Key to Odontomachus  species in the southeastern United States (adapted from Deyrup and Cover 2004; MEM collection records, and personal communication from Mark Deyrup)
Workers and queens
1 Petiole with conspicuous transverse striae
...2
  Petiole smooth, lacking transverse striae, or with at most, only a few feeble striae basally
...3
2(1) Large, HL usually greater than 2.5 mm, TL about 8.0-8.5 mm; transverse striae on petiole conspicuous anteriorly, laterally, and baso-posteriorly, but reduced or lacking on remainder of posterior region; paired, slender, acute metasternal spines present (may have to remove one hind leg including coxa to see this character) (Gulf Coast)
  Smaller, HL usually less than 2.5 mm, TL usually less than 8.0 mm; petiole entirely covered with strong, deep, striae - striae depth and conspicuousness not diminished on posterior side of petiole; lacking paired metasternal spines (southern FL)
3(1) Hairs on first tergite of gaster extremely fine and dense, spaces between hairs less than 1/3 as wide as length of hairs (native species, GA to AL)
  Hairs on first tergite of gaster sparse, spaces between hairs at least 1/2 as wide as length of hairs
...4
4(3) Basalar lobe striate (only known from sand ridges in south-central peninsular FL)
  Basalar lobe smooth (found in SW US into LA)
Two other species, O. bauri and O. insularis, are possible in the Southeast. Odontomachus bauri is native to Central and South America, but has been reported from the West Indies, and O. insularis is also known from the Caribbean region. Odontomachus bauri is a large, dark reddish-brown species with long scapes and with the entire posterior face of the petiole having conspicuous transverse striae. The longer scapes and larger size of workers differs from O. ruginodis, and the entire posterior face of the petiole being covered with transverse striae should separate O. bauri from O. haematodus. Odontomachus insularis is most similar to O. clarus and O. relictus, but differs by having the petiolar spine drawn out into a long, slender spine.
Key to Males
1        Color entirely yellow to orangish-yellow
...2
  Body with at least some areas dark brown to blackish-brown
...3
2(1) Ocelli on conspicuous turrets; each ocellus large with greatest length more than the distance between lateral ocellus and eye (GA through MS)
  Ocelli not on conspicuous turrets; ocelli smaller with greatest length slightly less than the distance between lateral ocellus and eye (common in along Gulf Coast)
3(1) Entire body brown
...4
  Head and thorax yellowish with some brownish infuscation, propodeum dark brown, petiole and gaster brownish, and appendages yellowish (southern FL)
4(3) Ocelli small, diameter about two thirds of distance between lateral ocellus and eye; southwestern species to Louisiana
  Ocelli mounted on conspicuous turrets; each ocellus large, diameter of each ocellus obviously wider than the distance between lateral ocellus and eye; only known from sand ridges in peninsular south-central Florida
As mentioned earlier, O. bauri and O. insularis, are possible in the Southeast. Males of O. bauri are yellowish with three broad, dark stripes on the dorsum of the pronotum. Males of O. insularis are black with a dark brown gaster.