Stephanodiscus makarovae Genkal in Nov. Syst. Nizsh. Rast. 15: 13, pl. 2, fig. 1. 1978.

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

Stephanodiscus makarovae Genkal in Nov. Syst. Nizsh. Rast. 15: 13, pl. 2, fig. 1. 1978.

Morphological description.

Frustule disciform, valve with slightly convex or concave centre, frequently flat, diameter 5.9-8.3 μm, striae are double, rarely triple, in numbers of 14-16 in 10 μm. One central process is present. Spines pointy, small-scale, growing from each costa (Fig. 5F ).

Ecology.

Planktonic in rivers, lakes and reservoirs, freshwater, but mainly in mesotrophic-eutrophic water bodies. In addition, reported occurrence of this species in high numbers in highly mineralized waters ( Genkal 2007; Genkal et al. 2009; Tsarenko et al. 2009).

Distribution.

Stephanodiscus makarovae was observed downstream from Mykolaiv city in the Southern Bug River (Table 1 ). It was observed in the Dnipro River and its reservoirs, the Danube River and in the coastal area of the Black Sea ( Genkal et al. 2009; Tsarenko et al. 2009; Genkal and Terenko 2014).

As for general distribution, this taxon has only a few records around the world - Europe (Russia, Ukraine), Asia (Armenia, Russia), Africa (Egypt) ( Kulikovskiy et al. 2016; Genkal et al. 2020).

Comments.

According to Houk et al. (2014), S. makarovae ( Genkal 2007) was erroneously included in the synonym C. delicatus (Genkal) Casper & Scheffler, since, according to the diagnosis, the marginal fultoportulae of S. makarove have 2 satellite pores, and for C. delicatus 3. The difference in the number of satellite pores at the marginal fultoportulae in centric diatoms is a good diagnostic feature. For S. makarovae , the valve relief also varies from flat to slightly convex or concave, and there are also other morphological differences (see same publication Genkal 2007). As for the transfer of S. makarovae to the genus Cyclostephanos , this is a debatable issue and molecular genetic studies are needed.

Figures

Figure 5. SEM images of species found in the transitional zone at Mykolaiv city (A, B, E-H valve views, C, D girdle views): A Minidiscus proschkinae with arrows showing rimoportula and marginal fultoportula B-D Skeletonema subsalsum with arrows showing marginal fultoportulae E Stephanodiscus hantzschii with arrow shown spines F Stephanodiscus makarovae with arrows showing marginal and central fultoportulae G, H Stephanodiscus minutulus with arrows showing spines and central fultoportula. Scale bars: 3 μm (A); 4 μm (B, F, H); 5 μm (C, D, G); 10 μm (E).