New data on flatfish scuticociliatosis reveal that Miamiensis avidus and Philasterides dicentrarchi are different species

• Published in: Parasitology
• Main Authors: Felipe, Ana Paula de, Lamas, Jesús, Sueiro, Rosa-Ana, Folgueira, Iria, Leiro, José-Manuel
• Other Authors: European Commission, Xunta de Galicia
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2017
• Subjects: Paralichthys adspersus; Scophthalmus maximus; Scuticociliates; SSUrRNA gene; α-β-tubulin gene; Turbot
• Online Access: http://hdl.handle.net/10261/177213; https://doi.org/10.1017/S0031182017000749; https://doi.org/10.13039/501100000780; https://doi.org/10.13039/501100010801

ParaFishControl is coordinated by Spanish National Research Council (CSIC). Scuticociliatosis is a severe disease in farmed flatfish. However, the causative agent is not always accurately identified. In this study, we identified two isolates of scuticociliates from an outbreak in cultured fine flounder Paralichthys adspersus. Scuticociliate identification was based on morphological data, examination of life stages and the use of molecular approaches. The isolates were compared with a strain of Philasterides dicentrachi from turbot Scophthalmus maximus and with a strain deposited in the American Type Culture Collection as Miamiensis avidus ATCC® 50180™. The use of morphological, biological and molecular methods enabled us to identify the isolates from the fine flouder as P. dicentrarchi. Comparison of P. dicentrachi isolates and M. avidus revealed some differences in the buccal apparatus. Unlike P. dicentrarchi, M. avidus has a life cycle with three forms: macrostomes (capable of feeding on P. dicentrarchi), microstomes and tomites. Additionally, we found differences in the 18S rRNA and α- and β-tubulin gene sequences, indicating that P. dicentrarchi and M. avidus are different species. We therefore reject the synonymy/conspecificity of the two taxa previously suggested. Finally, we suggest that a combination of morphological, biological, molecular (by multigene analysis) and serological techniques could improve the identification of scuticociliates parasites in fish. This study was financially supported by grant AGL2014-57125-R from the Ministerio de Economía y Competitividad (Spain), by grant GPC2014/069 from the Xunta de Galicia (Spain) and by PARAFISHCONTROL project. This project received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 634429. Peer reviewed