Isospora neorivolta SP. N. from the domestic dog

The endogenous development of canine Isospora rivolta (Mahrt, J Protozool 14: 754--759, 1967) was compared with the development of I. ohioensis (Dubey, Parasitology, 1978, In press) in intestines of dogs. A new name, Isospora neorivolta, is proposed for the canine I. rivolta because of developmental differences from I. ohioensis. The major difference between these 2 coccidia is their site of development. Isospora neorivolta develops predominantly in the lamina propria of the posterior half of the small intestine, whereas I. ohioensis develops only in the epithelium and infection occurs throughout the small intestine. Additional information on the development of I. neorivolta in dogs is given.