Polyopisthocotylid Monogenean Infections of Amberjacks Seriola spp. in Japan

Abstract

Development of Zeuxapta seriolae (Monogenea: Polyopisthocotylea, Heteraxinidae) collected from Seriola dumerili was described and compared with that of Heteraxine heterocerca, the same heteraxinid species from Seriola quinqueradiata. ​Based on the morphology of the two monogeneans from very young with a symmetrical body to adult, specimens retrieved from the gills of cultured and wild Seriola spp. (S. quinqueradiata, S. dumerili and S. aureovittata) collected in Japan and its adjacent areas during 1975–2019 were identified. ​Heteraxine heterocerca, previously known only from S. quinqueradiata and S. dumerili, was also recorded from S. aureovittata, and Z. seriolae hitherto known only from S. dumerili and S. aureovittata, was recorded from S. quinqueradiata. ​As a result, both H. heterocerca and Z. seriolae were confirmed from all the three Seriola spp. ​Cultured S. quinqueradiata and S. aureovittata were often infected with both H. heterocerca and Z. seriolae, whereas wild Seriola spp. were infected with a single species of gill monogenean. ​Culture seeds of foreign origin should be monitored continuously, as information on the polyopisthocotylean monogenean infections of Seriola species known outside Japan is quite limited.