Centric diatom diversity in the lower part of the Southern Bug river (Ukraine): the transitional zone at Mykolaiv city Author Bilous, Olena P. https://orcid.org/0000-0001-5229-3667 Institute of Hydrobiology, NAS of Ukraine, 12 Geroyiv Stalingrada Ave., Kiyv 04210, Ukraine bilous_olena@ukr.net Author Genkal, Sergey I. I. D. Papanin Institute for Biology of Inland Waters of RAS, Settle Borok, Nekouz District, Yaroslavl Region 152742, Russia Author Zimmermann, Jonas Botanischer Garten und Botanisches Museum Berlin, Freie Universitaet Berlin, Koenigin-Luise Str. 6 - 8, Berlin 14195, Germany Author Kusber, Wolf-Henning Botanischer Garten und Botanisches Museum Berlin, Freie Universitaet Berlin, Koenigin-Luise Str. 6 - 8, Berlin 14195, Germany Author Jahn, Regine Botanischer Garten und Botanisches Museum Berlin, Freie Universitaet Berlin, Koenigin-Luise Str. 6 - 8, Berlin 14195, Germany text PhytoKeys 2021 2021-05-20 178 31 69 http://dx.doi.org/10.3897/phytokeys.178.64426 journal article http://dx.doi.org/10.3897/phytokeys.178.64426 1314-2003-178-31 286CBEFF513C55E1B66F6224758AC2F6 Cyclostephanos invisitatus (M.H. Hohn & Hellerman) Stoermer, E.C. Ther. & Hak . in Theriot, Stoermer and Hakansson , Diatom Res. 2: 256, figs 10 d-f. 1988. Basionym. Stephanodiscus invisitatus M.H. Hohn & Hellerman, Trans. Am. Microscop. Soc. 82 (3): 325. 1963. Morphological description. Frustule disciform, valve face flat, 9.4-14.5 μm in diameter, multiseriate striae 10-14 in 10 μm , ribs are continuing on curve of the valve, spines grow from every rib (Fig. 7H ). Ecology. Cyclostephanos invisitatus was recorded as planktonic species from rivers, ponds, lakes, reservoirs and seas, freshwater, brackish and marine waters. Also known from waters of eutraphentic conditions, moderate and higher trophy and moderate alkalinity ( Krammer and Lange-Bertalot 2000 ; Siver et al. 2005 ; Kirilova et al. 2010 ; Hofmann et al. 2018 ). Distribution. C. invisitatus was found 5 km downstream Mykolaiv city (Table 1 ), and was recorded for this River earlier ( Bilous et al. 2012 ; Bilous et al. 2014 ; Belous 2016 ). In turn, it is common for the Dnipro River and there are some findings in the Danube River ( Tsarenko et al. 2009 ). Probably a cosmopolitan species, known from Europe (Germany, Hungary, Poland, Russia), Asia (Armenia, Azerbaijan, Russia), Northern America (USA), Africa (Egypt); Caspian Sea ( Wojtal and Kwandrans 2006 ; Tsarenko et al. 2009 ; Kiss et al. 2012 ; Genkal et al. 2020 ).