[Diagnosis of species of the genus Dermacentor Koch in Siberia and the Far East by the sexually immature phases (Ixodoidea, Ixodidae)].

Keys to four known species of the genus Dermacentor from Siberia and Far East of the USSR are based on their nymphs and larvae. Analysis of laboratory cultures served as a basis for distinguishing differential characters of preimaginal phases. Stability of characters in the distribution area of each species was verified on natural material from many geographical localities. A wide range of structures was used for species identification as follows: peculiarities of scutum, peritreme, anal valve, organs of gnathosoma, chaetotaxy and morphometrical characteristics and ratios. Keys can be used for identifying species from the European part of the USSR and north-eastern Kazakhstan.