Relationships within the black yeast genus Exophiala based on ITS1 sequences

Abstract

Relations between type isolates of recognized species and synonymous names in the black yeast genus Exophiala and some similar taxa were analysed on the basis of their ribosomal internal transcribed spacer region 1 (ITSl) DNA sequences. Synonymy of Mycotorula schawii with E. dermatitidis , and of Hormodendrum negronii with E. jeanselmei var. lecanii-corni were confirmed. The synonymy of E. salmonis and E. brunnea was not confirmed. Sporotrichum gougerotii and Torula bergeri proved to be identical but in contrast to earlier reports this taxon differs from E. castellanii. Exophiala castellanii, E. angulospora, E. moniliae, E. dopicola, E. brunnea and E. alcalophila were recognized as separate species. Several clusters of closely related species were found, among which were E. pisciphila, E. psychrophila and E. salmonis on the one hand and E. dermatitidis, E. jeanselmei var. heteromorpha, Sarcinomyces phaeomuriformis and Pullularia prototropha on the other. Nadsoniella nigra and its var. hesuelica were found to be identical. They clustered with Phaeococcomyces elegans, Sporotrichum gougerotii and Torula bergeri . A further cluster comprised E. jeanselmei var. jeanselmei, P. exophialae and E. spinifera . The varieties of E. jeanselmei were found to be unrelated and should therefore be maintained as separate species. In general, the phylogenetic relationships established in this study did not conflict with those found in sequencing studies of small and large subunit RNA genes.