Isospora pitiguari n. sp. (Apicomplexa: Eimeriidae) from the rufous-browed peppershrike (Aves: Passeriformes: Vireonidae) Cyclarhis gujanensis Gmelin, 1789.

In the current study, a new coccidian species (Protozoa: Apicomplexa: Eimeriidae), collected from the rufous-browed peppershrike Cyclarhis gujanensis Gmelin, 1789, is reported from Brazil. Isospora pitiguari n. sp. has oocysts, which are spherical to sub-spherical, 26.8 × 25.7 μm, with smooth, bilayered wall ~1.5 μm thick. Micropyle, oocyst residuum, and polar granule are absent. Sporocysts are rounded to slightly ovoidal, 14.4 × 11.6 µm. Stieda body flattened and substieda body prominent and rounded. Sporocyst residuum is composed of granules of different sizes. Sporozoites are vermiform with one refractile body and a nucleus. This is the first description of an isosporoid coccidium infecting a New World vireo.