Acarospora strigata

Acarospora strigata is an areolate to verruculous crustose lichen that grows on rock around the world, in full sun or shade, and in mesic to arid habitats.: 220  It is brown but may appear white or pale gray if it is covered in a pruina.: 220  The lichen is common in southwestern deserts of North America. Areoles (from tiny to 3 mm) surrounding dark reddish-brown to black apothecia (fruiting bodies) are both highly variable in shape and size, and variable in size relative to each other.: 220  Measuring 0.1–1 mm, the apothecia range in size from small dots on the areoles to almost as wide as the areole.: 220  They can be pointlike to round, polygonal to stellate radiating fissures, and one to many per areole. Areoles may be cracked on the surface, especially toward the apothecia.: 220  Lichen spot tests are all negative.: 220 ...read more on Wikipedia.