Melosira varians C. Agardh, Syst. Alg.: 64. 1816.

Bilous, Olena P., Genkal, Sergey I., Zimmermann, Jonas, Kusber, Wolf-Henning & Jahn, Regine, 2021, Centric diatom diversity in the lower part of the Southern Bug river (Ukraine): the transitional zone at Mykolaiv city, PhytoKeys 178, pp. 31-69 : 31

Melosira varians C. Agardh, Syst. Alg.: 64. 1816.

Synonym.

Aulacoseira varians (C. Agardh) Simonsen.

Morphological description.

Frustule is cylindrical, valve flat, 15.7-46.6 μm in diameter with numerous small-scale granules, 5.7-15.5 μm high (Fig. 2H ).

Ecology.

Common species for freshwaters in streams and lakes, as well as in slightly brackish waters, oligotrophic, eutrophic to dystrophic or polluted environments ( Nardelli et al. 2016; Hofmann et al. 2018). Taxon has preferences of alkaline conditions (pH 7-8.5), with moderate oxygen, regularly found in humid environments, requiring periodically high levels of nitrogen ( Soltanpour-Gargari et al. 2011).

Distribution.

Valves were found near Mykolaiv city in the Southern Bug River in our previous sampling study (Table 1 ; Genkal and Bilous 2015). In Ukraine, it is known from the Southern Bug and lakes in the basins of the rivers Danube, Dnister, Siverskyi Donets, Desna, Prypiat, Dnipro and its reservoirs and estuary.

On the global level, it is a widely distributed taxon, known from Europe (i.e. Berlin, Germany, see Geissler and Kies 2003), Russia ( Genkal et al. 2020), Asia (Iran), North America (Canada, USA), Africa (Egypt, RSA); Adriatic, Aral, Azov, Baltic, Barents, Black, Caspian, Kara, Mediterranean, North and Red Seas, and throughout North America ( Stoermer and Julius 2003). It is also very common in Brazilian waters ( Stoermer and Julius 2003; Tremarin et al. 2009; Nardelli et al. 2016).

Figures

Figure 2. SEM (A-D, H) and LM (E-G) images of species found in the transitional zone at Mykolaiv city: A-G Melosira subglobosa (A, F girdle views, B-E, G, valve views) H Melosira varians, partial valve view and girdle view of complete frustule. Scale bars: 10 μm (A-C, E-H); 20 μm (D).