Description: This is a scarce crustose lichen of acid rocks (sandstone underhangs, especially), roots and tree bark in dry, sheltered situations, occasionally spreading to moorland shrubs where suitable. The whitish thallus is pink when fresh, very conspicuous, and is usually thick and soft on rock, but more immersed when on bark. The small black discs are slightly elongate (to 1.2mm long) in shape and lacks frosting (pruina). It is known in Ireland from both oak and birch bark. Local; mostly northern and western Ireland.

Key Identification Features:

• Pink-white thallus, thick and soft, spreading over sheltered underhangs, especially those on grits or sandstones; also dry tree bark
• Discs small (longer than wide), black, not pruinose.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Arthonia arthonioides at iNaturalist World Species Observations database.