K. svenska Vetensk-Akad. Handl., ny följd 17, 6: 40, 1880.
Synonyms: Arthothelium lirellans (Almq.) Coppins
Description: Thallus inapparent, not lichenized, appearing as yellowish patches on the bark. Apothecia arthonioid, immarginate, round to elongate and branched, 0.5-0.7 x 0.1-0.4 mm, level with thallus, black, epruinose, 45-70 µm tall. Epithecium brown to olivaceous brown, 15-25 µm high, often inspersed with small bark fragments, K+ greenish; hymenium colourless, but often intspersed with amorphous, olivaceous brown pigments, c. 30-40 µm high, I+ and K/I+ blue, the brownish pigments K+ olive-green; paraphysoids anastomosing, simple or sparingly branched in upper part, 1-2 µm thick; hypothecium colourless, up to 15 µm high. Asci 8-spored, broadly clavate, semi-fissitunicate, with a very faint K/I+ bluish tube in the tholus. Ascospores submuriform, with 5-7 transverse septa and a single longitudinal septum in 1-3 transverse segments, persistently hyaline, obovoid, 17-28(-30) x 8-12 µm, the outer wall I+ red. Pycnidia rare, roundish, brown-black, the wall brown, K+ greenish. Conidia bacilliform, 3.5-5 x 0.5-1 µm. Photobiont absent. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a non-lichenized species growing on smooth bark; known from Carinthia (Austria) not far from the Italian border, to be looked for in Italy.