Blood smears from wild-caught, long-term captive tortoises, Testudo marginata, revealed the presence of gametocytes of a Hemolivia mauritanica-like hemogregarine in the erythrocytes of 72% tortoises examined. Significant parasitemia was also found in animals living several years in captivity. Experimentally infected tortoises showed no evidence of a decrease in parasitemia level more than 15 mo after infection. Morphologically, stages found in tortoises' erythrocytes were indistinguishable from those referred to by previous workers as H. mauritanica from Testudo graeca. Moreover, successful experimental transmission to Hyalomma aegyptium confirms the conspecificity with H. mauritanica. The occurrence of H. mauritanica gametocytes in tortoise living up to 8 yr in captivity is suggested to result from continuous, long-lasting cyclic merogony in tortoises' parenchymatous organs, which is an unknown phenomenon in the life cycle of Hemolivia spp.