Global revision of the dulotic ant genus Polyergus (Hymenoptera: Formicidae, Formicinae, Formicini) Trager, James C. Zootaxa 2013 3722 4 501 548 4L738 [151,391,1594,1620] Insecta Formicidae Polyergus Animalia Hymenoptera 10 511 Arthropoda species breviceps    Polyergus breviceps: Kannowski, 1956: 185; Wheeler, 1968: 163. Material of the unavailable names fusciventris, silvestrii, montezuma,referred to  brevicepsby Creighton (1950), here referred to  P. bicolor, P. mexicanus,and  P. topoffi. Former syntypes(N=3 on a single pin, including lectotype) HL 1.36–1.40 (1.37), HW 1.32–1.36 (1.35), SL 0.90–0.96 (0.92), ½ VeM 3–6 (5), ½ PnM 12–20 (16), WL 1.96–2.02 (1.99), GL 1.64–1.88 (1.77), HFL 1.32–1.36 (1.35), CI 97–100 (98), SI 66–71 (68), HFI 97–103 (101), FSI 138–53 (147), LI 3.32–3.40 (3.37), TL 4.96–5.28 (5.14). Measurements (N=58) HL 1.24–1.60 (1.46), HW 1.28–1.64 (1.48), SL 0.84–1.08 (0.98), ½ VeM (3, one specimen) 5–17 (9.52), ½ PnM 8–22 (14.97), WL 1.88–2.40 (2.14), GL 1.64–2.60 (2.13), HFL 1.30–1.72 (1.52), CI 0.96–1.08 (1.01), SI 61–78 (67), HFI 94–115 (103), FSI 138–170 (155), LI 3.12–3.96 (3.60), TL 4.96–6.52 (5.73).  Worker description.  Polyergus brevicepsis more narrowly defined here than has been conventional in North American ant taxonomy. It is a broad-headed and short-limbed species, but most easily distinguished by its abundant pilosity. This is among the two smaller Nearctic species, though averaging somewhat larger than partially sympatric  bicolor, and larger than some isolates of  mexicanus. Head suborbicular to (less often) subquadrate, its length and breadth about equal, or not uncommonly the breadth a bit greater, sides quite rounded, outer margins of eyes not or at most slightly extending beyond sides of head; vertex flat or broadly and shallowly concave, the flat portion or concavity about as wide as the space between mandibles; vertex pilosity conspicuous and abundant, usually 16–24 (6–30) macrosetae; scape not reaching vertex corners by about twice its maximum diameter, clavate in the apical third; pronotum usually with 22–36 (16–44) erect setae, including a few shorter ones near the lower margins; mesonotal profile flat or very weakly convex for most of its length; propodeum evenly rounded; petiolar dorsum rounded and shallowly emarginate; first tergite densely pubescent; first tergite pilosity flexuous, basally suberect and distally subdecumbent, about as dense in posterior half of tergite as in its anterior half, appearing to be in 5 or 6 transverse arrays. Head matte; mesonotum matte; gaster matte; slightly shining lateral portions of all tagmata in some specimens. Color usually dull red with infuscation of dorso-posterior portions of tergites. Pilosity matching color of body to slightly darker, pubescence yellow gray.   Discussion.  Polyergus brevicepsis here restricted to a broad-headed and short-limbed species, one most easily distinguished by its abundant pilosity. In addition to its abundant pilosity and short scapes, it shows marked preference for  F. cinereagroup hosts and their typically open, moist grassland or sedge meadow habitat. More pilose examples of  mexicanusfound both at the northern and southwestern portions of its range are those most likely to be confused morphologically with  breviceps.Where  mexicanusand  brevicepsoccur together (in close parapatry) in the West,  mexicanusoccurs in well drained soils, often in conifer forests on podzols, while  brevicepsoccurs in wet meadows with organic-rich soils. Even when its pronotal and mesonotal dorsal pilosity is abundant,  P. mexicanuslacks the pilosity on the sides of the pronotum, lacks or at least has little vertex pilosity, has a shinier head, and is deeper red in color, with gray rather than yellowish gray pubescence. In the Chicago region,  brevicepsis readily distinguished, even in the field, from the local version of  mexicanusby its clearly smaller size, and its association with  F. montana, contrasting with  mexicanus’s larger size, and association with  F. subsericea. In the Dakotas and Rockies, a closer examination may be required to discriminate  brevicepsfrom other  Polyergus, though these other congeners are more often found in upland prairie, open woodland or forest, rather than the usually moist (including saline and alkaline) meadow habitats preferred by  breviceps. True  brevicepsdoes not occur in Pacific Coast states or provinces. The majority of the literature regarding P. b re v i c e p sregards either  mexicanusor  topoffi(Topoff 1982, 1985, Topoff et al. 1984, 1985a, 1985b, 1988a, 1988b, 1989, Topoff and Greenberg 1988, Topoff 1990, Topoff and Mendez 1990, Topoff and Zimmerli 1993, Zimmerli and Topoff 1994, and included references), and true  brevicepsis in fact little studied. As indicated in the synonymy above, the “ typeseries” of  brevicepsincluded the original Breckenridge, CO material, plus two samples collected later at other localities that I identify as  bicolorand  mexicanus. I restrict the typeto the Breckenridge material (CASENT0179559), and exclude the other samples, one being a sample of  bicolor(CASENT0179561) and the other a sample of  mexicanus(CASENT0179560). Once the characterization of  brevicepsis clear, it may be noted that there is remarkably little variation in this species, notwithstanding its broad but spotty distribution. Western samples have slightly, but insignificantly shorter average SL and HFL.   Etymology.Emery coined this name from the Latin “brevis” plus “-ceps” to mean short-headed (in contrast to the more elongate head shape of  rufescens).  Natural history.This ant is common in wet to mesic prairies and mesic or wetter old fields of northwestern IN and the Chicago Region, and is distributed west to the Rocky Mountains and south to the White Mts. of northeastern AZ. The raiding of  P. brevicepsfollows familiar patterns described for other species. I have not directly observed mating and colony foundation, but have seen alates fly from the nest several hours before the late afternoon raids, and I also have seen a lone, dealate gyne wandering near a mound of  F. montanain a prairie near Chicago. It would seem such lone gynes are capable of colony foundation, even with this rather aggressive host and its populous colonies.  Polyergus brevicepsis naturally a species of wet and mesic prairie and meadow habitats, though it persists in drier, but formerly wet, locations after habitat degradation and hydrological disruption, if the host remains abundant (I have observed this both in CO and IL). Wheeler (1910, p. 477) describes a situation near Florissant CO, of  Polyergus(which I surmise to be  breviceps) living with “  F. neocinerea” (  F. canadensis) in conspicuous mounds raised above the moist soil of a mountain meadow, and what he took to be the same species (but which I surmise to be  mexicanus) living with  F. argenteain less conspicuous nests on the wooded slopes above this meadow. In the Chicago region, tallgrass prairie restoration plantings are colonized by  F. montanain just a few years, and  brevicepsseems to arrive almost or indeed concurrent with them, just a few years after conversion from plowed crop land. This may occur through  brevicepsgynes teaming up with young  F. montanagynes or incipient host colonies, as has been reported for  P. topoffi.(See account for this species, below.)  Polyergus brevicepsnormally parasitizes members of the  F. cinereacomplex;  F. montanain the humid prairies of the Great Lakes and northern Plains states, and  F. canadensisin western mountain meadows. Some samples studied also included  F. altipetensor less often, the less closely related  F. neoclaraor  F. occulta. A few samples have been found from drier western grassland sites with these less pilose hosts, and these  brevicepsseem to average a bit less pilose than those with  cinereagroup hosts, but still have telltale pronotal lateral pilosity. These also differ in proportions (narrower head, slightly longer limbs) from typical  P. breviceps, and may represent another species or a hybrid. Near Taos NM, I once observed raiding columns from two colonies of this species cross paths, resulting in a battle lasting two days, including over night, with high mortality. One of the colonies disappeared after this.   Distribution of studied specimens.ARIZONA Apache Co. Williams Valley 33°51.8’N 109°13.2’W8690’ Elev. 12-X-2004#3490 RA Johnson (RAJC); COLORADO Alamosa Co. Alamosa, 2286m. Pasture 28-VI-1945E. V. Gregg (FMNH); COLORADO Boulder Co. Niwot. Minims. Nest in garden. (colony P1) 16 Aug. 1982JC Trager (incipient colony, JCTC); COLORADO Boulder Co. Niwot. (=incip. P1, Aug. 1982) 4 Jul. 1985JC Trager (JCTC); COLORADO Boulder Co. Lagerman Reservoir, Niwot, 1548m. 26.x.1961. Mound in wet meadow. R. E. Gregg (FMNH); COLORADO Park Co. Hartsel VII-4-32Creighton (FMNH); COLORADO Park Co. Taryall. R Savolainen #102/98 (JCTC); COLORADO (Gunnison Co?) Snodgrass Mtn. Gothic. 2920m. Masonry dome nest. J. Atticott (FMNH); COLORADO Gunnison Co. Crested Butte Savolainen 1998 43/98, 45/98; COLORADO Gunnison Co. Farnum Peak GG 1998 Savolainen 102/98, 108/98, 110/98 (JCTC); COLORADO Gunnison Co. Gothic 1998 Savolainen 39/98, 47/98, 49/98 (JCTC); COLORADO Routt Co. Steamboat Springs VII-1-19436800’ Owen Bryant (FMNH); COLORADO Weld Co. St. Vrain Nuclear Site, Platteville 1478 m 10-VII-1976Col. W. Brewer (FMNH); IDAHO Twin Falls Co. South rim, Snake River Canyon Twin Falls. 1067m, 11.vi.1967sagebrush-rabbit brush. Mound near brush. R. E. Gregg w/  F. neoclara(FMNH); ILLINOIS Cook Co. Chicago VII-10-33M Talbot (JCTC); ILLINOIS Cook Co. Chicago 4-30-33M Talbot #33-45 (JCTC); ILLINOIS Cook Co. US45 Chicago Pond on top of mound M Talbot #33-221 (JCTC); ILLINOIS Cook Co. Chicago 8-102 140 St. off Halsted 10-30-38 ASWinds (JCTC); ILLINOIS Cook Co. Chicago 142 St. and Halsted, Harvey low prairie #11 13.VII.1939R. E. Gregg (FMNH); ILLINOIS Kane Co. FermiLab prairie planting, on interp trail. 1800hr 23 Aug 2008Abundant  F. montana(lone gyne, JCTC); ILLINOIS Lake Co. Site 16 SBM 415 31 May 2011Sean Menke (JCTC); ILLINOIS Will Co. Mokena 96th Ave. near W. L. S. Transmitter 4-IX-1942prairie #24 R. E. Gregg (FMNH); INDIANA Lake Co. Hammond mound by ditch 4-27-1933M Talbot #33-30 (JCTC); IOWA Dickinson Co. Iowa Lakeside Lab. August 1997R Savolainen #s 63/97 & 67/97 (JCTC); NEBRASKA Morrill Co. North Platte River Wetlands. Salt Marsh. J. Jurzenski Coll’n #Morr 01-07-25-01; NORTH DAKOTA Barnes Co. 2236 19.VII.1963G.C. & J.N. Wheeler (LACM); NORTH DAKOTA Barnes Co. Conservation Area 19-VII- 1963#2236 G.C. & J.N. Wheeler (LACM); NORTH DAKOTA Cavalier Co. Waterloo Twp. 13/7/54#77 Don Sather LACM); NORTH DAKOTA Grand Forks Co. 45 Mekinock 10-VII-1932C.V. Johnson (LACM); NORTH DAKOTA Grand Forks Co. Powell VIII-1-1932#701 C.V. Johnson (LACM); NORTH DAKOTA Grand Forks Co. T152NR52W Sec. 9 26-VII-1959#2166 G.C. & J.N. Wheeler (LACM); NORTH DAKOTA Grand Forks Co. Oakville Township Oakville Prairie Sec. B 14-VII-1949#408 G.C. & J.N. Wheeler (LACM); NORTH DAKOTA Grand Forks Co. 16-151-51 13-VII-19642552 G.C. & J.N. Wheeler (LACM); NORTH DAKOTA Ramsey Co. Twp. Fancher Sec. 22 VIII-17-1951#157c and IX-11-1951# 188 P.B. Kannowski (LACM); NORTH DAKOTA Ramsey Co. Twp. DeGroat Sec. 18 IX-18-1951# 168 P.B. Kannowski (LACM); NORTH DAKOTA Ramsey Co. Twp. T53R64 Sec. 16 IX-30-1951# 221 P.B. Kannowski (LACM); NORTH DAKOTA Walsh Co. Twp. Ardoch s.4 2-VII-1950# 180 W.E. LaBerge (LACM); NORTH DAKOTA Ward Co. Kenmare VII-27-1954G.C. & J.N. Wheeler (LACM).