Pertusaria hymenea  

Thallus superficial, in small patches or wide spreading, thin to moderately thick, continuous, somewhat waxy, margin ± entire, rarely zoned; upper surface grey to yellow-green-grey or dark grey, smooth in young thalli, becoming roughened and ± tuberculate, often with deep rimose cracks. Fertile warts to 2 mm diam., often numerous and crowded, obscuring the thallus, semi-globose, often distorted (plicate-deformed), ± constricted at base, containing 1(-4) apothecia.
Anamorph: conidiomata pycnidia, immersed, the ostiole pale. Conidia 13-25 × ca 0.5 μm, straight or somewhat curved.
Teleomorph: ascomata apothecial in structure but initially appearing almost perithecial, discs (0.3-) 0.6-1 (-1.8) mm diam., rounded or rather irregular, often widening, the surface brown- or grey-black, often ± grey-white pruinose, surrounded by an uneven, often somewhat elevated thalline exciple. Epihymenium K+ violet. Interascal tissue composed of copious trabeculate pseudoparaphyses ca 1 µm diam., frequently branched and anastomosing. Asci 350-450 x 55-80 µm, clavate-ellipsoidal, very short-stalked, the apex obtuse with a broad ocular chamber, thick-walled and dehiscing with an irregular apical split, the outer gelatinous layer K/I+ blue, 8-spored. Ascospores arranged biseriately, (60-) 85-110 (-120) × (20-) 30-50 μm, ellipsoidal to fusiform-ellipsoidal, sometimes inaequilateral, distinctly narrower when immature, the wall 5-9 μm thick, to 15 µm at the apex and base, zoned, with a broad gelatinous sheath with a surface that may be minutely transversely striate.
Chemistry: thallus C+ yellow, K–, KC+ orange, Pd–, UV± pale orange (thiophaninic acid, ± O-methylmonochlornorlichexanthone and ± gyrophoric acid).