The evolutionary line of Dipetalonema can apparently be divided into four groups: I: Australian species; II: paleoendemic South American species; III: the Tetrapetalonema group; IV: the Acanthocheilonema group. Loxodontofilaria at present insufficiently known to be classified and several species belonging to the Acanthocheilonema group are the object of the present study. Descriptions are given of Loxodontofilaria asiatica n. sp., parasite of Elephas indicus in Burma, Cercopithifilaria degraaffi n. sp., parasites of Papio ursinus in South Africa, C. cephalophi n. sp., parasite of Cephalophus dorsalis and C. gabonensis n. sp., parasite of Atherurus africanus in Gabon. Additional morphological data are given on Cercopithifilaria didelphis, C. rugosicauda, Acanthocheilonema pachycephalum, A. viteae, Molinema dessetae, Dipetalonema gracile, Orihelia sp., Skrjabinofilaria skrjabini, Breinlia (B.) spratti, Litomosa sp., Loxodontofilaria hippopotami. Yatesia n. gen. with type species Yatesia hydrochoerus (Yates, 1980), is proposed, distinguished by specialized characters of the posterior extremity. The genus Cercopithifilaria is used to accomodate species considered as specialized Acanthocheilonema. Chenofilaria is placed in synonymy with Acanthocheilonema. Loxodontofilaria includes the three filarid species from elephants, L. loxodontis, L. gossi, L. asiatica n. sp. and the species from the Hippopotamus, L. hippopotami; D. okapiae is considered a species inquirenda. The interpretation given for the neotropical fauna is the following: --Skrjabinofilaria, Orihelia, Dasypafilaria and Dipetalonema may be true paleoendemics in South America. --Molinema and Ackertia on the one hand and Yatesia on the other may be forms of African origin introduced at the end of the Eocene during the migration of African rodents into South America. The cpature in American reptiles (the genus Macdonaldius) could have occurred during this period. --Surprisingly, the two species of Dipetalonema in Didelphis may be late captures of neartic origin: A. pricei from Acanthocheilonema in carnivores and C. didelphis from a Cercopithifilaria in eutherian mammals.