A new species of Choleoeimeria (Apicomplexa: Eimeriidae) infecting the lizard Chalcides sepsoides (Sauria: Scincidae) in Egypt

Chalcides sepsoides collected from Nile Delta were infected with a new Choleoeimeria species. The prevalence of infection was 20 % (7/36). Oocysts were cylindrical, measuring 22.5 × 14 (20.6–24.7 × 11.8–15.9) µm. They were colorless with a smooth double–layered oocyst wall but lack micropyle, polar granules and oocyst residuum. Sporocysts were subspherical in shape, with a prominent meridional suture and measuring 7.6 × 6.5 (7.5–7.8 × 6.2–6.7) µm. Steida and substeida bodies were absent but sporocyst residuum, in the form of many coarse granules was observed. Each sporocyst contained two sporozoites. Sporozoites were banana shaped, each with a central nucleus and refractile body localized in one end. Sporozoite measured 10.6 × 2.0 (10.2–10.8 × 1.8–2.1) µm. When oocysts were preserved in 2.5% (w/v) potassium dichromate solution for about two weeks, excystation occurred and sporozoites were seen free within the oocyst. Endogenous development of the parasite was restricted to the biliary epithelium. Meronts at different stages of growth, microgamonts and macrogametes were described and measured. Hypertrophy of the infected host cells and their displacement above the epithelial layer was remarked.