Sinuolinea capsularis (Myxosporea: Sinuolineidae) Isolated from Urinary Bladder of Cultured Olive Flounder Paralichthys olivaceus

Sinuolinea capsularis Davis, 1917 is myxosporean that infect the urinary system of the host fish. Insufficient morphological and molecular data of S. capsularis exits, and it is therefore difficult to make an accurate identification of the parasite. We tried a series of morphological and molecular analysis to identify an myxosporean isolated from urinary bladder of cultured olive flounder, Paralichthys olivaceus, from Jeju island in the Republic of Korea. Some of them were observed under a light microscope and SEM, and remain samples were used molecular and phylogenetic analysis. Mature spores were subspherical, measuring 13.9±0.6 μm in length and 13.8±0.8 μm in width. Two spherical polar capsules on opposite sides in the middle of the spore had a diameter range of 4.3±0.4 μm. Scanning electron microscopy revealed that spores a severely twisted the suture line. By the morphological comparison and analysis, it was identified as S. capsularis. In addition, we obtained the partial 18S rDNA of S. capsularis and first registered it in NCBI. Phylogenetic analysis showed that S. capsularis clustered with Zschokkella subclade infecting the urinary system of marine fish, and it supported the infection site tropism effect on phylogeny of marine myxosporeans as well as the origin of Sinuolinea is not monophyly.