New species and new records of Cosmolaelaps Berlese (Acari: Laelapidae) from Russia, with a review of the Russian species of the genus Author Joharchi, Omid Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, Semakova Str. 10, 625003 Tyumen, Russia. Author Döker, Ismail 0000-0002-2741-4946 Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, Semakova Str. 10, 625003 Tyumen, Russia. & Cukurova University, Agricultural Faculty, Department of Plant Protection, Acarology Laboratory, 01330, Adana, Turkey. https: // orcid. org / 0000 - 0002 - 2741 - 4946 (Joharchi) https: // orcid. org / 0000 - 0002 - 1412 - 1554 (Döker) https: // orcid. org / 0000 - 0003 - 2831 - 7213 (Khaustov) Author Khaustov, Vladimir A. Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, Semakova Str. 10, 625003 Tyumen, Russia. text Zootaxa 2022 2022-05-06 5133 4 486 508 journal article 55626 10.11646/zootaxa.5133.4.2 0cd92d63-eeac-48d6-9c9d-270f866de7d3 1175-5326 6530956 BD6A434A-21D7-49FC-A09F-FEF4BC740B14 Cosmolaelaps sejongi Keum, Jung and Joharchi Cosmolaelaps sejongi Keum, Jung and Joharchi, 2017: 487 . ( Figures 45–49 ) Specimens examined . Six females, Sakhalin Island, Russia , 46°44'06"N 142°12'17.5"E , 11 August 2021 , O. Joharchi coll., in the nest of Lasius umbratus (Nylander) ( Hymenoptera : Formicidae ) (in TUMZ). FIGURES 45–49. DIC micrographs of Cosmolaelaps sejongi Keum, Jung and Joharchi , female. 45, idiosoma in dorsal view; 46, idiosoma in ventral view; 47, general view of some opisthonotal setae; 48, sternal and genital shields; 49, general view of opisthogastric area. Remarks . Cosmolaelaps sejongi was described from Republic of Korea ( Keum et al ., 2017 ). It has been found from soil around roots of an oak tree ( Keum et al ., 2017 ), and is now recorded in Russia for the first time, in the nest of L . umbratus . Our specimens agree well with the description given by Keum et al . (2017) . The species is easily recognised by the distinctive shape of the post-anal seta (thickened, sparsely barbed and apically hook shaped), which is inserted on a small tubercle ( Figs 46, 49 ); dorsal shield setae thick and long, most setae long enough to reach well past the base of next posterior seta, and Z5 sparsely barbed, longer and thicker than J5 ( Figs 45, 47 ); sternal setae short, not reaching base of following setae ( Figs 46, 48 ); soft opisthogastric cuticle bearing 16 pairs setae, Jv5 well thickened, apically hook shaped and subequal in length with post-anal seta ( Figs 46, 49 ).