Distribution: N - TAA (UPS-L-166791: Brackel 2016).
Description: Thallus inapparent, not lichenized, developing on the thalli of Biatora efflorescens. Apothecia arthonioid, immarginate, dark brown to almost black, epruinose, slightly convex, irregularly rounded, 0.1-0.45 mm across, scattered or in groups of 2-6. Proper exciple very poorly developed; epithecium pale brown to brown, 4-12 μm high, K-, I+ rust-red, K/I+ blue; hymenium colourless, 20-55 μm high, I+ reddish brown, K/I+ blue; paraphysoids branched and anastomosing, 1-2 μm thick, the apical cells not markedly swollen; hypothecium pale brown to brown, 25-40 μm high in central part, the lower part immersed in the thallus of the host, K-, I+ reddish brown. Asci 8-spored, broadly clavate to ovoid, semi-fissitunicate, with a large apical dome and a distinct ocular chamber, the apex with a K/I+ blue, elongated ring structure and paler bluish tholus flanks, Arthonia-type. Ascospores 1-septate, slightly constricted at septum, with more or less equal cells, ellipsoid, 10-14 x 4-5(-6) μm, slightly verrucose at maturity, with a thin perispore. Photobiont absent. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a recently-described parasite of Biatora efflorescens, perhaps more widespread in the Alps.