Three new, minute testate amoeban species smaller than 15 μm, including one new genus, are described from the plankton of the River Danube (Hungary) using high resolution video micrography. Pseudodifflugia klarae nov. spec. is characterised by an oval/pyriform, rigid, slightly compressed, scarcely or densely agglutinated test with a length of 8–14 μm. Its aperture is irregular in outline and inconspicuous; the nucleus contains one nucleolus and a few bent rods in the nucleoplasm. Bereczkya nov. gen., an incertae sedis cercozoan, has a minute spherical cell enclosed in a thin, rigid, more or less agglutinated organic test that is filled entirely by the cytoplasm. Its test bears an irregular and inconspicuous aperture. A collar-like ectoplasmic rim is situated in the aperture, from which a pseudopodial stem with filopodia is erected. The nucleus is slightly irregular, without a central nucleolus, but it contains rod-shaped granules in the nucleoplasm. Bereczkya minuta nov. spec. (test length: 3.5–8 μm, the diameter of the ectoplasmic rim: 0.8–2.3 μm) has a spherical test with asymmetric swellings and depressions, agglutinated with refractile mineral and other flat or irregularly-shaped xenosomes that may sometimes be almost entirely absent. Paramphitrema muelleri nov. spec. has a tubular or lemon-like test (length: 13–17 μm), which tapers towards the rigid apertures. The test is rigid, agglutinated and ism circular in cross section. The nucleus is vesicular. Thin filopodia, as well as 1–2 thick, straight, unbranched, tubular pseudopodia are produced.