Bradynema listronoti n. sp. was collected from the haemocoel of adults and the environment of the carrot weevil, Listronotus oregonensis in Quebec, Canada. It is the first species of Bradynema to be reported from weevils and is described and illustrated herein. Bradynema listronoti n. sp. appears to be closest to B. trixagi because of the shared characteristic of a peloderan bursa in males which is not present in the other seven described species in the genus. Bradynema listronoti n. sp. can be differentiated from all members of the genus by the possession of a degenerate, but sometimes visible, stylet remnant, non-degenerate pharynx in males and by the often dorsally-curved C-shaped body (ventral side is convex) of parasitic females. The vestigial stylet in all stages argues for placement of B. listronoti n. sp. within the genus Bradynema, but some characteristics, such as a non-degenerate pharynx in males, suggest placement in a new genus or affinities with other genera in the Allantonematidae, e.g., Allantonema. Molecular analysis of the near full length SSU, D2/D3 expansion segments of the large subunit (LSU) rDNA and partial mitochondrial DNA COI (mtCOI) suggest that this nematode is unique and D2/D3 analysis supports monophyly with B. rigidum, the only other member of the genus to be sequenced.