RESUMO
A new lung-dwelling nematode species is described from the common lancehead Bothrops atrox (Linnaeus) in the Brazilian Amazon Region. The species is assigned to the genus Serpentirhabdias Tkach, Kuzmin & Snyder, 2014 based on the presence of six lips arranged in two lateral groups, the absence of prominent cuticular inflations, and lung parasitism in snakes. Serpentirhabdias atroxi n. sp. differs from other species of the genus mainly by details of the morphology of the anterior end: cuticularised ring surrounding the anterior part of the buccal cavity and six minute onchia present in the oesophastome. Serpentirhabdias atroxi n. sp. is the seventh species of the genus known from the Neotropical Realm and the second species described from viperid snakes.