Acanthocephalan parasites of the flounder species Paralichthys isosceles, Paralichthys patagonicus and Xystreurys rasile from Brazil / Acantocéfalos parasitos de espécies de linguados Paralichthys isosceles, Paralichthys patagonicus e Xystreurys rasile no Brasil

Abstract Flounders are commercially and economically important fish. A total of 120 specimens of flounders (60 Paralichthys isosceles, 30 Paralichthys patagonicus and 30 Xystreurys rasile) were collected off the coast of the state of Rio de Janeiro, Brazil. The fish were measured, necropsied and filleted, and then had their organs investigated for acanthocephalans. Taxonomic identification of the parasites was based on morphological, morphometric and genetic characters. Paralichthys isosceles and P. patagonicus were parasitized by juveniles of Serrasentis sagittifer, Bolbosoma turbinella, Corynosoma australe and C. cetaceum; Xystreurys rasile was parasitized by C. australe. Genetic characterization confirmed the identification of specimens of Bolbosoma turbinella and Corynosoma australe, as demonstrated by phylogenetic analyses using both ITS and cox1 molecular targets. Parasite indices of prevalence, intensity, mean intensity, abundance, mean abundance, and range of infection, as well as infection site, were evaluated for each parasite species. This is the first report of S. sagittifer parasitizing P. isosceles and P. patagonicus, and B. turbinella parasitizing P. patagonicus.

Resumo Os linguados são peixes comercial e economicamente importantes. Um total de 120 espécimes de linguados (60 Paralichthys isosceles, 30 P. patagonicus e 30 Xystreurys rasile) foram coletados no litoral do estado do Rio de Janeiro, Brasil. Os peixes foram medidos, necropsiados, filetados e tiveram seus órgãos investigados para a presença de acantocéfalos. A identificação taxonômica foi baseada em caracteres morfológicos, morfométricos e genéticos. Paralichthys isosceles e P. patagonicus estavam parasitados por acantocéfalos juvenis de Serrasentis sagittifer, Bolbosoma turbinella, Corynosoma australe e C. cetaceum; Xystreurys rasile estava parasitado com C. australe. A caracterização genética confirmou a identificação dos espécimes de Bolbosoma turbinella e Corynosoma australe, como demonstrado por análises filogenéticas usando ambos marcadores moleculares ITS e cox1. Foram analisados os índices parasitários: prevalência, intensidade, intensidade média, abundância, abundância média, amplitude de variação da infecção e sítio de infecção de cada espécie de parasito. Este é o primeiro registro de S. sagittifer parasitando P. isosceles e P. patagonicus, e de B. turbinella parasitando P. patagonicus.

Prevalence and molecular characterisation of Acanthocephala in pinnipedia of the North and Baltic Seas.

Harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) are final hosts of acanthocephalans in the German North and Baltic Seas. Parasitic infections in seals can cause pathological changes, which may result in deteriorated health of the host. Common gastrointestinal parasites of harbour and grey seals are acanthocephalans and a number of 275 of 2460 (11.2%) investigated seals from 1996 to 2013 were infected with Corynosoma spp. (Acanthocephala, Polymorphidae). The prevalence showed a wave-like pattern: it increased from 1.2% and 0.4% in 1996 and 1997, respectively, to 23.9% during the second phocine distemper epizootic in 2002 and decreased to 6.2% in 2004. In 2005, prevalence peaked again with 25.0% followed by a decrease to 9.3% in 2009 and an increase to 38.5% in 2012. Statistical analysis revealed that harbour seals originating from the North Sea showed a higher prevalence than grey seals, whereas no significant difference between grey and harbour seals from the Baltic Sea was observed. Furthermore, juvenile pinnipedia from the North Sea were significantly less infected with Corynosoma spp. than seals older than seven month. Molecular species identification as well as phylogenetic relationship analysis among the detected Corynosoma species were achieved by sequencing and comparisons of the ribosomal ITS1-5.8S-ITS2-complex and cytochrome-c-oxidase I gene. Molecular analysis resulted in a newly arranged distribution of Acanthocephala in the North Sea as in contrast to previous studies, C. strumosum could not be confirmed as predominant species. Instead, C. magdaleni and a C. magdaleni isolate (isolate Pv1NS) with an atypical number of longitudinal rows of hooks at the proboscis were detected. Furthermore, morphological and molecular analyses indicate the possible finding of a cryptic species (Candidatus Corynosoma nortmeri sp. nov.).