Occurrence of scuticociliatosis in olive flounder Paralichthys olivaceus by Phiasterides dicentrarchi (Ciliophora: scuticociliatida).

In the course of identifying scuticociliates recently obtained from systemically infected olive flounder Paralichthys olivaceus in Korea, we found a scuticociliate species whose small subunit ribosomal RNA (SS rRNA) gene was not amplified by species-specific primers previously designed for Uronema marinum and Pseudocohnilembus persalinus. By studying morphological characteristics of wet-mounted and stained specimens, we identified the species as Philasterides dicentrarchi, which has been reported to cause systemic infection in the European sea bass Dicentrarchus labrax and turbot Scophthalmus maximus. In this study, we compared morphological characteristics of our specimens with previously reported Philasterides species, including P. dicentrarchi, and sequenced the SS rRNA gene in order to design P. dicentrarchi specific primers. This is the first report on scuticociliatosis caused by P. dicentrarchi from marine fish in Asia.