Molecular diversity, new species and antifungal susceptibilities in the Exophiala spinifera clade

Black yeasts morphologically identified as Exophiala cf. spinifera were re-analyzed on the basis of morphology, nutritional physiology and ITS rDNA sequencing data. Ribosomal small subunit (SSU) DNA sequence data confirmed that strains belonged to a clade containing the ex-type strain of E. spinifera. Variation in the Internal Transcribed Spacer (ITS) region of the rDNA was studied within this group. Five infraspecific groups were delineated. Phylogenetic analysis of the SSU rDNA data revealed that several of the strains analyzed were located at considerable evolutionary distance from the E. spinifera clade. ITS rDNA sequencing showed that the deviating strains could not be identified with any existing species. Two new species, E. attenuata and E. nishimurae, were therefore proposed. Antimycotic susceptibility data of the new species were compared with those obtained with members of the E. spinifera clade.