Post-mortem myoliquefaction caused by myxozoans of the genus Kudoa was observed in Japanese flounder Paralichthys olivaceus and Chinese sea bass Lateolabrax sp. cultured in Japan. Morphological and molecular analyses of the myxozoan from Japanese flounder identified it as Kudoa thyrsites, which has been described from various marine fishes in different oceans. The parasite from Chinese sea bass was similar to K. thyrsites, having stellate spores with one polar capsule larger than the other three. However, the spore size was smaller than that of K. thyrsites. The small subunit rDNA sequence from the Kudoa sp. of Chinese sea bass was distinct from that of K. thyrsites and phylogenetic analysis placed it as an outlier to K. thyrsites. Therefore, we describe the myxozoan from Chinese sea bass as Kudoa lateolabracis n.sp.