Isospora ohioensis sp. n. proposed for I. rivolta of the dog

A new name, Isospora ohioensis, is proposed for I. rivolta-like oocysts from dog feces. The name I. rivolta is retained for the cat species. The structure of the oocysts of I. ohioensis is described from a cloned culture of oocysts. Oocysts are 24 by 21 mum, sporocysts 17 by 12 mum, and sporozoites 10 by 3 mum. In cross-infection experiments none of 6 coccidia-free dogs shed oocysts after consuming feline I. rivolota, and none of 4 coccidia-free cat shed oocysts after eating canine I. rivolta.