Description: Thallus foliose, heteromerous, to 3-10(-15) cm across. Lobes 5-10 mm wide, loosely attached. Upper surface smooth, glossy, brown-grey to grey-blue when dry, dark blue-grey when wet; medulla ochre-yellow; lower surface pale brown, darker towards the center, not tomentose. Apothecia frequent, on lower surface at apices of lobes, 0.5-1 cm across, reniform or oval, the disc brown, the dorsal surface conspicuously scabrid-areolate and ridged. Epithecium brownish; hymenium colourless, c. 70 μm high paraphyses simple, conglustinate; hypothecium colourless to yellowish. Asci 8-spored, fissitunicate, the thickened apex with a K/I+ blue ring, Peltigera-type. Ascospores 3-septate, brownish, broadly ellipsoid, 16-20 x 5-7 µm. Pycnidia rare, immersed. Conidia bacilliform. Photobiont: cyanobacterial ( Nostoc, not in chains). Spot tests: cortex K-, C- KC-, P-; medulla K+ pink to red. Chemistry: emodine and hopane triterpenoids in the medulla.
Note: a mild-temperate to humid subtropical lichen found on bark, epiphytic bryophytes and mossy rocks in humid, open forests; this is the most frequent species of Nephroma in the country, descending to sea level in Tyrrhenian Italy.