Abstract
Twenty strains previously assigned to the species Bullera variabilis Nakase & Suzuki were reclassified using a molecular taxonomic approach. The strains were regrouped first by nucleotide sequence comparison of the rDNA internal transcribed spacer (ITS) regions, including the 5.8S gene. Phylogenetic positions of B. variabilis strains with different ITS region sequences were then analysed based on their 18S rDNA sequences. The taxonomic status of the original Bullera variabilis strains was clarified further by DNA--DNA hybridization experiments. Of the 20 strains studied, five remained in the species B. variabilis, six strains were reassigned to the species Bullera mrakii and three novel species were proposed for eight of the nine remaining strains, namely Bullera pseudohuiaensis sp. nov. (one strain; type strain JCM 5984(T)=AS 2.2203(T)), Bullera komagatae sp. nov. (one strain; type strain JCM 5983(T)=AS 2.2202(T)) and Bullera pseudoschimicola sp. nov. (six strains; type strain JCM 3915(T)=AS 2.2201(T)). The remaining strain, JCM 6140, was closely related to B. pseudoschimicola. However, differences in ITS region sequences between strain JCM 6140 and strains of B. pseudoschimicola, and the intermediate DNA--DNA relatedness to representative strains of B. pseudoschimicola did not allow a definite taxonomic decision to be made for strain JCM 6140.