K. Vetensk.-Akad. Nya Handl., 30: 147, 1809. Basionym: Opegrapha betulina Pers. - Ann. Bot. (Usteri), 7: 31, 1794.
Synonyms: Graphis juglandis Garov. ex A. Massal.; Graphis massalongii Kremp.
Distribution: N - Ven (Lazzarin 2000b), Lomb (Lazzarin 2000b). C - Umb (Brackel 2015).
Description: Thallus crustose, continuous to finely cracked, white, pale grey or brownish, dull, often delimited by a dark prothallus. Apothecia lirelliform, black, raised or embedded in the thallus, oblong to linear, more or less flexuose, branched and acute at the ends, 2-8 x 0.1-0.3 mm, with an at least centrally expanded, pruinose or epruinose disc, a well-developed, 15-45 µm thick proper margin with entire lips, and a conspicuous, c. 0.2 mm thick, pseudothalline margin filled with calcium oxalates crystals. Proper exciple carbonized laterally, poorly developed and not carbonized at base; epithecium brown; hymenium colourless, not inspersed with oil droplets, 90-100 µm high; paraphyses simple, dense, 1.5-2 µm thick, with brownish tips; subhymenium colourless. Asci (6-)8-spored, cylindrical-clavate, non fissitunicate, dehiscent by an apical split, K/I-, Graphis-type. Ascospores 5-11-septate with lens-shaped lumina, hyaline (pale brown when overmature), 15-45 x 5-9 µm, the wall I+ blue-violet. Pycnidia rare, immersed. Conidia bacilliform, 2-5 x 1 µm. Photobiont trentepohlioid. Spot tests: cortex and medulla K-, C-, KC-, P-. Chemistry: without lichen substances.
Note: a taxon of the G. scripta-group with apothecia additionally surrounded by conspicuous often raised white thalline margins, found on the bark of broad-leaved trees in various forest types; widely distributed in the Holarctic region. See also comment on the genus.