Caloplaca ceracea forme saxicole des murs.
Caloplaca oxfordensis ss. auct. brit. ?
This form is characterized by its granular to subsquamulose crustose thallus (especially towards the margin), gray-greenish in dry weather, green, yellowish-green to greenish in wet weather. Apothecia numerous, first yellow then later with a flat, reddish-brown to yellowish-brown disc (wax appearance) and a fine, more or less crenate and persistent margin, yellowish-white, yellow. Polarilocular spores, 12-16 x 7-9 µm and a 4-5 (6) µm septum according to our measurements. K + purple on the margin of the apothecia. This form comes on old granite walls but turned alkaline, damp and in the shade. In the field, this form by the coloring of its apothecia evokes Candelariella vitellina forma flavovirella but their margin is K + purple.
N.B. This form is perhaps the Caloplaca oxfordensis of the British authors by its yellow apothecia at the beginning but this requires confirmation.