Three new species of Isospora Schneider, 1881 (Apicomplexa: Eimeriidae) from the lesser seed-finch, Oryzoborus angolensis (Passeriformes: Emberizidae) from Brazil

Abstract

Three new coccidian (Apicomplexa: Eimeriidae) species are reported from the lesser seed-finch, Oryzoborus angolensis from Brazil. Sporulated oocysts of Isospora curio n. sp. are spherical to subspherical; 24.6 x 23.6 (22-26 x 22-25) μm, shape-index (SI, length/width) of 1.04 (1.00-1.15). Oocyst wall is bilayerd, ∼ 1.5 μm thick, smooth and colourless. Micropyle and oocyst residuum are absent. The sporocysts are ovoid, 13.2 x 10.9 (15-17 x 10-13) μm, SI = 1.56 (1.42-1.71), with a small Stieda body and residuum composed of numerous granules scattered among the sporozoites. Sporozoites are elongated and posses a smooth surface and two distinct refractile bodies. Oocysts of Isospora braziliensis n. sp. are spherical to subspherical, 17.8 x 16.9 (16-19 x 16-18) μm, with a shape-index of 1.06 (1.00-1.12) and a smooth, single-layered wall ∼ 1 μm thick. A micropyle, oocyst residuum and polar granules are absent. Sporocysts are ellipsoid and slightly asymmetric, 13.2 x 10.8 (12-14 x 9-12) μm, SI = 1.48 (1.34-1.61). Each sporocyst contains a barely visible Stieda body and a residuum composed numerous of granules. Sporozoites are elongated and each of them contains two distinct refractile bodies. Oocysts of Isospora paranaensis n. sp. are subspherical to broadly ellipsoid 24.3 x 19.8 (22-26 x 18-22) μm, SI = 1.22 (1.15-1.38) with smooth single-layered wall ∼ 1.5 μm thick. A micropyle and oocyst residuum are absent, but one distinct ellipsoid polar granule (2.5-3.5 x 1.5-2.5 μm) is present. Sporocyst are ovoid, 15.7 x 10.1 (14-18 x 8-12) μm, SI = 1.46 (1.31-1.72), with distinct Stieda and sub-Stieda bodies. Each sporocyst contains a spherical sporocyst residuum, 4 μm in diameter. All described isosporan species represent a possible cause of acute coccidiosis for O. angolensis in captivity.