Physcia subalbinea Taxon Atlantique
This taxon (or this form?) also nitrophilous, but less than the type, differs from the type only by its occurrence on well-exposed rocks close to the sea of the Atlantic coasts, more rarely on the bark of isolated trees close to the sea This taxon is sometimes difficult to separate from Physcia caesia which can sometimes come close but has less separated and less smeared lobes (but there seem to be intermediaries).
N.B. This taxon should probably retain its old name of Physcia caesia var. caesiella because it is closer to Physcia caesia than to Physcia subalbinea ss str. which is a Mediterranean species.