ABSTRACT A new coccidian species parasitizing white-necked thrushes Turdus albicollis Vieillot, 1818 is described from the Parque Nacional do Itatiaia, in Southeastern Brazil. Isospora machadoae sp. nov. has oocysts that are sub-spherical, 22.2 × 21.2 µm, with bilayered wall, ~1.3 μm thick. Outer layer is rough with micropyle and micropyle cap. Oocyst residuum is absent, but one or two polar granules are present. Sporocysts are ellipsoidal, 13.3 × 9.7 µm. The Stieda body is flattened to half-moon-shaped and substieda body rounded. Sporocyst residuum is present, composed of scattered spherules of different sizes. Sporozoites are vermiform with a refractile body and a nucleus. These parasitized thrushes had no apparent clinical signs of coccidiosis or high densities of oocysts in feces. This condition may be associated with a specific low pathogenicity of I. machadoae sp. nov. and/or with the conserved habitat of these birds, which ensures the ecological niches and thus the immunocompetence to wildlife.

Uma descrição do coccídio Isospora hemidactyli da lagartixa doméstica Hemidactylus mabouia, muito comum em residências da região metropolotana do Rio de Janeiro, foi feita neste estudo. Os histogramas e a regressão linear para esta espécie confirmaram a homogeneidade de seus oocistos apesar da grande amplitude de variação. Além disto, oocistos polisporocísticos também foram recuperados das fezes de H. mabouia e foram semelhantes aos descritos anteriormente no gênero Adelina. Esta espécie devia estar parasitando um invertebrado ingerido pela lagartixa doméstica, e por essa razão, é um pseudoparasita. Oocistos de I. hemidactyli foram sub-esféricos a elipsóides, 24,4 × 22,3μm, com parede simples e um grânulo polar. Os esporocistos foram subesféricos a elipsóides, 11,8 × 9,8μm com corpos de Stieda e substieda, resíduo e esporozoítas com corpo refráctil. Oocistos do pseudoparasita Adelina sp. foram elipsóides, 36,3 × 30,9μm, com parede dupla e sem micrópila, resíduo e grânulo polar. Oito a 15 esporocistos estavam presentes e foram subesféricos a elipsóides, 12,4 × 11,2μm. Os corpos de Stieda e substieda estavam ausentes. Os esporozoítas apresentam corpos refrácteis em ambas as extremidades.

A description of the coccidium Isospora hemidactyli from the house gecko Hemidactylus mabouia, a very common at dwellings in Rio de Janeiro Metropolitan Region, was made in this study. Histograms and linear regression were made for this species and determined the homogeneity of these oocysts despite of large range. Besides it, polysporocystid oocysts also were recovered from feces of the H. mabouia house gecko and they were similar to those described previously as the genus Adelina. This species should be parasitizing an invertebrate ingested by house gecko, and for that reason, is a pseudoparasite. Oocysts of I. hemidactyli were subspherical to ellipsoidal, 24.4 × 22.3μm, with single-layered wall and one polar granule. Sporocysts were subspherical to ellipsoidal, 11.8 × 9.8μm with Stieda and substieda bodies, residuum and sporozoites with refractile body. Oocysts of the pseudoparasite Adelina sp. were ellipsoidal, 36.3 × 30.9μm, with bi-layered wall and without micropyle, residuum and polar granule. Eight to 15 sporocysts were presents and were subspherical to broadly ellipsoidal, 12.4 × 11.2μm. Stieda and substieda bodies were absent. Sporozoites present refractile bodies at both ends.

Isospora vanriperorum de trinca-ferro verdadeiro (Saltator similis) é descrita no sudeste do Brasil. Os oocistos são esféricos a subesféricos medindo 19,4-26 por 18,3-26μm (23,1 por 22,4μm), índice morfométrico de 1,04 com parede única, fina, lisa e amarelada. A micrópila e o resíduo estão ausentes, mas um grânulo polar elíptico está presente. Os esporocistos são ovóides medindo 14,5-20,2 por 8,1-12,5μm (16,3 por 10,8μm), índice morfométrico de 1,53 com corpo de Stieda proeminente, corpo de substieda mal discernível e resíduo central e granular.

Isospora vanriperorum from the green-winged saltator (Saltator similis) is described in Southeastern Brazil. Oocysts are spherical to subspherical, 19.4-26 by 18.3-26μm (23.1 by 22.4μm), shape index 1.04 with a single layered wall, fine, smooth and yellowish. Micropyle and residuum are absents, but one elliptical polar granule is present. Sporocysts are ovoid, 14.5-20.2 by 8.1-12.5μm (16.3 by 10.8μm), shape index 1.53 with prominent Stieda body, barely discernible substieda body and residuum centered and granulated.