The First Isospora Species (Apicomplexa: Eimeriidae) Described from the Northern Yellow-Shafted Flicker (Colaptes auratus luteus) in Ontario, Canada

Purpose Members of the genus Isospora commonly infect a wide variety of wild birds. By combining morphometric and genetic data, we are able to differentiate and describe a new apicomplexan parasite, Isospora picoflavae n. sp., from the Northern Yellow-shafted Flicker ( Colaptes auratus luteus ) in Ontario, Canada. Methods Unsporulated oocysts were observed in intestinal contents obtained during necropsy; these oocysts completed exogenous sporulation within 7 days at room temperature. Complete nuclear 18S rDNA and complete mitochondrial genome sequences were obtained from this previously undescribed Isospora sp. to compare with related coccidia. Results Sporulated oocysts were subspherical in shape measuring an average of 22.7 × 21.7 μm ( n = 53; mean shape index 1.05) containing a near-spherical polar granule. Sporocysts were ovoidal to ellipsoidal in shape, measuring an average size of 17.0 × 10.5 μm ( n = 9; mean shape index 1.62). Sporocyst residuum was concentrated in an irregular, spherical mass in the middle of each sporocyst. The isolated oocysts differed morphologically from other Isospora species reported to infect members of the family Picidae. Based on phylogenetic analyses using either combined nuclear 18S rDNA and mitochondrial cytochrome c oxidase I (COI) sequences or complete mitochondrial genome sequences, this Isospora sp. n. isolated from the Northern Flicker grouped within a clade containing Isospora species described from various passeriform hosts. Conclusion Based on combined morphological and molecular data, the oocysts found in the gastrointestinal contents of Colaptes auratus luteus represent a new species of Isospora named herein as Isospora picoflavae n. sp.