Phylogenetic relationships of the Physciaceae inferred from rDNA sequence data and selected phenotypic characters

Abstract

The monophyletic origin of the ascomycete family Physciaceae, its position within the Lecanorales and the phylogenetic structure within the family were investigated using nuclear rDNA sequence analyses. The common origin of the Caliciaceae and Physciaceae as previously shown (Wedin et al 2000) was confirmed. Further it could be shown that the Caliciaceae are nested within the Physciaceae. A unique region in loop 37 of the SSU rRNA secondary structure model was identified, which characterizes the Physciaceae/Caliciaceae. The SSU rDNA sequence data did not support a particular relationship with any other Lecanoralean family. Analyses of ITS rDNA sequences revealed a bifurcation of the Physciaceae/Caliciaceae clade, which was found to be congruent with the distribution of certain morphological characters. The congruence with the ITS phylogeny demonstrated the phylogenetic significance of ascus type, hypothecium pigmentation, ascospore characters and excipulum type. Fine-structure details of ascospores and the structure of excipula were found to be important in the recognition of convergences in these traits. Other previously used characters, i.e., growth habit, certain ascospore types or structure of the upper cortex, were found to be of multiple origins within the Physciaceae. All monophyletic lineages of noncrustose growth habit exhibit uniform ascospore types, indicating a higher evolutionary age of ascospore types than foliose growth habit. The taxonomic segregation of the Physciaceae into the Physciaceae and Caliciaceae is proposed here.

• acetate-polymalonate pathway
• ascospore type
• ascus type
• atranorin
• Bayesian analysis
• Caliciaceae
• excipulum type
• growth habit
• hypothecium pigmentation
• internal transcribed spacer
• Lecanorales
• lichenized ascomycetes
• molecular phylogeny
• rRNA
• SSU
• systematics

We are grateful to Patrick Dornes, Anders Nordin and the herbarium curators Walter Obermayer, Harrie Sipman and Dagmar Triebel as well as Helmut Mayrhofer for providing valuable sample vouchers and helping in sample determination; to Virginia Souza-Egypsi and Alfredo Espinosa for excellent guidance on various excursions; to Elke Zufall-Roth for excellent assistance in the lab; to Dominik Hepperle and Frank Kauff for valuable advice in phylogenetic analyses; and to Helmut Mayrhofer, David Hewitt and Patrick Dornes for helpful comments on the manuscript. Special thanks are due to François Lutzoni, who generously provided lab facilities for part of the SSU sequences. This work was supported by a grant of the Deutsche Forschungsgemeinschaft extended to T.F. (Fr 905, 7–1, 7–2).