About Acarospora schleicheri (Ach.) A.Massal.
Acarospora schleicheri, commonly called the soil paint lichen, is a bleached to bright yellow areolate to squamulose lichen. It typically grows up to 10 cm (4 inches) across on soil, and is classified as terricolous. It grows in arid habitats of southern California, Baja California, Europe, and Africa. This species produces rhizocarpic acid as a secondary metabolite; this compound gives the lichen its yellow coloration and protects it from sun exposure. Its lower surface is also yellow, and it may appear greenish when it is moist. The roundish, angular, or irregularly shaped squamules measure 0.5–4 mm in diameter. It hosts 0–1 apothecia embedded in its thallus, and sometimes 2–3. The apothecia have roundish discs 0.4–1.2 mm across, which range in color from black to reddish-brown or dark brown. These discs sometimes fill the areola, giving them a lecanorine form. It reproduces vegetatively directly on soil. Its asci are club-shaped (clavate) and contain 100 or more spherical to ellipsoid spores. All lichen spot tests for this species give negative results, and it glows orange under ultraviolet light (UV+ orange).
