A new species of Caryospora (Apicomplexa: Eimeriidae) from the sharp-shinned hawk, Accipiter striatus (Aves: Accipitriformes).

An injured juvenile sharp-shinned hawk, Accipiter striatus Vieillot, 1807 (Aves: Accipitriformes), housed and treated at the College of Veterinary Medicine Teaching Hospital at Kansas State University, Manhattan, Kansas, USA, was found to be passing oocysts of an undescribed species of Caryospora in its feces. Sporulated oocysts of Caryospora petersoni n. sp. were subspherical, with a bilayered wall, and they measured 43.1 × 39.8 μm; micropyle, oocyst residuum, and polar granule were absent. Sporocysts were subspherical to spherical, 23.4 × 23.3 μm; Stieda, substieda, and parastieda bodies were absent, but a spherical sporocyst residuum was present as a compact mass, ~15.1 μm wide, composed of many homogeneous globules. The new species represents the first caryosporan documented from this species of hawk.