New species of Isospora (Apicomplexa, Eimeriidae) from the troupial and white-edged oriole (Icterus spp.) (Aves, Passeriformes, Icteridae)

Two new species of coccidia are described from passeriform (Icteridae) birds housed at the National Aquarium in Baltimore. Oocysts of Isospora icterus sp. n. from the troupial, Icterus icterus, are subspherical, 28.9 x 27.2 (27.2-32.0 x 25.0-30.0) μm, with a thick, bi-layered wall; shape index (length/width) is 1.06 (1.00-1.12). A micropyle is absent but a small oocyst residuum and large, irregularly shaped polar granule are present. Sporocysts are ellipsoidal, 17.8 x 12.8 (16.8-19.2 x 12.0-13.6) μm, with Stieda and substieda bodies; shape index 1.39 (1.33-1.52). A sporocyst residuum is present, consisting as numerous fine granules. Sporozoites possess a small anterior and larger posterior refractile bodies. Oocysts of Isospora graceannae sp. n. from the white-edged oriole, Icterus graceannae, are subspherical, 23.9 x 22.3 (20.0-26.4 x 18.6-25.0) μm, with a thick, bi-layered wall; shape index 1.07 (1.00-1.17). A micropyle is absent, but a small oocyst residuum and polar granule that often appears splintered are present. Sporocysts are ellipsoidal, 15.5 x 10.7 (14.2-16.2 x 10.0-11.4) μm, with Stieda and substieda bodies; shape index 1.44 (1.36-1.54). A sporocyst residuum is present, consisting as dozens of granules scattered among the sporozoites. Sporozoites with small anterior and larger posterior refractile bodies.