A new species and new records of the genus Eustigmaeus (Acari: Prostigmata: Stigmaeidae) from Western Siberia.

A new species of the genus Eustigmaeus Berlese, 1910 (Acari: Stigmaeidae), E. tjumeniensis sp. nov. is described from mosses of fens in Western Siberia, Russia. Eutigmaeus collarti (Cooreman, 1955), E. ioanninensis Kapaxidi and Papadoulis, 1999, E. jiangxiensis Hu, Chen and Huang, 1996 are recorded from Russia for the first time. Eustigmaeus parvisetus (Chaudhri, 1965) is recorded from Eurasia for the first time. Eustigmaeus collarti and E. parvisetus are redescribed based on material from Western Siberia. A key to Eustigmaeus species of Russia is provided.