A new species of Demidospermus Suriano, 1983 (Monogenea, Dactylogyridae) parasitic on Loricariichthys platymetopon Isbrücker et Nijssen (Loricariidae, Siluriformes) from the Upper Paraná River floodplain, Brazil

Demidospermus paranaensis sp. nov. is described from the gills of Loricariichthys platymetopon Isbrücker et Nijssen (Loricariidae, Siluriformes) from the Upper Paraná River floodplain, Brazil. This new species differs from other members of Demidospermus in the following features: tegument with annulations throughout trunk and peduncle, eyes absent, longer male copulatory organ (MCO) with ovate base. Demidospermus paranaensis sp. nov. is similar to its congenerics by having tandem gonads, a counterclockwise-coiled MCO, non-articulated groove-like accessory piece serving as a MCO guide, sinistral vaginal aperture, and V-shaped haptoral bars.