Description: Known from west Mayo, this species of Caloplaca (best seen on sallow, but also on heather stems) colonises twigs and small branches of isolated trees, often in remote or far-flung places. The small grey thalli are abundantly fertile with rust-red discs.

Key Identification Features:

• On small branches and twigs of sallow
• Thallus tiny, grey with abundant rust-red discs.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Marchantiana asserigena at iNaturalist World Species Observations database.