Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Life habit: lichenized Thallus: crustose, areolate, granular or film-like, or evanescent, or endolithic upper surface: grayish green or yellowish green to brownish photobiont: primary one a chlorococcoid alga (Leptosira), secondary photobiont absent; algal layer: not well developed Ascomata: perithecial, immersed or sessile; exciple: pale to medium brown or black, without an involucrellum, lacking ostiolar filaments; interascal filaments: present, persistent, not or sparsely branched asci: cylindrical or narrowly clavate, thin-walled; apex: slightly thickened, I+ blue, with a narrow cylindrical axial mass; 8-spored ascospores: hyaline, simple, ellipsoid, thin-walled, smooth, without halo Conidiomata: not seen Secondary metabolites: not detected Geography: widespread but often overlooked Substrate: soil, detritus, rock. Notes: "Thrombium" discordans (Nyl. in Hasse) Zahlbr., found on bark of oak in the San Gabriel Range (Hasse 1903), does not belong to the genus. It has perithecioid apothecial ascocarps and non-amyloid asci.