Thallus white, rarely greyish-white, episubstratal, thin, engulfing substrate, margin ± entire and unzoned, surface smooth to ± tuberculate, at times ± shining, continuous, never areolate-cracked, isidiate. Isidia initally papillate becoming columnar, often 1-2-branched at apices, bases well constricted with sides and tips only occasionally fused (0.2-)0.7(-1.2) mm diam., (0.4-)2(-7) mm tall. Fertile verrucae lecanorine, concolorous with thallus, terminal, embedded in tips of isidia, ± numerous and locally crowded, but usually narrower than isidia, often infrequently fused, 1-3 × 0.4-1.0 mm diam. Disc flesh-coloured to dominantly dark brown or black, plane or innate, occasionally convex, usually white-pruinose, 0.2-0.9 mm wide. Apothecia 1 per verruca, only slightly wider than disc, 0.37-0.96 mm diam. Epithecium brown, dark brown or black. Hypothecium colourless or pale brown. Asci clavate (150-)230(-340) × (43-)70(-120) µm. Ascospores 1 per ascus, oval, ellipsoid or cylindrical, generally deformed, frequently germinated and filled with oil bodies (100-)170(-270) × (38-)60(-115) µm, wall (2-)11(-30) µm thick. Chemistry: Cortex K-, C-, Pd-; medulla K+ yellow-red-brown, C-, Pd+ yellow-orange. Fumarprotocetraric and protocetraric (tr.) acids.