Thallus crustose, immersed or effuse, of discrete, ± spherical granules (goniocysts) to 40 µm diam., or convex to subglobose areolae, scattered to coherent and clustered, or coalescing to form an uneven, sometimes rimose crust, prothallus absent. In section ecorticate but sometimes covered by a hyaline, amorphous layer (to 12 µm thick) and outermost hyphae sometimes pigmented. Photobiont green, globose, thin-walled, small, 0.4-7 µm diam., often occuring in pairs (Micareoid), or more rarely thick-walled and larger. A few species with in areolae-like cephalodia. Apothecia small, 1 mm or less diam., adnate, sessile or rarely stalked, convex to ± globose and often tuberculate, epruinose, hyaline, black, dull brown to grey, immarginate or very faintly marginate, never with a distinctly raised marginal rim. Hymenium I ± blue (amyloid). Asci clavate or clavate-cylindrical, Lecanoralean with an amyloid tholus, 8-spored. Ascospores colourless, smooth-walled, variously shaped, ellipsoid, ovoid, fusiform or acicular, rarely more than 6 µm wide, simple to multiseptate, never muriform. Paraphyses scanty to numerous, septate, mostly branched, especially above, often anastomosing, 0.7-1.7 µm thick at mid-hymenium, apices not regularly clavate or capitate, without a dark-brown apical cap, sometimes irregularly incrassate and with pigmented walls in upper 5-15 µm, or more rarely throughout. Hypothecium (including subhymenium) variously pigmented, of interwoven hyphae that become outwardly orientated towards the hymenium, mixed with wider, short-celled ascogenous hyphae. Excipulum often absent or indistinct, if discernible then non-amyloid, of radiating branched and anastomosing paraphyses-like hyphae, distinct and ± separate in K. Pycnidia often present, very varied in form, innate to sessile or stalked, stalks (pycnidiophores) sometimes branched. Walls hyaline or pigmented. Conidiogenous cells ampuliform to cylindrical, phialidic, sometimes with 1-3 proliferations. Conidia hyaline, smooth-walled, of three basic types: (1) microconidia ± cylindrical, eseptate, aguttulate, 3.5-9 × 0.5-1.0 µm, on innate to sessile pycnidia usually less than 50 µm diam.: (2) mesoconidia cylindrical, ellipsoid, obovoid, ovoid-obling, eseptate, often biguttulate, sometimes constricted in middle, mostly 2.8-8 × 1-2 µm, in innate, emergent, sessile or stalked pycnidia 30-200 µm diam.: (3) macroconidia curved, hamate or filiform, rarely helicoid c. 1-1.5 µm wide, 50-300 µm long.