Mazzanema n. gen. and Mazzanema fortuita n. comb. for Longistriata fortuita Freitas, Lent, and Almeida, 1937 (Nematoda: Heligmonellidae), a parasite of the marsh rat Holochilus chacarius (Rodentia: Cricetidae) from northern Argentina.

The species described as Longistriata fortuita Freitas, Lent, and Almeida, 1937 is here redescribed from new material collected from the type host, Holochilus chacarius balnearum Thomas, and the type locality, San Martín del Tabacal, Salta, Argentina. Neotypes are designed for the species since the type material deposited by the authors is lost. The original description did not include the synlophe or the female and both are here described.