Key to MYRMICINAE Genera in the southeastern United States (adapted from Bolton 1994)

1            Postpetiole joined to the dorsal surface of the first gastral segment; the gaster in dorsal view heart shaped; petiole dorsoventrally flattened and without a node
 

Postpetiole joined to the anterior face of the first gastral segment; gaster not heart shaped in dorsal view; petiole usually with a node, but if reduced then not dorsoventrally flattened

...2
2(1)      Antenna with 7 segments; antennal scrobes present and running down below the eye (possible, found in FL)
  Antenna with either less than 7 segments or more than 7 segments; antennal scrobes may be present, but above or in front of the eye and not below the eye
...3
3(2) 

Apical and preapical antennal segments forming a strong and obvious club of two segments

...4
  Antenna ending in a club of 3 segments or more
..7
4(3)     Antenna with 4-6 segments; petiole and postpetiole usually with spongiform tissue present
  Antenna with 9-11 segments; petiole and postpetiole without spongiform tissue
...5
5(4)  Frontal carina present, running back almost to occipital margin; broad, but shallow antennal scrobes present; median part of clypeus without a pair of longitudinal carinae; propodeum with a pair of long spines
 

Frontal carinae absent; antennal scrobes absent; median part of clypeus with a pair of longitudinal carinae medially or at lateral edges; propodeum unarmed

...6
6(5)
Petiole subsessile, node not strongly produced; mandible with 5 or 6 teeth; antenna 11 segmented (including scape)
Petiole with well developed anterior peduncle; petiole with obvious node; mandible with 4 teeth; antennna 10 segmented (including scape)
7(3) Antenna with 11 segments (including scape)
...8
  Antenna with 12 segments (including scape)
...14
8(7)   In profile, eye located close to posterior margin at the apex of a deep antennal scrobe, the scrobe runs forward from anterior margin of eye and is bounded above by the massively  expanded frontal carina
  Eyes located near midlength of head (in profile); antennal scrobe either absent or present, but running above the eye and extending beyond the level of the eye and eye not located at apex of scrobe
...9
9(8)  Lateral parts of clypeus forming a raised, sharp edged rim in front of antennal insertions; sting with a lamellate appendage found apicodorsally that projects at an angle to the long axis of the sting shaft
...Tetramorium (part)
  Lateral parts of clypeus not forming a sharp edged rim in front of antennal insertions; sting lacking lamellate appendage
...10
10(9)   With head in profile, a diagonal superocular carina present that runs from the eye to the insertion point of the mandibles; promesonotal dorsum with numerous tubercles, teeth, or spines
...11
 

With head in profile, there is no superocular carina present; promesonotal dorsum without tubercles, teeth, or spines, (propodeum armed with a pair of spines or teeth)

...13
11(10)  

Promesonotum with blunt tubercles; frontal lobes projecting forward (in full face view), anteriorly reaching or overlapping the anterior and lateral parts of the clypeus; mandible with 5 teeth; propodeum angular to bidendate

  Promesonotum with elongate, sharp spines or teeth; head in full face view not having frontal lobes reaching anterior margins of lateral part of clypeus; mandible usually with more than 7 teeth; propodeum bispinose
..12
12(11)

Dorsal area of promesonotum with only 2 pairs of spines; first tergite of gaster without raised cuticular tubercles

 

Dorsal area of promesonotum with 3 or more pairs of spines; first tergite of gaster with numerous raised cuticular tubercles (common, in various habitats)

13(10)    Antennal scrobes present; apical margin of mandible with 4 teeth
  Antennal scrobes absent; apical margin of mandible with 5 or 6 teeth
..Temnothorax (in part)
14(7)     Ventrolateral margin of head with sharp carina on each side, which run from near the inner ventral base of mandible to below the eye and ascend the occipital surface posteriorly; petiole sessile, propodeum bispinose
 

Ventrolateral margin of head without sharp carina on each side; petiole usually pedunculate

...15
15(14) Lateral part of clypeus is raised into a sharp ridge or wall on each side in front of the antennal insertions; sting with a lamellate appendage found apicodorsally that projects at an angle to the long axis of the sting shaft
...Tetramorium (part)
 

Clypeus not raised laterally into sharp-edged ridge; sting lacking apicodorsal lamellate appendage

...16
16(15) Middle and hind tibial spurs simple or absent
...17
  Middle and hind tibial spurs pectinate (high power magnification is needed to see this, 80X or above is recommended)
...23
17(16) Median area of clypeus abruptly raised and somewhat narrowed, with a pair of fine longitudinal carinae that diverge anteriorly, area between these carinae concave to flat
...18
  Median area of clypeus not abruptly raised, flat to convex (transversely), without a pair of fine longitudinal carinae medially, clypeus occasionally with a single median carina
...19
18(17)   Propodeum unarmed, without spines or teeth, angular to rounded; masticatory margin of mandible with 3 or 4 teeth or denticles
 

Propodeum with a pair of teeth or spines; masticatory margin of mandible with 5 or more teeth or denticles (antennal club of 4 segments)

19(17)  Masticatory margin of mandible with 0-6 teeth
...20
  Masticatory margin of mandible with 7 or more teeth
..22
20(19)  

Mandible massive, edentate or with rounded vestiges of teeth, or with 2 teeth basally followed by an area with no teeth (diastema), then 1 or 2 teeth apically; with the alitrunk in profile, the pronotum or the pronotum plus the mesonotum form a convex arc; dorsal surface of propodeum depressed far below level of promesonotum (dimorphic workers, soldier with large heads, club of antenna longer than rest of funiculus)

...Pheidole (in part)
 

Mandible delicately constructed, having 5 or 6 regular teeth decreasing in size from apex to base; the alitrunk in profile with dorsal outline flat to shallowly convex; dorsal surface of propodeum on same level or just slightly lower than promesonotum

...21
21(22)  Midpoint of anterior clypeal margin with an unpaired, long seta projecting forward over mandibles; lateral part of clypeus flattened and projecting over mandibles; dorsal area of head and body without standing setae
  Midpoint of anterior clypeal margin without unpaired setae extending over mandibles, usually with a pair of setae on either side of the midpoint of clypeus; lateral parts of clypeus not flattened or projecting forward over mandibles; standing setae present on dorsum of body
...Temnothorax (in part)
22(19)

Palp formula 2,2 or 3,2; masticatory margin of mandible having third tooth (from the apex) smaller than fourth, or the smaller third tooth followed by a minute denticle before fourth tooth (minor workers) or mandible having 2 large apical and 1 or 2 enlarged basal teeth with the margin between these teeth crenulate to low-dendate (most major workers)

...Pheidole (in part)
 

Palp formula 4,3 or 5,3; masticatory margin of mandible with the third tooth from apex larger than the fourth; major workers never having dentition as above (body long and slender, long legs, antennae surpassing occipital region of head, mandible usually with more than 8 teeth)

23(16) Ventral surface of head with a psammophore (series of long hairs), metanotal groove not impressed; strongly dimorphic, majors with large heads (at least in our sp.), metasternal process in the form of two large prominent teeth palp formula 5, 3 at most
  No psammophore, metanotal groove distinctly impressed; workers not dimorphic; metasternal process a pair of raised flanges; palp formula 6, 4