K/I+ blue ring, Peltigera-type. Ascospores 3-septate, pale brown, 18-21(-22) x 5-6 μm. Photobiont cyanobacterial (Nostoc the cells not in long chains). Spot tests: cortex K-, C-, KC-, P-; medulla K+ pink to red. Chemistry: anthraquinones and hopane triterpenoids in the medulla.
Note: a Mediterranean-Atlantic species found on rocks, more rarely on bark, in exposed situations, but in humid areas, usually at relatively low elevations. It is included in the Italian red list of epiphytic lichens as “Vulnerable” (Nascimbene & al. 2013c).