Pertusaria leioplaca  

Thallus superficial or partly immersed, thin, margin ± entire and unzoned; upper surface grey-white to yellow or green-grey, smooth, even to somewhat roughened, not or weakly rimose-cracked, densely packed with clusters of coarse crystals, sometimes partially immersed. Fertile warts (0.6-) 1.5-2 (-2.5) mm diam., scattered or occasionally contiguous in small clusters, concolorous with the thallus, shallowly domed to hemispherical or irregularly conical with a spreading base, often flat-topped.
Anamorph: conidiomata pycnidia, rare. Conidia 7-10 × 0.5-1 μm.
Teleomorph: ascomata apothecia, 1(-2) per wart, generally level to slightly immersed, often widely spaced. Disc punctiform, ostiole-like. Epithecium K– or K+ pale purple, often difficult to detect due to the limited extent of the epithecium. Interascal tissue composed of copious trabeculate pseudoparaphyses 1-1.5 µm diam., frequently branched and anastomosing. Asci 225-245 x 35-46 µm, cylindrical with a short tapering stalk, the apex rounded with a broad ocular chamber, thick-walled and dehiscing with an irregular apical split, the outer gelatinous layer K/I+ blue, (2-) 3-5 (-6) spored. Ascospores arranged uniseriately, 37-53 x 23-27 (4- and 5-spored asci), 62-73 x 26-37 (2- and 3-spored asci), ellipsoidal, sometimes slightly inaequilateral, the wall 3-4.5 μm thick, to 7 µm at the apex and base, with a broad gelatinous sheath with a smooth surface.
Chemistry: thallus C–, K+ yellow, KC+ yellow, Pd+ orange-red or Pd–, UV± pale orange (coronaton, ± stictic and ± norstictic and constictic acids).