Molecular phylogeny of the ballistoconidium-forming anamorphic yeast genus Bullera and related taxa based on small subunit ribosomal DNA sequences

Abstract

The sequence of the small subunit ribosomal coding gene (SSU rDNA) was determined for the type strains of seven species of the genus Bullera and two species which are now regarded as synonyms of species in the genera Bullera and Udeniomyces. The phylogenetic trees for these yeasts were constructed by neighbor-joining and maximum likelihood methods, including supposedly related yeasts and filamentous fungi whose SSU rDNA sequences were already known. Fifteen presently recognized species of Bullera were divided into two phylogenetic groups. Bullera mrakii, B. huiaensis, B. sinensis, B. oryzae, B. coprosmaensis, B. crocea, B. armeniaca, and B. variabilis constitute one cluster. In this cluster, the topologies of B. variabilis and orange-colored species, B. crocea and B. armeniaca, are different according to the neighbor-joining and maximum likelihood trees. Bullera pseudoalba, B. alba, B. unica, B, hannae, B. globispora, B. miyagiana, and B. dendrophila constitute another cluster. In this cluster, B. pseudoalba, B. alba, B. unica, and B. hannae constitute a branch but B. globispora, B. miyagiana, and B. dendrophila are located at positions far from one another although the former two species constitute a cluster in the maximum likelihood tree. Among the above species, B. dendrophila constitutes a cluster with Tsuchiyaea wingfieldii and Filobasidiella neoformans. The neotype strain of B. grandispora, which is now regarded a synonym of Udeniomyces piricola, is located close to the position of type strain U. piricola.