Alyxoria varia forme saxicole Cf.
This form is characterized by its occurrence on veins of calcite, sheltered and subjected to the projections of sea water in blocks of dolerite on the shore. Thallus not visible or reduced to a few dirty whitish traces. Apothecia small in the form of simple, black, rounded or short lirellae. Club asci of 70-90 x 15-20 µm according to our measurements. Spores spindle-shaped, colorless, 3-5-septate, 20-25 x 4-5 µm according to our measurements.
N.B. Microscopically quite similar to Opegrapha areniseda but the latter species has, in principle, a thick thallus and many pycnidia.