Species reassignment of Geotrichum bryndzae, Geotrichum phurueaensis, Geotrichum silvicola and Geotrichum vulgare based on phylogenetic analyses and mating compatibility.

The present classification of Galactomyces and its anamorph, Geotrichum, is based on various studies that used morphology, ecology, biochemistry, DNA-DNA reassociation comparisons and gene sequencing. In this study, the identities of strains of the Centraalbureau voor Schimmelcultures yeast culture collection, as well as seven strains from South Africa, were examined by analyses of the nucleotide divergence in the internal transcribed spacer regions of the nuclear rRNA gene (nrRNA) operon, the D1/D2 domains of the 26S rRNA gene and partial actin gene sequences as well as compatibility studies. The South African strains were assigned to species in the genus Galactomyces. The phylogenetic analyses and mating studies revealed that Geotrichum silvicola and Geotrichum bryndzae are synonyms of Galactomyces candidus and that Geotrichum vulgare is a synonym of Galactomyces pseudocandidus.

Four new species in Lipomyces.

For new species in Lipomyces are described. In terms of nuclear genome comparison the genus Lipomyces comprises three species-clusters. A key to the nine species now assigned to the genus, is given. The delimitation of species by (i) rRNA nucleotide sequence analyses of the 18S and 25S subunits and (II) nDNA homology determinations, do not invariably lead to the recognition of congruent taxa. The family of the Lipomycetaceae, nevertheless provides an illuminative model for phylogenetic studies in terms of more appropriate ribosomal nucleotide sequence analyses of both its teleomorphic and anamorphic members.

Diversity and affinities among species and strains of Lipomyces

Phylogenetic relationships of the yeast genus Lipomyces were studied using sequences from fragments of 5.8S rRNA gene and from internal transcribed spacer region ITS2 of 13 strains (7 type strains included) representing five species and subtaxa, and originating from different geographical locations (Japan, Trinidad, Nigeria, North America, Western Europe, Russia, South Africa, Mauritius). Parsimony and distance analyses were performed. Tree topology from the parsimony and distance analyses of the sequence confirmed the results of nDNA reassociation. Results segregate the 13 isolates of Lipomyces into five major clades.(Au)

Myxozyma neglecta sp. nov. (Candidaceae) a new yeast species from South Africa.

Three strains of Myxozyma mucilagina including the type strain were reexamined. Based on differences in their carbon utilization pattern, mobility of isoenzymes, mol% G + C of their DNA and extent of DNA complementary the new species Myxozyma neglecta is proposed.

Diversity and affinities among species and strains of Lipomyces.

Phylogenetic relationships of the yeast genus Lipomyces were studied using sequences from fragments of 5.8S rRNA gene and from internal transcribed spacer region ITS2 of 13 strains (7 type strains included) representing five species and subtaxa, and originating from different geographical locations (Japan, Trinidad, Nigeria, North America, Western Europe, Russia, South Africa, Mauritius). Parsimony and distance analyses were performed. Tree topology from the parsimony and distance analyses of the sequence confirmed the results of nDNA reassociation. Results segregate the 13 isolates of Lipomyces into five major clades.

Lipomyces mesembrius sp. nov., a member of the L. starkeyi species-complex.

Lipomyces starkeyi is known to be associated with three strains-clusters showing high mutual nDNA reassociation within each cluster, but which reassociate ambiguously with the type of L. starkeyi. Representative strains of L. starkeyi and Cluster alpha were examined for possible genetic exchange by the prototrophic selection technique. Since no genetic recombination was detected, the strains are presumed to be genetically isolated. Cluster alpha is consequently assigned to the rank of species as Lipomyces mesembrius. A description of the new species is given. Lipomyces kononenkoae ssp. spencermartinsiae has been raised to the rank of species as L. spencermartinsiae.

Species delimitation in the genus Lipomyces by nuclear genome comparison.

Species delimitation in Lipomyces was attempted by nuclear genome comparison in conjunction with the re-evaluation of 48 physiological characters of 65 strains. High intraspecific (> 75%) and low interspecific (< 28%) similarity values established that L. japonicus, L. lipofer and L. tetrasporus are genetically isolated, and also distinct from L. kononenkoae and L. starkeyi. Ambiguous similarity values were obtained with L. kononenkoae and L. starkeyi. Strains previously assigned to L. kononenkoae constitute two related clusters. While similarity values within each cluster range from 76-99%, representatives of the two clusters reassociate for only 47%. Since these clusters are differentiated by their ecologically relevant maximum growth temperature, L. kononenkoae is subdivided. Strains previously assigned to L. starkeyi resolve into four closely related clusters. While similarity values within each cluster range from 78-100%, representatives of the four clusters reassociate for only 59-69%. Since these four clusters are poorly differentiated, the subdivision of L. starkeyi does not appear possible without recourse to other criteria. Four unassigned strains constitute a further two clusters. Reassociation within these clusters is of the order of 91-100%, while reassociation between them occurs only at 59%. Reassociation of representatives of these clusters with those of the L. kononenkoae and L. starkeyi complexes is around 40% and 31%, respectively. These two clusters consequently appear to be intermediate between L. kononenkoae and L. starkeyi, and will, as such, have to be considered in any delimitation of these two species. A key to the taxa of Lipomyces and related genera of the Lipomycetaceae is given.

Babjevia gen. nov.--a new genus of the Lipomycetaceae.

The species described as Lipomyces anomalus Babjeva & Gorin shows significant genetic and phenotypic divergence from the type species Lipomyces starkeyi Lodder & Kreger-van Rij in terms of rRNA base sequence substitution and ascosporal and septal ultrastructure. The species is consequently reclassified in the new, unispecific genus Babjevia, as Babjevia anomala.

The Lipomycetaceae, a model family for phylogenetic studies.

The Lipomycetaceae (Endomycetales) are known from the genera Dipodascopsis, Lipomyces and Zygozyma with budding anamorphic states in Myxozyma. The family is easily recognized culturally and physiologically but is phenotypically and ecologically extremely diverse. This natural taxon is phylogenetically distinct from the Saccharomycetaceae, but probably related to the Dipodascaceae. The possible evolution of the lipomycetaceous anamorphs is discussed.

Myxozyma neotropica sp. nov. (Candidaceae)--a new yeast species from Costa Rica.

Two strains of an undescribed, soil-borne species of the genus Myxozyma were recovered. They differ from other accepted species of this genus in their carbon assimilation pattern, mol% G+C and low extent of DNA complementary. A description of the new species, Myxozyma neotropica, and a key to the species accepted in the genus are given.

Kluyveromyces piceae sp. nov., a new yeast species isolated from the rhizosphere of Picea abies (L.) Karst.

Two strains of an undescribed species of the genus Kluyveromyces were recovered from the rhizosphere of spruce. A description of the new species, Kluyveromyces piceae, is given and its classification on basis of ascospore shape, substrate utilization, G+C-content, DNA-DNA-reassociation data and habitat specificity is discussed.

Septal micropores in Zygozyma and their taxonomic significance.

Septal micropores or plasmadesmal canals have been observed in two species of the lipomycetaceous genus Zygozyma. The presence of these canals is considered as further evidence for the connexion between the Lipomycetaceae and the Dipodascaceae. The genus Zygozyma has been emended.

Zygozyma smithiae sp.n. (Lipomycetaceae), a new ambrosia yeast from southern Africa.

A new species of the genus Zygozyma, Z. smithiae, was recovered from frass of the ambrosia beetle, Crossotarsus externedentatus in Northern Natal. A description of the new species and key to the genus are given.

Arxula gen. nov. (Candidaceae), a new anamorphic, arthroconidial yeast genus.

The new genus Arxula is proposed for the classification of xerotolerant, ascomycetous, anamorphic, arthroconidial yeasts. The genus is considered to be of endomycetaceous affinity.

Debaryomyces udenii, sp. nov. (Saccharomycetaceae), a new species from soil.

A new, soil-associated species of the genus Debaryomyces, D. udenii, is described. The species is characterized by pusticulate rather than verrucate ascospores, and slowly lytic asci.

Zygozyma suomiensis, sp. nov. (Lipomycetaceae), a new species from Finland.

A new species of the genus Zygozyma, Z. suomiensis, is described, based on the study of a single strain, derived from a bovine skin lesion.

Myxozyma kluyveri sp. nov. (Candidaceae)--a new species from southern Africa.

Four strains of an undescribed, soil-borne species of the genus Myxozyma were recovered. A description of the new species, Myxozyma kluyveri, and a key to the species accepted in the genus are given.

New basidiomycetous yeasts from southern Africa. IV. Sporobolomyces phylladus sp. nov., characterized by the coenzyme Q9 system (Sporobolomycetaceae).

Six strains of an undescribed, leaf-borne species of the genus Sporobolomyces were recovered. A description of the new species, Sporobolomyces phylladus, is given.

Redefinition of Candida Berkhout and the consequent emendation of Cryptococcus Kützing and Rhodotorula Harrison.

On the basis of affinitive characters Candida has been restricted to anamorphs related to the Endomycetales. The excluded basidiomycetous anamorphs have been transferred to the emended genera Rhodotorula and Cryptococcus.

New basidiomycetous yeasts from southern Africa. III. Sporobolomyces phyllomatis sp. nov. (Sporobolomycetaceae).

Three strains of an undescribed, leaf-borne species of the genus Sporobolomyces were recovered. A description of the new species, Sporobolomyces phyllomatis, is given.