Genus Polyergus (Formicinae)

• Polyergus Latreille, 1804: 179. Type species: Formica rufescens Latreille, by monotypy.

• OVERVIEW.   The species of this genus are obligatory or true slave-making ants. In nest founding, the female enters a nest of the host species, eventually kills the rightful queen, and uses the host workers to tend her brood. A colony of Polyergus will conduct slave raids on nests of species of Formica, and workers of the host are taken and used by the Polyergus colony to feed and rear the brood and excavate the nest. Polyergus workers are incapable of surviving without slaves. In laboratory colonies, a colony without slaves will starve to death even when plentiful food is available.
• ZOOGEOGRAPHICAL REGIONS.  Holarctic.


      
Photo of Polyergus samauri. Courtesy of Japanese Ant Database


• RECOGNITION.   Polyergus speciemens are most commonly seen above ground when conducting slave raids. These large ants are distinctive looking and easily recognized. Total length 4-7 mm. Mandibles falcate (sickle shaped), with numerous denticles but no teeth. Lower rim of antennal socket nearly touching posterior border of clypeus (distance between them less than 1/4 the maximum diameter of the antennal socket). Antennae 12 segmented, filiform; scape slightly thickened apically. Eye well-developed; located more than its greatest diameter from the base of the mandible. Occelli distinct. Head subrectangular. Metanotal impression strong with a pair of distinct proterburant spiracles. Propodeal spiracle oval to slit shaped. Metapleural gland opening indistinct. Petiole a thick, rounded node. Pilosity sparse especially on mesonotum. Body shining and yellowish to reddish. Highly variable morphology especially color and scape length. Single specimens (or a short series) difficult or impossible to determine the species.
• SIMILAR GENERA.   Polyergus is a close relative of genus Formica. The two are easily distinguished by their mandibles. All species of Formica have triangular mandibles with distinct masticatory and basal margins.
• TRIBE.  Formicini.
• REVISIONS.   Smith, M.R. 1947g: 150–161 .— Creighton, 1950a: 552–560 (key to Nearctic species, distribution) .
• TAXONOMY.   Creighton, 1950a: 552–560 .— Forbes & Brassel, 1962: 79–87 (male genitalia and terminal segments) .— Wheeler, J. 1968: 156–164 (male genitalia and taxonomy) .— Agosti, 1994b: 109 (diagnosis of w.q.m.) .— Bolton, 1994: figs. 106, 107 (SEM (full face and lateral view) of w.) .—Bolton, 2003: 277.
• MISCELLANEOUS.   Hölldobler, B. & Wilson, 1990: 452–464 (general discussion of slavery) .

• breviceps. Polyergus rufescens subsp. breviceps Emery, 1893k: 666 (w.) . [USA, CO, Breckenridge Co.; No types in USA.] Raised to species: Kannowski, 1956a: 186; Wheeler, J. 1968: 163.
• bicolor. Polyergus rufescens subsp. bicolor Wasmann, 1901: 369 (w.q.m.) . [USA] Synonymy: Wheeler, J. 1968: 163.
• silvestrii. Polyergus rufescens subsp. breviceps var. silvestrii Santschi, 1911d: 7 (w.m.) . [USA] Note that the original citation is not 'Santschi, 1909' as in Smith, D.R. 1979: 1466. Synonymy: Creighton, 1950a: 559 .
• montezuma. Polyergus rufescens subsp. breviceps var. montezuma Wheeler, W.M. 1914c: 56 (w.q.m.) . Unavailable name. [Mexico, Hildago] Synonymy: Creighton, 1950a: 559 .
• umbratus. Polyergus rufescens subsp. breviceps var. umbratus Wheeler, W.M. 1915b: 419 (w.) . Unavailable name. [USA, CA, Santa Cruz Co.] Synonymy: Bolton, 1995b: 342.
• fusciventris. Polyergus rufescens subsp. breviceps var. fusciventris Wheeler, W.M. 1917a: 555 (w.) . Unavailable name. [USA, CO, El Paso Co.] Synonymy: Creighton, 1950a: 559 .
• umbratus. Polyergus rufescens subsp. umbratus Creighton, 1950a: 560 (w.) . [USA, CA, Santa Cruz Co.] First available use of the unavailable name Formica rufescens subsp. breviceps var. umbratus Wheeler, W.M. 1915. Synonymy: Wheeler, J. 1968: 163.

• DISTRIBUTION. Ontario, MI west to British Columbia south to IN, IL, MO, KS, NM, AZ, CA. This is the common western species.
• LITERATURE OVERVIEW. Topoff, La Mon, Goodloe & Goldstein, 1984. Behav. Ecol. Sociobiol. 15: 273-279 gives a good overview of the behavior of this species.
• TAXONOMY. Cole, A.C. 1942: 385 .— Smith, M.R. 1947g: 152, 157–159, 161 (in part as P. rufescens bicolor, P. rufescens breviceps umbratus, P. rufescens breviceps fusciventris, P. rufescens breviceps silvestri) .— Wheeler, G.C. & Wheeler, J. 1968a: 214 (larva, as P. rufescens) .— Wheeler, J. 1968: 156–164.
• MISCELLANEOUS. Wheeler, W.M. 1910b: 475–482.— Wheeler, W.M. 1916h: 107–118 (slave raids) .— Smith, M.R. 1929a: 329–333 .— Mallis, 1941: 82 (distribution in CA) .— Buren, 1944a: 310–311 (brief natural history, distribution in IA (in part as Polyergus rufescens bicolor Wheeler)) .— Wheeler, G.C. & Wheeler, E.W. 1944: 260.— Gregg, R.E. 1946: 754 .— Gregg, R.E. 1963: 635–643 .— Wheeler, G.C. & Wheeler, J. 1963: 275–277.— Hung, 1973: 253–259 (reproductive biology) .— Topoff, La Mon, Goodloe & Goldstein, 1984: 273–279 (scouts use optical orientation (including position of sun and polarized light' to find and return from a nest to be plundered, chemical trails laid on slave raid, both optical and chemical clues used in returning from raid, intraspecific raids occur) .— Hölldobler, B. 1985: 225.— Topoff, Inez-Pagani, Mack & Goldstein, 1985: 289–295 (raiding activity) .— Topoff, La Mon, et.al. 1985: 259–267 (orientation to polarized light, colony size and booty captured is 3-7 times larger than in P. lucidus) .— Topoff, Pagani, et.al. 1985: 1041–1046 (scouts use exclusively visual orientation not chemical trails) .— Topoff, Bodoni, et.al. 1987: 261–270 (foraging pattern, reliance on visual orientation, scouts initiate raids) .— Choe, 1988: table 1 (worker reproduction in queenless nests) .— MacKay, Lowrie, et. al. 1988: 120 (occurrence in NM) .— Topoff & Greenberg, 1988: 81–87 (mating occurs during slave raid) .— Topoff & Greenberg, 1988: 81–87 (mating occurs during slave raids, queens attract males with chemicals from mandibular gland) .— Topoff, Cover, Greenburg, et.al. 1988: 209–218 (secretions from Dufour's gland of q. reduces aggression by host workers during colony take over, queens are unable to take over queenless host colonies, mating occurs during slave raids) .— Topoff, Cover & Jacobs, 1989: 545–556 (recruitment and raiding behavior) .— Topoff & Mendez, 1990: 819–820 (raiding behavior) .— Topoff & Zimmerli, 1993: 479–286 (nest founding by social parasitism) .— Savolainen & Seppä, 1996: 31–36 (estimates of genetic relatedness show this species to be polygynous and/or polyandrous) .— Johnson, C.Vander Meer & Lavine, 2001: 1787–1804 (nest founding) .
• PHOTOS.

• longicornis. Polyergus lucidus subsp. longicornis Smith, M.R. 1947g: 155 (w.) . [USA, SC, Florence Co.; USNM]

• MISCELLANEOUS. Carter, 1962b: 202–203 (habitat, distribution in NC) .— Trager & Johnson, 1985: 262–265 ( identified as P. lucidus Mayr, it may acutally be the subspecies P. lucidus longicornis Smith) .— Vargo & Gibbs, 1987: 479–482 (raiding behavior, nuptial flight) .

• lucidus. Polyergus lucidus Mayr, G. 1870b: 952 (w.q.m.) . [USA, CT; No types in USA.] Wheeler, G.C. & Wheeler, J. 1968a: 214 (l.) . Race of rufescens: Forel, 1886h: 200. Revived status as species: Dalla Torre, 1893: 214; Wheeler, W.M. 1917k: 465; Smith, M.R. 1947g: 152; Creighton, 1950a: 557. Current subspecies: nominal plus longicornis.
• montivagus. Polyergus lucidus subsp. montivagus Wheeler, W.M. 1915b: 419 (w.q.m.) . [USA, CO, El Paso Co.] Synonymy: Creighton, 1950a: 557 .

• DISTRIBUTION. MA south to SC west to ND, IA, CO, NM.
• LITERATURE OVERVIEW. The key references for the natural history of this species are Talbot, 1968: 299-313, and Cool-Kwait & Topoff, 1984. Insectes Soc. 31: 361-374,
• TAXONOMY. Mayr, G. 1886d: 424 .— Smith, M.R. 1947g: 152–155, 156, fig. 1 (description w., distribution. figure (lateral view) of w., in part as P. lucidus montivagus) .— Wheeler, G.C. & Wheeler, J. 1968a: 214 (larva) .— Warren & Rouse, 1969: 60 (diagnosis of w., distribution in AR) .
• MISCELLANEOUS. McCook, 1880: 376–384.— Wheeler, W.M. 1906e: 86–89 (laboratory experiments on nest founding) .— Wheeler, W.M. 1910b: 482–486.— Smith, M.R. 1934a: 360–361.— Buren, 1944a: 310 (brief natural history, distribution in IA) .— Gregg, R.E. 1963: 633–635 .— Wheeler, G.C. & Wheeler, J. 1963: 274–275 (diagnosis of w., habitat, distribution in ND) .— Harman, 1968: 217–223 (ecology, near Chicago) .— Marlin, 1968: 207–209 (colony formation) .—Talbot, 1968: 299–313.—Talbot, 1968: 46–52.— Marlin, 1969: 108–115 (raiding behavior) .— Marlin, 1971: 181–189 (mating, nesting, and ant enemies) .— Kwait & Topoff, 1983: 307–312 (colony relocation) .— Cool-Kwait & Topoff, 1984: 361–374 (detailed natural history observations, observations of both field and laboratory colonies, behavioral repetoire) .— Goodloe & Sanwald, 1985: 297–302 (colony founding) .— Trager & Johnson, 1985: 262–265 (first report from Florida, raiding behavior, host F. archboldi, identified as P. lucidus Mayr, it may acutally be the subspecies P. lucidus longicornis Smith) .

• laeviceps. Polyergus rufescens subsp. laeviceps Wheeler, W.M. 1915b: 420 (w.) . [USA, CA, San Francisco Co.; AMNH]

• DISTRIBUTION. California.
• TAXONOMY. Smith, M.R. 1947g: 152, 160 (description w.) .— Creighton, 1950a: 559–560 .
• MISCELLANEOUS. Mallis, 1941: 82.