What is "lobothallia"

Lobothallia is a genus of lichens in the Megasporaceae family with foliose thalli that become crustose areolate in the center with age, and grow on calcareous to siliceous rocks. The crustose part of the body may keep its lower cortex, though not always. Dark brown to black apothecia may be sunken into the surface of the thallus, as indicated in the common name puffed sunken disk lichen. Members grow in 3–5 cm or more radiating lobes ( placoidioid). The photobiont is green alga from the genus Trebouxia. The genus is represented in Eurasia, Asia, North Africa, Central America, western North America, and Australia.