ORIGINAL PAPER Starmerella syriaca f.a., sp. nov., an osmotolerant yeast species isolated from flowers in Syria Matthias Sipiczki Received: 30 September 2014 / Accepted: 6 January 2015 Ó Springer International Publishing Switzerland 2015 Abstract Four strains of a novel asexual ascomyce- tous yeast species were isolated from Malva sp. flowers in Syria. Sequencing of the regions spanning the small subunit, 5.8S, and the D1/D2 domains of the large subunit ribosomal RNA genes showed that the isolates were conspecific. Comparative analysis of these sequences and the corresponding sequences of the type strains of ascomycetous yeasts revealed that the novel species is phylogenetically related to members of the Starmerella clade. Its closest relative is Candida vaccinii. For the new species the name Starmerella syriaca is proposed. Its strains are osmo- tolerant and produce pseudohypha-like structures capable of penetrating agar media. The type strain is 2-1362 T (=CBS 13909 T = NCAIM Y.02138 T = CCY 090-003-001 T ). The GenBank accession num- bers for its nucleotide sequences are: JX515986 (D1/ D2 LSU), JX515987 (ITS1-5.8S-ITS2) and JX515988 (SSU). Mycobank: MB 810090. Keywords Starmerella Á Candida Á Flower yeast Á sp. nov. Á Dimorphism Introduction Flowers usually harbour yeast communities which are thought to be vectored by flower-associated insects (for reviews see Lachance et al. 2001b; Pozo et al. 2011). The yeasts in the flowers are either active colonists of the flower nectar (e.g. Brysch-Herzberg 2004; Herrera et al. 2009, 2010; Pozo et al. 2011, 2012) or passive contaminants (e.g. Sipiczki 2013a). Many of them are osmotolerant (e.g. Tokuoka et al. 1987; Pozo et al. 2011) and can also occur in other substrates with high sugar content (e.g. Rosa et al. 2003). Certain strains isolated from flowers turned out to be dimorphic capable of developing invasive filamentous forms under laboratory conditions (e.g. Nakase et al. 2010; Sipiczki 2012, 2013a). Fungal di- and polymorphism is a complex phenomenon which enables the organism to adapt its growth strategy to various substrates by changing its morphology and physiology (for reviews see Madhani and Fink 1998; Sanchez-Martinez and Perez-Martin 2001). For exam- ple di- or polymorphic species produce yeast cells in liquid environment and develop pseudohyphae or hyphae when a solid substrate is to be colonised (e.g. Sipiczki et al. 1998). The comparative analysis of a large number of fungal genome sequences revealed that the ability to switch from filamentous growth to unicellular yeast form arose early in fungal evolution and became dominant independently (by convergent evolution) in multiple clades, most likely via parallel diversification of Zn-finger transcription factors (Nagy M. Sipiczki (&) Department of Genetics and Applied Microbiology, University of Debrecen, Debrecen 4032, Hungary e-mail: gecela@post.sk 123 Antonie van Leeuwenhoek DOI 10.1007/s10482-015-0377-7