Life habit: lichenized or non-lichenized, saprobic Thallus: crustose, mostly immersed in substrate, lacking a cortex upper surface: whitish or pale gray photobiont: primary one trentepohlioid alga or absent, secondary photobiont absent Ascomata: perithecial, almost entirely immersed to sessile, black (rarely pink or whitish), simple to compound involucrellum: often present, brown-black, hemispherical to ± globose ascomatal wall: black, not continuous below the hamathecium, composed of ± cellular hyphae without bark cells exciple: globose, surrounding the center, colorless or pale brownish hamathecium: long-celled pseudoparaphyses, slender, branched, anastomosing above the asci, non-amyloid asci: bitunicate, cylindrical to clavate, with an apical dome and with an indistinct or short and broad ocular chamber, non-amyloid, 4-8 spored ascospores: uniseriate, hyaline, ellipsoid to clavate-fusiform, 1 (-3)-septate with eusepta, 11-22.5 x 4.5-6.5 µm; walls: occasionally ornamented with tiny warts Conidiomata: pycnidial, immersed to sessile, ± globose or conical, black conidia: ovoid to ellipsoid to bacilliform, simple, hyaline Secondary metabolites: none detected Geography: cosmopolitan in temperate and tropical regions but most diverse in the tropics Substrate: usually on bark, but also on calcareous or non-calcareous rock. Notes: It differs from Arthopyrenia in several features, particularly in the structure of the involucrellum, which is not clypeate. Acrocordia has a different ascal structure and ellipsoid ascospores with a warted epispore.