Evolutionary relationships of Hyphodiscus hymeniophilus (anamorph Catenulifera rhodogena) inferred from β-tubulin and nuclear ribosomal DNA sequences

During an investigation of lignicolous ascomycetes from Luxembourg, we isolated a Phialophora-like species that produced striking red colonies. To confirm the identity of this fungus as Catenulifera rhodogena, we compared it with isolates of Catenulifera rhodogena and Hyphodiscus hymeniophilus on a variety of media. Portions of the beta-tubulin gene and the nuclear ribosomal DNA cistron (internal transcribed spacers (ITS) and large subunit (LSU)) were sequenced to examine the relationship of isolates of Catenulifera rhodogena and Hyphodiscus hymeniophilus from different substrates and to test the hypothesis that Cadophora and Catenulifera are congeneric. The phylogenetic position of Catenulifera within the Ascomycota was investigated based on the analysis of the small-subunit (SSU) rDNA sequences. The isolates examined were indistinguishable micromorphologically and closely related phylogenetically. Three strains of Catenulifera rhodogena from bark or wood and one strain from Piptoporus betulinus formed a strongly supported clade in analyses of beta-tubulin and ITS sequences. This clade did not encompass the ex-type isolates of Cistella rubescens and Scopulariopsis rhodogena or a second isolate of Catenulifera rhodogena from Piptoporus betulinus. Analysis of partial LSU sequences confirmed the close phylogenetic relationship of Catenulifera rhodogena and Hyphodiscus hymeniophilus but provided no evidence that the isolates could be grouped by substrate or that Catenulifera is synonymous with Cadophora. The position of Catenulifera within the Helotiales was not resolved based on the comparison of LSU and SSU sequences, but the isolate for which we obtained complete SSU sequence grouped with the root endophyte Phialocephala fortinii. Comparison of ITS sequences confirmed the close phylogenetic relationship of Hyphodiscus to members of the Dermateaceae and Hyaloscyphaceae.