Description: A rare but easily overlooked lichenicolous species resembling C. sessile (described elsewhere) with discs (<2mm diam.) sunk into the thallus of Pertusaria pseudocorallina. In Ireland, it is known only from County Mayo.

Key Identification Features:

• Parasitic on the acid-rock lichen Pertusaria pseudocorallina
• Discs are sunken in the thallus and mazaediate (black-filamentous and sooty to touch).

Original text submitted by Vince J. Giavarini

Distribution Map from NBN: Acolium marcianum at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Acolium marcianum at iNaturalist World Species Observations database.