On hard calcareous rocks and sandstone rocks, usually in dry, sunny and nitrophilous conditions, mainly in natural, incl. maritime habitats, occasionally on walls, mortar or concrete.

Belgium: Mosan: RRR.

Luxembourg: - .

France: Mar.: RR, Brab.: RRR, Mosan: RRR.

This species is probably much more common, but the entire material of C. saxicola still needs to be critically revised.

Lit.: Gaya (2009).