- Volume 46, Issue 2, 1996

Strains of the phenotypically similar species Saccharomyces castellii, Saccharomyces dairensis, and Saccharomyces transvaalensis, recently separated on the basis of DNA base sequence homologies and electrophoretic karyotypes, have been reexamined by techniques of conventional taxonomy. While the limited physiological differences observed are somewhat restrictive for species distinction, it is possible to separate some of these taxa by using a minimal number of macromolecular and phenotypic criteria. Two strains formally classified as S. dairensis constitute a new species since, while having minimal nucleotide base sequence homology with the other species, they were found to have a 97% DNA-DNA reassociation rate with each other. This species is described as Saccharomyces rosinii in honor of Gianfranco Rosini, late professor of enology and microbiology of the University of Perugia, Perugia, Italy.