AbstractPterygodermatites (Paucipectines) zygodontomis, a nematode parasite of the small intestine of the rodentNecromys lasiurus, from Uberlândia, Minas Gerais state, Brazil, was analysed by light and scanning electron microscopy. Additionally, phylogenies were inferred from the mitochondrially encoded cytochromecoxidase I gene (MT-CO1). Details of the helminth surface, such as the oral aperture, cephalic papillae, papillae in the posterior region of the body and longitudinal cuticular elements represented by spine-like projections and fans are presented, adding new taxonomic details. Molecular phylogenetic analysis, based on the MT-CO1, demonstrated thatP. (P.)zygodontomisandPterygodermatites (Paucipectines) jaegerskioldiform a unique evolutionary unit in accordance with the subgenusPaucipectinesand corroborated their occurrence in cricetid and didelphid hosts.