An Species (Apicomplexa: Eimeriidae) Identified From a Black-Faced Cuckoo-Shrike () (Gmelin, 1789) (Passeriformes: Campephagidae) in Western Australia.

We describe and characterize a new species from the black-faced cuckoo-shrike () in Western Australia, using both morphological and molecular approaches. Microscopic analysis of a fecal sample revealed 20 ellipsoidal oocysts, which are subspheroidal to ovoid, measuring 40-43 × 39-41 μm (mean 41.4 × 39.6 μm) with a length/width (L/W) ratio of 1.0-1.1 (mean 1.04). The oocyst wall is bi-layered (1.5 μm thick), with a smooth outer layer constituting approximately two thirds of the total thickness. A micropyle is present, characterized by a slight invagination of the inner layer (6.0 μm wide), but no micropyle cap is observed. Both the oocyst residuum and polar granule are absent. Sporocysts ( = 20) are ellipsoidal, measuring 23-24 × 13-14 μm (mean 23.3 × 13.4 μm) with an L/W ratio of 1.7-1.8 (mean 1.74). A flattened to knob-like Stieda body (1.5 × 3.0 μm) is present, while sub-Stieda and para-Stieda bodies are absent. The sporocyst residuum is composed of granules clustered by a membrane, forming an irregular shape (12.0 × 8.0 μm). Sporozoites exhibit anterior and posterior refractile bodies and a nucleus. Molecular analyses of the 18S rRNA, 28S rRNA, and COI gene loci demonstrated that this species forms a distinct clade with in phylogenetic trees based on all three loci. It shares genetic similarities with of 98.8%, 93.7%, and 98.9% for the 18S rRNA, 28S rRNA, and COI loci, respectively. Phylogenetic analysis confirms that this new species is closely related to . Based on these findings, we propose this isolate as a new species, n. sp. This is the first coccidian species identified from the Campephagidae family in Australia.