Syn.: R. gennarii Bagl., R. demissa auct., R. salina Degel., R. subexigua (Nyl.) H. Olivier

Saxicolous, on calcareous, natural and artificial substrates, incl. rocks, walls, mortar, corticolous, on Betula, Populus, etc., and lignicolous, on decorticated wood, particularly common in rather nutrient-enriched or dusty situations.

Belgium: Mar., Fl.: C, Camp.: AC, Brab.: AC, Mosan: AR, Ard.: RR.

Luxembourg: Ard.: RR, Lorr.: RR.

France: Mar.: AC, Boul.: R, Pic.: RR, Lorr.: RR.

Lit.: Boul.: 73, Mü1: 157, NL84: 17, NL92: 162, NL93: 46, VGH: 114, Giralt et al. (1997: 124-127, 132-134).