Porpidia flavocruenta  

Thallus epilithic, thin to moderately thick, 0.1-0.2 mm, yellow-orange to yellow-brown, occasionally pale yellow-grey, often irregularly cracked-areolate, the surface uneven with low warts from which the apothecia arise. Prothallus black, visible at the thallus edges where adjoining other lichens.
Anamorph: conidiomata stromatic, frequent, irregularly discoid, 100-150 μm diam., black, innate to sessile, sometimes with an orange pseudothalline margin, surface gnarled when old, the conidia apparently dispersing through irregular splits in the upper wall. Conidiophores not well differentiated, with conidiogenous cells terminal or lateral immediately below septa. Conidiogenous cells 7-11 x 1-1.5 µm, cylindrical or slightly tapering, proliferating percurrently, periclinal thickening and collarettes inconspicuous. Conidia 6-8 x ca 1 µm ((10-)12-14 × ca 1 μm fide Fryday et al. 2009), cylindrical, aseptate, hyaline, smooth- and thin-walled, without a perispore, gelatinous sheath or appendages.
Teleomorph: ascomata apothecia, large (0.8-) 1.2-1.5 (-2.0) mm diam., black, sessile with a slightly constricted base, orbicular, sometimes becoming flexuose when mature. Disc usually flat, sometimes becoming convex in mature apothecia, occasionally umbonate, often grey- or orange-pruinose, the margin raised and persistent, ca 100 µm wide. Exciple composed of radiating cellular hyphae, inner cells orange-brown (K± crimson, N-; ± unknown pigment),  3-5 μm diam., the outer rim 17-25 μm wide, blue-black or occasionally brown-pruinose (K± crimson, N+ red, ± unknown pigment), composed of globose cells 6-7 μm diam. Epithecium pale olivaceous (K–, N+ red), sometimes with blue-green pigmentation below. Hymenium hyaline, I+ blue, 135-150 μm tall. Subhymenium hyaline, ca 50 μm thick. Hypothecium ca 100 μm high, dark brown (K–, N-). Interascal tissue of paraphyses, numerous, branched and anastomosing, 1-1.5 μm diam. with scarcely swollen apices. Asci 70-80 × 15-17 μm, cylindrical. Ascospores 15-19 × 8-10 μm, ellipsoid, aseptate, hyaline, rather thin-walled, smooth, with a narrow perispore.
Chemistry. Thallus C–, K–, KC-, Pd–. No substances detected by TLC.