• Journal of fish pathology
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• v.35 no.2
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• pp.177-183
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• 2022

We described Trichodina hokkaidoensis Mizuno, Matsuda, Nishikawa and Ito, 2022 from olive flounder Paralichthys olivaceus by morphological observation and molecular analysis. Morphological parameters of our specimen from 4 different sampling sites (Gangneung, Jeju, Wando, Taean) mostly coincided with those of T. hokkaidoensis. Some morphometric parameters of this trichodinid showed some inconsistency, depending on the sampling locations, but all of their partial small subunit ribosomal DNA sequences (1,182 bp) showed 100% homology with T. hokkaidoensis, originally described from artificially reared juvenile barfin flounder Verasper moseri from Japan. T. hokkaidoensis is known to cause epidermal damages to the host fish. However, there was no considerable pathological lesions in the olive flounder harboring T. hokkaidoensis in this study. The pathogenicity of T. hokkaidoensis against olive flounder needs to be investigated.