Provided with a vast hydrographic system, Brazil stands out for the ichthyofaunistic freshwater diversity, which is also equivalent to the wide variety of fish parasites. These parasites however still need to be studied further due to their importance in the ecosystem, such as the stabilization of the food chain and regulation of the population of their hosts, also, as indicators of environmental quality. Widely distributed in South America, the fish species Steindachnerina insculpta that belongs to the family Curimatidae has so far thirteen helminth parasite species reported, including four monogeneans, three digeneans, five nematodes, and one acanthocephalan. However, only Sphincterodiplostomum musculosum metacercariae were previously sequenced and deposited in GenBank. Thus, the present study aims to evaluate the helminth fauna associated with S insculpta from the Pardo River, Salto Grande, São Paulo, and contribute to the molecular characterization of these parasites. The taxonomic study will be performed with helminths previously collected in 30 specimens of S. insculpta sampled with a sieve or seine net. Morphological and morphometric analyses of the parasites will be performed using a computerized image analysis system with Differential Interference Contrast. The ecological descriptors of parasitism (prevalence [P], mean intensity of infestation [IMI], and mean abundance [AM]) will be calculated. For molecular analysis, the DNA from parasite samples will be extracted and amplified. After obtaining the sequences, the phylogenetic reconstruction will be performed by the Maximum Likelihood and Bayesian Inference methods. This study is expected to contribute to the knowledge of fish parasite fauna in the Neotropical region.
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