Heterocephalacria sinensis sp. nov., phaeotremella lacus sp. nov. and solicoccozyma aquatica sp. nov., three novel basidiomycetous yeast species isolated from crater lakes

The Arxan–Chaihe volcanic field of the Da Hinggan mountains in north-East PR China hosts various typical crater lakes. In this study we performed a yeast diversity survey using water sampled from five crater lakes and a total of 122 yeast strains belonging to 33 species of 25 genera were isolated. Three strains, TFL1-L, TFL2B and ATC4C, were identified as three novel species belonging to the Tremellomycetes based on a multiple gene phylogeny and on the comparison of physiological data. A phylogenetic study employing the sequences of seven genes indicated that the new species were more related to three separated phylogenetic lineages of the Tremellomycetes and their closest relatives were Heterocephalacria arrabidensis, Phaeotremella skinneri and Solicoccozyma keelungensis. The divergence values of the D1/D2 domain of LSU sequences of strains TFL1-L, TFL2B and ATC4C from H. arrabidensis CBS 8678^T, P. skinneri CBS 5029^T and S. keelungensisSN-82^T were 4.8,3.4,2.1 %, respectively. The divergence values of the sequences of ITS regions between strains TFL1-L, TFL2B and ATC4C and their close relatives (H. arrabidensis, P. skinneri and S. keelungensis) were 16.1, 5.9 and 8.1 %, respectively. Moreover, the three strains differed from their phylogenetic neighbours by the ability to grow on distinct carbon and nitrogen sources. On the basis of these findings, it is suggested that these strains represent three novel species for which the names Heterocephalacria sinensis sp. nov. (holotype CGMCC 2.5595), Phaeotremella lacus sp. nov. (holotype CGMCC 2.5580) and Solicoccozyma aquatica sp. nov. (holotype CGMCC 2.5574) are proposed.