Acarospora praeruptorum occurs in Europe and was described from Fennoscandia where it is rare. The type is a small specimen collected growing in a south-facing gneiss underhang in Sweden. It can also be small, for instance, growing on the edge of thin-layered slate in Germany. In the Czech Republic most collections are from diabase below 500 m usually in full sun. Acarospora praeruptorum in the Czech Republic as well as A. irregularis were often identified as A. nitrophila. All varieties of A. nitrophila reported by Magnusson (1929) from Czech Republic are also A. praeruptorum.
The species has light to dark brown areoles or squamules often growing in imbricate clusters. The squamules vary in width and height from 0.4–2.0 mm wide and up to 1 mm tall depending on amount of light, competition from other lichens, and maybe even rock type. The cortex is usually 50–70 µm thick. Apothecia are up to 1 mm wide and are either immersed or elevated in a thalline margin with a parathecium expanded around the disc to usually ca. 30 µm. The hymenium height is usually 120–150 µm high. The hymenial gel is red in Lugol’s. It is not unusual for apothecia to be rare.
Literature: Magnusson A.H. (1929): A monograph of the genus Acarospora. – Kungliga Svenska Vetenskaps-Akademiens Handlingar 7: 1–400.taxonomic classification:
All records: 30, confirmed 23. One click on a selected square displays particular record(s), including their source(s).