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, fragmented or forming rosettes up to 3-4(-10) cm in diam., pale grey-brown to deep brown-black, usually closely appressed. Lobes 2-6 mm wide, fragile, thin, 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. Medulla ochre yellow to yellow-orange, the hyphae encrusted with acicular, pale yellow crystals. Lower surface pale at margins, brown-black in central parts, matt, smooth to ridged-undulate, without a tomentum. Apothecia rare, developing on the underside of lobes, ear- to kidney-shaped, to 3 mm across, with a brown-black disc and an entire margin. Epithecium brownish; hymenium colourless, c. 70 μm high; paraphyses simple, conglustinated; 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 in short 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).