Key to Neivamyrmex species in or possible in MS or AL (from Creighton 1950; Watkins 1985)
Key to Workers

1   Petiole with anteroventral tooth having a prominent acute spine directed posteroventrally (may be difficult to see, sometimes concealed by metacoxa); color usually black to brownish black
  Anteroventral tooth (if present) without a prominent acute spine directed posteroventrally; color variable, but never black

Upper surface of head opaque, densely granulate

  Head mostly shining, not with granulate sculpture
3(2)   Propodeal declivity slightly concave and forming an angular corner with dorsal surface
  Propodeal declivity not concave, forming a rounded corner with dorsal surface
4(2)  Petiolar node elongate, almost twice as long as broad
  Petiolar node subquadrate, about as broad as long
Key to Males
Mandible spatulate, distal half as broad or broader than basal part
  Mandible sickle shaped, slender and gradually tapering apically (in N. pilosus, the inner median part of mandible is convex)
2(1)    Gaster black to blackish brown; the setae on venter of petiole are short (hairs shorter that width of metatibia), white, and directed posteroventrally; just above the antennal fossa, a prominent swelling is present
  Gaster reddish brown; the setae on venter of petiole long (hairs longer than width of metatibia), golden, and erect; area above antennal fossa with transverse swelling only weakly developed or absent
3(2)    Apex of stipes with a tall dorsal projection; mandible typically about equally wide along entire length out to a tapered apex; TL 11 -13 mm
  Apex of stipes without dorsal projection; mandible with distal two thirds usually slightly convex along inner border; TL 10 - 11 mm

The distance from lateral ocellus to the margin of the compound eye less than the diameter of median ocellus

  The distance from lateral ocellus to the margin of the compound eye about 1.5 to 3 times the diameter of the median ocellus