Description: The powdery yellow-green thallus of this species is so distinctive when growing over mats of oceanic mosses or liverworts on wet or dry acid bark, it can become an immediate attention-grabber. A dab of bleach producing a C+ persistent orange reaction is the clincher. Currently, there are records from Counties Wicklow, Mayo (west), Fermanagh and Donegal (west).

Key Identification Features:

• Thallus conspicuous and eye-catching, powdery-granular, yellow-green on leached acid bark, often overgrowing mosses and liverworts
• Tests C+ KC persistent orange, never fleeting.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Micarea xanthonica at iNaturalist World Species Observations database.