Athallia cerinella (Nyl.) Arup, Fröden & Sochting     

=Caloplaca cerinella (Nyl.) Flagey

      Thallus crustose, very thin, 1-3 cm in diameter, whitish, greyish-white. Apothecia tiny, often clustered and tightly packed, flat disc, lemon yellow, pale yellow, orange-yellow, paler margin, persistent. Utriform asci, 40-60 x 15-20 µm according to our measurements, typically with (8) 12-16 spores. Polarilocular spores, colorless, 8-12 x 5-7 µm with equatorial thickening between 3-5 µm according to the literature; 8-12 x 5-6 (8) µm with an equatorial thickening of 4-6 µm (1/2 to 1/3 of the length) according to our measurements. Paraphyses terminated by small blackish masses. Thallus: K-, apothecia: K + purple. Nitrophilic species, probably common but going unnoticed, occuring on the smooth bark of the trunks or twigs of deciduous trees with the lichens of this type of environment: Xanthoria, Physcia,... See very similar Caloplaca cerinelloides but with 8-spore asci.