Arthonia

Arthonia is a genus of lichenized fungi in the family Arthoniaceae. It was circumscribed by Swedish botanist Erik Acharius in 1803. The genus is characterized by its ascomata (fruit bodies) that are immersed in the thallus (the vegetative part of the lichen), and its ascospores that are typically ellipsoid to fusiform. Arthonia species are commonly found in temperate and boreal regions, growing on bark, wood, and soil. They are often used in ecological studies and lichenometry, a method of dating environmental changes based on the growth rates of lichens. Arthonia species are also known for their potential to produce secondary metabolites with antimicrobial properties. The genus includes over 100 species, with Arthonia phaeocarpum being one of the most well-known and widely distributed species.