Postmortem myoliquefaction associated with multivalvulid myxozoans was found in fillets of red barracuda (Sphyraena pinguis) and splendid alfonso (Beryx splendens), which were imported to Japan from China and South Africa, respectively. Morphological examinations of the myxozoans from the somatic muscle of red barracuda revealed that spores (30.3–44.7 μm in maximum thickness) had 4 distinct winglike valves, in which 1 extremely large (12.7 × 5.8 μm), 2 small, and 1 vestigial polar capsule were present. The small subunit ribosomal DNA sequence analysis showed that the myxozoan cluster within a clade was composed of Kudoa thyrsites, Kudoa minithyrsites, and Kudoa lateolabracis, all having stellate spores with 1 polar capsule larger than the other 3. On the basis of these characteristics, we describe this parasite as Kudoa megacapsula n. sp. Morphological and molecular analyses of the myxozoan from splendid alfonso identified it as K. thyrsites, which has been described from many marine fishes. To our knowledge, this is the first record of K. thyrsites in splendid alfonso.