Integrated Description of Paradiplozoon gladysae n. sp. (Polyopisthocotyla: Diplozoidae), Parasitising the Gills of Labeo victorianus (Teleostei: Cyprinidae) in the River Nyando, Lake Victoria Basin, Kenya

Polyopisthocotylans of the Diplozoidae are hematophagous gill parasites of freshwater cyprinoids; however, their diversity in East African river systems remains poorly characterised. In this study, we describe Paradiplozoon gladysae n. sp., a novel diplozoid recovered from the gills of an endemic cyprinid Labeo victorianus Boulenger in the River Nyando, a tributary of Lake Victoria in western Kenya. An integrated approach combining light and scanning electron microscopy and molecular characterisation of ITS2 rDNA was used to examine the collected species. In general, P. gladysae n. sp. is distinguished from congeners by its small clamps and the unique morphology of its median plate. Molecular analysis of the ITS2 region of rDNA confirmed the genetic distinctiveness of the new species and placed the species within the highly supported clade of African species formed by P. koubkovae Řehulková, Nejat, Benovics, 2023; P. ichthyoxanthon Avenant-Oldewage, van Vuren, Mashego, 2013; and P. vaalense Dos Santos, van Vuren, Avenant-Oldewage, 2013, with P. vaalense being the closest sister taxon to the newly determined species. However, the analysis revealed a clear distinction, with a 39 bp difference and an uncorrected genetic p-distance of 6.8% between P. gladysae n. sp. and P. vaalense. The discovery of P. gladysae n. sp. adds to the growing diversity of diplozoid polyopisthocotylans in East Africa and highlights the River Nyando as an important but understudied hotspot for freshwater parasite biodiversity.