Aspicilia caesiocinerea (Nyl. ex Malbr.) Arnold
Circinaria caesiocinerea (Th. Fr.) A. Nordin
Thallus crustose, up to 15 cm diam., rather thick, rimose, cracked, areolate, with angular areoles warted at the edge, or flat or depressed, pale grey-brown, grey-blue, green-blue, and prothallus pale grey or dark, delimiting. Apothecia 1-1,5 mm diam., immersed but potentially sessile, crater-like, disc concave then flat more or less round to slightly angular, black, not pruinose, thalline margin evident from an early stage, thin, entire, somewhat wavy, but prominent and persistent. Ascii most-often 8-spored (seldom 4-spored), more or less cylindrical, apex swollen I+. Ascospores simple, highly variable, broadly ellispsoid, 15-30 x 7-15 µm (19-29 x 10-15 µm according to our measures). Photobiont: Chlorococcales. C-, K-, KC-, Pd-. On nutrient-rich siliceous rocks well exposed to sun, used as bird-perching zones. Not especially maritime but frequent near the coast. See also in the coastal zone Aspicilia leprosescens , less fertile, and of which the thallus is covered with schizidia.