Pertusaria leioplaca (Ach.) DC.Thallus crustose, thinly episubstratic or partly endosubstratic, continuous to (rarely) finely cracked, whitish, ash-grey or yellowish grey, smooth to tuberculate, densely covered with clusters of small crystals, unzoned. Apothecia perithecioid, completely immersed in scattered, basally enlarged. 0.5-1.5(-2.5) mm wide, conical, often flat-topped fertile warts opening through a punctiform ostiole, with 1-2(-4) ostioles per wart. Epithecium colourless to dark brown to black-brown, K-; hymenium colourless; paraphyses lax, branched and richly anastomosing; hypothecium colourless to pale yellow. Asci (3-)4-spored, broadly cylindrical, the apex with a broad ocular chamber, the outer sheath K/I+ blue, otherwise K/I-, with an inner extensible layer, <i>Pertusaria</i>-type. Ascospores 1-celled, hyaline, ellipsoid, (40-)50-90(-130) x (20-)25-40(-50) µm, with a 4-15 µm thick, 2-layered, smooth wall (the outer wall much thinner than the inner one), the apices to 28 µm thick. Pycnidia rare, immersed. Conidia bacilliform, 7-10 x 0.5-1 µm. Photobiont chlorococcoid. Spot tests: thallus K- or K+ faintly yellow, C-, KC+ yellow, P- or P+ orange-red, UV- or UV+ pale orange-pink. Chemistry: 4,5-dichlorolichexanthone and stictic acid (major), constictic and norstictic acids (minor or traces). 