Lobothallia is a genus of lichens in the family Megasporaceae.

Species in the genus have foliose thalli that become crustose areolate in the center with age, and grow on calcareous to siliceous rocks.

[2]: 306  Members grow to 3–5 cm (1.2–2.0 in) or more radiating lobes (placodioid).

[3] The photobiont is green alga from the genus Trebouxia.

[3] The genus is represented in Eurasia, Asia, North Africa, Central America, western North America, and Australia.