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

(from Creighton 1950; Johnson 1988; Buren 1968, Blaimer and Ward 2022)

1    Postpetiole suboval and entire, without a median sulcus; size minute
  Postpetiole divided by distinct median sulcus; size larger, not minute
2(1)    Gaster covered with somewhat dense erect setae; erect setae 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 setae; setae on alitrunk dorsum long and tapering; color yellow to yellow orange; sculpture on side of alitrunk limited to mesopleural area
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, not shining; head with erect to semi-erect setae present, many of these setae flattened and slightly spatulate (narrowed basally and becoming wider apically)
  Head not granulate, shining; if erect setae present on head, then these setae are all filiform and tapering, not flattened and spatulate
5(4)      Pronotal pleurae sculptured, roughened looking and opaque
  Pronotal pleurae mostly unsculptured and with a large band having a smooth, reflective, or shiny surface
6(5)    The pronotum with a band of erect setae occurring transversely and other erect setae scattered randomly across the mesonotum
  The pronotum with erect setae confined to the humeral shoulders; there may be occasional erect setae on the anterior margin of the propodeum
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
  Propodeal spines long and in dorsal view the apices diverge from the longitudinal body axis
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, setae on the head are fine and in orderly rows; 1 or 2 (rarely 3) erect setae on each humeral shoulder of pronotum
  The pubescence on the head and thorax is suberect or erect (at least some of them) and the setae on the head do not lie in orderly rows; 2-4 (or occasionally more) erect setae on each humeral shoulder of pronotum