Poeltinula

Poeltinula is a small genus of lichen-forming fungi in the family Rhizocarpaceae. It comprises three species of crustose lichens that grow on limestone. The genus was established in 1984 by the lichenologist Josef Hafellner and is characterized by its inconspicuous, paint-like growth that often goes unnoticed until the distinctive black fruiting bodies appear. These lichens are recognized by their dark spores that turn bright red when treated with ammonia solution and their fruiting bodies that turn crimson when tested with potassium hydroxide solution.