A new species, Acerentulus bulgaricus sp. nov., belonging to the confinis group, is described from Bulgaria. This species is characterized by long foretarsal sensilla a and b, the posterior position of foretarsal seta δ4, the presence of seta P1a on abdominal tergites II–VII and seta P3a on abdominal tergite VII, possession of eight anterior setae on abdominal tergite VII and composed spsm pores on sternite VI. The new species differs from all members of the confinis group in possessing P1a setae on tergites II–VII. Otherwise it is similar in body chaetotaxy and porotaxy to three species of the cunhai group, A. proximus, A. correzeanus and A. tuxeni. The identification key to 22 Acerentulus species belonging to confinis group is revised.