Syn.: P. caesia (Nyl.) Forssell

On calcareous or slightly schistose rocks, incl. on tufa, in shaded or periodically humid habitats.

Belgium: Mosan: AR.

Luxembourg: Lorr.: RRR.

France: Mosan: RRR.

The material referred to this species in the study area might be heterogeneous.

Lit.: Ertz: 20, NL97: 31-32.