Description: This rare lignum specialist appears to be more fungus than algae. Search for the dark brown discs (0.3-0.6mm diam.) on the dry wood of pine and yew. These are indented like a new tractor tyre and carry coarse radial cracks. The massive spores (to 170&

371;m long) are muriform (multi-celled). In Ireland, the lichen grows on yew lignum in County Kerry. I have seen it on the branches of pine, growing in the native Caledonian pinewoods of Scotland.

Key Identification Features:

• Dark brown discs like tractor tyres in miniature growing on bare lignum (yew or pine)
• Massive muriform spores.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Xerotrema megalospora at iNaturalist World Species Observations database.