Synonyms: Ionaspis annularis H. Magn.; Ionaspis heteromorpha (Kremp.) Arnold; Ionaspis ochracella (Nyl.) H. Magn.; Ionaspis reducta H. Magn.; Ionaspis rhodopis var. melanopsis (Sommerf.) Zahlbr.; Ionaspis schismatopis (Nyl.) Hue
Distribution: N - Ven (Nimis 1994), TAA, Lomb (Nascimbene & al. 2021), Piem (TSB 34612).
Description: Thallus crustose, endosubstratic or rarely thinly episubstratic, continuous and film-like or rimose-areolate in older parts, pale yellow-grey to reddish brown. Apothecia 0.1-0.25 mm across, immersed in pits and often surrounded by a thin circular crack, with a greenish black, concave disc, and a thin, more or less prominent, concolorous margin which is more evident in the wet state. Proper exciple green to blue-green K- N+ red; epithecium deep blue-green, K-, N+ red; hymenium 100-140(-160) µm high, mostly colourless; paraphyses simple or sparingly branched, submoniliform in upper part, the apical cells not swollen; hypothecium colourless. Asci 8-spored, cylindrical-clavate, the outer wall K/I+ blue, but the inner walls and apical dome K/I-. Ascospores 1-celled, hyaline, globose to broadly ellipsoid, 7-14 x 6-10 µm. Pycnidia immersed, with a green wall reacting N+ red. Conidia bacilliform. Photobiont trentepohlioid, the cells 10-18 µm wide. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a probably holarctic species found on dolomite and hard limestone in rather sheltered situations, with optimum near treeline.