Taxonomia e ecologia dos parasitos branquiais de Serrasalmus marginatus Valenciennes, 1837 (Characiformes: Serrasalminae) da planície de inundação do alto rio Paraná, PR/MS, Brasil.

Abstract

Serrasalmus marginatus Valenciennes, 1837, is one of the most abundant species in the upper Paraná River floodplain and started to occur in this region after the flooding of the Sete Quedas Falls, by the construction of the reservoir of Itaipu in 1983. Sixty-one specimens were collected in the upper Paraná River floodplain, Brazil, from lagoons of the subsystems Paraná, Ivinheima and Baia in February 2008, with the aim to study gill parasites. Parasites of 15 taxa were collected, from three metazoan groups: Monogenea, Digenea and Acarina. Fish presented high diversity of species of monogeneans of the family Dactylogyridae, subfamilies Anacanthorinae and Ancyrocephalinae, differentiated mainly by the morphological characteristics of the sclerotized structures (haptoral sclerites and copulatory complex). The host's standard length (LS), sex and relative condition factor (Kn), in general, did not influence the prevalence, richness, abundance and diversity of parasites. Abundance, richness, dominance, Brillouin diversity and co-occurrence patterns of parasites, as well as ordination gradients based on the abundance, indicated differences between the infracommunities of gill parasites of the subsystems, mainly between the subsystems Paraná and Baia. Regarding the gill parasites of S. marginatus, the Ivinheima subsystem presented an intermediate position in relation to the others. The absence of interspecific associations between the most prevalent and abundant parasites in the analyzed subsystems and the lack of correlations between the infrapopulations of parasites and the characteristics of each host, demonstrate the important role of the habitat in the structure of the infracomunities of gill parasites on S. marginatus from the subsystems of the upper Paraná River floodplain.