First record of euglenophytes of the genus Trachelomonas in mountain lakes of Lori Province in the Republic of Armenia.

Representatives of the genus Trachelomonas, representing the phylum Euglenozoa, are eukaryotic mixotrophic organisms that can benefit from photoauxotrophy and osmotrophy, as can other chloroplast-bearing euglenophytes. For this reason, they prefer aquatic ecosystems with large amount of dissolved organic matter as a carbon source. Such bodies of water are usually small in size, with a well-developed littoral belt where decaying vegetation provides the substances necessary for the growth of these flagellates. Three small, mountainous lakes in Lori Province in northern Armenia were sampled to identify the flora of the genus Trachelomonas. This was the first floristic study of euglenophytes in Armenia. Using the scanning electron microscopy (SEM) technique, we identified 26 taxa belonging to the genus, of which 23 were taxa given for the first time for Armenia. The three others, T. hispida, T. oblonga, and T. volvocina, were reported from different aquatic ecosystems in Armenia, but were not documented by microphotography. In our study, in addition to these taxa, the genus Trachelomonas was represented by the most abundant T. acanthostoma and less common species such as T. compacta, T. lomnickii, T. neotropica, and T. zorensis. SEM-energy dispersive spectroscopy (SEM-EDS) studies provided information on the chemical composition of Trachelomonas envelopes (loricae). According to the few data on the subject, the main mineralising elements were iron and manganese in varying proportions. However, it turned out that most loricae smooth on the surface were characterised by a high iron content with a negligible contribution of manganese. Spiny loricae, however, had a high or fairly high proportion of manganese in addition to a high iron content as a mineralising element.