Bull. Geogr. Bot., 27: 213, 1917. Basionym: Arthonia vagans var. peltigerina Almq. - K. Svenska Vetensk.-Akad. Handl., 17, 6: 50, 1880.
Distribution: N - Frl (Hafellner 1999, Brackel 2016).
Description: Thallus inapparent, not lichenized, the hyphae developing inside old parts of thalli of Peltigera-species, the infected parts appearing bleached. Apothecia arthonioid, developing in the cortex of the host, more or less round, adnate, often grouped in subconcentric rings, 0.1-0.3 mm across, with a black, convex disc, without a proper margin. Proper exciple poorly developed; epithecium fuliginous brown; hymenium colourless, I+ red, K/I+ blue; paraphysoids indistinct; hypothecium colourless or pale brown, I+ red, K/I+ blue; Asci 8-spored, broadly clavate to subglobose, semi-fissitunicate, with a large, non-amyloid apical dome, and a distinct ocular chamber, Arthonia-type. Ascospores 1-septate, hyaline, (10-)13-18(-20) x 4-6 µm, with a gelatinous sheath. Photobiont absent. Spot tests: K-, C-, KC-, P-. Chemistry: without lichen substances.
Note: a lichenicolous fungus growing on the thalli of Peltigera-species, probably more widespread, especially in the Alps.
Growth form: Lichenicolous fungus
Substrata: soil, terricolous mosses, and plant debris