Formica dolosa

Formica dolosa is a wide ranging species that is most abundant on well-drained acidic silicaceous soils in habitats such as barrens, glades, prairies, open oak or pine woodlands, and savannas. Nests are commonly at the base of a grass clump or other herbaceous vegetation, although they may nest under rocks or wood. (Trager 1998, Trager et al. 2007, Nemec et al. 2012)

Identification
A member of the Formica pallidefulva group.

The propodeal crest of F. dolosa is nearly always rounded in profile, and is typically sharp or even carinulate in the other species. This large, hairy, densely pubescent and faintly bicolored ant is most likely to be confused with Formica biophilica. Compared to F. biophilica, F. dolosa has conspicuous appressed pubescence on the mesosoma, has more abundant, but slightly shorter gastral pilosity (longest macrochaetae up to 0.30 mm), has longer, denser pubescence on the gaster (compare Figures. 2b and 2e), and averages larger and heavier-bodied. The number of macrochaetae on the pronotum usually exceeds that on the propodeum of F. dolosa, (46 of 54 specimens) whereas the number on the propodeum more often exceeds that on the pronotum of F. biophilica (20 of 32 specimens). F. dolosa usually has relatively smaller eyes compared to F. biophilica. In the field, F. dolosa occupies the drier end of the habitat spectrum, the two overlapping mainly in high pine woodlands in the South, and in dry-mesic prairies further north. In the Northeast, larger, more pilose workers of Formica incerta are often misidentified as F. dolosa, but F. dolosa averages larger and more pilose with denser pubescence, has longer scapes and legs; is generally lighter, more yellowish or reddish in color, and is more strictly associated with sandy soils. (Trager et al. 2007)

Distribution
Widely distributed from New England across the Great Lakes region, west to Wisconsin and Iowa and south to northern Florida, the Gulf Coast states and Texas. Records of this ant in Colorado by Gregg are all misidentified Formica incerta (L. Rericha, personal communication). F. dolosa is decidedly most abundant on acid-soil sites. These include a variety of droughty or well-drained habitats such as barrens, glades, prairies or open oak or pine woodlands on silicaceous soils. Though reported (as schaufussi) from plowed fields and pastures in the Northeast, F. dolosa is not usually common in anthropogenic communities. J. Trager found F. dolosa in calcareous glades in Alabama and Missouri, but it is not abundant in these sites. In stark contrast to F. incerta and Formica biophilica, F. dolosa does not nest in mesic habitats or in moist, fertile soils. (Trager et al. 2007)

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



Biology
Trager et al. (2007) - Nests may be hidden beneath a rock or piece of wood, but most nest entrances are at the base of a grass clump or other herbaceous plant. Some open on bare ground, the entrance surrounded by a crater of excavated soil adorned with plant fragments, charcoal bits or fine gravel. J. MacGown collected F. dolosa in nests at the bases of large trees on relatively drier and more open ridges in mixed forests in northern Mississippi and from an infrequently mowed area under loblolly pines near his house in Oktibbeha Co. MS. The nest at the latter site was a low mound about 45 cm across and about 15 cm high at the midpoint. Part of the mound was inhabited by Camponotus castaneus Latreille.

In the East and Gulf Coast states, F. dolosa is host to the slavemaker Polyergus lucidus longicornis M. R. Smith. J. Trager’s collection contains samples of this slavemaker with F. dolosa slaves from Massachusetts, New York, New Jersey, South Carolina and Mississippi. In Missouri, F. dolosa is occasionally among the many hosts of Formica pergandei, but we have only observed them in combination with other host species (see “Natural History” of Formica biophilica for a case in point). In Florida, J. Trager observed F. dolosa and Formica archboldi competing for domination of colonies of Toumeyella scales on long-leaf pine “grass-stage” seedlings. Occasionally, fights would arise in which the larger F. dolosa threw or chased F. archboldi workers to the ground.

Winged sexuals were collected in nests in mid-June in Florida and Georgia, and one male was found in a nest in western Missouri in August. Both worker and sexual pupae are always enclosed in a cocoon.

Nomenclature



 *  dolosa. Formica (Neoformica) pallidefulva subsp. dolosa Buren, 1944a: 309 (w.) U.S.A. [First available use of Formica pallidefulva subsp. schaufussi var. dolosa Wheeler, W.M. 1912c: 90; unavailable name and unnecessary replacement name for meridionalis Wheeler, W.M. 1904f: 370, unavailable name; see there.] Wheeler, W.M. 1913f: 554 (q.). Subspecies of schaufussi: Creighton, 1950a: 551. Raised to species: Trager, MacGown & Trager, 2007: 619.

Worker
Trager et al. (2007) - The largest, most pilose, most densely pubescent and least shiny of reddish-yellow members of the pallidefulva group (Formica archboldi is duller, but always much darker and averages smaller). Weakly bicolored; head, mesosoma and legs light coppery red (south) to yellowish or reddish brown (north); gaster a little darker than head and mesosoma. Dorsal sclerites of mesosoma with abundant erect pilosity (Figure 4e); erect macrochaetae on gaster abundant and long (longest macrochaetae 0.16-0.30 mm), straight to slightly curved. Mesosoma, especially propodeal dorsum pubescent; gaster dulled by long, dense, pale grayish, appressed microchaetae (Figure 2e). Gaster with small shallow foveolae in some samples, these nearly lacking in others. The propodeal crest is nearly always rounded in F. dolosa. The larger workers of this species are the largest eastern U.S. Formica, matched within the genus only by the allopatric and otherwise quite different Formica ravida Creighton.

Queen
Trager et al. (2007) - Color, gastral pubescence, abundant pilosity and lack of shininess like the workers’, with the usual differences in size. Sculpture a little more accented with notable fine tessellation of entire head, mesosoma and gastral dorsum; wings, when present, clear brownish to dark smoky gray. Three mesoscutal spots present as in Formica incerta, but these relatively pale and diffuse.

Male
Trager et al. (2007) - Pubescence dense and pilosity abundant; surface sculpture punctate; head and gaster dark brown, mesosoma reddish brown to dark reddish brown with legs the same color; wings dark smoky gray. Larger than the nearly similar F. incerta, in which the mesosoma is normally about the same color as the head and gaster.

Type Material
Trager et al. (2007) - Formica (Neoformica) schaufussi subsp. dolosa Buren, 1944: 309. [First available use of dolosa.] Syntype workers, Bull Creek, Travis Co., Texas (W. M. Wheeler) [Examined. Three workers on one pin, labeled “true types of dolosa” by S. Cover, and two gynes on one pin labeled syntypes by S. Cover].

Etymology
This name comes from the Latin adjective dolosus, meaning cunning or sly. Perhaps Wheeler was referring to the fleetness of its escape when alarmed, as this species is very shy and an excellent “escape artist”. (Trager et al. 2007)