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Species: Trachymyrmex septentrionalis   (McCook, 1881) 

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Current Valid Name:

Taxonomic History (provided by Barry Bolton, 2023)

Atta septentrionalis McCook, 1881a PDF: 362 (w.) U.S.A. (New Jersey). Nearctic. Primary type information: Type-material: syntype workers (number not stated). Type-locality: U.S.A.: New Jersey, Island Heights, N bank Tom’s River, ix.1880 (H.C. McCook or G.K. Morris). Type-depository: no material known to exist. AntCat AntWiki HOL

Taxonomic history

Wheeler, 1907d PDF: 707 (q.m.); Wheeler, 1949 PDF: 673 (l.)
Junior synonym of Atta tardigrada: Forel, 1885a PDF: 358; Mayr, 1886d PDF: 442; Cresson, 1887 PDF: 259; Emery, 1895d PDF: 329.
Synonym of Trachymyrmex virginiana (nomen oblitum): Wheeler, 1902g PDF: 29; Wheeler, 1907d PDF: 706; Emery, 1924f PDF: 345; Smith, 1951c PDF: 831; Smith, 1979: 1411; Bolton, 1995b: 421; Rabeling et al., 2007 PDF: 17 (nomen oblitum).
Material of the unavailable name Trachymyrmex septentrionalis obscurior crystallina referred here by Weber, 1958b PDF: 53; Smith, 1979: 1412; Rabeling et al., 2007 PDF: 17.
Material of the unavailable name Trachymyrmex septentrionalis obscurior irrorata referred here by Weber, 1958b PDF: 53; Smith, 1979: 1412; Rabeling et al., 2007 PDF: 17.
// Distribution


  Geographic regions (According to curated Geolocale/Taxon lists):
    Americas: Mexico, United States
  Biogeographic regions (According to curated Bioregion/Taxon lists):
    Nearctic, Neotropical

Distribution Notes:

South, and Illinois River sands


Sandstone woodland, sand prairie, sandy old field, or other sandy or other highly-drained, acid soil habitats (loess hills)

Taxonomic Treatment (provided by Plazi)

Treatment Citation: Rabeling, Ch., Cover, S. P., Johnson, R. A. & Mueller, U. G., 2007, A review of the North American species of the fungus-gardening ant genus Trachymyrmex (Hymenoptera: Formicidae)., Zootaxa 1664, pp. 1-53

T. septentrionalis (McCook)HNS

Oecodoma virginiana BuckleyHNS, 1867: 346. Syntype worker(s), near Aquia , Virginia, U.S.A. (repository unknown) [not examined]. Synonymy under septentrionalisHNS by Wheeler, 1902: 29; here confirmed. Younger name valid under ICZN Article 23.9 (see discussion below)

Atta septentrionalis McCookHNS, 1881: 362. Worker described; Island Heights, Pine Barrens , New Jersey, U.S.A. (repository unknown) [not examined]

Atta septentrionalis McCookHNS; Wheeler 1907: 707 [description of queen and male]

Atta septentrionalis McCookHNS; Forel 1912: 182 [combination in Atta (Trachymyrmex)HNS]

Atta septentrionalis McCookHNS; Gallardo 1916: 242 [combination in TrachymyrmexHNS]

Atta (Trachymyrmex) septentrionalis var. obscurior WheelerHNS, 1907: 709. Syntype worker(s) described, Austin , Travis County, Texas, U.S.A.

Atta (Trachymyrmex) septentrionalis obscurior WheelerHNS; Wheeler 1911: 247 [raised to subspecies of septentrionalisHNS]

Atta (Trachymyrmex) septentrionalis obscurior WheelerHNS; Wheeler 1911: 246 [description of queen]

Trachymyrmex septentrionalis obscurior (Wheeler)HNS; Creighton 1950: 324 [Combination in TrachymyrmexHNS]

Trachymyrmex septentrionalis obscurior (Wheeler)HNS; Weber 1958: 53 [Synonymy, under septentrionalisHNS]

Atta (Trachymyrmex) septentrionalis obscurior var. crystallina WheelerHNS, 1911: 247. Syntype workers, queens and males; Huntsville Walker County, Texas, U.S.A. [unavailable name]

Trachymyrmex septentrionalis obscurior var. crystallina WheelerHNS; Creighton 1950: 324 [material referred to obscuriorHNS]

Atta (Trachymyrmex) septentrionalis obscurior var. irrorata WheelerHNS, 1911: 247. Syntype workers; Huntsville , Walker County, Texas, U.S.A. [unavailable name]

Trachymyrmex septentrionalis obscurior var. irrorata WheelerHNS; Creighton 1950: 324 [material referred to obscuriorHNS]

Atta (Trachymyrmex) septentrionalis obscurior var. seminole WheelerHNS, 1911: 247. Syntype worker(s), queen(s) and male(s); Miami , Florida, U.S.A. [unavailable name]

Trachymyrmex septentrionalis seminole (Wheeler)HNS; Creighton 1950: 324 [subspecies of septentrionalisHNS, first available use of seminoleHNS]

Trachymyrmex septentrionalis seminole (Wheeler)HNS; Weber 1958: 53 [Synonymy, under septentrionalisHNS]

Atta (Trachymyrmex) septentrionalis var. vertebrata WheelerHNS, 1911: 246. Syntype workers and queens; Lakehurst , New Jersey, U.S.A.

Trachymyrmex septentrionalis var. vertebrata WheelerHNS; Creighton 1950: 323 [Synonymy, under septentrionalisHNS]


Worker: HL 0.84-0.96, HW 0.88-1.0, CI 104-105, SL 0.84-0.96, SI 96, ML 1.12-1.32. A relatively small (HL 0.84-0.96, HW 0.88-1.0), conspicuously tuberculate species with normally proportioned legs and antennal scapes (SI 96). Head slightly broader than long (CI 104-105), sides subparallel behind the eyes, gradually tapering anteriorly between the eyes and the mandibular insertion. Posterior margin moderately concave. Preocular carinae long, traversing 2/3 to 3/4 of the distance between the eye and the frontal carina but not nearly touching the frontal carinae. In full-face view, frontal lobes rounded or subtriangular, usually somewhat asymmetric, with the anterior side longer than the posterior. Anterolateral promesonotal teeth welldeveloped, thin, sharply pointed in dorsal view, projecting somewhat upward as well as horizontally. Anterior median pronotal tubercles upright, toothlike in posterior view. Propodeal teeth usually longer than the distance separating their bases, often spinelike, pointed. Posterior margin of head, mesonotal dorsum, dorsal surfaces of petiole, postpetiole and gaster conspicuously tuberculate, tuberculi largest particularly on posterior corners of head and on the first gastric tergite. Color brownish yellow to medium reddish-brown.

Queen: HL 1.05-1.2, HW 1.1-1.25, CI 104-107, SL 1.05-1.15, SI 96-100, ML 1.55-1.85. As in worker diagnosis, but with caste-specific morphology the mesosoma related to wing-bearing. Dorsolateral pronotal teeth variable in size, but sharply triangulate in dorsal view, often blunt in anterior view. Ventrolateral pronotal teeth variable, but generally lobelike. Mesoscutum coarsely, longitudinally rugulose, finely tuberculate, tuberculi with short, sharply recurved hairs. First gastric tergite with numerous small tubercles bearing short, recurved, decumbent, recurved setae.

Male: HL 0.75, HW 0.8-0.9, CI 100-107, SL 0.9-1.1, SI 113-122, ML 1.5-1.85. In frontal view, posterior corners of the head angulate, angles formed by short, tuberculate ridges best seen in dorsal view; ocelli small and inconspicuous. Dorsoventral pronotal teeth, short, sharp, triangulate in dorsal view; ventrolateral teeth short, triangular or lobelike. Sculpture of mesoscutum coarse, irregular, rugulose, sometimes weakly longitudinal. Tuberculi generally absent (miniscule, if present) on first gastric tergite.


Trachymyrmex septentrionalisHNS is disturbingly similar to the allopatric T. carinatusHNS, but separable by the characters given in the key and by their non-overlapping distributions; carinatusHNS occurs only in the desert southwest, septentrionalisHNS occurs in Texas and the states north and east of there. Molecular evidence suggests the similarity is convergent (see Figure 21 & General Discussion). It is likely that collections identified in the literature as T. septentrionalisHNS from Durango, Mexico may actually represent T. carinatusHNS (Rojas Fernandez 1994).

Solely considering the publication date, Oecodoma virginiana BuckleyHNS (1867) would have seniority over McCook 's (1881) Atta septentrionalisHNS. But since Buckley 's species description is insufficiently detailed to either recognize T. septentrionalisHNS or distinguish between septentrionalisHNS and its congeners, Wheeler (1902) proposed Oocodoma virginiana BuckleyHNS to be a junior synonym of Atta septentrionalis McCookHNS. We agree with Wheeler and continue using the species name septentrionalisHNS. Unfortunately, the locality of both types is unknown and we could not examine them.


McCook (1881) described the worker of T. septentrionalisHNS based on material collected from Island Heights in the New Jersey Pine Barrens. The species name septentrionalisHNS refers to the seven plowing oxen, the brightest stars of the Great Bear constellation, which dominate the skies of the northern hemisphere. Thus, septentrionalis loosely translates to "northern" in the context of North American fungus-growing ants.


Trachymyrmex septentrionalisHNS has the most extensive distribution of all attine ants in the US. It has been collected from Texas to Florida and as far north as central Illinois, southern Ohio and Long Island, New York. Like most fungus-growing ants, the distribution of T. septentrionalisHNS is locally patchy. In part, this may be a consequence of the distribution of suitable soils.

In the northern part of its range, T. septentrionalisHNS occurs exclusively on pure sand soils in open habitats and open woodlands of the Pine Barrens. In the southern US, T. septentrionalisHNS is abundant in a wide variety of similar oak and pine dominated habitat types, all characterized by very sandy soils and light (if any) shade. It has also occasionally been found nesting in sandy clay soils in well-developed forests with considerable shade, particularly in the southern part of its range.

During periods of high nest excavation activity in spring and fall, the crescent shaped mounds of T. septentrionalisHNS are distinctive and conspicuous (Tschinkel & Bhatkar 1974). Older colonies may have several chambers, connected by one to few tunnels and inhabit a few hundred individuals (Weber 1972). As the northernmost distributed species of TrachymyrmexHNS, colonies of T septentrionalisHNS hibernate during the winter and the fungus garden assumes a dormant condition. The length of hibernation varies considerably with respect to latitude. The northernmost populations in New York and New Jersey have short active periods from early May to September, whereas Florida populations remain active during the winter, as long as temperatures exceed 18ºC (Weber 1972). The army ant Neivamyrmex nigrescensHNS and the ectatommine ant Gnamptogenys hartmaniHNS are known to raid colonies of T septentrionalisHNS (Cole 1939).

Additional material examined: U.S.A.: Alabama, Autauga County: Prattville (AS Mikheyev); Mobile County: Dauphin Island (WS Creighton), Theodore (EO Wilson); Arkansas, Miller County: State Line Rd. (UG Mueller); Washington County: Devil 's Den State Park (AS Mikheyev); District of Columbia, Washington (T Pergande, HS Barber); Florida, Alachua County: Archer (M Deyrup), Gainesville (M Deyrup, KW Copper); Baker County: Osceola National Forest, East Tower, 250 (M Deyrup); Bay County: St. Andrews State Recreation Area (M Deyrup); Bradford County: Hampton (M Deyrup); Brevard County: Micco 6mi W Micco Rd (M Deyrup), Melbourne Beach 2mi S Ecological Preserve (M Deyrup), Eau Gallie (M Deyrup), Indian River City, Dicerandra Preserve (M Deyrup), Titusville (M Deyrup); Broward County: Hollywood, Topeekeegee Yugnee Park (M Deyrup), Ft. Lauderdale (DE Read); Citrus County: 12mi NW Brooksville, Withlacoochee State Forest (M Deyrup), Pine Oak Estates, 488, 3mi NE 495 (M Deyrup); Clay County: Camp Blanding (M Deyrup); Collier County: Rookery Bay Preserve (M Deyrup); Columbia County: O'Leno State Park (M Deyrup), Ichetucknee Springs State Park (M Deyrup), I-75 & I-10 , 0.5mi W (M Deyrup); Dade County: Coral Gables, Matheson Hammock (M Deyrup), Matheson State Park (EO Wilson); Desoto County: Arcadia, 13mi E, 2mi S of Headquarters (M Deyrup), Arcadia, W bank of Peace River (M Deyrup), Pine Level (M Deyrup); Dixie County: Jena (M Deyrup); Duval County: Jacksonville (M Deyrup), Fort George, Bis Talbot Is. State Park (Z Prusak); Escambia County: Pensacola (M Deyrup, EO Wilson); Franklin County: Carabelle Beach , 5mi W (M Deyrup); Gilchrist County: Trenton (M Deyrup); Glades County: Muse 2mi S (M Deyrup); Hardee County: Zolfo Springs (M Deyrup), Paynes Creek Historical Site (M Deyrup); Hendry County: 832 & 833 , 3mi NE (M Deyrup); Hernando County: Bayport (M Deyrup); Highlands County: Archbold Biological Station (SP Cover, M Deyrup, UG Mueller, C Rabeling, TC Schneirla, NA Weber), Sebring (M Deyrup), Highlands Hammock State Park (M Deyrup), Lakemont (M Deyrup); Hillsborough County: Tampa (M Deyrup); Holmes County: Ponce de Leon Springs State Park (M Deyrup); Jackson County: Three Rivers State Recreation Area (M Deyrup), Florida Caverns State Park (M Deyrup); Lake County: Lake Louisa State Park (M Deyrup); Ocala National Forest (M Deyrup); Lee County: Koreshan State Historic Site (M Deyrup); Leon County: Apalachicola National Forest (M Deyrup), Tallahassee (AS Mikheyev); Levy County: Bronson (M Deyrup); Liberty County: Torreya State Park (M Deyrup); Madison County: I-10 & SR 53 (M. Deyrup); Manatee County: Lake Manatee Recreation Area (M Deyrup), Bradenton (M Deyrup, GD Reynolds); Marion County: Ocala National Forest (M Deyrup), Wiersdale (H Spencer); Martin County: Jonathan Dickinson State Park (WF Buren, M Deyrup, UG Mueller), Port Sewall (AL Melander); Miami-Dade County: Miami (WM Wheeler); Monroe County: Bahia Honda State Recreation Area (M Deyrup); Nassau County: Fort Clinch State Park (M Deyrup); Okaloosa County: Eglin Air Force Base (M Deyrup), Crestview (M Deyrup); Orange County: Orlando (M Deyrup), Wekiwa Springs State Park (M Deyrup, Z Prusak); Osceola County: Kenansville (M Deyrup), Kissimmee (M Deyrup); Pasco County: St. Leo (M Deyrup); Pinellas County: Fort Desoto Park (M Deyup), Belleair (AT Slosson); Polk County: Haines City (M Deyrup, DE Read), Winter Haven (C Dykes); Putnam County: Crescent (WM Mann); Santa Rosa County: Milton 10mi E (M Deyrup); Sarasota County: Venice (M Deyrup); Seminole County: Oviedo 1mi N (M Deyrup); St. Lucie County: Ft. Pierce (M Deyrup); Sumter County: Bay Hill (M Deyrup); Taylor County: Perry (M Deyrup); Volusia County: Blue Springs State Park (M Deyrup); Wakulla County: Wakulla Springs (M Deyrup); Walton County: DeFuniak Springs (M Deyrup); Washington County: Falling Water State Recreation Area (M Deyrup); GEORGIA, Lowndes County: Valdosta (AC Cole); Macon County: Marshallville (FJ Bartel); Richmond County: Ft. Gordon (RR Snelling); Ware County: Waycross (AS Mikheyev); Illinois, Peoria County: Sand Ridge State Park (AS Mikheyev); Pope County: Dixon Springs State Park (AS Mikheyev); Kentucky, Marshall County: Kentucky Dam (WL Brown); Louisiana, Allen Parish, Reevers (AM Himler); Beauregard Parish: De Ridder (WF Buren); Rapides Parish: Alexandria (WF Buren); Hineston (UG Mueller); Red River Parish: Rt. 371, NE Hall Summit (UG Mueller); St. Tammany Parish: Sildell (J Mathew); Vernon Parish: LA10, mi 7 (UG Mueller); Walker County: Sam Houston National Forest (WL Brown); Webster Parish: Lake Bistineau St. Park (EG Riley), Sibley 3mi W (UG Mueller); Mississippi, Clarke County: Clarkco State Park (WP Mackay), Clay County: Cedar Bluff (AC Cole, LC Murphree); Forrest County: Hattisburg (AH Sturtevant); Hardin County: Mantee (UG Mueller); Harrison County: Gulfport (AC Cole); Lee County: Tupelo (MR Smith); Lowndes County: Columbus (MR Smith); Monroe County: Quincy (MR Smith); Oktibbeha County: Agricultural College (MR Smith), Starkville (AS Mikheyev); Stone County: Wiggins (AH Sturtevant); Wayne County: Waynesboro (AH Sturtevant); North Carolina, Bladen County: White Oak (LR Sasser); Dare County: Roanoke Island (NA Weber); Richmond County: Hoffman (AS Mikheyev); New Jersey, Burlington County: Lebanon State Forest (AS Mikheyev), Moorestown (NJR White); Cumberland County: Bridgeton (FM Schott), Vineland (M Treat); Middlesex County: Bonhamtown (LB Woodruff); Ocean County: Howardsville (WL Brown), Lakehurst (WM Wheeler, WM Mann, R Crozier), Lakewood (FM Schott), Pine Barrens (NA Weber); New York, Suffolk County: Centereach, Long Island (AS Mikheyev); Oklahoma, Beckham County: Sayre (AC Cole); South Carolina, Dillon County: Lake View (DL Stephan); Florence County: Florence (MR Smith); Jasper County: Tillman (RA Mendez); Oconee County: Oconee State Park (MR Smith); Pickens County: Clemson College (MR Smith); Tennessee, Davidson County: Nashville (WS Creighton); Dickens County: Montgomery Bell Park (Pfitzer & Scott); Sevier County: Chilhowee Mtns. (AC Cole); Webster County: Shiloh National Military Park (UG Mueller); Texas, Anderson County: Palestine (FC Bishopp); Angelina County: Angelina National Forest (AS Mikheyev, C Rabeling); Bastrop County: Stengl Biological Station (UG Mueller, C Rabeling); Baylor County: at Brazos River, River Road (UG Mueller), 10km N Kurten (WP Mackay), College Station (EG Riley, NA Weber); Brown County: Brownwood (WD Pierce); Caldwell County: Powell Road (UG Mueller); Cass County: Atlanta State Park (JD Moody); Denton County: Denton (WH Long, WM Wheeler); Fannin County: Ivanhoe (E & G Wheeler); Fort Bend County: Sugarland, Cullinan Park (UG Mueller); Franklin County: Montichello Missionary Baptist Church (UG Mueller); Grimes County: Rt.30, 3.7mi E Carlos (UG Mueller), Shiro (WF Buren); Hardin County: Rt 327, crossing of Village Creek (UG Mueller); Lamar County: Paris (A Rucker, CJ Brues); Liberty County: Liberty (UG Mueller); Medina County: Benton, near Devine (WH Long); Milam County: Milano (WM Wheeler); Montague County: Bonita, rest area E Rt. 82 & Rt. 1815 (UG Mueller); Montgomery County: Willis (JC Bridwell); Sabine County: 9mi E Hemphill (Anderson, Riley & Moody); San Jacinto County: Rt. 2025, Lone Star Trail Head (UG Mueller); Smith County: Tyler State Park, Blackjack Nature Trail trailhead (UG Mueller); Travis County: Austin (UG Mueller, C Rabeling, WM Wheeler), Montopolis (WM Wheeler); Walker County: Huntsville (Hartman); Washington County: Washington-on-the-Brazos State Park (UG Mueller); Wise County: 7.5mi SW Bridgeport (JV Moody); Wood County: 9mi E Minneola on US 80 (JV Moody), Goodwin Woods, 3.5mi SW Hainsville (EG Riley); Virginia, Appomattox County: Appomattox-Buckingham State Forest (S Rehner); Prince George County: Ft. Lee (RR Snelling); West Virginia, Putnam County: Barcroft (JC Bridwell).

Specimen Habitat Summary

Found most commonly in these habitats: 4 times found in Mixed hardwood forest, 1 times found in pine forest, sandy soil, 1 times found in Suburban with wide-spaced, 1 times found in Oak Pine Woods, 1 times found in oak woodland, 1 times found in pine flatwoods, 1 times found in Brickel Hammock, 1 times found in deciduous forest, 1 times found in pine/oak managed forest, 1 times found in Desert, ...

Found most commonly in these microhabitats: 3 times nest in soil, 3 times ground nest, 2 times crumb crater, 1 times sifted leaf litter, 1 times on peach, 1 times leaf litter, 1 times hemi-crater, 1 times ground forager(s), 1 times ex sifted leaf litter, 1 times ex rotten log, 1 times diurnal forager, ...

Collected most commonly using these methods: 7 times direct collection, 5 times search, 1 times collected in malaise trap, 1 times Winkler.

Elevations: collected from 5 - 2480 meters, 317 meters average

Collect Date Range: collected between 1936-07-29 00:00:00.0 and 2021-07-01 00:00:00.0

Type specimens:

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