Lycaena ratushinskayae sp. n. is described from the Baitag mountain range isolated in the Dzhungarian Gobi desert, SW Mongolia. Externally the new species strongly differs from related taxa by a dark-gray underside and deep reddish upperside with widened blackish margins. A new study of the male genitalia is performed with the diagnosis of new and all related species. It is confirmed that juxta presents the most valuable sclerite for taxonomic purposes.

Plebejus chrisreai sp. n. and P. anikini azhbogdo ssp. n. are described from the Dzhungarian Gobi desert and the Transaltajan Gobi desert respectively. External distinctions as well as distinctions of the male genitalia are given for the new taxa and two related species known from Mongolia: Plebejus anikini Yakovlev, 2012 and P. germani Yakovlev, 2012. Genitalia of all the taxa mentioned are illustrated, the aedeagus and valva bear the most valuable taxonomic characters. Females of the new species have an unusual whitish colour of the upperside not known for the christophi species complex before. The distribution of Mongolian taxa and relatives from East Kazakhstan is discussed.

Neolycaena enkhnasani sp. n. is described from the Dzhungarian Gobi desert. The food plant is Halimodendron halodendron (Fabacea). The new species is distinguished from the related taxa known from East Kazakhstan by small size, dense gray suffusion on the hindwing underside, a delicate and partly reduced submarginal underside pattern as well as the characters of the genitalia: the shape of the valva in males and the shape of the antrum in females. Important new data about the distribution and distinctions of N. zaisana (Zhdanko, 2013) and N. balchaschensis Zhdanko, 1998 are published together with photos of the genitalia of all the three taxa.

In this paper, the lectotypes are designated and figured for Erebia kefersteinii (Eversmann, 1851), Clossiana selenis (Eversmann, 1837) and Melitaea arcesia Bremer, 1861. The holotype by monotypy of Melitaea baikalensis Bremer, 1861 is found and illustrated. The type localities of all mentioned taxa are discussed and clarified. The lectotypes and the holotype are deposited in the collection of Zoological Institute of the Russian Academy of Sciences, St. Petersburg.

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