Tetrameres numida n. sp. from the proventriculus of Helmeted guinea fowls, Numida meleagris, in South Africa is described from eight male and four female specimens. The new species shares some characteristics with other Tetrameres species, but can be differentiated by a unique combination of characters. It bears two rows of cuticular spines extending over the whole length of the body and possesses two spicules. The left spicule measures 1 699-2 304 ?m and the right one 106-170 mm. Caudal spines are arranged in three ventral and three lateral pairs and the tail is 257-297 mm long. Diagnostic criteria of some of the previously described species of the genus Tetrameres from Africa and other parts of the world have been compiled from the literature and are included here.