Life cycle of Isospora vittati n. sp. (Apicomplexa: Eimeriidae) infecting the bridled skink Trachylepis (Syn. Mabuya) vittata (Reptilia: Scincidae) in Egypt with checklist of Isospora spp. infecting the Egyptian reptilian fauna

Abstract The developmental stages of a new Isospora species, I. vittati, were described from the bridled skink Trachylepis vittata for the first time in Egypt. Fifty four skinks were collected in April and May 2019 from Baltim, Kafr El Sheikh Governorate, Egypt and examined for the presence of Coccidia. The prevalence recorded as 24.1% and it was higher in males than females. Oocysts were shed unsporulated, in early stages of sporulation and rarely sporulated. Events of sporulation and sporulation time were described. The sporulated oocysts, limited by bilayered wall, were spherical to subspherical measuring 21-25.6 x 19.2-23.4 μm. No micropyle, polar granule or oocyst residuum was noticed. The sporocysts were ovoid to ellipsoidal measuring 13.2-15 x 8.5-9.5 μm. Stieda, substieda bodies and sporocyst residuum were present. Experimental infection by sporulated oocysts was carried out and the developmental endogenous stages (merogony and gamogony) were followed up and described. The prepatent and patent periods were 6 and 4 days, respectively. Endogenous stages took place in the lamina propria and enterocytes of small intestine of the experimentally infected skinks. One generation merogony was occurred at 24-72 h p.i. The mature meronts measured 5.5- 18.8 x 5.4-17.3 μm and yielded up to 28 merozoites. Gamogony occurred at 84-96 h p.i. The mature microgamonts measured 11.1-12.6 x 8.4-11.2 μm and contained 16-40 small nuclei while the mature macrogamonts measured 15.2-18.2 x 14.8-16.4 μm and contained a large central nucleus and the two types of wall-forming bodies. Newly-formed zygotes or young oocysts were seen at 120 h p.i. measuring 16.8-20.2 x 14.2-17.8 μm. In addition, the checklist of Isospora spp. infecting the Egyptian reptiles, including the present species, was provided.