Systematics of dactylogyrids (Platyhelminthes, Monogenoidea) parasites of fishes of the family Pimelodidae from the Amazon and Parana rivers basins, Brazil

Author(s)

Julio Cesar Cenci Aguiar

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2017-08-28

Examining board members

Edson Aparecido Adriano; Marlene Tiduko Ueta; Maria Isabel Müller; Ricardo Massato Takemoto; Silmara Marques Allegretti

• Advisor: Edson Aparecido Adriano; Marcus Vinicius Domingues

Abstract

Dactylogyrids (Monogenoidea) probably represent the helminth group with largest diversity and abundance on the planet. Therefore, recognizing this diversity and understanding the evolutionary histories that shaped and led them to an adaptive radiation process is a current challenge. These parasites had their greatest success associated with freshwater fish, in which could eventually lead to disease and even induce host death. In the Neotropical region, habitat of the richest freshwater fish fauna in the world, dactylogyrids are not uniformly associated with these fishes, but best represented by the association to characiform hosts (54% of the diversity of Dactylogyridae), siluriform (24%) and perciform (14%). The greatest advances in the knowledge of this diversity of dactylogyrids occurred in the 1960s, but it is still characterized as incipient, mainly in relation to phylogenetic systematics. Thus, there are indications that less than 5% of this dactylogyrid diversity has been revealed for the Neotropical region, and this is result of the paucity of studies for many hosts species. In recent years, the parasitic dactylogyrids of siluriform from the Neotropical region have been receiving more attention and some dozens of species have been described in the last decade. This parasite host system has been considered as an interesting model to infer biogeographic hypotheses and co-evolution. However, to advance in this theme is necessary to have a minimum of knowledge about the relationship among the lineages. The present study provides results that allow advances in the understanding of evolutionary relationships within Dactylogyridae. These data were based on studies of phylogenetic systematics of parasitic dactylogyrids of pimelodid fish from the Amazonas and Paraná rivers basins, Brazil. The molecular phylogenetic inferences were potentiated by the development of new primers and the results obtained are presented in three chapters: the first chapter provides the description of a new species of Pavanelliella found parasitizing Brachyplatystoma rousseauxii, and based on the sequencing of the 18S partial rDNA and ITS1 corroborated the monophyly of the genus; the second chapter provides the description of a new species of Ameloblastella parasitizing Phractocephalus hemioliopterus and based on the sequencing of the D1-D3 regions of 28S rDNA, has been proposed a hypothesis of phylogenetic relationship for dacthylogirids; the third chapter was strongly based on the study of parasitic dactylogirids of P. hemioliopterus from Amazon river basin, but also of Hoplias malabaricus and Pimelodus maculatus from Paraná River basin. In this chapter, was described one species of Demidospermus, two species previously considered incertae sedis were transferred to this genus and the erection of a new genus was proposed. All proposals of the third chapter were supported by phylogenetic inference based on the complete 18S rDNA sequencing. The results obtained during the development of this thesis allowed to understand partially the complex evolutionary history of dactylogyrids, which may involve numerous events of secondary colonization of the marine environment, and reinvasions of freshwater environments, in addition to independent colonizations of phylogenetically close hosts from phylogenetically distant hosts (AU)

• FAPESP's process: 13/20770-5 - Taxonomy and molecular systematic of Monogenoidea (Platyhelminthes: Cercomeromorpha) parasites of four fish species of the family Pimelodidae (Siluriformes)from the Tapajós River, PA
• Grantee: Julio Cesar Cenci de Aguiar
• Support Opportunities: Scholarships in Brazil - Doctorate