About a new representative of the genus Aulacoseira Thw. (Bacillariophyta) for the flora of Ukraine

In this study, scanning electron microscopy images of valves of the centric diatom algae Aulacoseira subborealis (Nygaard) Denys, Muylaert et Krammer from from the Kaniv Reservoir and the Desna River are analyzed. The quantitative (colony size, valve diameter and mantle height, the ratio of mantle height to valve diameter, number of areola rows and areolae in 10 µm on the mantle, ring-shaped diaphragm size) and qualitative (short pointed spines, areolae arrangement on the valve face and the mantle) morphological characteristics correspond to the diagnosis of A. pusilla (F.Meister) A.Tuji & A.Houki, a new species for the flora of Ukraine. In the analyzed material, minimum values of the mantle height and the height/diameter ratio are lower than in the published data.