Isolation of heterothallic yeast strains ofMetschnikowia Kamienski and their mating reactions withChlamydozyma Wickerham spp

Isolation ofMetschnikowia bicuspidata var.australis in the haplophase from Antarctic waters, andM. bicuspidata var.zobellii in haplo-and diplophases at Chatham Is. N.Z., led to the study of mating reactions within theChlamydozyma - Metschnikowia complex. The results indicate the phylogenetic relationships between species. The plant-associatedCh. pulcherrima. Ch. reukaufii, andM. zygota are distinct species; when cross-mated they will conjugate but not produce asci. These three species are closely related toM. bicuspidata; when they are mated withM. bicuspidata and its varieties (var.australis and var.zobellii) asci are produced without spores. The taxonomic status ofM. bicuspidata and its varieties is based on less frequent formation of ascospores between than within taxa.The new varietyM. bicuspidata var.australis and the new combinationsM. zygota andM. bicuspidata var.zobellii are proposed.Contribution No. 925 from the Institute of Marine Sciences, University of Miami, Florida.