Two new species of Heligmonellidae, coparasites of Mastomys natalensis from Benin are described. Heligmonina kotoensis n. sp. belongs to the Heligmonina species with a 1-3-1 pattern for the right lobe of the caudal bursa and 1-4 for the left lobe. In H. kotoensis n. sp., H. thamnomysi (Durette-Desset, 1966) and H. bignonensis Diouf, Bâ & Durette-Desset, 1997, the dorsal ray is deeply divided. Heligmonina kotoensis n. sp. is differentiated from H. thamnomysi by the strong asymmetry of rays 8 and a different pattern of the synlophe. It is differentiated from H. bignonensis by the length of the left ala, which is less than the diameter of the body, by thick left ray 8 and by the length of the vestibule, which is twice as long as the sphincter. Neoheligmonella lamaensis n. sp. is related to N. mastomysi Diouf, Bâ & Durette-Desset, 1998 and N. skirringi Diouf, Bâ & Durette-Desset, 1998, both parasites of Mastomys erythroleucus from Casamance, by the features of the synlophe (dorsal ridge of the carene well developed, no gradient of size of the ridges on the ventral side). N. lamaensis n. sp. is differentiated from both species by the ratio of the length of the spicules to the length of the body and from N. mastomysi by the number of cuticular ridges and by rays 8 arising symmetrically from the dorsal ray. It is distinguished from N. skirringi by the length of the dorsal ridge of the carene which is smaller than the ventral ridge and by rays 2 and 3 being parallel to the body.
Nematoda, Trichostrongylina, Heligmosomoidea, Heligmonellidae, Nippostrongylinae, Heligmonina kotoensis n. sp., Neoheligmonella lamaensis n. sp., Muridae, Benin, parasites, new species.