Parvicapsula curvatura n. sp. in cultured olive flounder Paralichthys olivaceus and phylogenetic characteristics of the genus Parvicapsula

Ortholinea nupchi n. sp. (Myxosporea: Ortholineidae) from the urinary bladder of the cultured olive flounder Paralichthys olivaceus, South Korea

A new myxosporean parasite, Ortholinea nupchi n. sp. (Myxozoa; Bivalvulida), was isolated from the urinary bladder of the olive flounder Paralichthys olivaceus cultured on Jeju Island, Korea. Mature spores were subspherical in the valvular and apical views and ellipsoidal in the sutural view. The spores measured 7.6 ± 0.5 μm in length, 6.7 ± 0.3 μm in thickness, and 7.3 ± 0.5 μm in width. Two pyriform polar capsules measured 3.2 ± 0.1 μm in length and 2.7 ± 0.1 μm in width and were located at the same level at the anterior half of the myxospores. The suture line was straight in the middle of the spores, and the surface ridges ranged between five and seven, forming an intricate pattern. The result of the 18S rDNA comparison showed ≤ 93.0% similarity with other Ortholinea species. The phylogenetic tree demonstrated that O. nupchi n. sp. was closest to O. auratae and clustered with oligochaete-infecting myxosporeans (OIM) having urinary system infection tropism. Based on the comparison of environmental and host factors in the phylogenetic groups of the OIM clade, we propose that the infection of O. nupchi n. sp. originated from marine oligochaetes.

Morphology, seasonality and molecular characterization of Ceratomyxa draconis n. sp. parasite of Trachinus draco (L.) from the Bay of Bizerte, Tunisia

The specimens of Trachinus draco collected from the Bay of Bizerte were found to be infected with a new Ceratomyxa species described as Ceratomyxa draconis n. sp. The sequence of small subunit ribosomal RNA gene obtained in this study differs from other Ceratomyxa sequences available in GenBank. Mature spores of this species were elongated and crescent-shaped in sutural view, measuring 7.4 ± 0.77 (6.4-8.0) μm in thickness and 30.8 ± 1.65 (28.8-32.8) μm in width. The polar capsules were spherical, equal in size, and measuring 3.3 ± 0.2 (3.6-4.0) μm in diameter. The Ceratomyxa draconis n. sp. showed a clearly seasonal variation of prevalence with highest prevalence noted during summer months.

Kudoa ogawai (Myxosporea: Kudoidae) Infection in Cultured Olive Flounder Paralichthys olivaceus

Since Kudoa septempuntata was identified as a causative agent of food poisoning associated with raw olive flounder Paralichthys olivaceus, interest and concern regarding the parasite have increased. However, there have been no investigations or reports of other Kudoa species infecting the fish (except for K. paralichthys, which infects the brain) in Korea. We found cysts filled with myxospores of Kudoa species in muscles of cultured olive flounder specimens and identified these to the species level. Mature spores were quadrate, measuring 8.7±0.5 μm in length, 9.2±0.4 μm in thickness, and 12.9±0.6 μm in width. The spores containing 4 polar capsules had a length of 2.1±0.2 μm and a width of 1.8±0.3 μm. The partial 18S and 28S rDNA of isolates showed 99–100% similarities with K. ogawai. Using these morphological and molecular analyses, the species was identified as K. ogawai. This study is the first report of K. ogawai infection in cultured olive flounder in Korea.

A new species Myxodavisia jejuensis n. sp. (Myxosporea: Sinuolineidae) isolated from cultured olive flounder Paralichthys olivaceus in South Korea

A new myxosporean parasite, Myxodavisia jejuensis n. sp. (Myxozoa; Bivalvulida) is described from the urinary bladder of olive flounder Paralichthys olivaceus cultured on Jeju Island, Korea. Two long lateral appendages with whip-like extensions were attached to mature spores of triangular to semi-circular shape. The spores were measured at 13.1 ± 1.1 μm in length, 17.2 ± 1.0 μm in thickness, and 13.1 ± 1.0 μm in width. Two spherical polar capsules, with a diameter of 5.0 ± 0.4 μm, were observed on opposite sides in the middle of the spore. The suture line was straight or slightly sinuous on the middle of spores. The 18S rDNA from M. jejuensis n. sp. was used in BLAST and molecular phylogenetic analysis. The results demonstrated that M. jejuensis n. sp. was closest to Sinuolinea capsularis and that the infection site tropism was correlated with the phylogeny of marine myxosporeans. In addition, we designed specific primers to detect the 18S rDNA gene of M. jejuensis n. sp.; the results showed specific amplification in M. jejuensis n. sp. among the myxosporeans isolated from the urinary bladder of the cultured olive flounder.

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.