A phylogenetic study of Nephroma (lichen-forming Ascomycota)

Abstract

The phylogeny of Nephroma was studied by nucleotide sequences of the mitochondrial ribosomal small subunit (mtSSU rDNA) and the internal transcribed spacers of the nuclear ribosomal repeat (ITS), together with chemical characters. The biological material included both bipartite and tripartite species and all Nephroma species native to northern Europe. Phylogenetic analyses demonstrated that all Nephroma species form a monophyletic group and that Peltigera constitutes the sister group to Nephroma. The two gene regions revealed qualitatively similar relationships within Nephroma and chemical characters had a minor impact on tree topologies. The results demonstrated that tripartite Nephroma species do not form a monophyletic group within the genus, this being in agreement with previous findings from bi- and tripartite Peltigera species. The results also indicated that N. resupinatum does not form a monophyletic group with all other bipartite Nephroma species but form a sister group to the studied Nephroma taxa. Furthermore, N. helveticum s. lat. is highly variable and seems to represent aggregates of closely related taxa. Also N. laevigatum and N. resupinatum are genetically variable. All European Nephroma species can be rapidly and accurately identified on the basis of their fungal ITS sequences. This will prove useful in ecological and environmental studies.