Proteroiulus sp.

Material examined (IBER): 2 ♀♀, Tran Municipality, Lomnitsa village, N 42.521319, E 22.375491, the road to hut Rui, near a river, under the bark of Salix sp., 12.III.2016, leg. P. Mitov, det. BV.

Remarks. These specimens may actually be P. fuscus (Am Stein, 1857), a species which is widespread across Europe. In Bulgaria it has been twice recorded from subterranean habitats (Vagalinski & Stoev 2007). However, the two examined females are considerably thinner (0.4 mm diameter at mid-body) compared to the measurements given by Blower (1985) for P. fuscus, namely 0.5–0.9 mm in females. The second known species of the genus, P. broelemanni Lohmander, 1925, occurs in France and Spain. We don’t exclude the possibility that the examined specimens belong to a yet undescribed species of Proteroiulus but this needs to be confirmed with adult males.