in Wirth, Flechten Baden-Württembergs: 511, 1987. Basionym: Lecidella assimilis Hampe ex Körb. - Parerga Lichenol.: 202, 1861.
Synonyms: Lecidea assimilis (Körb.) Th. Fr.
Distribution: C - Sar.
Description: Thallus crustose, areolate, pale to dark brown, usually slightly glossy, often starting the life-cycle on other crustose lichens, the areoles contiguous, 0.3-1.6 mm wide, strongly convex to almost bullate. Medulla white, I-. Apothecia lecideine, epruinose, glossy black, scattered or clustered in small groups, mostly marginal on the areoles, sessile and constricted at base, round to angular by mutual pressure, 0.2-0.6(-0.8) mm across, with a concave to slightly convex disc and a thin, flexuouse, prominent proper margin. Proper exciple green-black or olive in outer part, dark brown or black in inner part; epithecium bright blue-green to emerald green, N+ purple-red; hymenium colourless to greenish in upper part, 45-65 µm high; paraphyses coherent, simple, frequently anastomosing, 1-2 µm thick at mid-level, the apical cells swollen, up to 2.5 µm wide; hypothecium almost colourless, 50-150 µm high. Asci 8-spored, clavate, very thin-walled, with a K/I+ blue, tall tholus penetrated by a faintly amyloid apical cushion, the wall K/I-, surrounded by a blue outer layer, Lecanora-type. Ascospores 1-celled, hyaline, broadly ellipsoid to ovoid, (8-)10-15 x 5-8(-9.5) µm. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC-, P- or rarely P+ red, UV-. Chemistry: thallus without lichen substances or with argopsin.
Note: a species with a thallus of minute pale brown glossy areoles which are diagnostic, found on exposed inclined rock faces of siliceous rocks, parasitic on other crustose lichens (e.g. species of Aspicilia, Lecanora, Lecidea, Tephromela); probably more widespread but not common, perhaps overlooked in Italy.
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)