Distribution: N - Frl (Tretiach & Hafellner 2000, Brackel 2016). C - Sar (Brackel & Berger 2019).
Description: Thallus apparently crustose, often forming white to cream-coloured, gall-like, flattened to convex warts on silicicolous Porpidia-species. Medulla of the galls I-. Apothecia black, 0.2-0.3(-0.5) mm across, sessile, with a sometimes umbonate disc and a persistent proper margin. Proper exciple of irregular chains of swollen cells, carbonaceous black in outer part, paler brown within; epithecium pale olive-brown; hymenium colourless, amyloid, 50-80 µm high; paraphyses coherent, branched and anastomosing, c. 2 µm thick at mid-level, the apical cells hardly swollen, up to 3 µm wide; hypothecium dark brown. Asci 8-spored, subcylindrical-clavate, the apex thickened, with a K/I+ pale blue apical dome usually with a distinct I+ blue, shallow subapical ring, Lecidea-type. Ascospores 1-celled, hyaline, ellipsoid, (9-)10-12(-13) x 5-6.5(-7.5) µm, without a perispore. Pycnidia black, c. 90 µm wide, the wall dark brown. Conidia simple, hyaline, bacilliform, 5.5.-8 x c. 1 µm. Photobiont apparently chlorococcoid, but the galls are most probably a reaction of the host thalli, the species being non-lichenized. Spot tests: those of the host lichens. Chemistry: probably without lichen substances.
Note: an obligately lichenicolous fungus growing on the thalli of Porpidia-species; probably more widespread in the Alps.