Two new species of Litomosoides (Nematoda: Filarioidea) in Sigmodontines (Rodentia: Muridae) from Rio de La Plata marshland, Argentina.

Two new species of coelomic filarioid belonging to Litomosoides are described from sigmodontine murids from the Rio de La Plata marshland, Argentina. Litomosoides bonaerensis n. sp., a parasite of Oligoryzomys delticola, belongs to the carinii group and is close to L. silvai, which differs by the head and tail papillae, buccal capsule and cavity, area rugosa, and morphology of the microfilaria. Litomosoides oxymycteri n. sp., from Oxymycterus rufus, belongs to the sigmodontis group. Differential diagnosis is based on the morphology of the buccal capsule, the head and tail papillae, and microfilaria. The ectoparasitic gamasid Ornithonyssus bacoti, in which several Litomosoides species develop, has been recovered from sigmodontines trapped in the study.