STEPHANOFILARIA THELAZIOIDES N-SP (NEMATODA, FILARIIDAE) FROM A HIPPOPOTAMUS AND ITS AFFINITIES WITH THE SPECIES PARASITIC IN THE AFRICAN BLACK RHINOCEROS

Stephanofilaria thelazioides n. sp. (Filarioidea: Filariidae: Stephano filariinae) is described from a hippopotamus Hippopotamus amphibius. T his nematode is close to S. dinniki Round, 1964, a parasite of the bla ck rhinoceros Diceros bicornis in Africa, but differs from it in the n umber of cuticular spines surrounding the mouth, the arrangement of th e cloacal papillae and the measurements of the spicules, gubernaculum and microfilariae. Species of the genus Stephanofilaria ia possess spi nes on the head which have been derived by modification of the sensory papillae. S.,thelazioides is the most primitive species of the genus and has the least modified arrangement of these papillae, with six bif id internal labial spines, four bifid external labial spines and four cephalic papillae, The genus appears to have diversified in various ma mmals which have in common a thick skin, such as rhinoceroses, elephan ts, buffaloes and now the hippopotamus. It appears to have become adap ted secondarily to domestic bovines, initially in Asia and subsequentl y in North America.