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(Map updated: 11 August 2009)

This species has not been recorded in Ireland since 1865 and is now considered to be extinct. It should be searched for. Its chief substrata are wooden posts and untreated wooden fencing. Wood is barely used as exterior fencing in Ireland today because of the high rainfall and has been replaced in many parts with concrete copies. C. inquinans is easy to recognise: it has a pale grey, warted thallus scattered with sooty-black discs (to 2mm diam.) surrounded by a thin, white disc margin. It occurs frequently on the tops of posts where the wood softens earlier. If touched with a fingertip, the discs leave a black stain the colour of charcoal.

Key characteristics

• Thallus pale to dark grey, minutely warted with sooty-black discs with a white fringing margin
• Tops of wooden fence posts and railings.

Original text submitted by Vince J. Giavarini