Astrothelium intermedium

Astrothelium intermedium is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae. It was formally described in 2008 from material collected on tree bark at Las Cruces Biological Station in Costa Rica, at about 1,200 m (3,900 ft) elevation. The lichen forms a smooth, glossy, olive-green crust that can spread over patches up to about 10 cm (4 in) across, with the fruiting bodies concentrated in low, wart-like lines across the surface. Under the microscope it produces colorless ascospores divided into several compartments....read more on Wikipedia.