Taxonomy, systematics and phylogeny of monopisthocotylans (Platyhelminthes: Monopisthocotyla) parasites of fish from Pindaíba River, Mato Grosso

• Grant number: 25/07772-6
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: December 01, 2025
• End date: February 29, 2028
• Field of knowledge: Biological Sciences - Zoology - Taxonomy of Recent Groups
• Principal Investigator: Reinaldo José da Silva
• Grantee: Melissa Miyuki Osaki Pereira
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

The Neotropical region is renowned for its rich diversity of freshwater fishes, which host a significant variety of parasites that play a fundamental role in regulating host populations and structuring aquatic communities. Among these parasites, monopisthocotyls stand out, ectoparasitic helminths belonging to the phylum Platyhelminthes, which exhibit remarkable diversity and a high frequency of occurrence in the region's fish fauna. Research on these parasites in Brazil is expanding, with over 80 genera proposed, indicating great potential for the description of new species. The present study aims to investigate the taxonomy, systematics, and phylogeny of monopisthocotyls associated with fishes collected from the Pindaíba River, Mato Grosso state, using both morphological and molecular methods, including ribosomal markers (SSU rDNA and LSU rDNA) and mitochondrial markers (COI). Collections will be carried out at strategic locations along the Pindaíba River, an important tributary of the Mortes' River, which is part of the region's hydrographic basin. The study began in 2024, with fish specimens obtained in August 2024 and March 2025, totaling 152 individuals belonging to 46 species. Preliminary analysis of infestation sites in 14 of these specimens (skin surface, nostrils, and gills) revealed the presence of parasites from two main families: Diplectanidae and a greater diversity within Dactylogyridae. The identified genera include Ameloblastella, Cosmetocleithrum, Demidospermus, Euryhaliotrema, Mymarothecioides, Pavaneliella, Rhinoxenus, Vancleaveus, and Whittingtonocotyle, highlighting the initial diversity of the parasitic fauna in the locality. These findings emphasize not only the sanitary relevance of monogeneans, given their high occurrence in native fishes, but also the need to expand the existing dataset to allow for more accurate inferences regarding these organisms. The combination of morphological and molecular tools is essential for the precise definition of species and genera, as well as for understanding the monophyly of groups and identifying new species. Accordingly, new data will be acquired as analyses progress, increasing our understanding of parasite diversity in fish from the Pindaíba River and, consequently, in the Neotropical region, while also contributing to the advancement of knowledge on parasitic biodiversity in Brazil and the structure of parasitic communities. (AU)