On siliceous or calcareous rocks or stones, rarely on mortar or on iron posts, always in or close to streams.

Belgium: Mosan: R, Ard.: R.

Luxembourg: Ard.: R, Lorr.: R.

France: Lorr.: RR.

Lit.: Ertz: 44, Mü4: 111, NL84: 18, NL97: 58, Molitor & Diederich (1997: 86-87), Thüs (2002).