Description: This rare species should be searched for on nutrient-rich rocks and boulders by lakes and rivers. From above, this species is easy to dismiss as P. orbicularis, but look closely at the lobes and at the absence of any orange pigmentation of the thallus. Then pay attention to the clusters arising from the lobes and spread across the thallus as these are not powdery soralia but clusters of fine brownish isidia. It is known from Connemara, County Galway and from County Donegal.

Key Identification Features:

• Orange pigmentation absent; thallus to 5cm diam.
• Lobe edges and centre of thallus with clusters of brown isidia; lake and river margins; underside black.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Phaeophyscia sciastra at iNaturalist World Species Observations database.