Lecanora achroa

Lecanora achroa has a yellowish gray to greenish gray, crustose thallus that lies atop a blackish-brown prothallus. The apothecia are sessile, and disc-shaped, measuring 0.3–0.8 mm (0.01–0.03 in) in diameter, with orange-brown discs. The ascospores are more or less ellipsoid in shape, measuring 10.5–16.5 by 6.5–8.6 μm.^[3]

The major secondary compounds found in Lecanora achroa are atranorin, 2'-O-methylperlatolic acid, and usnic acid. Species with a similar morphology include Lecanora helva and Lecanora leprosa, since both of them also have small apothecia with orange-brown discs.^[3] The Brazilian lichen Lecanora parachroa has morphological and anatomical features that are quite similar to L. achroa, but it differs in secondary chemistry, as it produces neither usnic acid nor 2′-O-methylperlatolic acid.^[4]

• List of Lecanora species