Helmintos parasitos de jundiá, Rhamdia quelen (Quoy & Gaimard, 1824) (Siluriformes) coletados em ambiente natural em estação de piscicultura, no sul do RS

Abstract

Rhamdia quelen (jundiá) is distribuited from the center of Argentina until the south Mexico. Is native specie of the Rio Grande do Sul (Brazil), presenting characteristics like rusticity, fast growing, resilience to temperature and salinity alterations and high productivity, which ones facilitate their handling in fish farms, the meat of South American catfish is appreciated for the human consume. The aim of the first study was to know the fauna components of some group of helmintes parasites in Rhamdia quelen, the fishes were collected in a fish farm located in Arroio Grande County (RS – Brazil) and in their natural habitat in the São Gonçalo Canal (RS- Brazil). The necropsy of 81 animals was performed and their parasites were classified by stereomicroscopy, fixed in Alcohol – Phormol – Acetic Acid (AFA) and conserved in alcohol 70°. One sample of each species was stained with Semichon carmim, cleared Faia creosote and placed in permanent glass slides with Canadian balsam, after that the parasites were photographed, illustrated (when was necessary) and identified at the possible taxonomic level. The collected data about host and parasite were analyzed and confronted with the images, measures and biology of both with the information available to perform the identification. Were found four genus of Digenetic Trematods, three belonging to genus of Acanthocephala and one which belonging to genus of Hirudinea. Two new species were described, Digenetic and Acanthocephala,, respectively. Rhamdia quelen is new host for Tylodelphys destructor, Centrorhynchus sp. and Polymorphus sp. The second study analyzed the parasitologic levels founded in Rhamdia quelen through the prevalence, mean abundance and infection mean intensity. The Mann-Whitney test was used to calculate the difference of the infection mean intensity between the sites where the fishes were collected. The Acanthocephala Polymorphus sp. presented the higher level of prevalence, 30,86%. The Clinostomum complanatum presented the higher level of infection mean intensity and mean abundance, 45,84% and 10,75%, respectively. The parasites Genarchella sp. and Centrorhynchus sp. were analyzed presented a non significant level (p=0,05). The hosts were captured in the natural habitat were more infected than that ones from the fish farm.