Acarospora fuscata is the most common Acarosporaceae in the Czech Republic and often the only member of the family in various habitats. It grows on a variety of non-calcareous rock in full sun or shade from lowlands to mountains and has been observed on Sněžka at ca. 1,590 m where it was rare.
Acarospora fuscata has areoles, broadly attached to the substrate, often elevated on a mycelial base, but not stipitate or squamulose, 1–3 mm wide, with or without free margins, the under surface usually brown or black, the upper surface usually a distinctive yellowish brown. Rarely are areoles pruinose. The cortex is red-pink in C/K-C in microscopic sections. The immersed apothecia are less than 1 mm wide, 1–10 per areole, rarely forming pseudo-lecanorine areoles 1 mm or less wide. The hymenium height has a wide range (80–)100–120(–140) μm high and the hymenial gel is in Lugol’s (IKI+) light blue to red, or red (hemiamyloid). IF Lugol’s is weak or old, the hymenial gel is light blue and may lead to it being misidentified as A. gallica. Phenotypic variability is frequent and depends on amount of light, whether rock is flat or rough, whether in under hangs or on vertical surfaces, or if in mixed saxicolous communities or solitary.
Acarospora squamulosa and A. rugulosa differ from A. fuscata in having large pseudo-lecanorine apothecia 1–3 mm wide with a rugulose disc. Acarospora gallica differs from A. fuscata in having euamyloid hymenial gel (dark blue) in Lugol’s. The conserved type of A. fuscata is from the Czech Republic.
Literature: Knudsen K., Malíček J. & Kocourková J. (2019): The conserved type of Lichen fuscatus [≡ *Acarospora fuscata*]. – Mycotaxon 134: 295–300.taxonomic classification:
All records: 475, confirmed 338. One click on a selected square displays particular record(s), including their source(s).