Habit: not lichenized, lichenicolous Thallus: absent, not lichenized Ascomata: initially perithecioid, later expanding and appearing apothecioid, solitary, immersed to adnate, 0.1-0.35 mm in diam. disc: pale orange-brown, concave to plane true exciple: pale greenish yellow-brown hymenium: hyaline, 65-75 µm tall, hymenial gel non-amyloid; paraphyses: simple to sparingly branched, c. 1 µm thick, without apical thickening, without periphysoids asci: flask-shaped, thin-walled, apex slightly thickened, 60-65(-75) x 12-14 µm, with an amyloid tube structures (I+ pale blue with a darker blue apex), multispored ascospores: hyaline, simple, ellipsoid, 4-6(-7.5) x 1.5-2 µm Pycnidia: not found Secondary metabolites: none. Substrate and ecology: on wood, soil, sandstone, or lichenicolous on various lichens World distribution: North America and Europe Sonoran distribution: mainland of southern California, presently known only from one collection on Palomar Mountain. Notes: Thelocarpon lichenicola is one of the more common species of the genus. It is characterized by the presence of simple to sparingly branched paraphyses, the absence of periphysoids, slightly thickened ascus apices, and the absence of a photobiont.