Morphological variability of Oswaldocruzia filiformis (Nematoda: Molineidae) in amphibians from European Russia

Abstract The morphological and morphometric variability of the nematode Oswaldocruzia filiformis from ten amphibian species ( Pelophylax ridibundus, lessonae, esculentus, Rana arvalis, temporaria, Bufo bufo, Bufotes viridis, Pelobates vespertinus, Bombina bombina Lissotriton vulgaris ) was studied. sampling performed during period 2018–2020 in fifteen localities European Russia. We examined following features: number crests mid-body level, shape lateral alae, cephalic vesicle, structure spicules males, male caudal bursa, dorsal ray bursa; measurements nine characteristics females seven characters subjected to variability. Significant differences O. both sexes different amphibians various regions were revealed. Likewise, significant revealed for most features same type bursa identical all males we have not found reproductive system females. Variability noted size vesicle at rib bursa. Differences Russia can be explained by phenotypic plasticity species. While variations morphology are caused host-induced parasite. nematodes their studied may changes ecological conditions habitats. broad increases adaptive capabilities helminth allows it parasitize a wide range hosts.