Description: This is the smallest of the Irish Dermatocarpon spp. with thalli 2-7mm diameter forming densely crowded colonies, growing on flat-topped boulders in fast-flowing streams. The pale grey to dark brown upper surface has an occasional sprinkling of pruina. Siliceous rocks intermittently washed by higher water levels are favoured. Present along rivers, streams and upland loughs. Medulla unchanged in iodine. South-west Ireland.

Key Identification Features:

• Tiny grey to dark brown thalli forming tight colonies on flat-toped, well drained boulders by or in streams or rivers — the colonies can sometimes resemble a large disintegrating crustose lichen
• Each thallus has a central holdfast.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Dermatocarpon leptophyllodes at iNaturalist World Species Observations database.