Synonyms: Arthonia glaucomaria var. pallidae Rehm ex Almq.; Celidium varians var. pallidae Rehm nom.nud.
Distribution: N - Lomb (Anzi 1860, Brackel 2008c, 2015, 2016), Piem (Brackel 2015, 2016). C - Laz (Brackel 2015, 2016), Abr (Brackel 2015, 2016), Sar (Brackel & Berger 2019). S - Pugl (Brackel 2015, 2016), Si (Brackel 2008c, 2015, 2016).
Description: Thallus endosubstratic, not evident and not lichenized, developing inside the apothecia, rarely the thallus, of epiphytic Lecanora-species. Apothecia arthonioid, to 0.25 mm across, forming dark spots, round to irregular in outline, with a black, epruinose, flat to slightly convex disc, without a distinct proper margin. Proper exciple poorly developed; epithecium greenish brown, 10-15 µm high; hymenium colourless, 40-55 µm high, I+ red; paraphysoids c. 2 µm thick at mid-level, the uppermost cells usually slightly swollen; hypothecium brown, up to 25 µm high. Asci 8-spored, broadly clavate to subglobose, semi-fissitunicate, with a large apical dome and a distinct ocular chamber, Arthonia-type. Ascospores 3-septate, hyaline to pale brown, narrowly ovoid, 14-17.5 x 5-7 µm, with a thin gelatinous epispore reacting I+ red, K/I+ blue. Photobiont absent. Spot tests: K-, C-, KC-, P-. Chemistry: without lichen substances.
Note: this widespread lichenicolous fungus causes dark spots on the whitish apothecia of Lecanora carpinea, L. chlarotera and L. albella.