Life habit: lichenized, not lichenized, or lichenicolous Thallus: crustose, continuous or minutely granulose, thin, usually inconspicuous, endo- to episubstratal surface: gray, green, greenish gray, blackish green, or colorless and translucent, often covered with a yellow pruina, lacking isidia or soredia photobiont: (if present) primary one a chlorococcoid alga, secondary one absent Ascomata: apothecioid or ±perithecioid, sessile or immersed, with constricted base, globose to conical, translucent, pale brown or often yellow, lacking a thalline margin proper exciple: hyaline, pale green or pale yellow epihymenium: green, yellow, hyaline, or brownish yellow hymenium: hyaline, hymenial gel non-amyloid; paraphyses: unbranched to sparingly branched and anastomosing; periphysoids present or not asci: flask-shaped, often apically narrowed, thin-walled, apex not or slightly thickened, non-amyloid or with an amyloid tube structures, 50-300-spored ascospores: hyaline, simple or one-septate, ellipsoid, cylindrical or elongate Conidiomata: pycnidial, immersed or sessile, colorless; conidiogenous cells: simple, acrogenous conidia: simple, fusiform or bacilliform Secondary metabolites: pulvinic acid derivates or absent Geography: cosmopolitan Substrate: on rocks, wood, soil, leather, decaying thalli of other lichens or lichenicolous. Notes: Thelocarpon hassei de Lesd. [Bull. Soc. Bot. France 78: 613 (1930)] is a corticolous species from the San Jacinto Mountains in southern California. The type, collected by Hasse, is presumed lost and we were unable to locate any specimens at this time.