Polyergus longicornis

A southeastern US species that exclusively raids nests of Formica dolosa.

Identification
P. longicornis is most likely to be confused with Polyergus ruber and especially Polyergus sanwaldi. Polyergus longicornis is distinguished from the largely sympatric ruber by its more abundant vertex pilosity, ½ VeM 13 + vs. 12 or less, nearly uniformly matte mesosoma and cephalic integument, and parasitism of Formica dolosa rather than Formica biophilica. Polyergus longicornis is distinguished from the allopatric, more northern P. sanwaldi by its proportionally longer scapes and legs, and its slightly narrower head.

Distribution based on Regional Taxon Lists
Nearctic Region: United States.

Trager (2013): Polyergus longicornis is a southeastern species, known from the Carolinas and Georgia, west to Mississippi. It is found in the open pinelands and oak-pine woodlands on sandy soils with host populations of F. dolosa.



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Biology
This species is known to enslave (Goodloe & Sanwald, 1985; MacGown & Brown, 2006; King & Trager, 2007; Trager, 2013; de la Mora et al., 2021; slave-maker misidentified as Polyergus lucidus in some publications).

Nomenclature

 *  longicornis. Polyergus lucidus subsp. longicornis Smith, M.R. 1947g: 155 (w.) U.S.A. Raised to species: Trager, 2013: 525.

Worker
Trager (2013) - (N=18) HL 1.60–1.80 (1.71), HW 1.52–1.72 (1.62), SL 1.67–1.89 (1.77), ½ VeM 13–22 (17.78), ½ PnM 0–9 (3.78), WL 2.52–2.88 (2.73), GL 2.08–2.68 (2.34), HFL 2.22–2.56 (240), CI 91–99 (95), SI 101–117 (109), HFI 139–158 (149), FSI 130–144 (136), LI 4.16–4.68 (4.44), TL 6.44–7.32 (6.78).

Head truncate-obovate to narrowly subhexagonal, generally more strongly tapering behind than in front of the eyes, HL > HW; with conspicuous and abundant vertex pilosity of 20–40 erect macrosetae; scapes at least equaling to notably longer than head, always surpassing vertex corners, gradually thickening apically, not notably clavate; pronotum with (3) 6–12 (18) erect macrosetae; mesonotal profile flat or very weakly convex for most of its length; propodeal profile evenly rounded, its dorsal and posterior faces indistinct; petiole a little narrower than propodeum, with convex sides, these convergent dorsad; petiolar dorsum convex, not emarginate; petiole in profile tapering and usually slightly recurved dorsad; first tergite very sparsely pubescent or completely lacking pubescence; first tergite pilosity sparse, usually a few on the anterior half, but these often deciduous; the macrosetae weakly flexuous.

Head matte; mesosoma matte; gaster weakly matte.

Color red with infuscation of appendages and posterior portions of tergites.

Etymology
Trager (2013) - Smith coined the name of this ant species as an adjective, from Latin “longus” + “cornus”, referring to its long scapes.