Description: This very rare lichen of moist siliceous rocks surrounding or lining the margins of loughs in the uplands has a tiny, areolate (cracked paving-stone-like), brown-black crustose thallus with just visible, immersed and concave, crater-like discs. The discs are distributed evenly between the areoles (one in each) and contain eight-spores/ascus; spores simple, ellipsoid 11–14 x 8–9µm. [This is one of a poorly understood species complex].

Key Identification Features:

• Thallus: tiny, crustose, finely cracked, brown-black; discs pore-like with a raised rim, one/areole
• Spores 8/ascus, simple, ellipsoid 11–14um long; moist siliceous rock.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Phylliscum rhodostictum at iNaturalist World Species Observations database.