Three New Species and a New Record of Aglaiogyrodactylus (Monopisthocotyla, Gyrodactylidea, Oogyrodactylidae) from Hisonotus spp. (Siluriformes, Loricariidae) in Brazil

Aglaiogyrodactylus Kritsky, Vianna & Boeger, 2007 comprises ectoparasitic metazoans recorded mainly on the body surface of loricariid fishes. Although the genus currently includes only eight species, its actual diversity remains largely underestimated. In this study, three new species of Aglaiogyrodactylus collected from specimens of Hisonotus spp. in Brazil are described, and a new locality record of Aglaiogyrodactylus pedunculatus Kritsky, Vianna & Boeger, 2007 is reported. The descriptions are based on diagnostic morphological characteristics, with the male copulatory organ as the main distinguishing structure. Aglaiogyrodactylus matildeae n. sp. presents an accessory piece composed of two branches: a sinistral spatulated branch and a dextral tubular branch. Aglaiogyrodactylus nonnae n. sp. possesses an accessory piece divided into three branches: two sinistral spatulated branches that serve as a guide for the male copulatory organ and a bifurcated dextral branch derived from an annular structure. Aglaiogyrodactylus marinae n. sp. presents an accessory piece formed by three branches, one spatulated sinistral branch with a semicircular end, and dextral branches with distal ends having inconspicuous digitiform projections. These descriptions expand the taxonomic knowledge of Aglaiogyrodactylus and document the occurrence of new lineages associated with Hisonotus spp. in southern Brazil.