KOCKOVAELLA, A NEW BALLISTOSPORE-FORMING ANAMORPHIC YEAST GENUS

A new genus Kockovaella Nakase, Banno et Yamada in the Hyphomycetes is described for yeasts that reproduce by non-ballistosporous stalked conidia, ballistospores and budding yeast cells. Strains in this genus have Q-10 as the major isoprenologue of ubiquinones, contain xylose in the cells, and are positive to diazonium blue B reaction. Two new species, Kockovaella thailandica (type species) and K. imperatae, are described in the genus. Kockovaella thailandica has a G + C content of DNA of 49.5 mol% (from T(m)) or 47.7-48.4 mol% (by HPLC) and forms asymmetrical kidney-shaped or ellipsoidal ballistospores, whereas K. imperatae has a G + C content of DNA of 52.3 mol% (from T(m)) or 49.0 mol% (by HPLC) and forms symmetrical globose to napiform ballistospores. Electrophoretic comparison of eight enzymes and DNA similarity indicated that K. thailandica and K. imperatae are distinct species from each other. The partial sequencing study on 18S ribosomal RNA suggested a close relationship among species of Kockovaella, Fellomyces and Sterigmatosporidium. The latter two genera resemble Kockovaella in the production of non-ballistosporous stalked conidia and the presence of xylose in the cells but produce neither ballistospores nor budding yeast cells.