The Charophytes (Characeae, Charophyceae) of the Caucasus

This first inventory of the charophytes of the Caucasus region was compiled based on records from published references, online sources, a review of herbarium collections, and our own field collections. The documented Caucasian charophyte flora includes 27 species from six genera: 18 <i>Chara</i> species, 6 <i>Nitella</i>, 2 <i>Tolypella</i>, and 1 species each of <i>Lamprothamnium</i>, <i>Nitellopsis</i>, and <i>Sphaerochara</i>. <i>Chara uzbekistanica</i>, <i>C. virgata</i>, and <i>C. contraria</i> var. <i>hispidula</i> are newly recorded for the Caucasus. The high species richness of the genus <i>Chara</i>, the much less diverse genus <i>Nitella</i>, and a few species of <i>Tolypella</i> and <i>Sphaerochara</i> in the Caucasian charophyte flora are typical traits of Palearctic charophyte floras. In total, there are 10 species recorded in Armenia, 16 in Azerbaijan, 18 in Georgia, and 16 in the mountainous region of the North Caucasian Federal District of Russia. Most of the species have wide distributions; none are endemic to the Caucasus. One of the most commonly recorded species in the region, <i>C. gymnophylla</i>, is a usual feature of the Mediterranean and West Asia. The Caucasian charophyte flora can be described as unsurprising from a large-scale perspective, considering its species distribution ranges. However, the association of species makes the region specific at the scale of West Asia when comparing it to its large neighboring areas.