In the West Palaearctic region, the range of B. distinguendus spans from the 45th parallel to hardly beyond the Arctic Circle. The most southern observations are from the French Jura Mts., N. Lombardia (Italy) and a few places in the south of the Carpathian Mts. (Romania). The location in Croatia, cited by Handlirsch (1888), is dubious.
The species is generally uncommon. As it is also regressing, most places of the map relate to old observations.
More east, it can be found throughout Siberia, to the Ussuri R., the Kamchatka, Sakhalin Is., Mongolia, Inner Mongolia, the Altai and the Sayan Mts. According to N. Bogatyrev, it is common in W. Siberia, around Novosibirsk.
P. Rasmont