Syst. Lich. Germ.: 420 (1855).
Basionym: Collema cyanescens Rabenh., Deutsch. Kryptogamenfl. 2: 50 (1845).
Type locality: Switzerland ["Helvetia"] (H-ACH - lectotype). Lectotypification by Galloway & Jörgensen 1995: 235.
Type locality coordinates: Data lacking.
Molecular barcode: Data lacking.
Thallus: foliose, loosely attached, stale grey, lobes flabellate, up to 1 cm wide, upper side smooth or faintly striate, underside lacking hairs, isidia elongate, cylindrical, sometimes branched, often transitional to or replaced by phyllidia, concolorous with the thallus. Apothecia rare, laminal, stipitate, thalline exciple thin to hardly apparent, sometimes minutely nodular, excipular cortex of several cell layers, paraplectenchymatous tissue absent at base above photobiont layer. Spores ellipsoid, faintly ornamented, muriform, 20-30 / 8 - 18 µm (Swinscow & Krog 1988: 136).
Photobiont: Nostoc spec.
Chemistry: No lichen substances.
Ecology: Corticolous. In East Africa in sheltered woodland and montane forest from sea lavel to 3000 m, common (Swinscow & Krog 1988: 137).
Distribution Type: Widespread in the tropics and in temperate regions.
Note: There are different author citations:
Leptogium cyanescens (Ach.) Körb. by Calvelo & Liberatore (2002: 86), Dunlap & Tiffany (1980: 47), Malone & Tiffany (1978: 77), Moore (1968: 185), Osorio (1972: 20, 1992: 54, 1998: 4), Spielmann (xx: xx), Steimann (1986: xx), Shushan & Anderson (1969: 465), Wilhelm & Ladd (1985: 221)
Leptogium cyanescens (Pers.) Körb. by Piepenbring (2006: 107), Reese & Tucker (1970: 697), Scholz (2001: 323), Tucker (1981: 66), Wirth et al. (2011: 49), Index Fungorum 1 September 2014 as well as
Leptogium cyanescens (Hoffm.) Körb. by Dzä (1988: 47).
Actually the Acharius description (Date ?) of this species as a variety is illegitim (Jørgensen per email 28 August 2014).