A COMPARISON OF SSU RDNA DATA AND MORPHOLOGICAL DATA IN ARTHONIALES (EUASTOMYCETES) PHYLOGENY

A phylogenetic analysis of the euascomycetous order Arthoniales, focus sing on the family roccellaceae was performed. The first half of the s mall subunit of ribosomal DNA (SSU rDNA) was sequenced from 12 taxa an d these sequences were analyzed cladistically together with seven sequ ences from GenBank. In the strict consensus of the 27 most parsimoniou s trees Lecanactis abietina was placed as a sister taxon to the remain ing group. Schismatomma and Syncesia were found nested within the fami ly roccellaceae. SSU rDNA was not informative enough to fully resolve relationships between the closely related genera Dirina and roccella. The molecular phylogeny was compared with an earlier morphological stu dy of Arthoniales. An incongruence test showed significant incongruenc e between the molecular and morphological data sets. Four major points of conflicts are discussed 1) the monophyly of Roccellaceae, the plac ements of 2) Schismatomma, 3) Lecanactis, and 4) Dendrographa. Finally , a combined analysis using both morphological and molecular data was performed. Most groups in the molecular tree were also present in the combined tree due to a lower level of homoplasy in the molecular data. At this point, we recommend combining data sets, as all available inf ormation of the studied taxa is utilized.