Revision of the characeae (Charales, Charophyceae) species and their distribution in Lithuania

The current inventory was mainly based on revising herbarium specimens collected since the 19th century and confirmed twenty-one Characeae species in Lithuania. They are representatives of five genera: Chara (12 species), Nitella (5), Tolypella (2), Lychnothamnus and Nitellopsis (by one species each). Thirteen species mentioned in references or labels of herbarium specimens were not confirmed. The occurrence of the Characeae species was recorded in 251 map grid cells (42% of the total number 593). Herbarium specimens were collected from 693 water bodies, mainly lakes. Chara globularis was the most common species, recorded in 150 map grid cells and more than 250 water bodies. Ten species (C. aspera, C. contraria, C. filiformis, C. subspinosa, C. tomentosa, C. virgata, C. vulgaris, Nitella mucronata, N. flexilis, Nitellopsis obtusa) were recorded in the interval from 100 to 50 grid cells and also belong to the group of common species. Chara papillosa and C. strigosa were recorded less than in 50 grid cells and should be considered quite common. Eight species (C. baltica, C. canescens, Lychnothamnus barbatus, Nitella confervacea, N. gracilis, N. syncarpa, Tolypella nidifica, T. prolifera) were recorded in ten or fewer grid cells and belong to the group of rare or very rare species. The occurrence of species that have not been confirmed by the herbarium specimens was discussed.