Aquatic Heteroptera (Nepomorpha, Gerromorpha) in small intermittent rivers of Ukraine steppe zone

Abstract. Small intermittent rivers are some of the most widespread types of water currents in the steppe zone. In the ecosystems of the intermittent rivers we have found 28 species of water bugs that compose the majority of the described fauna in the south Ukraine. Our study added two new species to the faunistic list of this zone (Sigara fossarum, Hydrometra gracilenta), and finally confirmed the presence of Micronecta scholtzi in Ukraine. We also studied the seasonal changes of biotopic distribution and quantitative characteristics of aquatic Heteroptera. It was shown thatfor water bugs the ecosystem of the small intermittent rivers consists of three closely connected components: the riverbed, the flooded areas and the extra inundated constant basins. During the droughty period when the riverbed is dry, the extra inundated basins (including artificial ones – sandy pits) serve as refugia. The wintering of many species takes place there, especially when the riverbed is not filled before the cold period. However, the reproduction of most species takes place in the riverbed and associated flooded areas. Thus, this work is a confirmation and development of the concept for “a uniform architectonic complex of a river valley”.