Integrative taxonomy, phylogeny and coevolution of monogenoids (Platyhelminthes: Cercomeromorpha) parasites of Ariidae (Osteichthyes: Siluriformes) from Brazilian coast

Author(s)

Geusivam Barbosa Soares

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2023-06-06

Examining board members

Edson Aparecido Adriano; Silmara Marques Allegretti; Simone Chinicz Cohen; Ricardo Massato Takemoto

• Advisor: Edson Aparecido Adriano; Marcus Vinicius Domingues

Abstract

This study, through integrative approaches, focused on knowing and describing the diversity of monogenoid parasites of Ariidae fish from the Brazilian coast, proposing phylogenetic hypotheses for the studied monogenoids, testing the evolutionary validity of their taxa by proposing taxonomic changes compatible with the obtained results, and elucidate the coevolutionary processes responsible for the diversification patterns of these parasites of Ariidae from the Atlantic coast of South America. The study is presented in the form of chapters. In the Chapter I, based on morphological and molecular data (18S rDNA, ITS1, 5.8S rDNA, and ITS2), is described a new monogenoid species, with the proposal of a new genus, as well as the evaluation of the phylogenetic relationships between monogenoids that parasitize Siluriformes from Oriental region. In Chapter II is described a new Udonellidae species found parasitizing Ariidae in the Brazilian coast. Based on morphological and molecular analyses (18S rDNA), it was possible to distinguish the new species from other valid species, and through phylogenetic analyses, a close relationship was found between the new species and Udonella australis, in a subclade of species that parasitize South American fishes. Based on these data, a possible scenario of initial radiation for globally distributed udonellids was discussed. In Chapter III, also using morphological and molecular analyses (18S rDNA), was possible to describes a new Chauhanellus species found in the gills of Ariidae in the South Brazilian coast, redescribes Chauhanellus velum, and provide new 18S rDNA sequences of several other Chauhanellus species parasitic to Ariidae from South America were provided. The 18S rDNA based phylogenetic reconstruction suggested that the new Chauhanellus species and C. velum are the first two divergent lineages of Chauhanellus from South America. Finally, it was possible to provide a pathway for future investigations seeking to test the monophyly of Chauhanellus and Hamatopeduncularia. With knowledge of the monogenoid species that occur in Ariidae, their phylogenetic relationships, and the associations between these parasites and their hosts, the Chapter IV closes the thesis with the application of a new coevolutionary approach, called Cophylospace, which allowed understanding the coevolutionary relationships between monogenoids and their Ariidae hosts from the Atlantic coast of South America. Sequences of the Cytb and RAG2 genes of host species and 18S rDNA, ITS1, 5.8S rDNA, and ITS2 of monogenoid species were used for phylogenetic reconstruction. The phylogeny of the parasites obtained in this study represents the first complete phylogenetic hypothesis of monogenoids parasitizing Ariidae in South America. The morphology of the anchor of the monogeneans, based on Procrustes coordinates, was used to assess whether closely related hosts are associated with morphologically similar parasite species. To evaluate the association between the parasite's phylogeny and the host morphology, a distance matrix based on morphological characters of the Ariidae was produced. The agreement between phylogenies and between phylogeny and morphology was measured using Procrustes R2 computed with Procrustean Approach to Cophylogeny (PACo). The Cophylospace analysis suggested that while the phylogenetic and morphological distance of monogenoids contributes similarly to explaining the pattern of parasite-host associations, the phylogeny of the parasites is more strongly associated with the morphological characteristics of the hosts than with the host phylogeny. This evidence suggests that cospeciation is not the major force that has driven the diversification of the studied monogenoids, and that the morphological traits of the hosts seem to be a the most important force. This result is consistent with evidence from other monogenoid-host systems (AU)

• FAPESP's process: 17/17531-0 - Integrative taxonomy, phylogeny and coevolution of monogenoids (Platyhelminthes: Cercomeromorpha) parasites of Ariidae (Osteichthyes: Siluriformes) from Brazilian Coast
• Grantee: Geusivam Barbosa Soares
• Support Opportunities: Scholarships in Brazil - Doctorate