Molecular phylogeny of Dictyosporium and allied genera inferred from ribosomal DNA

Abstract

The relationships among mitosporic fungi with cheiroid conidia in the genera Cheiromoniliophora, Dictyosporium, Kamatia and Pseudodictyosporium were investigated using sequences of small ribosomal subunit (SSU), internal transcribed spacer regions (ITS) and the 5′ portion of the large ribosomal subunit (LSU) of RNA. Six new SSU sequences were determined and analysed together with related sequences from GenBank using parsimony and Bayesian analyses. A second alignment with 15 ITS and seven partial LSU sequence of rDNA for an expanded set of taxa was also analysed to determine the relationships among various species and genera. Results indicated that the 'Dictyosporium' lineage of mitosporic fungi producing cheiroid conidia are closely related to one another and they form a strong monophyletic group in the Pleosporales. Dictyosporium appeared to be paraphyletic but its monophyly could not be ruled out. Most Dictyosporium species belonged in one of two lineages that correlated imperfectly with conidial shape and the number of conidial arms. The systematic positions of Dictyosporium australiense and D. toruloides were not fully resolved. The phylogenetic position of Digitodesmium was within Dictyosporium, although without statistical support. Cheiromoniliophora elegans, Kamatia indica and Pseudodictyosporium wauense were close relatives and formed a monophyletic clade divergent from species of Dictyosporium. Most morphological characters used to delineate genera and species correctly predicted phylogenetic relationships.