One morphologic type of sarcocyst was found in 26% (7/27) of Eurasian Coots ( Fulica atra) and was described as Sarcocystis fulicae n. sp. using morphologic, 18S ribosomal (r)DNA, 28S rDNA, and internal transcribed spacer 1 (ITS1) analysis. By light microscope, cysts were ribbon-shaped and measured 7.3 mm in length by 116 μm wide. Histologically, the cyst wall reached up to 1.2 μm in thickness and seemed smooth. The detected sarcocysts were packed with relatively small banana-shaped bradyzoites that were 6.7×2.0 μm in size. Ultrastructurally, the cyst wall amounted to 1 μm and had many conical protrusions but seemed almost smooth in some places. The parasitophorous vacuolar membrane appeared undulating, with knob-like blebs and invaginations. The cyst wall belonged to type 1d. Morphologically, cysts of S. fulicae differed considerably from cysts of Sarcocystis atraii previously described in the same host but were indistinguishable from those of Sarcocystis corvusi, Sarcocystis lari, and Sarcocystis wobeseri, which use birds as intermediate hosts. According to the phylogenetic and ecologic data, birds of prey, mostly the Western Marsh Harrier ( Circus aeruginosus) and the White-tailed Eagle ( Haliaeetus albicilla), are presumed to be definitive hosts of S. fulicae.
Keywords: 18S rDNA; 28S rDNA; Eurasian Coot; ITS1; Sarcocystis fulicae; phylogeny; transmission electron microscopy.