This is a wide-spread pioneer that occurs in full sun on a variety of rock types, including diabase, granite, sandstone, and schist, in Asia (Russia), North America (Greenland), and Europe, usually at lower elevations under 600 m. It is currently known in the Czech Republic from two collections in central Bohemia (Týřov, Prokopské údolí) at low elevations below 400 m. It is probably both infrequent and under-collected.
The thallus is areolate, often dispersed, the upper surfaces dull brown. An areole usually has one elevated apothecium with an parathecial margin the same color as thallus. The disc is usually rugulose and the ascospores are usually narrow, 1.0–1.5 µm wide. Acarospora discreta and A. durietzii are synonyms. Acarospora admissa can also be confused with A. intermedia which differs in having elevated apothecia with a thalline margin. Large specimens have been confused with A. squamulosa, but that species produces gyrophoric acid.
Literature: Knudsen K. & Kocourková J. (2020): Acarosporaceae of Belarus. – Herzogia 33: 394–406.taxonomic classification:
All records: 3, confirmed 3. One click on a selected square displays particular record(s), including their source(s).