COSMARIUM RETUSIFORME VAR. INCRASSATUM GUTWIŃSKI 1890 (ZYGNEMATOPHYCEAE, STREPTOPHYTA) – NEW RECORD OF RARE DESMID IN UKRAINE

Purpose. Adding a new taxon of the genus Cosmarium to the desmids flora of Chernihiv Polesie. Methodology. The landscape reserve of national significance “Zamglai” is one of the largest eutrophic swamps in the Chernihiv Polesie, which is an important refugium of hydrophilic phytodiversity of the forest zone, a place of concentration of a number of rare species of the boreal group and representatives of various biotic complexes. During the field research of the Zamglai bog complex, algal samples were collected and fixed with 4 % formalin for further study in laboratory conditions; pH and electrical conductivity of water were measured with a portable pH and conductivity meter. Microscopic examination of the samples was carried out using a light microscope equipped with a camera for taking microphotos. Identification manuals and monographs of the leading Ukrainian (Palamar-Mordvintseva, 1986, 2005) and European desmidiologists (Lenzenweger, 1999) were used for species identification.The iconotype provided in the original description of the newly recorded taxon (Gutwiński, 1892) was used. Scientific novelty. The second record in Ukrainian desmidioflora of a rare taxon from the genus Cosmarium is documented. Previously it was discovered 134 years ago (Gutwiński 1890) in the Roztochchia-Opillja mountain region, namely in the vicinity of Lemberg (former Kingdom of Galicia and Lodomeria, a part of the Austro-Hungarian Monarchy – now Lviv, Ukraine). This taxon was found by the authors for the first time in the Ukrainian Polesie (Chernihiv Polesie). Description, cell dimensions and microphotographs in three views are included in this publication. Conclusions. The description and photographs of the three cell views of the taxon given in the article fill the gaps in the illustrative material of the national reference publications (Palamar-Mordvintseva 1986: 167, fig. 37 item 16) and create better conditions for identification and new records of this taxon in Ukraine. The distribution area of Cosmarium retusiforme var. incrassatum Gutwiński 1890 has been expanded. The flora of desmids of the Ukrainian Polesie is enriched with a new infraspecific taxon.