Caloplaca aractina  

Thallus spreading (often to ca 50 mm diam.), crustose, dark leaden grey to almost black, the surface uneven but smooth, somewhat oily in texture, usually distinctly rimose to cracked-areolate, often with an irregular zoned margin bounded by a black prothallus.
Anamorph: not known.
Teleomorph: ascomata apothecia, to ca 1 mm diam., widely scattered and often sparse, initially immersed but soon becoming sessile to emergent. Discs brown-orange to brick red, flat, granular but not pruinose, sometimes irregular in outline. Thalline margin persistent, dark grey, rather thick and verrucose. Interascal tissue of simple paraphyses with scarcely swollen apical cells. Asci 51-59 x 17-21 µm, clavate with the central part sometimes significantly swollen, rather short-stalked, the apex rounded, thick-walled with a broad-ocular chamber, 8-spored. Ascospores irregularly biseriately arranged, 10-11.5 (-15) × (5-) 6-7 (-8) μm, broadly ellipsoidal, 1-septate, the outer wall thin, the septum median and 3-5 μm wide, ca 1/3 of the length of the ascospore, hyaline, smooth, without a gelatinous sheath or perispore.
Chemistry: thallus K–; discs of apothecia K+ purple.

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