Odonata of Aldan Ulus of Yakutia (East Siberia, Russia): 20 years later

Odonata of the Aldan Ulus (District) of Sakha Republic (Yakutia), East Siberia, Russia, were studied in late June – early July 2022 for the second time, 20 years after the analogous previous study (Kosterin 2004a), partly in the same localities. This time 20 species were found, that is 1.5 times more than 13 species on the previous study. This increase could be an effect of the current climate amelioration but no northward range extensions were registered, all species being known in Yakutia more northerly for quite a long time. Ten species were found in 2022 but not in 2002 (Coenagrion armatum, C. glaciale, C. hylas, C. lanceolatum, Erythromma najas, Aeshna crenata, A. juncea, Ophiogomphus obscurus, Leucorrhinia intermedia, Sympetrum flaveolum), while three species were found in 2002 but not this time (Aeshna caerulea, Nihonogomphus ruptus and Somatochlora sahlbergi). In total, 23 species have been registered in Aldan Ulus up to date. Variation in Enallagma cyathigerum, Erythromma najas, Somatochlora exuberata and Leucorrhinia orientalis is briefly discussed. Mass emergence of O. obscurus from the Aldan River on a rainy day (and even during showers) following a period of hot weather was observed and discussed.