Isospora bioccai (Cringoli and Quesada 1991) (Protozoa, Apicomplexa, Eimeriidae) is reported and described from captive canaries Serinus canaria forma domestica (Linnaeus 1758) in Mexico. The oöcysts are subspherical, 25.5 × 23.5 μm, with smooth, bilayered wall, ∼1.3 μm thick. Micropyle absent, oöcyst residuum absent, and polar granule present, 4-8 rice-grain-shaped. Sporocysts are ovoidal, 16.7 × 10.5 μm. Stieda body knob-like and substieda body trapezoidal of irregular base. Sporocyst residuum is composed of granules of different sizes. Sporozoites are vermiform with one refractile body and a nucleus. Gamogony was seen in the duodenum. In addition to new locality, this is the first description of I. bioccai from S. canaria.
Keywords: Coccidia; Fringillidae; Isospora bioccai; México; Passeriformes; Serinus canaria.