Description of two new Isospora species causing visceral coccidiosis in captive superb glossy starlings, Lamprotornis superbus (Aves: Sturnidae)

Dr Barta Lab


Isospora greineri sp. n. and Isospora superbusi sp. n. are described from captive superb glossy starlings, Lamprotornis superbus, from the Toronto Zoo succumbing to visceral coccidiosis. Sequence data from nuclear 18S recombinant DNA (rDNA) and mitochondrial cytochrome c oxidase subunit I (COI) loci from sporulated oocysts and infected tissues (liver, lung, or spleen) demonstrated two distinct Isospora sp. genotypes that varied in their relative abundance. In the tissues of one affected bird, as well as its associated fecal sample, two distinct COI sequences (1.7% divergence) and two distinct 18S rDNA sequences (0.6% divergence) were found at almost the same abundance; in other specimens, one of the 18S and one of the COI sequences were less abundant than the other. In the tissues of some birds, only a single COI and single 18S sequence were present. In all cases, the same pair of 18S rDNA and COI sequences fluctuated in abundance in parallel, indicating that there were two distinct species present rather than one species with more than one COI or 18S locus. The oocysts of these new species cannot be differentiated morphologically. Sporulated oocysts of both were spherical to subspherical measuring 17.7 ± 0.22 μm by 17.1 ± 0.20 μm with a mean L/W ratio of 1.03 ± 0.004. Sporocysts were ovoid measuring 13.5 ± 0.17 μm by 9.3 ± 0.15 μm with a mean L/W ratio of 1.4 ± 0.02. Sporocysts had a small Stieda body with indistinct sub-Stieda body; each sporocyst had a compact residuum. Two morphologically similar but genetically divergent Isospora species were shown to cause simultaneous enteric and extraintestinal infections in captive superb glossy starlings.



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