Type. Not cited in original description (Acharius 1803), only as “Habitat ad corticem Fagi”. Locality unknown, Herb Buse, LH s.n., s.d. (L  0700527, isotype).

Description. Lichenized fungus. Thallus crustose, thin, continuous, smooth, olive-brown, often with dark prothallus; vegetative diaspores absent; homoiomerous (not stratified); photobiont Trentepohlia alga.

Ascomata lirellate, sessile, sometimes branched, 0.4–5.0 × 0.1–0.4 mm, abundant. Disk flat to convex, black, not pruinose; exciple prominent, thick, carbonized, continuous below hypothecium; epithecium poorly developed; hymenium colorless, 40–85 µm high, I+ reddish-yellow; hypothecium brownish. Asci clavate, mature 50–90 × 15–25 µm, young 30–50 × 10–15 µm; inner layer of endoascus amyloid (I+ blue, K/I+ blue) nearly along its whole length; apical chamber small, with no apical nasse (vulgata-type); 8-spored. Ascospores colorless, narrowly acicular, straight or slightly curved, 5−15-septate, 20–60 × 3–10 µm, with well-developed perispore of 1.5–2.0 µm thick. Pycnidia small, black, numerous; conidia simple, straight or slightly curved, 6–11 × 0.8–2 µm.

Chemistry. Spot tests: UV-, K± dark brownish, C-, PD-; secondary metabolites unknown.

Substrate and Habitat. On bark of hardwood tree trunks in forests.

Distribution. North America, Eurasia, Africa; in North Carolina thoroughout.

Literature

Acharius, E. (1803) Methodus qua omnes detectos lichenes secundum organa carpomorpha ad genera, species et varietates redigere atque observationibus illustrare tentavit Erik Acharius (Methodus Lichenum). Stockholm (original description as Opegrapha rubella δ O. viridis).

Ertz, D. & A. Tehler. (2011) The phylogeny of Arthoniales (Pezizomycotina) inferred from nucLSU and RPB2 sequences. Fungal Diversity 49(1): 47-71.

Wieczorek, A. (2019) The lichen genus Opegrapha s.l. in Poland: Morphological variability, ecology, and distribution. Monographiae Botanicae 107: 1-163.