TYPE. SWEDEN. Anonymous s.n., s.d. (H-ACH 32A, lectotype selected by Sundin & Tehler (1998); S F71422, lectotype; UPS-ACH, isotype).

Description. Non-lichenized, allied fungus.

Thallus crustose, endophloeodal, indistinct or slightly “bleaching” the bark to whitish. Photobiont absent. Ascomata arthonioid apothecia (irregular – lirelliform, +/- branched), immersed to erumpent, 0.1-0.8 x 0.1 mm; thickness 30-60 μm; disk black, epruinose, +/- convex; exciple olivaceous brown, 5-10 μm; hyphae olivaceous brown, smooth, c. 2 μm thick. Epithecium olivaceous brown, 5-10 μm, K+ pale green; hymenium hyaline, 30-40 μm; paraphysoids richly branched, apices thickened with brown caps; hypothecium hyaline, up to 10 μm. Asci broadly ovoid, without distinct stipe; ascus wall not laterally thickened; tholus without horizontal layers, 20-30 x 14-20 μm. Ascospores narrowly ovoid, straight, persistently hyaline and smooth, 3-5-septate, not macrocephalic, 13-23 x 4-7 μm, gelatinous sheath absent.

Chemistry. Thallus I-, K/I+ blue; hymenial gel I+ blue, K/I+ blue; no lichen substances detected by TLC.

Substrate and Habitat. Corticolous on trees, where it is a pioneer, sun-loving species on young trunks and twigs of hardwoods.

Distribution. Widespread throughout Europe and North America; in North Carolina the species is represented by a single historical record [1886, Eckfeldt s.n., (US 01031907)] from the Blue Ridge ecoregion. Naevia punctiformis appears to be overlooked in the state.

Literature

Acharius, E. (1808) Förteckning på de i Sverige våxande arter af Lafvarnas Familj. Kongliga Vetenskaps Academiens Nya Handlingar 29:125-132 (original description as Arthonia punctiformis).

Cannon, P., D. Ertz, A. Frisch, A. Aptroot, S. Chambers, B. Coppins, N. Sanderson, J. Simkin & P. Woseley. (2020). Arthoniales: Arthoniaceae. Revisions to the British and Irish Lichens 1: 1-48.

Fink, B. (1935) The Lichen Flora of the United States. University of Michigan Press, Ann Arbor. 426 pp (as Arthonia punctiformis).

Sundin, R. & A. Tehler. (1998) Phylogenetic studies of the genus Arthonia. The Lichenologist 30(4-5): 381-413 (description as Arthonia punctiformis).

Thiyagaraja, V., Lücking, R., Ertz, D. et al. (2020)Evolution of non-lichenized, saprotrophic species of Arthonia (Ascomycota, Arthoniales) and resurrection of Naevia, with notes on Mycoporum. Fungal Diversity 102: 205–224.