Diaphanosoma brachyurum is a dominant component of summer zooplankton in Central Europe. So far only this species has been known from Poland, and other species from this genus have been found in neighboring countries. The aim of the present study was to present the factual distribution of Diaphanosoma species in Central Europe. We investigated Diaphanosoma individuals in 109 water bodies in Central Europe (mostly from Poland) by combining morphological analyses and molecular methods (mtDNA COI gene). Our research confirmed the presence of three other species - D. orghidani, D. mongolianum, and D. cf. lacustris. We provided a detailed morphological description for every species and pointed out that each species can be easily distinguished morphologically by armament of postero-ventral valve margins. The results of phylogenetic analysis based on 27 haplotypes of mtDNA COI gene lead to the same conclusion as morphology. Our genetic and morphological analysis confirms a close affinity between D. mongolianum and D. lacustris, as well as the presence of hybrids between these species. Nevertheless, the most common was D. brachyurum - it was found in 97 water bodies, and other Diaphanosoma species begin to penetrate Central Europe via rivers.