The principal goal of our study was to test whether ecologically and chemically different populations of lichens in the Physconia muscigena group belong to a single, or multiple, species. We used sequence data from three markers (ITS rDNA, mtSSU rDNA and TEF1-α) for the reconstruction of phylogenetic trees based on a sampling of mostly European and Canadian populations of P. muscigena (Ach.) Poelt, P. muscigena var. bayeri (Nádv.) Poelt and P. isidiomuscigena Essl. In addition, we sought any possible geographical or ecological trends among chemotypes and haplotypes. Results show that: 1) sequence data of ITS rDNA and TEF1-α show large genetic variation in the Physconia muscigena group, which does not correlate with geographical distribution or thallus chemistry; 2) Physconia muscigena var. bayeri and P. isidiomuscigena appear undifferentiated with P. muscigena in our phylogenetic trees, and the three species cannot be distinguished on the basis of ITS rDNA, mtSSU rDNA and TEF1-α sequences. We therefore synonymized Physconia muscigena var. bayeri with P. muscigena and we recombine P. isidiomuscigena as a variety of P. muscigena.