Genus Liometopum Mayr, 1861

Type species Formica microcephala Panzer, 1798, by monotypy.

Diagnosis (for fossil imprints). Size large or medium. Head of gynes wider than long, with concave occipital margin. Antennae geniculate in both sexes, 12-segmented in gynes and workers and 13-segmented in males. Scape of male short. Declivous part of propodeum stright or convex (not concave) in side view. Petiole with scale in gynes and triangylate in side view in males. Male genitalia large, not involved. Forewing with closed cells 1+2r, 3r, rm and mcu. Cell3r with apex removed from fore margin of wing. Icu> 1.45.

Species included. Seven living species distributed in temperate and subtropic zones of Eurasia and North America [Shattuck, 1992]. Seven fossil species have been described: L. oligocenicum Wheeler, 1915 (Baltic amber, Late Eocene), L.miocenicum Carpenter, 1930, L.scudderi Carpenter, 1930 (Florissant, USA, Oligocene), L.eremicum Zhang, 1989, L.patamophilum Zhang, 1989, L. lubricum Zhang, Sun et Zhang, 1994 (Shanwang, China, Miocene), and L. imhoffii Heer, 1849 (Radoboj, Croatia, Miocene) [Carpenter, 1930; Heer, 1849; Wheeler, 1915; Zhang, 1989; Zhang et al., 1994].