Aspidothelium glabrum

Aspidothelium glabrum is a species of corticolous (bark-dwelling), crustose lichen in the family Thelenellaceae. It was described in 2008 from material collected on bark in western Costa Rica, and has since been recorded in Brazil. The lichen forms pale mineral-gray patches that may be edged by a thin black border, and it produces tiny, glossy, cream-to-gray bumps on the surface that contain its spores. Under the microscope, its spore-producing sacs contain four colorless spores that are divided into many small compartments, a feature used to separate it from similar species....read more on Wikipedia.