Melosira subglobosa (Grunow) Houk, Klee & Tanaka in Fottea 17 (Supplement):17, pl. 17, figs 1-10; Pl. 19, figs 1-15; pl. 19, figs 1-11. 2017.

Synonyms.

Melosira borreri var. subglobosa Grunow, Melosira moniliformis var. subglobosa (Grunow) Hustedt.

Morphological description.

Frustule shape is cylindrical to approximately octagonal (Fig. 2A, F). Valve 12.5-26 μm in diameter, mantle height 3.1-8.5 μm . Valve face nearly octagonal with flat tops (Fig. 2B-E, G). Girdle with puncta forming straight and transverse rows 32-56 in 10 μm .

Ecology.

Marine and brackish, benthic-planktonic (tychoplanktonic) species, halophilic, widely distributed. Indicates significant organic pollution (eutrophication), α-mesosaprobiont (Kolpacov et al. 2014). This species prefers water enriched with dissolved organic matter, and is capable to switch from autotrophic to heterotrophic or mixed type of nutrition (Andreeva et al. 2008). Additionally, these diatoms are ubiquitous, and widely distributed in seas and estuaries of temperate zones in habitats with a moderate level with increased level of human impact (Kuzminova and Rudneva 2005; Ryabushko 2009).

Distribution.

Melosira subglobosa is one of the most common species at the sampling sites near the Mykolaiv area in the Southern Bug River (Table 1). For Ukrainian territory, it is known from the coastal zone in the northwestern part of the Black Sea, Crimean seaboard, and some estuaries.

For a worldwide distribution, it was recorded from coastal zones of Europe, and Asia; specifically, from Lake Aral, Baltic, Bering, Black, Caspian, Mediterranean, North and Norway Seas (Tsarenko et al. 2009).