Dr. Murai Éva szerk.: Parasitologia Hungarica 24. (Budapest, 1991)

eight daughter cells have been reported by Lorn et al. (1985) and Hedrick et al. (1988) also from other fishes. Furthermore, Baska and Molnár (1989) observed forms resembling the swimbladder stages in the blood of cyprinids. Up to the present, two Sphaerospora species of freshwater pereid fishes have become known: Sphaerospora markewitschi Donets, 1962 parasitizing the Don ruffe (Gymnocephalus acerina) and ruffe (G. cernua), and Sphaerosporapectinacea Bocharova et Donets, 1974, a parasite of the perch (Perca fluviatilis). The spores of both species were detected in the urinary tract. No presporogenic stages have been reported from these fishes so far. Of the two species, S. pectinacea has pathogenic importance: Pronin and Pronina (1985) reported that it caused swelling of the kidneys in perch. In the present paper a new species is described from striped ruffe (Gymnocephalus schraetzer) by the name of Sphaerospora danubialis sp. n. Besides its typical host, this parasite occurs also in ruffe (G. cernua) and pikeperch (Stizostedion lucioperca). Fig. 1. Schematic illustration of Sphaerospora danubialis spores from host fishes, (a) Spore in suturai view from striped ruffe; (b) Spore in upper view from striped ruffe; (c) Spore in suturai view from ruffe; (d) Spore in suturai view from pikeperch