Eyes medium to large in size, situated at the midlength or slightly forwards on sides of head. Anterolateral corners of pronotum round to angulate in dorsal view. Metanotal groove varying from deeply impressed to obscure or absent. Body hairs usually short, stout and erect, sometimes long or lacking. Leptothorax is a relatively large genus, comprising more than 200 described species, distributed world-wide except for the Australian region.
Most species are Palearctic or Nearctic.
The Palearctic fauna excluding that of Western Europe has not been taxonomically revised. In this work we treat 13 species, adding 8 unnamed forms to the Japanese fauna. Editor of the descriptions Original text by Mamoru Terayama, Keiichi Onoyama, and Masaaki Morisita. English translation by Mamoru Terayama, edited by Robert W. Taylor.