About Punctelia appalachensis (Culb.) Krog
Punctelia appalachensis, commonly called the Appalachian speckled shield lichen, is a foliose lichen species that belongs to the Parmeliaceae family. It occurs in eastern United States and eastern Canada. This lichen was first formally described in 1962 by lichenologist William Culberson, who classified it as a member of the genus Parmelia. Culberson collected its type specimen from tree bark in West Virginia. In 1982, Hildur Krog transferred the species to the newly defined genus Punctelia. The thallus of Punctelia appalachensis is shiny and greenish-gray; drier specimens are bluish-grey instead. Its surface is covered in maculae (spots or blotches) and pseudocyphellae. The underside of the thallus is black at least in its center, with pale brown edges. Its dark underside lets it be easily distinguished from other morphologically similar species that grow in its range, such as Punctelia rudecta and Punctelia caseana. This lichen most often grows on tree bark, though it can sometimes be found growing on rock.
