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(Map updated: 11 August 2009)

This Caloplaca is one of the grey thallus tribe with black discs. Its appearance is more that of an Aspicilia. The thallus can be large or very small and has a zoned margin limited by a black line. The small black discs that are immersed at first can be hazy blue-grey frosted. The spore septum is about one-third the length of the spore. It grows on hard limestones. C. variabilis has a thinner, darker grey thallus with black sessile discs. In Ireland, there is a good range of records from the north-east and south-west.

Key characteristics

• Thick, pale grey thallus, discs black, immersed at first, very like an Aspicilia
• Hard limestones and boulders.

Original text submitted by Vince J. Giavarini