New species of Diaphorocleidus and Urocleidoides with a redescription of Curvianchoratus hexacleidus (Monopisthocotyla: Dactylogyridae) parasitizing characiform fishes from the Munim River Basin, northeastern Brazil.

During a study on the helminth fauna of fishes from the middle Munim River Basin, State of Maranhão, northeastern Brazil, specimens of Monopisthocotyla were found. Two new species of Diaphorocleidus from the gills of Knodus guajajara, a fish species endemic to the Maranhão coastal river basins, belonging to the Stevardiidae and a new species of Urocleidoides found parasitizing Steindachnerina notonota, a curimatid fish distributed along coastal river systems of northeastern Brazil are described. Additionally, Curvianchoratus hexacleidus is redescribed from S. notonota, a new host record. These findings highlight the remarkable but still underexplored parasitic diversity of the state of Maranhão, underscoring its significance for taxonomic research and for advancing the knowledge of monopisthocotyleans.