Proteocephalids (Eucestoda: Onchoproteocephalidea) parasites of fishes from the Upper Parana Basin: diversity, phylogenetic relationships, and host-parasite associations

Abstract

South America has the highest diversity of freshwater fishes in the world. Fishes of the order Siluriformes and cichlids of the genus Cichla (Cichlidae), besides their high economic and recreational value, represent an important fraction of these ecosystems, playing an essential ecological role for the maintenance of the local biological diversity. Likewise, the proteocephalidean cestodes (Onchoproteocephalidea) may serve as important models for studies on the management and conservation of biodiversity, due to their intimate association with these fishes and the high richness of species. However, only a small portion of these parasites is known to science, usually described either based on an incomplete or inaccurate morphological characterization. Moreover, the evolutionary history of the group from the Neotropical region is unclear, considering the large polytomy formed by taxa in the recent phylogenetic analyses. These gaps make it hard to establish robust and unequivocal hypotheses concerning the validity of independent lineages/species and monophyletic groups and, hence, of all knowledge on the biodiversity of these organisms. Therefore, this research project aims at studying the diversity of proteocephalidean cestodes of siluriforms and Cichla spp. from tributaries of the Upper Parana in the State of São Paulo, through the integration of high-throughput sequencing strategies (mitogenomics), Sanger sequencing of established molecular markers, i.e. the large subunit nuclear ribosomal RNA gene (28S rDNA, D1-D3 domains) and the mitochondrial cytochrome c oxidase subunit I gene (COI), and morphological data (gross morphology, histology, and ultrastructure), to improve our understanding of the diversity, phylogenetic relationships, and host-parasite associations. (AU)