Redescriptions of Eimeria irresidua Kessel & Jankiewicz, 1931 and E. flavescens Marotel & Guilhon, 1941 from the domestic rabbit.

Eimeria flavescens and E. irresidua from the domestic rabbit are redescribed. The relatively smaller ovoidal oocysts of E. flavescens which measure on average 31.7 X 21.4 micrometer, possess a wide micropyle at the broad end. First-generation schizonts of this species develop deep in the glands of the lower small intestine. Merozoites migrate to the caecum and colon where second, third and fourth-generation schizonts develop in the superficial epithelium followed by the fifth-generation schizonts and gametocytes which form in the glands. In young Dutch rabbits E. flavescens is very pathogenic; low doses of oocysts produce a severe enteritis with high mortality and morbidity. The larger, broadly ellipsoidal oocysts of E. irresidua measure on average 38.4 X 23.2 micrometer and often possess a very small cryptic oocyst residuum. The endogenous stages develop in the small intestine only; first-generation schizonts in the glands and second-generation schizonts in the lamina propria whilst third and fourth-generation schizonts and gametocytes develop in the villous epithelium. E. irresidua is not pathogenic in young Dutch rabbits; even heavy infections produce only a transient pause in weight gain.