Morphological and phylogenetic investigations onnassulid ciliates (ciliophora, nassophorea, nassulida)isolated from the side of lake Van shore

This study was carried out on nassulid ciliates isolated from the shores of Lake Van and aquatic systems associated with the lake in Van Yüzüncü Yıl University campus. Three nassulid ciliate populations, Nassulides labiatus, Naxella lucida and Naxella sp., which could not be identified to species level due to insufficient samples, were identified. Morphological and morphometric descriptions of the isolated ciliates were made, SSU rDNA gene nucleotide sequences of Nassulides labiatus and Naxella lucida were revealed, phylogenetic relationships of nassulids based on SSU rDNA gene sequences were investigated, and the findings obtained were compared with literature data. Nassulides labiatus with oval outline, 80 × 150 µm, 8–15 hypostomial franges, 140 somatic kineties, oral basket supported by 30 nematodesmal rods, 20 µm long slitshaped cytopig positioned ventrally posteriorly; Naxella lucida is characterised by oval outline, size 65 × 50 µm, 4 hypostomial franges, 60 somatic kineties, oral basket supported by 16 nematodesmal rods, 30 µm long cytopig positioned posterior ventrally. The population of Naxella sp. was observed with very few individuals and has a typical nassulid morphology. By next generation sequencing (NGS) method, 1763 base pair nucleotide sequences for Nassulides labiatus and 1765 base pair nucleotide sequences for Naxella lucida were determined for SSU rDNA gene. The nucleotide sequences of Nassulides labiatus and Naxella lucida populations were compared with the nucleotide sequences of nassulids obtained from GenBank (NCBI) and 98.8% and 83.4% similarity were observed, with differences at nucleotide positions 27–272. SSU rDNA nucleotide sequences of Nassulides labiata and Naxella lucida were revealed for the first time in this study. Phylogenetic analyses showed that class Nassophorea is not monophyletic. Nassulides labiatus and Naxella lucida are closely related to the populations of Naxella paralucida KY652918, Nassula labiata KC832949, Nassula sp. EU286810 and Obertrumia georgiana X65149. There is very little molecular data on nassulid ciliates, of which there are many species. For this reason, it is not possible to compare the nucleotide sequences of many species. In order to accurately determine the kinship relationships of nassulid ciliates, SSU rDNA nucleotide sequences of many more species with detailed morphological descriptions are needed