Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.

Habit: non-lichenized or lichenized Thallus: scattered, globose warts, immersed or emergent from substrate, 0.2-0.3 in diam., up to 0.2 mm. high surface: pale brown, appearing flat on upper surface, with yellow pruina, with thin algal sheath, evanescent Ascomata: immersed, punctiform, perithecioid, 0.1-0.25 in diam., usually appearing darker than wart true exciple: colorless hymenium: hyaline; periphysoids 20-30 µm long, branched and easily detached in sectioning; without paraphyses. asci: 100-160 long and swollen, I+ pale blue, eventually dissolving when spores are mature, multispored ascospores: hyaline, simple, ellipsoid, 3-4.5 x 1.5-2 µm Pycnidia: not found Secondary metabolites: pulvinic acid derivates. Substrate and ecology: on wood, leather, rocks, cow manure, or decaying lichens World distribution: North America and Europe Sonoran distribution: mainland of southern California, presently known only from one collection in Santa Monica Mountains, non-lichenized on decaying Lecanora muralis. Notes: Thelocarpon intermediellum is a rare species of North America and Europe. It is characterized by its yellow pruina, its usual lack of a photobiont, the presence of periphysoids, and the lack of paraphyses.