Microparasitos eucariotos de Pristobrycon striolatus (Steindachner, 1908) (Characiformes: Serrasalmidae) e Hemiodus gracilis (Günther, 1864) (Characiformes: Hemiodontidae) oriundos do rio Tartarugalzinho, estado do Amapá, Amazônia Oriental

Abstract

The Amazon biome is one of the greatest biological treasures on Earth and an important component of the terrestrial system, it has great biodiversity and is home to one of the largest hydrographic basins on the planet, the Amazon basin. The state of Amapá is located within the Eastern Amazon and has a large number of rivers in its territory, among which is the Tartarugalzinho River, which is a river of importance for fishing, since it holds a large ichthyofauna. The main objective of this study was to investigate the microparasitic fauna of Pristobrycon striolatus and Hemiodus gracilis, both were fish species from the Tartarugalzinho River, state of Amapá, Eastern Amazon. The species Pristobrycon striolatus is distributed in South America, mainly in the Amazon and Orinoco rivers, has few studies about its parasitic fauna. Thirty specimens of P. striolatus were collected and macroscopic and microscopic parasitological analyzes were carried out in the laboratory, which found that it was parasitized by two microparasite taxa with the following prevalence: Phylum Cnidaria: Myxozoa represented by Henneguya sp. (16%), Myxobolus sp. (13%) and Meglitschia sp. (3.3%) and Phylum Apicomplexa represented by Calyptospora sp. (3.3%). Hemiodus gracilis is a species of fish popularly known as "southern cruise fish", it has a maximum size of 16 cm and is of ornamental importance. Forty specimens of H. gracilis were collected and later parasitological investigation analyzes were carried out using techniques previously described in the literature. The confirmation of the parasitism occurred after the visualization of the microparasite under light microscopy, which morphologically resembled members of the genus Ceratomyxa (Myxozoa) and had the host's gallbladder as the site of infection, with a prevalence of 82%, that is, 33 fish were parasitized. Then, a fragment of the infected organ was removed to perform the morphological analysis of the microparasite and later this same material was fixed in 80% alcohol to undergo molecular biology. The spores of Ceratomyxa tartarugalis n. sp. they were irregular in shape, with different sizes, asymmetrical, with spherical capsules and the following measurement values: 31.95±4.1 for length; 2.15±00.6 width and polar capsules had a length of 1.7±0.46 and a width of 1.31±00.6. The partial rDNA sequence of SSU Ceratomyxa tartarugalis n. sp. obtained in the present study had 1037 base pairs, of which 46.7% were G + C (A = 0.2780, C = 0.1890, G = 0.2567, T = 0.2763). Thus, it is possible to conclude that this study demonstrated that the fish species P. striolatus has a diverse microparasitic fauna, but with greater susceptibility to parasites of the Myxozoa Class and that through molecular and morphological methods it was possible to suggest a new species of microparasite Ceratomyxa tartarugalis n. sp. for H. gracilis.