Aulacoseira islandica (O. Muell .) Simonsen, Bacillaria 2: 60, pl. 1, figs 1-10. 1979.

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 islandica (O. Muell.) Simonsen, Bacillaria 2: 60, pl. 1, figs 1-10. 1979.

Basionym.

Melosira islandica O. Müll., J. Wiss. Bot. 43 (1): 56, pl. 1, figs 3-6. 1906.

Synonyms.

Melosira islandica subsp. helvetica O. Müll., M. islandica subsp. vaenernsis A. Cleve.

Morphological description.

Frustule cylindrical, valve face flat with randomly located areolae, diameter is 13.2-14.4 μm (Fig. 3A ). Curve of the valve with longitudinal areolae (12-14 in 10 μm) and transverse curly rows of areolae. The ringleiste is wide, connective spines are small-sized, sharp-ended, tear-drop-shaped or branched.

Ecology.

Aulacoseira islandica is most often occurring as planktonic or tychoplanktonic taxon in water bodies of different types in high latitude or high altitude oligotrophic to mesotrophic large waters ( Houk et al. 2010; Stoermer and Julius 2013; Genkal et al. 2020). Sometimes this species may even cause a spring bloom (Stoermer and Julius 2013).

Distribution.

This species was observed in all sampling sites and is the first confirmed record for the whole basin of the Southern Bug River (Table 1 ). In the mid-1930s Swirenko (1941) found this species as Melosira islandica var. helvetica O. Müller in the lower part of the River starting from Mygea rapids and some other lower stations along the River bed to the mouth ( Swirenko 1941). Aulacoseira islandica occurs in the Dnipro River basin and its reservoirs ( Tsarenko et al. 2009).

It is also a common species for Europe (Bulgaria, Iran, Finland, Germany, Lithuania, Romania, Russia, Sweden, Ukraine), Asia (Georgia, Russia, Turkmenistan), North America (Canada, Greenland, USA); Barents, Bering and White Seas ( Tsarenko et al. 2009).

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.