LAUSR

PURPOSE Myxosporeans of the genera Kudoa and Unicapsula (Cnidaria: Myxozoa: Myxosporea: Multivalvulida) may be causative agents of diseases that substantially lower the commercial value of certain marine fishes; thus, species identification is important to effectively manage outbreaks and control infections. METHODS AND RESULTS Our investigations of commercial fishes in the families Leiognathidae (three species), Ambassidae (one), Carangidae (five) and Gerreidae (one) in the South China Sea revealed new host records for Kudoa lutjanus (Ambassis martanus, and Gerres limbattus), Kudoa trachuri (Decapterus maruadsi, and Decapterus macrosoma), Kudoa uncinata (Photopectoralis bindus), and Kudoa longichorda (D. macrosoma) and new geographical distribution records for Kudoa javanensis (Alepes djedaba), K. trachuri, and K. longichorda. Moreover, three new Kudoa spp. were described based on detected specimens forming pseudocysts in trunk muscle myofibres. These included Kudoa corniculata n. sp. from Eubleekeria jonesi, and Leiognathus equulus; Kudoa hirsuta n. sp. from Trachurus japonicas, D. maruadsi, and D. macrosoma; and Kudoa parvibulvosa n. sp. from Megalaspis cordyla. To identify these species, their myxospores were morphologically and molecularly characterised based on the small and large subunits of their ribosomal RNA genes. CONCLUSIONS In this study, we demonstrated morphometric variations in the myxospores of various species and an atypical K. uncinata morphotype with unequal polar capsules. Hence, taxonomic identification of myxosporeans require molecular characterisation.