The distribution of B. subterraneus is very wide. However, as its population densities are generally low, it may be locally overlooked. In the west, it has been found in the north of the Iberian peninsula, in the Pyrenees and the Cordillera Cantabrica. In the British Is., it is restricted to England and a few places in Wales.
In Fennoscandia, it is found in many places up to the 60th parallel. It is found in every country of western and central Europe, but in the Mediterranean regions, it is restricted to the montane stages. It is found throughout Italy, but always in the mountains and not in Sicily. In the Balkan, it extends south to the Olympus and Pilion Mts. In eastern Europe, the species has been signalled in Estonia, Lithuania, Belarus, Ukraine, Romania and, in Russia, up to the 60th parallel. Panfilov (1957) mentions it in the Krim, the Caucasus, the south of the Ural Mts., S. and E. Kazakhstan, the Tien Shan Mts., the Altai, the Baykal'sk and N. Mongolia. In Asia Minor, it has been encountered on the Anatolian plateau, in Transcaucasia and N. Iran.
The darker forms (ssp. subterraneus) are restricted to S. Scandinavia and to Switzerland, N. Italy and S.-E. France. The light-coloured forms (ssp. latreillellus) are found elsewhere.
B. subterraneus latreillellus has been introduced in New Zealand, where it is restricted to the South Island and remains much less common than the other imported species.
P. Rasmont