Mycoblastus sanguinarius  

Thallus pale to mid grey, greenish when wet, often very irregular and uneven, thick and ± coarsely verrucose or papillose-warted, appearing marbled, continuous or ± cracked, more rarely thin, with scattered low warty papillae, a pale to dark grey prothallus sometimes present. Soralia rare; when present rounded, scattered, often few or confined to a few areas on a thallus, concolorous with or paler than the thallus, convex, efflorescent.
Anamorph: conidiomata pycnidia, often present, 40-50 µm diam, wall dark green. Conidia bacilliform, 6-9 × ca 1 µm.
Teleomorph: ascomata apothecia, 0.5-1.7 (-3.0) mm diam., usually frequent, black, becoming convex or hemispherical, sessile or slightly constricted beneath, developing on a bright carmine-red thalline cushion that may be exposed when the thallus is damaged or abraded. Asci 1- (to 3-) spored. Ascospores 70-100 × (28-) 35-45 µm, cylindrical with rounded ends; wall 6-7 µm thick, laminar.
Chemistry: cortex C–, K+ yellow, Pd+ yellow; medulla K+ red (in part), UV– (atranorin, chloratranorin, rhodocladonic acid (= mysaquinone), caperatic acid); soralia Pd–; hypothecium and tissue under the apothecium carmine to blood-red, K+ bright red, pigment diffusing into solution.