Cyclotella cryptica Reimann, J.C. Lewin & Guillard in Phycologia 3: 82, figs 4-11. 1963.

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

Cyclotella cryptica Reimann, J.C. Lewin & Guillard in Phycologia 3: 82, figs 4-11. 1963.

Morphological description.

Frustule cylindrical, the medium part of a valve slightly tangentially undulated, or flat, valve diameter is 6.4-6.7 μm, a clear boundary between edge and central zone is absent, striae wedge-shaped, 8 in 10 μm, single central fultoportula (Figs 6H , 7A ).

Ecology.

Cyclotella cryptica is a planktonic species, known from marine and brackish environments, may be found in high chloride concentrations. It occurs at maximum abundance around 20 °C ( Liu and Hellebust 1976; Makarewicz 1987; Mills et al. 1993). Cyclotella cryptica is a saprophilic species ( Barinova et al. 2019), requires NO3 as its source of nitrogen and Ni ions in order to grow autotrophically, however is capable of heterotrophic growth in bottom water or mud enriched in glucose and known to grow mesotrophically ( Oliveira and Antia 1984; Saros and Fritz 2000).

Distribution.

Valves were identified at the site in the south of Mykolaiv city in the Southern Bug River (Table 1 ).

It is a widespread species, recorded for Europe, North America, and Asia ( Mills et al. 1993; Guiry and Guiry 2021).

Figures

Figure 6. SEM (A-F, H) and LM images (G) of species found in the transitional zone at Mykolaiv city, valve views: A Stephanodiscus minutulus with arrows shown marginal and central fultoportulae B, C Cyclotella atomus var. atomus with arrows shown marginal and central fultoportulae D-F Cyclotella atomus var. gracilis with arrows shown marginal and central fultoportulae on D picture, only central fultoportula on E and central fultoportula and alveolae on (F) G Cyclotella choctawhatcheeana with arrow shown central fultoportulae H Cyclotella cryptica with arrows shown marginal and central fultoportulae. Scale bars: 3 μm (B, C); 4 μm (D, F); 5 μm (A, E, H); 10 μm (G).

Figure 7. SEM (A-E, G, H) and LM images (F) of species found in the transitional zone at Mykolaiv city, valve views: A Cyclotella cryptica B Cyclotella marina C, D Cyclotella meduanae E, F Cyclotella meneghiniana G Cyclostephanos dubius H Cyclostephanos invisitatus, with arrows shown on A, D, H marginal and central fultoportulae, B marginal fultoportulae, F central fultoportulae. Scale bars: 2 μm (B, D); 4 μm (A); 5 μm (C, E); 10 μm (F-H).