Description of Saprolegnia velencensis sp. n. (Oomycota), a novel water mold species from Lake Velence, Hungary.

Here, we describe a novel water mold species, Saprolegnia velencensis sp. n. from Lake Velence, in Hungary. Two strains (SAP239 and SAP241) were isolated from lake water, and characterized using morphological and molecular markers. In addition, phylogenetic analyses based on ITS-rDNA regions and on the RNA polymerase II B subunit (RPB2) gene complemented the study. The ITS-rDNA of the two strains was 100% identical, showed the highest similarity to that of S. ferax (with 94.4% identity), and they formed a separate cluster in both the ITS-rDNA and RPB2-based maximum likelihood phylogenetic trees with high bootstrap support. Although mature oogonia and antheridia were not seen under in vitro conditions, the S. velencensis sp. n. could be clearly distinguished from its closest relative, S. ferax, by the length and width of sporangia, as the new species had shorter and narrower sporangia (163.33±70.07 and 36.69±8.27 μm, respectively) than those of S. ferax. The two species also differed in the size of the secondary cysts (11.63±1.77 μm), which were slightly smaller in S. ferax. Our results showed that S. velencensis sp. n. could not be identified with any of the previously described water mold species, justifying its description as a new species.