Isospora massardi sp. nov. (Apicomplexa: Eimeriidae) from the white-necked thrush Turdus albicollis (Passeriformes: Turdidae) from Brazil.

A new coccidian species (Protozoa: Apicomplexa: Eimeriidae) are reported from the white-necked thrush Turdus albicollis Vieillot, 1818, a very common species in South America. Isospora massardi sp. nov. oocysts are subspherical, 18.6 × 17.7 μm, with smooth, bilayered wall, ~0.9 μm. Micropyle, oocyst residuum are absent, but two polar granules are frequently present. Sporocysts are ovoidal, 14.8 × 9.3 μm. Stieda body is knob-like to rounded and substieda body is rounded. Sporocyst residuum is composed of scattered spherules of different sizes. Sporozoites are vermiform with posterior and anterior refractile bodies and a nucleus. This is the sixth description of an isosporoid coccidium infecting a New World turdid bird.