Abstract
Fourteen ballistoconidium-forming yeast strains were isolated from leaves of plants collected in the Ogasawara Islands, which are isolated islands in the Pacific Ocean, about 1000 km south of the Japanese mainland, in the subtropical zone. The 14 isolates were characterized by the absence of xylose in whole-cell hydrolysates, the presence of Q-10(H(2)) as the major ubiquinone isoprenologue, G+C contents of 47.6--52.0 mol%, the inability to ferment sugars or to assimilate nitrate and positive Diazonium blue B and urease reactions. They formed a phylogenetically coherent cluster within the Erythrobasidium lineage in the Urediniomycetes of the Basidiomycota based on 18S rDNA sequences. Analyses of the nucleotide sequences of internal transcribed spacer regions and DNA complementarity showed that four genospecies were recognized among the 14 isolates. A mating reaction was observed in one of the four genospecies, which produced one-celled basidia on dikaryotic hyphae with clamp connections. On the basis of the morphological, physiological, chemotaxonomic and phylogenetic analyses, a new teleomorphic genus, Bannoa, is proposed, in which one novel species is described, Bannoa hahajimensis gen. nov., sp. nov. (type strain OK-248(T)=JCM 10336(T)=CBS 9039(T)). The other three anamorphic genospecies are described as Sporobolomyces bischofiae sp. nov. (type strain OK-257(T)=JCM 10338(T)=CBS 9041(T)), Sporobolomyces ogasawarensis sp. nov. (type strain OK-14(T)=JCM 10326(T)=CBS 9038(T)) and Sporobolomyces syzygii sp. nov. (type strain OK-227(T)=JCM 10337(T)=CBS 9040(T)).