Published online by Cambridge University Press: 19 May 2009
A new Coccidia species is reported from the natural population of Pied Flycatcher (Ficedula hypoleuca) in northern Germany. Sporulated oocysts were found in faeces from 6 of 8 sampled adults. The spherical oocysts of the new Isospora species have a brownish, smooth, bi-layered wall. Average size of sporulated oocysts was 19·4×19·3 μm (17·5–22·8 μm×17·5–22·8 μm) with a shape index (length/width) of 1·0. The sporulated oocysts have no micropyle or residuum, but enclose several small polar granules that often cluster into 2–3 dumbbell-shaped formations. Sporocysts are slightly elongated, rounded at the end opposite the Stieda body, 15·3 μm×9·2 μm in size (13·8–16·1 μm× 8·5–10·3 μm), and have a shape index of 1·7 (1·6–1·8). The Stieda body has a prominent knob-like cap, whereas the substieda body is absent. Sporocysts contain a small compact sporocyst residuum and 4 sporozoites. COI haplotypes identical to those isolated from faecal oocysts were PCR amplified from the blood of 13-day-old nestlings, suggesting that the newly described species has extra-intestinal stages in blood. This represents the first description of a new avian Isospora species supported by molecular sequence data from the same oocysts that are described morphologically.