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(Map updated: 11 August 2009)

This crustose species is typical of shady, siliceous rocks and pebbles such as in woodlands, alongside streams and upland rivers and around the edges of ridge tor outcrops. The thallus is most often chocolate brown and randomly studded with tiny black, dot-like, spherical discs (perithecia). When the discs are examined under a microscope slide the spores are seen to be three-septate and shaped like a top. It is frequent in suitable habitats throughout Ireland.

Key characteristics

• The scattered, small black fruits on a chocolate brown thallus indicate this species. There are several less common species from which it can only be reliably separated by microscopic examination of the spores
• The species needs shade and dampness and can endure temporary, but not prolonged inundation.

Original text submitted by Simon Davey