Key to the species of Temnothorax in or possible in the southeastern United States (Creighton 1950; Deyrup and Cover 2004; MacKay 2000)
1       Antennae twelve segmented
...2
  Antennae eleven segmented
....4
2(1) Antennal scrobes present; apical margin of mandible with 4 teeth
  Antennal scrobes absent; apical margin of mandible with 5 or 6 teeth
...3
3(2)     Antennal scapes not surpassing the occipital margin; dorsum of the pro-mesonotum flat or feebly convex in profile; metanotal groove not deeply impressed, at most with a shallow impression
...4
 

Antennal scapes surpassing the occipital margin; dorsum of the promesonotum convex in profile; metanotal groove deeply impressed

4(3)    

Color blackish, occasionally with dark red on the alitrunk; postpetiole, in dorsal view, much wider than long

  Color yellowish, head usually darker than body; postpetiole, in dorsal view, about as wide as long
5(1)     Head and body, excluding gaster, covered with coarse, raised reticulations (found in tropical FL)
  Head and body not covered with covered with coarse, raised reticulations
...6
6(5)     Head and alitrunk not shining and without conspicuous sculpture; only a few hairs on body, these hairs scale-like; postpetiole unusually large
  Head and alitrunk partially shining or strongly sculptured; number of hairs on body vary, but none scale-like; postpetiole not enlarged
....7
7(6)   Propodeal spines longer than one-half the distance which separates their bases
....8
  Propodeal spines short and dentiform, their length less than one-half the distance which separates their bases
8(7)  Dorsal surface of head smooth and shining; the length of the propodeal spines usually nearly as as long as the distance between their tips
...9
  Dorsal surface of the head feebly shining or completely opaque, sculpturing variable but never giving the surface a smooth and shining appearance; the propodeal spines are often shorter than the distance between their tips
...10
9(8)   In profile the propodeal spines form an angle of nearly 180° with the dorsum of the propodeum
  In profile the propodeal spines form an angle of approximately 150° with the dorsum of the propodeum
10(9)   

Head with the longitudinal rugae very delicate, not much coarser than interrugal sculpture and often forming reticulations with it

...11
  Head with coarse longitudinal rugae, which are notably heavier than interrugal sculpture and not forming reticulations with it
...12
11(10)      Propodeal spines set close together at bases, spines about twice as long as distance between bases; postpetiole, in dorsal view, subquadrate, slightly broader than long
  Propodeal spines well separated at bases, about as long as distance between bases; in dorsal view, postpetiole broader than long
12(10)    Dorsum of postpetiole lightly punctured, not completely opaque; dorsum of the mesonotum with longitudinal rugae largely replaced by punctures; propodeal spines less than half as long as the distance which separates their tips
 

Dorsum of postpetiole heavily punctured and completely opaque; dorsum of the mesonotum with the longitudinal rugae not replaced by punctures; propodeal spines more than half as long as the distance which separates their tips

...smithi (Baroni Urbani) (= wheeleri Smith)
Note:  There is some disagreement on the status of T. pergandei and T. p. floridanus. At one point T. floridanus was a subspecies of T. pergandei.  Some consider them to both be good species (pers. comm James Trager).  In this case they can be distinguished by the differences in petiolar nodes, in T. pergandei the node (in profile) is low and angular and the crest of the node is flat or with a concave depression from behind; also the color is piceous brown.  In T. floridanus, the petiolar node in profile is blunt with a rounded crest and from behind the crest is slightly convex; the color is more variable from piceous brown to yellowish-red.