Aulacoseira subarctica (O. Muell .) Haworth in Round. Alg. aquat. environm.: 143-144. 1988.

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

Aulacoseira subarctica (O. Muell.) Haworth in Round. Alg. aquat. environm.: 143-144. 1988.

Basionym.

Melosira italica subsp. subarctica O. Müll., Jahrb. Wiss. Bot. 43: 78, pl. 2, figs 10-11. 1906.

Synonyms.

A. italica subsp. subarctica (O. Müll.) Simonsen.

Morphological description.

Frustules are usually low to high-cylindrical, valve face flat. Valve is 16.6 μm in diameter, 4.4 μm high, number of areolae lines on valve bend 15 in 10 μm, in the line 18 areolae in 10 μm. Ringleiste is wide, linking spines are large, sharpened (Fig. 3C ).

Ecology.

Aulacoseira subarctica is a planktonic alga in lakes, rivers, reservoirs and temporary water bodies and is confined to higher latitudes. It usually appears in response to moderate increases in nutrients, supposedly to phosphorus concentrations controlling its presence and is disadvantaged by further enrichment ( Chris et al. 2003).

Distribution.

Occurred in the Southern Bug River in Mykolaiv city (near Varvarivskyi Bridge) (Table 1 ). This species is known from the Dnipro River basin ( Tsarenko et al. 2009).

Aulacoseira subarctica is widely distributed across Europe (Germany, Great Britain, Holland, Norway, Russia, Ukraine, Scandinavia), Asia (Russia, Japan, China), North America, Australia and New Zealand. The species is rare in the tropics, and positive identifications are lacking for Africa ( Chris et al. 2003).

Figures

Figure 3. LM (A, B) and SEM (C-H) images of species found in the transitional zone at Mykolaiv city: A Aulacoseira islandica, valve view B Aulacoseira nivalis, valve view C Aulacoseira subarctica, girdle view of complete frustule D-H Actinocyclus normanii valve view (D pseudonodulus shown with arrow, E, G) and girdle view (H, F). Scale bars: 10 μm.