Description: This crustose, coastal lichen resembles crazy paving. It has a brown, C+ red, cracked thallus with a grey-violet cast, scattered with black discs. The species has a black prothallus (a kind of base which it sits on) which shows as a black margin around the edge of the thallus and as black veining through the cracks. It is most frequent on cliffs of siliceous rock in maritime areas where it occurs above the orange lichen zone. It is widely occurring along all coastal areas of Ireland.

Key Identification Features:

• The colour, habitat and C + red reaction of the cortex should help to separate it
• The species never strays far from the sea.

Original text submitted by Simon Davey

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

iNaturalist: Rhizocarpon richardii at iNaturalist World Species Observations database.