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(Map updated: 11 August 2009)

This species inhabits the crystalline interstices of coarse siliceous rocks such as granite. The grey, virtually invisible, thallus and vague black prothallus means the shiny black discs stand out as the most conspicuous feature. The thick, notched, C- disc-rim or exciple is often suffused with red. The similar L. diducens has its exciple C+ carmine-red in section. In Ireland, the species has been recorded widely from granitic rocks. In var. brachyspora the grey thallus is easily conspicuous and the spores broader.

Key characteristics

• Thallus usually invisible, the prothallus reduced to a black smear; discs black with thickish, very conspicuous, usually reddened exciple which is C- in section
• In the crystalline crevices of granitic rocks.

NBN Atlas mapping: Species account : NBN Atlas UK Species Observations database

iNaturalist: Species account : iNaturalist World Species Observations database

Original text submitted by Vince J. Giavarini