Phylogenetic relationships of Stereocaulaceae based on simultaneous analysis of beta-tubulin, GAPDH and SSU rDNA sequences

The phylogenetic relationships of the lichenised ascomycete family Stereocaulaceae were investigated with partial beta-tubulin, partial glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and SSU rDNA sequence data. Due to the marked length variation in the SSU rDNA sequences, the analyses were performed with direct optimization. The combined analysis of the beta-tubulin, GAPDH and SSU rDNA sequences as well as the separate analyses of beta-tubulin and GAPDH data recognized the monophyletic group comprising Lepraria, Muhria and Stereocaulon. In the combined analysis Stereocaulon tornense appears as a basal taxon in the Stereocaulon clade, suggesting that the crustose growth form and the absence of cephalodia are primitive features within the genus. Muhria is nested in Stereocaulon and groups with the crustose S. cumulatum and S. leucophaeopsis. The genus Lepraria is monophyletic if Leproloma is included, but species that were represented by several specimens in our study, i.e., Lepraria jackii and Leproloma membranaceun, do not appear as monophyletic entities. The genus Pilophorus is included in Cladoniaceae. Combined analysis of the three data-sets clearly led to an increase in support values compared to the separate analyses, showing high support for the monophyly of families Cladoniaceae and Stereocaulaceae and for the sistergroup relation for the two families. The relationships between higher groupings did not reach high support values probably due to the incongruencies among the three datasets