Polyergus

Trager, James C., 2013, Global revision of the dulotic ant genus Polyergus (Hymenoptera: Formicidae, Formicinae, Formicini), Zootaxa 3722 (4), pp. 501-548 : 509

Key to Polyergus workers

1 Entire body dark brown to blackish; pilosity of anterior first tergite gently curved to nearly straight; eastern temperate or desert central Asia............................................................................ samurai group...2

- Body rich orange to brownish red, with varying amounts of dark brown or blackish coloring on the legs, lower mesosoma, and gaster; pilosity of anterior first tergite conspicuously bent or strongly flexuous in the one Eurasian species; European Atlantic Coast east to western Asia (about 88O E), otherwise North American............................................ 3

2 Browner, matte, larger species—LI of most workers> 375 (usually> 390); with longer scapes—SI of most workers 81–85; dry, open habitats, but of humid temperate Japan, Korea, China, eastern Russia; hosts F. japonica , F. glabridorsis , rarely others.............................................................................................. samurai

- Blacker, somewhat shining, smaller species—LI <375 (usually <370); with shorter scapes—SI 74–81; steppe deserts of Mongolia, Tuva, adjacent south-central Russia; with F. candida or F. kozlovi as hosts............................ nigerrimus

3 Gastral tergites with pubescence very sparse or lacking, smooth and often strongly shining; North American, most abundant from Atlantic Coast states west to Mississippi Valley (one species extends west to southern Rocky Mountains).................................................................................................. lucidus group...4

- Gastral tergites with dense pubescence yielding a silky sheen, obscuring the surface of the integument beneath; Eurasian and North American, in North America from western Great Lakes, prairie and Rocky Mountain states and provinces, to Pacific Coast and Mexican mountains........................................................... rufescens group ... 9

4 Vertex pilose, ½ VeM usually> 10; head and mesosomal dorsum matte and sides at most feebly shining; host F. dolosa .... 5

- Vertex less pilose, ½ VeM usually <8; head and mesosomal dorsum matte or shiny; but if matte, then sparsely pilose; host is never F. dolosa ....................................................................................... 6

5 Scapes and legs shorter, SI <105, usually <100, FI <140; northern species, New England west to the Dakotas.... sanwaldi

- Scapes and legs longer, SI> 100, but usually> 110, FI> 140; southern species, North Carolina to Florida, west to Mississippi and southern Missouri......................................................................... longicornis

6 Rear portion of head less pilose, ½ VeM usually <5; head and mesosoma matte or weakly shining on sides; host F. pallidefulva or F. a rc h bo l d i ....................................................................................... 7

- Rear portion of head pilose, ½ VeM usually> 5; all tagmata at least partly shiny; host F. incerta or F. biophilica .......... 8

7 Larger and less pilose species, LI of most specimens> 390; ½ VeM 0–1 (very rarely more); eastern Canada to northern Florida, west to Wisconsin, Colorado, New Mexico; host F. pallidefulva ........................................ montivagus

- Smaller and slightly more pilose, LI of most specimens <390; ½ VeM 1–5; Florida; host F. a rc h bo l di ........... oligergus

8 Smaller, shorter-limbed, SL 1.19–1.36, HFL 1.72–2.04; northeastern, Midwestern, and higher altitude Appalachian distribution; host F. incerta .............................................................................. lucidus

- Larger, longer-limbed, SL 1.68–1.79, HFL 2.08–2.44; southern and south central USA and foothill Appalachian distribution; host F. biophilica .................................................................................. ruber

9 Pilosity of anterior first tergite usually gently curved to nearly straight; North American species...................... 10

- Pilosity of anterior first tergite mostly strongly curved or conspicuously bent; continental Europe east to mountains of Kyrgyzstan, Kazakhstan, western China (about 88O E)....................................................... rufescens

10 Vertex lacking pilosity or with ½ VeM <8, usually <4; pronotal erect pilosity usually all dorsal; hosts in the F. f us c a group, or less often, in the F. neogagates group, but exclusive of the F. c i ne re a complex.................................... 11

- Vertex notably pilose, ½ VeM> 6, usually 10–30; pronotum always with some erect setae on sides near lower edges; hosts usually (at least predominantly) F. montana , F. canadensis , and/or F. altipetens ............................... breviceps

11 Head and pronotum moderately pilose, ½ VeM <6 (rarely more), ½ PnM usually> 4; sometimes with infuscated posterior tergites, if gaster appears entirely brown or blackish, ½ PnM> 4............................................... 12

- Head and pronotum non-pilose or sparsely pilose, ½ VeM 0, ½ PnM 0–2; distinctly bicolored, head and mesosoma red, gaster entirely dark brown to blackish; western Great Lakes states to Dakotas, Manitoba, usually in moist or bog forests; host F. subaenescens (less often F. neorufibarbis )............................................................... bicolor

12 Scapes fall short of vertex corners by a scape width or more, SI <85; legs shorter, HFI <120, usually <110; hosts various, but apparently never F. mok i .............................................................................. 13

- Scapes nearly reaching to slightly surpassing vertex corners, SI> 85, usually> 90; legs longer, HFI> 120; coastal hills of southern CA and BC, MEX; host F. moki ............................................................. vinosus

13 Head often and especially sides of mesosoma weakly to conspicuously shining; scapes not reaching vertex corners by about 1.5–2 scape widths, scapes distally clavate, SI 65–82, but usually <77; legs shorter, HFI 99–120 (but usually <113 and always <110 in southern Arizona and Mexico); upper elevation conifer forests of Mexican mountains, north to British Columbia, Rocky Mountain and Plains states, east to Mississippi Valley; hosts are a wide variety of high elevation or northern F. fusca and F. neogagates group species................................................................. mexicanus

- Head and mesosoma typically entirely matte, or at most weakly shining; scapes longer, not reaching vertex corners by 1.5 scape widths or often less, scapes thickened distally, but at most weakly clavate, SI 75–86, usually> 79; legs longer, HFI 108–