Thalassiosira incerta I.V. Makarova in Bot. mater. otd. spor. rast. Bot. inst. AN SSSR 14: 50, pl. 1, figs 9-16. 1961.

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

Thalassiosira incerta I.V. Makarova in Bot. mater. otd. spor. rast. Bot. inst. AN SSSR 14: 50, pl. 1, figs 9-16. 1961.

Synonym.

Coscinodiscus bulla M.H. Hohn & Hellerman.

Morphological description.

The frustule is cylindrical, valves approximately flat, 21.4-27.8 μm in diameter, in the middle of a valve 5 processes are located, 4-5 marginal fultoportulae in 10 μm, situated on the valve margin (Fig. 4F ). The rimoportula is short-necked with an elongated, compressed narrow lip usually perpendicular to the margin.

Ecology.

The species was recorded as planktonic in water bodies of different types, typical for eutrophic/hypertrophic and highly saprobic marine, brackish, and fresh waters. It is euryhaline and eurythermal, in addition to being known as an alkaliphilic taxon ( Okhapkin et al. 2016). Thalassiosira incerta was named an invasive taxon for Russia ( Kaštovský 2010; Korneva 2014).

Distribution.

Thalassiosira incerta was recorded near Mykolaiv city in the Southern Bug River (Table 1 ). For Ukrainian territory, there are few records from reservoirs of the Dnipro River and some estuaries of the Black Sea and coastal waters near Crimea ( Tsarenko et al. 2009).

This taxon is quite cosmopolitan, and distributed in the Boreal of Europe (Great Britain, Russia, Ukraine), Asia (Azerbaijan), North America (Canada, USA), Africa (Egypt); Aral, Black and Caspian Seas ( Sims 1996; Kuo and Guo 2003; Okhapkin et al. 2016; Genkal et al. 2020).

Figures

Figure 4. SEM (A, B and E-H) and LM (C, D) images of species found in the transitional zone at Mykolaiv city: A-D Pleurosira laevis A, C valve views with arrows shown the ocelli B girdle view E Conticribra weissflogii, valve view with arrows shown central and marginal fultoportulae F Thalassiosira incerta, valve view with arrow shown central fultoportulae G Thalassiosira faurii, valve view H Minidiscus proschkinae, valve view with arrow in the centre shown central fultoportula, and closer to the edge - rimoportula. Scale bars: 10 μm (C-G); 30 μm (A); 50 μm (B); 3 μm (H).