Species: Punctelia borreriGrowth type foliose.
Photos: On trees and upland rock. Co. Cork, SW Ireland.
Specimen immediately below identified by John Douglass
Adpressed blue-grey to greenish-grey thallus with rounded, slightly notched lobes. Lower surface black with simple rhizines that are absent near margins. Small, punctiform pseudocyphellae become +/- sorediate. Apothecia are occasional with red-brown discs, the uneven margins +/- sorediate. Laminal pycnidia.
Infrequently recorded but can be mistaked for P. subrudecta.
Occurs on well-lit nutrient-rich trees and mossy rocks.
Cortex: K-, C+ yellow. Medulla and soralia: C+ pinkish-red, P-
Similar: Punctelia reddenda. Black under surface, medulla C-. Punctelia subrudecta. Pale under surface, Medulla C+ red
Punctelia borreri. March and November 2009. Fertile specimen May 2010