[Modified from Nimis 2023] Thallus crustose, whitish to greenish-grey, 30-50 µm thick, paraplectenchymatous but not subgelatinous when wet; prothallus indistinct. Photobiont trentepohlioid chlorophyte. Ascomata perithecia, black, 50-160 µm diam., immersed to semi-immersed, the upper part exposed or covered by a thin thalline layer. Involucrellum present, 130-235 x 45-90 µm, 12-70 µm thick; exciple of cellular hyphae, brown-black in upper part, pale or hyaline in lower part; pseudoparaphyses slender, branched and anastomosing, long-celled, ~1 μm thick; periphyses absent; hymenial gel I-. Asci 8-spored, cylindrical, K/I-, fissitunicate, the apical dome with an indistinct ocular chamber, with biseriately arranged ascospores. Ascospores 1-septate, with equal or slightly unequal cells, hyaline, 9-15 x 3.6-7 µm. Pycnidia unknown.
Chemistry. Spot tests negative; lichen substances not detected.
Substrate and Habitat. Saxicolous on siliceous rocks in or near water, amphibious, in shaded environments.
Distribution. Europe, North America, Australasia.
Literature
Nimis P.L., (2023) ITALIC - The Information System on Italian Lichens. Version 7.0. University of Trieste, Dept. of Biology, (https://dryades.units.it/italic), accessed on 2023-12-16.
Steiner, J. (1913) Adnotationes lichenographicae II. Österreichische Botanische Zeitschrift63: 335-342 (original treatment a Arthopyrenia carinthiaca).