Hidden diversity of camallanid nematodes in freshwater fishes: description of Procamallanus australiensis sp. nov. and implications for host range and parasite transmission

Context Parasites of Australian freshwater fishes remain poorly studied despite their ecological, aquaculture and biosecurity importance. Aims This study aimed to characterise selected helminth parasites collected from Australian freshwater fishes, by using morphological and molecular approaches. Methods Freshwater fishes from New South Wales and Queensland were examined for parasites by using visual inspection and incubation methods. Recovered nematodes were examined morphologically and genetically by using 18S rRNA, 28S rRNA and COI gene regions. Key results A new species, Procamallanus australiensis sp. nov., was identified from native freshwater fishes and the introduced mosquitofish, Gambusia affinis. Phylogenetic analyses demonstrated that the Australian specimens formed a genetically distinct lineage within the Camallanidae. In addition, acanthocephalan specimens tentatively identified as Acanthocephalus lucii were detected in Murray cod. Conclusions The findings showed previously overlooked parasite diversity in Australian freshwater ecosystems and provided the first integrative characterisation of Procamallanus from Australian freshwater fishes. Implications Improved knowledge of freshwater fish parasites is important for biodiversity research, aquaculture health management and understanding potential biosecurity risks associated with introduced species. ZooBank: urn:lsid:zoobank.org:pub:CFAB1B01-D9B2-4A0E-8A80-808EC49EDDDA