Formica fossaceps

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Formica fossaceps
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Formicini
Genus: Formica
Species group: rufa
Species: F. fossaceps
Binomial name
Formica fossaceps
Buren, 1942

Formica fossaceps casent0103366 profile 1.jpg

Formica fossaceps casent0103366 dorsal 1.jpg

Specimen labels

Buren (1942) reported the type material was collected from a nest that was "located around the base of a bush, plant debris being used in the construction of a low dome. Immediately under this dome were the brood, workers, and sexual forms.


This species seems definitely related to Formica rufa and its numerous subspecies and varieties. It differs from all of them, however, by the paucity of both pilosity and pubescence, the very shining surface, and the depth of the clypeal fossae. Formica obscuriventris seems to be most closely related in the structure of the clypeal fossae and the funiculi. F. fossaceps can be distinguished from obscuriventris by the smaller size of the female, the more shining surface of both female and worker, the deeper clypeal fossae, the more bead-like funicular joints, the ecarinate clypeus, and by the lack of pilosity on the dorsal surfaces of both female and worker. In addition fossaceps has a somewhat differently shaped head. (Buren 1942)

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: 50.152° to 38.39466667°.

Tropical South

Distribution based on Regional Taxon Lists

Nearctic Region: Canada, United States (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.


Association with Other Organisms

Explore-icon.png Explore: Show all Associate data or Search these data. See also a list of all data tables or learn how data is managed.



MCZ-ENT00028996 Formica fossaceps hef.jpgMCZ-ENT00028996 Formica fossaceps hal.jpgMCZ-ENT00028996 Formica fossaceps had.jpgMCZ-ENT00028996 Formica fossaceps lbs.jpg
. Owned by Museum of Comparative Zoology.
Formica cf fossaceps hef 3-2.jpgFormica cf fossaceps hal.jpgFormica cf fossaceps had.jpgFile:FormFormica fossaceps casent0103368 head 1.jpgFormica fossaceps casent0103368 profile 1.jpgFormica fossaceps casent0103368 dorsal 1.jpgFormica fossaceps casent0103368 label 1.jpg


Images from AntWeb

Formica fossaceps casent0103367 head 1.jpgFormica fossaceps casent0103367 profile 1.jpgFormica fossaceps casent0103367 dorsal 1.jpgFormica fossaceps casent0103367 dorsal 2.jpgFormica fossaceps casent0103367 label 1.jpg
Paratype of Formica fossacepsQueen (alate/dealate). Specimen code casent0103367. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by USNM, Washington, DC, USA.


The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • fossaceps. Formica fossaceps Buren, 1942: 402 (w.q.m.) U.S.A.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.



Length, 6.65-7.71 mm.

Head, excluding the mandibles, slightly longer than broad, narrower in front than behind, with feebly excised or straight posterior border and nearly straight sides. Clypeus evenly rounded in front, ecarinate or distindly carinate only at the extreme front. Clypeal fossae strikingly deep; antennal fossae also rather deeply impressed. Maxillary palpi short. Apex of frontal area rounded. Frontal carinae diverging, about twice as long as the diameter of the antennal foramina. Frontal furrow indistinct, ending in a shallow pit level with the eyes. Eyes hairless. Scapes surpassing posterior lateral corners of the head by nearly two-fifths of their length. Funicular joints gradually decreasing in length toward the penultimate, the second approximately four-fifths as long as the first and about one-third again as long as the penultimate, the third slightly shorter than the second; joints 5-8 rather unusual in appearance, each narrow at the base but swollen to more than 1% times the base width near the apex. To the naked eye these joints are somewhat bead-like.

Pro- and mesonotum not as convex as in Formica obscuriventris. Meso-epinotal depression not as deep. Epinotum in profile with subequal base and declivity, the base slightly convex, the declivity feebly concave. Petiole large, higher than the epinotum, in profile cuneate, the superior border very sharp. Seen from behind, the petiole broad, measuring up to . 77 mm. wide, and strongly subangularly or convexly produced upward.

Head and legs moderately shining, gaster more shining but not as highly polished as that of the female, the shagreening on the gaster very fine and superficial. Thorax subopaque.

Erect hairs absent on most body surfaces, present on the dorsum of gaster near the apex, venter of gaster, venter of petiole, and coxae. Pubescence very short and sparse. especially on the head and gaster, rather dense only on the base of gaster, petiole, epinotum and appendages. Head and thorax ferruginous, appendages brown, entire gaster deep black.

Media Worker

Length, 5.23-6.62 mm. ..

Differing from the major in having the head straight or slightly convex behind, the clypeal fossae a little less deep, the basal funicular joints shorter in proportion to the penultimate, the middle joints less bead-like, and the head and thorax often infuscated.

Minima Worker

Length, 3.70-4.58 rom.

Differing from the major in having the head definitely longer than broad and slightly convex behind, the clypeus distinctly carinate, the clypeal fossae more normal in depth, funicular joints 2-10 more nearly subequal in length, and the middle joints not bead-like. Also differing in having the body a little less shining and the head and thorax heavily infuscated.


Length, 7.19-7.84 mm.

Although little shorter than the females of Formica obscuriventris, strikingly more slender and much less massive than this species.

Head, including the mandibles, triangular in shape; the outer borders of the mandibles nearly aligned with the sides of the head; excluding the mandibles, slightly longer than broad (about 1.38mm. wide), one-third again as wide behind as in front, with straight posterior border and sides. Clypeus evenly rounded in front, ecarinate. Clypeal fossae extraordinarily deep, the middle part of the clypeus between them strongly convex in transverse section. Frontal carinae diverging, approximately twice as long as the diameter of the antennal foramina. Frontal furrow very short and indistinct, not reaching beyond the frontal carinae. Funiculi much as in the major worker, but joints 5-8 not as bead-like and the second joint only a little shorter than the first. Eyes hairless, a little larger than those of the worker. Thorax narrower than the head about 1.2 mm. wide. Petiole large, cuneate in profile, with sharep superior border, subangularly produced upward when seen from behind.

Entire body, especially the gaster, glaborous and extremely smooth. Thorax a little less shining than the head and gaster. Shagreening on the gaster scarcely perceptable, the surface marked only by the very sparse, minute punctures from which the pubescence arises.

Pilosity entirely lacking on all dorsal regions of the body body; some slender, scattered hairs on the ventor of the gaster and coxae. Pubescence very fine, short, and sparse, about .01-.02 mm. in length, rather dense only on the base of the gaster and appendages, extremely parse on the head.

Head and thorax light brownish red. Gaster entirely deep black except at the extreme base. Head lightly infuscated behind the eyes. Mesonotum heavily infuscated in a median frontal spot and along the parapsidal sutures. Scutellum and metanotum black.


Length, 8.06 mm.

Head, excluding the mandibles, distinctly broader than long, much broader behind than in front. Mandibles feebly 3-toothed. Clypeal fossae very deep. Funicular joints 2-10 gradually decreasing in length, the penultimate a little over one-half as long as the second, the second one-fourth again as long as the first. Petiole in profile, with convex anterior and flat posterior surfaces; seen from behind, subrectangular, the superior border sinuate but nearly truncate, the sides almost straight.

Head and thorax mainly opaque, the declivity of the epinotum glabrous; gaster feebly shining.

Paratype Specimen Labels

Erect hairs nearly absent on the dorsal surfaces of the body, a few on the gula, profuse on the venter of the gaster toward the apex. Pubescence sparse, but longer and much denser than in the worker and female.

Color black, the antennae dark brown, legs light brown.

Type Material

Described from 12 females, 93 workers, and 1 male taken from a nest in wooded pasture near Winterset, Iowa, June 27, 1941.


References based on Global Ant Biodiversity Informatics

  • Allred D. M. 1982. Ants of Utah. The Great Basin Naturalist 42: 415-511.
  • Allred, D.M. 1982. The ants of Utah. Great Basin Naturalist 42:415-511.
  • Bestelmeyer B. T., and J. A. Wiens. 2001. Local and regional-scale responses of ant diversity to a semiarid biome transition. Ecography 24: 381-392.
  • Choate B., and F. A. Drummond. 2012. Ant Diversity and Distribution (Hymenoptera: Formicidae) Throughout Maine Lowbush Blueberry Fields in Hancock and Washington Counties. Environ. Entomol. 41(2): 222-232.
  • Choate B., and F. A. Drummond. 2013. The influence of insecticides and vegetation in structuring Formica Mound ant communities (Hymenoptera: Formicidae) in Maine lowbush blueberry. Environ. Entomol. 41(2): 222-232.
  • Glasier J. R. N., S. Nielsen, J. H. Acorn, L. H. Borysenko, and T. Radtke. 2016. A checklist of ants (Hymenoptera: Formicidae) of Saskatchewan. The Canadian Field-Naturalist 130(1): 40-48.
  • Menke S. B., E. Gaulke, A. Hamel, and N. Vachter. 2015. The effects of restoration age and prescribed burns on grassland ant community structure. Environmental Entomology
  • Menke S. B., and N. Vachter. 2014. A comparison of the effectiveness of pitfall traps and winkler litter samples for characterization of terrestrial ant (Formicidae) communities in temperate savannas. The Great Lakes Entomologist 47(3-4): 149-165.
  • Wheeler G. C., J. N. Wheeler, and P. B. Kannowski. 1994. Checklist of the ants of Michigan (Hymenoptera: Formicidae). The Great Lakes Entomologist 26(4): 297-310
  • Wheeler, G.C. and J. Wheeler. 1988. A checklist of the ants of Montana. Psyche 95:101-114
  • Wheeler, G.C., J. Wheeler and P.B. Kannowski. 1994. CHECKLIST OF THE ANTS OF MICHIGAN (HYMENOPTERA: FORMICIDAE). Great Lakes Entomologist 26:1:297-310
  • Wheeler, G.C., J. Wheeler, T.D. Galloway and G.L. Ayre. 1989. A list of the ants of Manitoba. Proceedings of the Entomological Society of Manitoba 45:34-49