Description: This species is easily overlooked as an Arthopyrenia. It is a ‘bark-pimple’ lichen of smooth-barked trees, neat in presentation, with a creamy thallus limited by purple-black edging. The tiny, convex discs (pimple-like perithecia) are evenly scattered. On examining the spores under a microscope squash, these will be found to be brown, sole-shaped and one-septate (to 21µm or more long). It is this browning of the spores within the spore sac (ascus) which instantly reveals their identification within Mycomicrothelia. In Ireland, the species can be found on hazel, ash and holly. The related M. atlantica has smaller spores and a stippling of pycnidia between the discs. In Ireland, it occurs mainly in the north and west.

Key Identification Features:

• Bark-pimple lichen with brown, one-septate spores
• On smooth bark.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Mycomicrothelia confusa at iNaturalist World Species Observations database.