Acarospora fuscata ("brown cobblestone lichen") is a glossy pale or yellowish-brown areolate lichen with angular areolas that grows up to 10 cm (4 in) wide on non-calcareous rock in low and high elevations.

[3] It grows in southern California and on the eastern part of the Sierra Nevada range.

[2]: 217  More common in the Sierras is the similar species Acarospora thamnina, which is truly squamulose with overlapping scales.

The asci are club shaped (clavate), with over 100 spores.

[3] Lichen spot tests are K−, C+ vaguely pink, KC+ red, and P−.