Description: The discs of this lichen are so robust they resemble the ‘knocked-out-of-shape’ wheels of a car. Here is a species with a barely conspicuous thallus and discs glued to the rock like buttons. To find it, you would need to be on the coast near a sandy shore or edge of a cove where the outcropping rock is somewhat exposed. The discs are red-black to black and contain multispored spore-sacs (asci). Discs can grow up to 6mm diam. The black disc rim is often disjointed and grooved. It favours crystalline siliceous rocks. In Ireland, the species is known from the coastal granite of west Galway.

Key Identification Features:

• Thallus immersed though not obvious; discs common, massive (to 6mm diam.), red-black, containing multispored asci
• On slightly disintegrating, hard granitic rock (gneiss, granite) near the sea.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Sarcogyne clavus at iNaturalist World Species Observations database.