thallus_color_black
black
areoles rounded to irregular, 0.5-1.5 mm wide, crowded and contiguous; prothallus black, marginal and between areoles or not apparent; photobiont cells 6-11 µm wide; medulla white, lacking calcium oxalate (H2SO4-), I-
Buellia subarnoldii
Buellia subarnoldii