Staurastrum cyclacanthum var. pseudobrevissimus - a new variety of desmids and some other rare taxa found in peat bogs (Western Pomerania, Poland)

New variety of Staurastrum cyclacanthum var. pseudobrevissimum and four other taxa: Korshikoviella limnetica, Polyedriopsis spinulosa, Monactinus simplex var. echinulatum and Cosmarium sp. rarely reported from the studied region of north-western Poland are noticed. For all of them, detailed descriptions with original documentation and ecological characteristics of the studied sites are presented in this article.