title: Evidence of multiple species of Chilodonella (Protozoa, Ciliophora) infecting Australian farmed freshwater fishes.
abstract: Parasitic Chilodonella species, Chilodonella piscicola and Chilodonella hexasticha, cause considerable economic losses globally to freshwater farmed fish production. Some genetic studies of Chilodonella spp. have indicated that many species within the genus may form cryptic species complexes. To understand the diversity of Chilodonella spp. infecting Australian freshwater farmed fish, specimens were isolated from infected barramundi (Lates calcarifer) and Murray cod (Maccullochella peelii) from fish farms in tropical north Queensland (QLD), temperate Victoria (Vic) and New South Wales (NSW) for genetic and morphological analysis. Parasites were stained and measured for morphological description and comparative phylogenetic analyses were performed using the mitochondrial small subunit (mtSSU) rDNA marker. Morphological analyses revealed four distinct morphotypes of Chilodonella infecting farmed barramundi and Murray Cod. Three putative species were isolated from barramundi (Chilodonella hexasticha, C. acuta and C. uncinata) and one from Murray cod (C. piscicola). However, phylogenetic analyses detected only three distinct genotypes, with the putative C. hexasticha and C. piscicola sharing 100% sequence identity. This suggests that Australian isolates of C. hexasticha and C. piscicola could represent the same species and may exhibit phenotypic plasticity. Further molecular analysis, including isolates from the type localities, should be performed to support or refute the synonymy of these species.
authors.affiliation: Marine and Aquaculture Sciences, College of Science and Engineering and Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, 4811, QLD, Australia. Electronic address: giana.bastosgomes@my.jcu.edu.au.
authors.forename: Giana
authors.initials: G
authors.lastname: Bastos Gomes
authors.affiliation: Marine and Aquaculture Sciences, College of Science and Engineering and Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, 4811, QLD, Australia; Fish Health Laboratory, Department of Fisheries Western Australia, South Perth 6151, WA, Australia.
authors.forename: Terrence L
authors.initials: TL
authors.lastname: Miller
authors.affiliation: Marine and Aquaculture Sciences, College of Science and Engineering and Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, 4811, QLD, Australia.
authors.forename: David B
authors.initials: DB
authors.lastname: Vaughan
authors.affiliation: Marine and Aquaculture Sciences, College of Science and Engineering and Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, 4811, QLD, Australia.
authors.forename: Dean R
authors.initials: DR
authors.lastname: Jerry
authors.affiliation: Department of Economic Development, Jobs, Transport and Resources, 5 Ring Road, Bundoora, VIC 3083, Australia.
authors.forename: Christina
authors.initials: C
authors.lastname: McCowan
authors.affiliation: Department of Economic Development, Jobs, Transport and Resources, Chief Veterinary Officer's Unit, 475 Mickleham Road, Attwood, VIC 3049, Australia.
authors.forename: Tracey L
authors.initials: TL
authors.lastname: Bradley
authors.affiliation: Marine and Aquaculture Sciences, College of Science and Engineering and Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, 4811, QLD, Australia.
authors.forename: Kate S
authors.initials: KS
authors.lastname: Hutson
mesh_terms: D000818:Animals; D016770:Ciliophora Infections / Q000469:parasitology / Q000662:veterinary*; D060085:Coinfection / Q000662:veterinary; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005393:Fish Diseases / Q000469:parasitology*; D016803:Hymenostomatida / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000648:ultrastructure; D009517:New South Wales; D010473:Perciformes; D010802:Phylogeny; D011793:Queensland; D014739:Victoria
chemical_list: D004272:DNA, Mitochondrial; D016054:DNA, Protozoan; D004275:DNA, Ribosomal
keywords: Aquaculture; Chilodonella hexasticha; Chilodonella piscicola; Ciliate; Fish parasite; mtSSU rDNA