A new feather mite species, Dolichodectes sibiricus sp. n. (Pterodectinae), is described from the Dark-sided Flycatcher, Muscicapa sibirica Gmelin, JF, captured on the southern coast of Lake Baikal, Buryatia, Russia. The new species is closest to D. allocaulus (Gaud and Mouchet 1957) and D. platynocercus (Gaud and Mouchet, 1957) from Africa and is distinguished from them in the following features. In males of D. sibiricus, the lateral enlargements of opisthosomal lobes are of a complicated form and consist of distinct angular projections bearing setae f2 and rounded ledges at level of setae h2, and the aedeagus extends to the level of setae ps3; in females, the prodorsal and hysteronotal shields lack ornamentation, the terminal appendages at their bases are 2–2.5 times thicker that setae h2, and setae e2 are situated closer to the level of setae e1 than to the posterior margin of the hysteronotal shield. Brief comments on the systematics of the genus Dolichodectes, a key to the known species, an updated checklist of the world fauna, as well as host associations are provided.