Trapelioid fungi constitute a widespread groupof mostly crust-forming lichen mycobionts that are key tounderstanding the early evolutionary splits in theOstropomycetidae, the second-most species-rich subclassof lichenized Ascomycota. The uncertain phylogeneticresolution of the approximately 170 species referred tothis group contributes to a poorly resolved backbone forthe entire subclass. Based on a data set including 657newly generated sequences from four ribosomal and fourprotein-coding gene loci, we tested a series of a priori andnew evolutionary hypotheses regarding the relationshipsof trapelioid clades within Ostropomycetidae. We foundstrong support for a monophyletic group of nine coretrapelioid genera but no statistical support to reject thelong-standing hypothesis that trapelioid genera are sisterto Baeomycetaceae or Hymeneliaceae. However, we canreject a sister group relationship to Ostropales with highconfidence. Our data also shed light on several longstandingquestions, recovering Anamylopsoraceae nestedwithin Baeomycetaceae, elucidating two major monophyleticgroups within trapelioids (recognized here asTrapeliaceae and Xylographaceae), and rejecting themonophyly of the genus Rimularia. We transfer elevenspecies of the latter genus to Lambiella and describe thegenus Parainoa to accommodate a previously misunderstoodspecies of Trapeliopsis. Past phylogenetic studies inOstropomycetidae have invoked Bdivergence order^ fordrawing taxonomic conclusions on higher level taxa.Our data show that if backbone support is lacking, contrastingsolutions may be recovered with different oradded data. We accordingly urge caution in concludingevolutionary relationships from unresolved phylogenies.

Information on the ecology and distribution of Myriospora species in the Baltic coastal zone of Germany isprovided. The three species (M. myochroa, M. rhagadiza, M. smaragdula) occurring in the study area arewidely distributed, but show differences in frequency and distribution pattern. Myriospora rhagadiza is rathercommon but strictly restricted to the Baltic shoreline in contrast to the other two species.

The phylogeny of the Acarosporaceae (Lecanoromycetes, Acarosporomycetidae, Acarosporales) is investigated using data from three molecular markers; nuclear ITS-LSU rDNA, mitochondrial SSU and β-tubulin. Acarosporaceae is shown to be constituted by six main clades; Myriospora, Timdalia, Pleopsidium, a clade composed by Acarospora rhizobola and A. terricola, the poorly supported Sarcogyne clade (including several Polysporina and Acarospora species) and the Acarospora clade (including the type of Polysporina, P. simplex, and several other Polysporina species). The common ancestor of the Acarosporaceae did not produce strongly black pigmented (carbonized or melanized) ascomata, but this trait has arisen secondarily and independently numerous times in the evolution of the group. The number of changes in character states of both carbonized epihymenium and carbonized exciple are considerably more than the minimum number. The genera Sarcogyne and Polysporina—largely circumscribed based on the presence of black pigmented ascomata—are shown to be distinctly non-monophyletic. The presence of green algae in the ascoma margin (lecanorine or lecideine ascomata) may vary even within single species.

 Fourteen species of lichenized or lichenicolous fungi are reported new to either Norway or Sweden or both countries. Several of these are rare and almost unknown. The reported species are: Acarospora insignis (new to Norway), A. pyrenopsoides (Norway, Sweden), A. versicolor (Norway), Calvitimela perlata (Sweden), Lecidea degeliana (Sweden), Nephroma helveticum (Sweden), Peltula placodizans (Norway), Phacographa protoparmeliae (Norway), Rhizocarpon pycnocarpoides (Norway, Sweden), Sarcogyne algoviae (Sweden), Sarcogyne hypophaeoides (Norway, Sweden), Tephromela grumosa (Norway), Tremella lobariacearum (Norway) and Tremella wirthii (Sweden). In addition Cladonia albonigra is confirmed from Sweden. Sarcogyne hypophaeoides is lectotypified and is also reported new to Austria.