in Lea, Cat. Pl. Cincinnati: 47, 1849. Basionym: Collema corticola Taylor - London J. Bot., 5: 195, 1847.
Synonyms: Leptogium cimiciodorum A. Massal.
Distribution: N - VG, Ven (Lazzarin 2000b, Nascimbene & Marini 2010), Lomb, Piem. C - Tosc, Laz (Munzi & al. 2007), Abr (Recchia & Villa 1996). S - Camp (Jatta 1909-1911), Cal (Puntillo 1996), Si (Ottonello & al. 2011).
Description: Thallus foliose, subgelatinous when wet, 2-8 cm in diam., loosely adnate. Lobes irregular, elongate, plane but inrolled apically, separate, 2-10 mm wide, to 300 µm thick, with rotund, entire, often upturned apices. Upper surface medium grey, dull, strongly and irregularly wrinkled, not isidiate. Upper and lower cortices consisting of a single layer of irregularly isodiametrical cells, internally with loosely interwoven chains of Nostoc and hyphae. Lower surface pale grey, smooth to wrinkled, with scattered tufts of white hairs, but not densely tomentose. Apothecia common, laminal, sessile, 0.5-2 mm across, with a brown, concave to convex disc and a often wrinkled thalline margin. Proper exciple euparaplectenchymatous; hymenium colourless, 90-150 µm tall; paraphyses simple, 2-3 µm wide, slightly inflated apically; subhymenium colourless. Asci 8-spored, cylindrical-clavate, the apex thick, with a I+ blue apical dome and a I+ blue annulus projecting downwardly. Ascospores hyaline, submuriform, 3-5-septate transversely, 0-1-septate longitudinally, ellipsoid to slightly subfusiform, 30-56 x 10-20 µm. Photobiont cyanobacterial (Nostoc), in long chains. Spot tests: all negative. Chemistry: without lichen substances.
Note: a mild-temperate to humid subtropical lichen found in ancient, humid forests. Most of the records are old: presently the species is extinct in large parts of the country, especially in northern Italy.