Candelariella aurella  

Thallus thin, of scattered yellow to green-yellow convex rounded granules 0.5-1.5 mm diam., without marginal lobes, sometimes inconspicuous and almost lacking. Prothallus thin, continuous, dark grey to black, often extensive and dominant especially in urban areas. Isidia and soredia absent. Photobiont chlorococcoid.
Anamorph: not known.
Teleomorph: ascomata apothecia, frequent, 0.2-1.2 mm diam., discrete, ± regularly dispersed or sometimes more crowded, bright yellow. Thalline exciple ± entire, sometimes becoming partly excluded, disc ± flat. Epithecium yellow-brown, granular, hymenium 50-75 μm tall, I+ blue, hypothecium hyaline. Interascal tissue of paraphyses 1.5-2.5 µm diam., sometimes branched near the tips, the apices swollen, to ca 6 µm diam. Asci 35-45 x 12-17 µm, clavate, with a conspicuous apical cap which strongly blues in iodine in its basal part and with a distinct apical cushion, 8-spored. Ascospores 10-18 × 5-6 μm, cylindric-ellipsoidal to ellipsoidal, straight or curved, hyaline, aseptate, smooth-walled, without an epispore, gelatinous sheath or appendages.

Candelariella aurella forma smaragdula is similar, except for the citrine-green thallus. It sometimes occurs interspersed with normal thalli, and its phylogenetic status needs investigation.