Keys to Genera of Formicinae of Mississippi
(based on Workers
)
(from Creighton 1950 & Bolton 1994)

1 Antennae with 9 segments (fig. 1), workers minute, monomorphic, frontal carinae close together, thorax short and stout
  Antennae with 12 segments (fig. 2)
...2
2(1) Alitrunk in profile evenly convex, the propodeum not depressed below the level of promesonotum, and metanotal groove unimpressed or very slightly impressed, except in the subgenus Colobopsis, which has the propodeum depressed and metanotal groove strongly impressed, but in this case, the head of major is cylindrical and truncate anteriorly; mesothoracic spiracles on sides of thorax at level below dorsal face of propodeum; antennal scape usually inserted well behind posterior edge of clypeus
  Alitrunk in profile, with the propodeum distinctly depressed below level of promesonotum, metanotal groove always distinctly impressed; mesonotal spiracles usually in this impression on or near dorsal surface of thorax; antennal scapes inserted at or close to posterior border of clypeus
...3
3(2) Mandibles sickle shaped, their inner borders finely serrate; palp formula 4,2
  Mandibles triangular, masticatory margin with distinct dentition, palp formula different
...4
4(3) Maxillary palps with only 3 segments and very short
  Maxillary palps with 6 segments and long
...5
5(4) Frontal carinae prominent and their lateral margins slightly reflected upward; very distinct ocelli present
  Frontal carinae not prominent, poorly marked and their lateral margins flat; ocelli indistinct or absent
...6
6(5) Dorsal surface of head and body with coarse, long, and dark setae arranged in distinct pairs; with head in full-face view, eye at or in front of midlength (anterior to midlength) of side of head
...7
  Dorsal surface of head and body without coarse setae arranged in distinct pairs, may have lighter pilosity abundant to absent; with head in full-face view, eye behind midlength (posterior to midlength) of the side of head
...8
7(6)
Scapes and legs very long (SI > 165, FI >115); color weakly shining black or gray with bluish reflections; pubescence sparse, short, and barely visible (usually associated with human dwellings and urban areas)
Scapes and legs not unusually long (SI < 130, FI < 105); color varies, but never with blueish reflections; shiny or dull, if dull, then due to dense pubescence
8(6) Mandible with 6 teeth, very rarely with 7; anterior face of first gastral segment broadly and transversely concave throughout its height; antennal scapes long, projecting past occipital region by at least half their length; mesothorax constricted immediately behind pronotum
  Mandible with at least 7 teeth, usually more; anterior face of first gastral segment not broadly and transversely concave throughout its height; antennal scapes shorter, projecting past occipital region by much less than half their length; mesothorax not constricted immediately behind pronotum