Blastenia crenularia  

Thallus crustose, dark grey, occasionally pale grey or buff-coloured, rarely immersed and inconspicuous, usually forming a roughened, continuous or cracked-areolate surface, the edges not placodioid or lobed. Isidia, soredia and blastidia absent. Photobiont trebouxioid.
Anamorph: conidiomata pycnidia, 100-200 µm diam., brown-red, often densely covering the thallus. Conidia small, bacilliform or ellipsoidal, hyaline, aseptate.
Teleomorph: ascomata apothecia, to 1 mm diam., scattered to contiguous, ± rounded but usually with the rim slightly flexuose or contorted, flat to convex. Thallin margin absent. Proper margin well-defined and glossy when young, brown-red, algae are absent below the hymenium. Disc rust-red to red-brown, rarely dark orange-red, unchanged in colour when wet, sometimes discoloured with dark patches, pruinose. Epithecium with a well-developed crystalline layer that dissolves in KOH, subhymenium pale. Interascal tissue of thick-walled flexuose paraphyses to 3.5 μm diam., branched towards the apices, the tips only slightly broadened. Asci clavate, fairly short-stalked, 8-spored. Ascospores arranged biseriately, 12-14 × 6-8 μm, ellipsoidal, polarilocular, the septum ca 5 μm thick, to half of the length of the ascospore, hyaline, smooth-walled, without a gelatinous sheath or epispore.
Chemistry: thallus K–, epithecium K+ purple.