This species previously included in the genus Leptothorax (Myrafant) is now placed in the genus Temnothorax (Bolton 2003). The small brownish-yellow workers of T. unifasciatus may be distinguished from those of the three similar British and Channel Islands species - T. albipennis, T. interruptus and T. nylanderi - by their possession of a clearly-defined, continuous dark band across the first gastral tergite.
Temnothorax unifasciatus occurs in the Channel Islands, but is absent from England, Wales, Scotland and Ireland except for a single record from West London, see above photo, a probable accidental import. Elsewhere, T. unifasciatus is found throughout southern, western and central Europe, and in parts of Eastern Europe. It has also been recorded from Morocco and southern Sweden (Collingwood 1979; Czechowski, Radchenko & Czechowska 2002).