Microsporidia <i>Glugea</i> sp. Found in the Abdominal Cavity of Wild Surge Grouper <i>Epinephelus socialis</i> Caught in the Ogasawara Islands, Japan

Numerous blackish-brown foreign bodies of varying sizes were found in the abdominal cavity of a wild surge grouper Epinephelus socialis caught by angling in the Ogasawara Islands, Tokyo, Japan, in June 2023. ​These contained ellipsoidal to pyriform microsporidian spores, with a mean length of 5.9 μm and a width of 2.7 μm. ​Sequencing of the small subunit rRNA gene of the spores revealed a close phylogenetic relationship with Glugea microsporidia, including Glugea epinephelusis, G. nagelia, G. arabica, G. serranus, and G. eda. ​This suggests that the microsporidia belong to the genus Glugea and that the foreign bodies within the surge grouper's abdominal cavity were Glugea cysts. ​This study represents the first report of Glugea sp. parasitizing surge grouper.