Subfamily ECTATOMMINAE
Tribe ECTATOMMINI

Gnamptogenys triangularis (Mayr)

Gnamptogenys triangularis face

Gnamptogenys triangularis side

Gnamptogenys triangularis, full face view of a worker (click image to enlarge).

Gnamptogenys triangularis, side view of a worker (click image to enlarge).

Gnamptogenys triangularis, full face view of a worker (click image to enlarge).
Photo courtesy of http://www.antweb.org/

Gnamptogenys triangularis, side view of a worker (click image to enlarge).
Photo courtesy of http://www.antweb.org/

Gnamptogenys triagularis male full face view
Gnamptogenys triangularis, full face view of a male (click image to enlarge).
Gnamptogenys triangularis, side view of a male (click image to enlarge).
Gnamptogenys triangularis, side view of a male (click image to enlarge).

Introduction
Gnamptogenys triangularis and G. hartmanni are the only two members of the subfamily Ectatomminae known to occur in the southeastern US. These very distinctive ants can be recognized immediately by their relatively large size (3.5-5.0 mm in total length), the deep horizontal grooves covering the entire body, and single petiolar node. .

Identification
Medium sized (about 5.0 mm in total length), dark brown, single petiolar node, deep horizontal grooves covering head and entire body. Twelve-segmented antennae, scapes barely surpass occipital margin; large prominent eyes;mandibles triangular, with basal margin flat; propodeum with small triangular spines; posterior lobe of subpetiolar process low, much smaller than large anterior tooth (from Longino 1998). The only other species in the genus in the Southeast, G. hartmanni is smaller (only 3.5 - 4.0 mm TL), pale reddish brown, and lacks the small teeth on the propodeum.

Biology and Economic Importance
This species is reported to be a predator of millipedes (Lattke 1995). A small colony was found by Lloyd Davis in forested habitat in Harrison Co., MS in June in a small rotting branch on the ground. We have collected males and females in malaise traps in several counties southern MS from mid May through mid July, and David Cross collected a male on 12 November 2010 in Forrest County, MS.

Distribution
An exotic species from the Neotropics-Costa Rica to Argentina (Longino 1998). In the U.S. this species has been reported from FL (Deyrup 2003), and has also been collected in Mobile County, AL and Forrest, Harrison, Pearl River, and Stone Counties in MS.

Literature Cited
Deyrup, M. 2003. An updated list of Florida ants (Hymenoptera: Formicidae). Florida Entomologist 86: 43-48. 

Lattke, J. E. 1995. Revision of the ant genus Gnamptogenys in the New World (Hymenoptera: Formicidae). Journal of Hymenoptera Research 4:137-193.

Longino, J. T. 1998. Gnamptogenys triangularis (Mayr 1887). http://academic.evergreen.edu/projects/ants/Genera/Gnamptogenys/SPECIES/triangularis/triangularis.html. Accessed 15 January 2009.

Links
AntWeb Images
Discover Life Images
http://academic.evergreen.edu/projects/ants/Genera/Gnamptogenys/SPECIES/triangularis/triangularis.html