A redescription of the type specimens of the three following species is given: L carinii (Travassos, 1919) from Sciurus sp. in Brazil. L, sigmodontis Chandler, 1931 from Sigmodon hispidus and L. scotti Forrester et Kinsella. 1977 from Oryzomys palustris in North America. A description of two brazilian species is also given: L. galizai n. sp. from (Ecomys trinitatus tapajinus and L. kohnae n. sp. from Nectomys squamipes. The conclusions are: The type species of the genus Litomosoides: L. sigmodontis, and L.carinii are two distinct species. As a result, the filaria which is widely used in drug trials has to be reinstated sigmodontis and not curinii. With the exception of the two parasite species of Geomyid rodents, which show affinities with the genus Litomosa, the species of Litomosoides may be devided into two groups, principally based on the morphology of the spicules: the sigmodontis group, with 13 species; the carinii group, with 8 species. Each group includes parasites of Chiuroptera, Marsupials and Rodents. The two new species (L. galizai and L. kohnae) belong to the group sigmodontis; they are characterised by the shape of the buccal capsule, the size of the spicules, the structure of the female body-wall and the microeilaria.