Key to Crematogaster species in or possible in the southeastern United States

(from Creighton 1950; Johnson 1988; Buren 1968)
1    The postpetiole is suboval and entire, without a median sulcus; size minute
...2
  The postpetiole is divided by distinct median sulcus; size larger, not minute
...4
2(1)    Gaster covered with somewhat dense erect hairs; erect hairs on alitrunk dorsum short and flattened; color yellow or sometimes bicolored; sculpture on side of alitrunk extending to include sides of propodeum (This species is found in the West Indies, but is possible, especially in south Florida). 
...steinheili Forel
(no photo at this time)
  Gaster with sparse erect hairs; hairs on alitrunk dorsum long and tapering; color yellow to yellow orange; sculpture on side of alitrunk limited to mesopleural area
...3
3(2)      Propodeal spines directed upward and are about one-half as long as the distance which separates their bases; rugae on pronotum usually lateral in position; coloration darker than minutissima and size larger, nests in open areas, roadsides, etc.
  Propodeal spines directed more backward than upward and less than one-half the distance which separate their bases; two prominent rugae near the middle of the pronotum; color light yellow and smaller than missuriensis; nests in rotting logs in woods
4(1)     Head granulate and not shining; head with erect flattened hairs
  Head not granulate, shining; if erect present on hair, then not flattened, but filiform and tapering
...5
5(4)      Pronotal pleurae sculptured, roughened looking and opaque
...6
  Pronotal pleurae mostly unsculpured and with a large band having a smooth, reflective, or shiny surface
...8
6(5)    The pronotum with a band of erect hairs occuring transversely and other erect hairs scattered randomly across the mesonotum
  The pronotum with erect hairs confined to the humeral shoulders; there may be occasional erect hairs on the anterior margin of the propodeum
...7
7(6)     The thoracic dorsum with rugoreticulatum
  The thoracic dorsum with longitudinal, short striations or ridges, with granulation or punctation in between
8(5)   Propodeal spines short and in dorsal view the inner margins are parallel to the longitudinal body axis
...9
  Propodeal spines long and in dorsal view the apices diverge from the longitudinal body axis
....10
9(8)   Color dark brown to black; nest in many different trees, shrubs, and vines in a wide variety of habitats
  Head, alitrunk, petiole, and postpetiole dark red, gaster black; nest in open grown pines
10(8)   The pubescence on the head and thorax appressed, the hairs on the head are fine and in orderly rows; 1 or 2 (rarely 3) erect hairs on each humeral shoulder of pronotum
  The pubescence on the head and thorax is suberect or erect (at least some of them) and the hairs on the head do not lie in orderly rows; 2-4 (or occasionally more) erect hairs on each humeral shoulder of pronotum
Note:  Some taxonomists think C. pilosa should be split into two species: C. pilosa and C. clara Mayr.  In this case, they can be distinguished by C. pilosa having suberect hairs on the gaster and legs as well as the head and thorax, and usually having some distinct rugae on the thorax.  C. clara only has suberect hairs on the head and thorax, and the thorax is either smooth or faintly punctate.  Others are of the opinion that C. clara is a junior synonym of C. laeviuscula Mayr, a western species and the eastern species are all C. pilosa.