Katarina Winka

Comparing bootstrap and posterior probability values in the four-taxon case.

Assessment of the reliability of a given phylogenetic hypothesis is an important step in phylogenetic analysis. Historically, the nonparametric bootstrap procedure has been the most frequently used method for assessing the support for specific phylogenetic relationships. The recent employment of Bayesian methods for phylogenetic inference problems has resulted in clade support being expressed in terms of posterior probabilities. We used simulated data and the four-taxon case to explore the relationship between nonparametric bootstrap values (as inferred by maximum likelihood) and posterior probabilities (as inferred by Bayesian analysis). The results suggest a complex association between the two measures. Three general regions of tree space can be identified: (1) the neutral zone, where differences between mean bootstrap and mean posterior probability values are not significant, (2) near the two-branch corner, and (3) deep in the two-branch corner. In the last two regions, significant differences occur between mean bootstrap and mean posterior probability values. Whether bootstrap or posterior probability values are higher depends on the data in support of alternative topologies. Examination of star topologies revealed that both bootstrap and posterior probability values differ significantly from theoretical expectations; in particular, there are more posterior probability values in the range 0.85-1 than expected by theory. Therefore, our results corroborate the findings of others that posterior probability values are excessively high. Our results also suggest that extrapolations from single topology branch-length studies are unlikely to provide any general conclusions regarding the relationship between bootstrap and posterior probability values.

Molecular evidence for recognizing the Chaetothyriales

The 18S rRNA gene sequences from the bitunicate ascomycetes Ceramothyrium linnaeae (Chaetothyriaceae) and Coccodinium bartschii (Coc- codiniaceae) were determined and aligned with the corresponding sequences from 33 other ascomycetes and one basidiomycete, Boletus satanas. Phylogenetic analyses of these sequences supported previous re- ports that the Herpotrichiellaceae (Capronia, black yeasts, etc.) are distant from Dothideales and Pleo- sporales. A new sequence of Ceramothyrium linnaeae, representing the family Chaetothyriaceae, is mono- phyletic with representatives of the Herpotrichiella- ceae, suggesting that both families can be accom- modated in the order Chaetothyriales. The concept of Chaetothyriales can not be based on the presence of periphysoids, since Coccodinium bartschii, which also has periphysoids, clustered with members of the Dothideaceae. The Chaetothyriales are not closely re- lated to other bitunicates, but are the sister group of either Eurotiales or Lecanorales/Peltigerales.

Generic concepts and correlations in ascomycetes based on molecular and morphological data: Lecythothecium duriligni gen. et sp. nov. with a Sporidesmium anamorph, and Ascolacicola austriaca sp. nov

A new species in the new monotypic genus Lecythothecium, having a Sporidesmium anamorph, and the new species Ascolacicola austriaca are de- scribed, illustrated with line drawings and photo- graphs, and classified using a combination of mor- phology and sequence data. A new chloridium-like synanamorph of Umbrinosphaeria caesariata is report- ed. To classify the two new species, other phenotyp- ically similar perithecial ascomycete genera, viz. As- cotaiwania, Coniobrevicolla, Crassochaeta, Herbampul- la, Savoryella and Umbrinosphaeria, were compared morphologically and for the large nuclear ribosomal RNA gene (LSU rDNA). Despite the basic similarity in regard to perithecia, asci, apical annulus and as- cospores, the classification of the two new species was problematic in that each possessed some phenotypic characters of several genera but could not be easily placed in any. Parsimony and distance analyses of LSU rDNA sequences of the fungi mentioned and representative taxa of seven ascomycetous orders were performed. The phylogeny showed Lecythothe- cium duriligni with a Sporidesmium anamorph to have affinity with the Chaetosphaeriaceae (98-100%). Um- brinosphaeria caesariata having Sporidesmium and chloridium-like synanamorphs also nested with high bootstrap value (98-100%) in the Chaetosphaeri- aceae. The affinity of Ascolacicola austriaca lies with the Annulatascaceae/Trichosphaeriaceae in our phy- logeny. The taxonomic and phylogenetic value of the massive, wedge-shaped apical annulus that character-

Papulosa amerospora accommodated in a new family (Papulosaceae, Sordariomycetes, Ascomycota) inferred from morphological and molecular data

To investigate the systematic position of the unitunicate pyremomycetePapulosa amerospora, we performed phylogenetic analyses of SSU rDNA sequences from 37 ascomycetes. Among these sequences were some new ones from taxa that might be related toPapulosa: Hyponectriaceae (Hyponectria buxi, Monographella nivalis), Phyllachorales (Phyllachora graminis), and Xylariales (Barrmaelia melanotes, Poronia punctata). Our results showed 100% bootstrap support for a clade of all unitunicate pyrenomycetes, the class Sordariomycetes. We also found strong support for recognizing the subclasses Hypocreomycetidae and Xylariomycetidae. The remaining taxa, belonging to subclass Sordariomycetidae, appeared as a polyphyletic group in one analysis, but was monophyletic when shorter SSU sequences were used.Barrmaelia melanotes, Poronia punctata, Hyponectria buxi, andMonographella nivalis are members of Xylariomycetidae, but we could not determine whetherMonographella should be included in Hyponectriaceae. The new family Papulosaceae is erected forPapulosa on molecular and morphological bases, but the exact systematic position ofPapulosa within subclass Sordariomycetidae is still uncertain, since the genus did not cluster consistently with any of the included taxa. Phyllachorales are not closely related to Diaporthales, as previously suggested.