Key to Polyergus workers in southeastern United States (by James C. Trager)

Note: All Polyergus species in the Southeast are host specific. Correct identification of the host Formica species that inhabit the nest with them is a reliable identification characteristic of the Polyergus species.

 

1

Gastral tergites with very sparse pubescence or none, integument smooth and often strongly shining; Atlantic Coast of the United States west to Mississippi Valley (one species extends west to southern Rocky Mountains)  

lucidus group
…2

 

Gastral tergites with dense pubescence yielding a silky sheen, but obscuring the dorsal surface of the integument beneath; Mississippi Valley to the West Coast of United States, in the Southeast, only west of the Mississippi river   

breviceps
group
...6

2

Rear margin of head pilose, with 10 or more stout, erect setae near each rear corner of the head; head and mesosomal dorsum matte and sides at most feebly shining; host F. dolosa  

...longicornis
M. R. Smith

 

Rear margin of head less pilose, with 8 or fewer (usually 0-5) stout, erect setae near each rear corner of the head; head and mesosomal dorsum matte; sides shiny, but if appearing not very shiny, then the entire ant is sparsely pilose; host is never F. dolosa  

...3

3(2)

Rear margin of head less pilose, with <5 (usually <3) stout , erect setae near each rear corner of the head; head and mesosoma matte or weakly shining on sides; host F. pallidefulva or F. archboldi  

...4

 

Rear margin of head pilose, rear margin of head usually with >4 stout , erect setae near each rear corner of the head; all tagmata at least partly shiny; host F. incerta or F. biophilica  

...5

4(2)

Larger and less pilose species, combined length of head and thorax >3.90mm; rarely more than one (usually none) stout erect seta on each rear corner of the head; eastern United States west Rocky Mt. foothills, in the Southeast, rare in all states, in Florida, limited to the panhandle; host F. pallidefulva  

...montivagus
Wheeler

 

Smaller and slightly more pilose, combined length of head and thorax of most specimens <3.80mm (occasional ergatoids larger); with 1 or 2 (rarely up to 5) erect setae near each rear corner of the head; possibly endemic to Florida; host F. archboldi   

oligergus Trager

5(4)

Smaller, scape shorter, scape length <1.35mm, hind femur length usually <2.0mm; eastern and central United States, in the Southeast only in high altitude Appalachian “balds”; host F. incerta  

…   lucidus Emery

 

Larger, longer-limbed, scape length >150mm, hind femur length usually >210mm; southern and south central USA (including foothill Appalachian) distribution; host F. biophilica  

ruber
Trager

6(5)

Rear margin of head lacking pilosity or with <4 stout, erect setae near each rear corner of the head; pronotal erect pilosity all dorsal; Missouri, Arkansas; host F. subsericea 

...mexicanus Forel

 

Rear margin of head notably pilose, >10-30 stout, erect setae near each rear corner of the head; pronotum always with some erect setae on sides near lower edges; not in the Southeast but may be found in far northern Missouri; host F. montana

...breviceps Emery

 

For more information see:

Trager, J.C. 2013. Global revision of the dulotic ant genus Polyergus (Hymenoptera: Formicidae, Formicinae, Formicini). Zootaxa 3722 (4): 501-548.