On shaded or exposed, calcareous outcrops; also on a wall close to a river, almost at water level.

Belgium: Mosan: R, Ard.: RR.

Luxembourg: Lorr.: RRR.

France: - .

Two distinct taxa might be involved: P. rehmicus s.s. with large ascospores (16-25 × 6-12 μm) is known from Luxembourg, and P. byssoides with smaller ones (10-16 × 6-9 μm) is known from Belgium.

Lit.: NL97: 28-29.