Endoparasite fauna of Brycon amazonicus and B. melanopterus(Characidae, Bryconinae) from Negro and Solimões rivers, Amazon, Brazil

ABSTRACTCongeneric host species present similar biological and behavioral aspects, what may favor the presence of a similar parasite fauna. The aim of the present study was to compare the composition and structure of the parasite community from congeneric species, Brycon amazonicus and B. melanopterus, collected on the Negro and Solimões Rivers. The fish internal organs were longitudinally opened and analyzed under stereomicroscope. The examination revealed that B. amazonicuswas parasitized by Procamallanus(Spirocamallanus) inopinatus(26.7% and 35.5%), Contracaecum type 2 (10% and 16.13%) and Rhabdochona acuminata(0% and 3.23%), prevalence values for Negro and Solimões River, respectively. The analysis of B. melanopterus, a fish species found only in the Solimões River, revealed P.(S.) inopinatus(33.3%), Contracaecum type 1 (60%) and R. acuminata(3.34%). These results indicate that the taxonomic proximity of the hosts was a stronger influence on the parasite species than external host environment.