Published online by Cambridge University Press: 28 January 2004
The phylogenetic relationships of Tholurna dissimilis were investigated in relation to a phylogeny of twenty-three species in Caliciaceae and eighteen species from Physciaceae. ITS and LSU regions of the nuclear ribosomal DNA were used for the reconstruction of phylogenies by maximum parsimony methods. Calicium adaequatum was shown to be the closest relative of and possibly congeneric with Tholurna. Calicium is thus not monophyletic unless Tholurna is included. Calicium in the molecular phylogeny contains several distinct clades, which to some extent can be characterized morphologically. Cyphelium in a traditional sense is probably not monophyletic. Cyphelium s. str. has immersed apothecia, large smooth spores and a very thin excipulum throughout. C. inquinans and C. karelicum, which form a distinct and highly supported clade, may be accommodated in Acolium, possibly along with other Cyphelium and Calicium species. The phylogenies presented here do not support the recognition of neither Physciaceae nor Caliciaceae in a narrow sense, but they also do not exclude this. Numerous spliceosomal and unclassified insertions were found in the LSU sequences. They to some extent offered phylogenetic information both with respect to location and by their sequence similarities.