Pyrenula dermatodes is a real rarity, not only in Ireland, but in Europe in general. The often reddish lichen forms large patches on holly in oceanic woodlands. There are few undisturbed oceanic types of woodland left in Ireland and consequently few specimens of Pyrenula dermatodes. This is a perfect example of ’save the habitat to save the species’. Where it does occur, it is often common; several trees within a 100m or so can have large displays of the red crustose patches. Its largest stomping ground is the National Park at Killarney in Co. Kerry; other haunts include Glenveagh National Park in Donegal and small woodlands in Mayo south of Clew Bay and the Glengariff region of west Cork. It is almost unknown outside of Ireland.
If a Red Data Book for the lichens of Ireland ever emerges, then this chap should be planted firmly on the cover.