Peltigera membranacea forme saxicole.

    Differs from the type by its large size: up to 20 (30) cm across, its very long and radiating lobes, fan-shaped, and its (exclusive?) habitat: submerged siliceous rocks (well above the Dermatocarpon luridum zone and just below the Ephebe lanata zone) of streams and small rivers where Osmonda regalis can thrive.