Interspecific Variability of Filarioid Nematodes of the Genus Setaria Viborg, 1795 Occurring in Wild Ruminants in Europe: A Review

Abstract Nematodes of the genus Setaria (Spirurida, Filarioidea) are parasites of vertebrates except fish. Dangerous are their larvae (microfilariae) that may migrate to the central nervous system of hosts causing serious neuropathic disorders of vertebrates including human. Setaria cervi, S. labiatopapillosa, and S. tundra are potential parasites in wild ruminants in Europe. The most recent studies of variability among Setaria spp. are based on a combination of morphometric and molecular methods. Although there is no clear consistency in the morphological structures used by different authors, a morphological key was compiled based on the body length, the arrangement of peribucal crown, and the number of papillae in the caudal part of the body. The barcoding system of Setaria genus is based on sequences of conserved gene polymorphisms such as COX1 and rDNA genes. The published sequences of COX1 gene in Setaria populations were analysed using in silico phylogenetic analysis by the maximum likelihood method (Tamura-Nei model). This analysis confirmed that the COX1 nucleotide polymorphisms genes are species-specific and represent the theoretical basis for the development of markers enabling barcoding system in the genus Setaria.