Verrucaria placida  

Thallus thin, 26–65 µm thick, subgelatinous, translucent when fresh and wet, smooth, ± matt or slightly glossy, continuous, grey-green to mid brown, contiguous conspecific thalli not separated by dark lines. Cells irregularly arranged or in weakly defined columns, coherent, without air spaces between the cells. Cortex poorly differentiated, comprising a thin layer with few or no photobiont cells, cortical pigment, when present, brown; without a dark basal layer.
Anamorph: not known.
Teleomorph: ascomata perithecia, forming conic-hemispherical mounds 400–600 µm diam., at first covered by the thallus up to the apex, later sometimes eroded to expose the black ostiolar region. Ascomata 250–310 µm diam. Involucrellum conical, reaching to the substratum, dark brown, K+ dark grey. Interascal tissue absent, periphyses 20–45 µm long. Asci clavate, I–, fissitunicate, the wall thickened above, ocular chamber usually present; dehiscence by extrusion of an endotunica to form a delicate rostrum, 8-spored. Ascospores arranged biseriately, (19–) 21.5–26.5 (–30.5) x (8–) 9–10.5 (–12) µm, length/breadth ratio (2.0–) 2.2–2.7 (–3.0), ellipsoidal, hyaline, aseptate, with a perispore that apparently degenerates with maturity of the spores.