This one is completely different from what I observed before. Here are some features: - the more remarkable is the "frosted" zone near the margin of thallus; - the lobes are almost flat at the center and concave at the margin; - sorediate, mainly at the center of thallus. According to CNALH the above mentioned "frosted" zone is a distinguish feature of P. undulata. I didn't find conclusive photographs. Can it be this species?