Verrucaria murina  

Thallus usually superficial, rarely immersed, thin, greenish to dark brown, often in small flecks and patches, often comprising distinct goniocysts. Cortex poorly defined, epinecral layer absent. Isidia, blastidia and soredia absent. Photobiont chlorococcoid.
Anamorph: not known.
Teleomorph: ascomata perithecia, 150-300 µm diam., moderately projecting to prominent, shallowly domed, not covered by the thallus; occasionally collapsed when dry (in shaded specimens that have a thin involucrellum). Involucrellum appressed to the peridium and scarcely distinguishable from it, or appressed above and spreading slightly below. Basal wall poorly developed, often almost flat, thin and pale brown. Interascal tissue absent, the ostiolar canal lined with rather short thick-walled periphyses. Asci clavate, short-stalked, fissitunicate, the wall thickened above and the ocular chamber inconspicuous, with rostrate dehiscence, not staining in iodine, 8-spored. Ascospores arranged biseriately, (13.5-) 18.5-24 (-28.5) × (6-) 8.0-11.5 (-14.5) μm, length/width ratio (1.6-) 2.0-2.5 (-3.3), rather variable in shape but usually ellipsoidal, hyaline, aseptate, thin- and smooth-walled, with an evanescent gelatinous sheath.