Trachymyrmex septentrionalis

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: 17-18

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Trachymyrmex septentrionalis


T. septentrionalis (McCook)  HNS 

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

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

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

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

Atta septentrionalis McCook  HNS  ; Gallardo 1916: 242 [combination in Trachymyrmex  HNS  ]

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

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

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

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

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

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

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

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

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

Atta (Trachymyrmex) septentrionalis obscurior var. seminole Wheeler  HNS  , 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 septentrionalis  HNS  , first available use of seminole  HNS  ]

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

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

Trachymyrmex septentrionalis var. vertebrata Wheeler  HNS  ; Creighton 1950: 323 [Synonymy, under septentrionalis  HNS  ]


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 septentrionalis  HNS  is disturbingly similar to the allopatric T. carinatus  HNS  , but separable by the characters given in the key and by their non-overlapping distributions; carinatus  HNS  occurs only in the desert southwest, septentrionalis  HNS  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. septentrionalis  HNS  from Durango, Mexico may actually represent T. carinatus  HNS  (Rojas Fernandez 1994).

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


McCook (1881) described the worker of T. septentrionalis  HNS  based on material collected from Island Heights in the New Jersey Pine Barrens. The species name septentrionalis  HNS  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 septentrionalis  HNS  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. septentrionalis  HNS  is locally patchy. In part, this may be a consequence of the distribution of suitable soils.

In the northern part of its range, T. septentrionalis  HNS  occurs exclusively on pure sand soils in open habitats and open woodlands of the Pine Barrens. In the southern US, T. septentrionalis  HNS  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. septentrionalis  HNS  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 Trachymyrmex  HNS  , colonies of T septentrionalis  HNS  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 nigrescens  HNS  and the ectatommine ant Gnamptogenys hartmani  HNS  are known to raid colonies of T septentrionalis  HNS  (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)  .














Trachymyrmex septentrionalis

Rabeling, Ch., Cover, S. P., Johnson, R. A. & Mueller, U. G. 2007


Oecodoma virginiana Buckley

Latreille 1818