Methodus Lichenum: 132 (1803).
Basionym: Lichen lepadinum Ach., Lichenographiae Suecicae Prodromus: 30 (1798).
Photobiont: Trentepohlia.
Chemistry: No lichen substances (Hale 1978: 44). Thallus Pd-, K-, lichen products not detected by TLC, but sometimes with a yellowish pigment, K+ yellow intensifying. Calcium oxalate (Purvis et al. 1995: 344).
Ecology: Corticolous.
Thallus: crustose, epiphloeodal but thin and in part evanescent, pale tannish, 2 - 5 cm broad. Apothecia dispersed, emergent, 0.5 - 1.0 mm in diameter, noncarbonized, lacking a columella, the proper exciple well developed, free, splitting, the pore open, round, 0.2 - 0.4 mm in diameter, spores 4 - 8 in ascus, 20 - 26 / 80 µm, with numerous locules, I- or bluish (Hale 1978: 44). Thin to thick, up to 200 µm smooth, + uneven, greyish fawn to ochraceous, mainly superficial, in section medulla with numerous crystals, which are particularly well-developed in the thalline margin of the ascomata. Ascomata numerous, up to 2 mm diam., immersed in hemisphaerical warts, urceolate with ostiolar opening up to 0.5 mm wide; thalline