Introduction
The genus Stigmatomma is found in tropical and temperate regions of the world. In the Nearctic region, they usually occur in wooded areas. Members of this genus are found in soil and leaf litter throughout the United States, except in the north central region. Currently, three species are recognized in the U.S., but only two have been found in the Southeast,Stigmatomma pallipes (Haldeman), a widespread species distributed throughout much of the United States, and S. trigonignatha Brown, known only from North Carolina.

Identification
Stigmatomma individuals range in size from 4 to 6.5 mm and are reddish-brown in color. They possess very distinctive mandibles, which are long and linear with the inner border having a row of coarse, bidentate teeth and a single, long, curved tooth apically. The mandibles are inserted at the anterolateral corners of the head. The anterior border of the clypeus is denticulate. The eyes are minute. The antenna is 12 segmented and with a short scape. The petiole is attached to the first gastral segment broadly, and only separated by a constriction. Stigmatomma pallipes can be distinguished from S. trigonignatha by the presence of a tooth on each side of the head near the point of mandibular insertion and by the mandible being slender for its entire length, rather than having the basal portion enlarged and triangular in shape, as in S. trigonignatha.

Biology and Economic Importance
Habitat: Although only one or two specimens are usually collected at any given time, this species does not seem to be uncommon in the Southeast. It is typically found in mesic and dry-mesic woodlands and forests, but has been collected in prairies, and other habitats throughout the southeastern United States. We have even collected this species in arid inland sand dunes at the Ohoopee Dunes Natural Area in Emanuel County, Georgia. This species usually nests in rich, slightly moist, soil beneath rotting logs or stones, in leaf litter at tree bases, or in decomposing logs and stumps. Colonies are relatively small. Although this species can be visually detected in the field, its dark coloration makes it somewhat difficult to find. Most specimens tend to be collected in soil or litter samples.

Natural History: The main source of food of this species is reported to be chilopods (Smith, D. R., 1979). Foragers hunt singly for geophilomorph centipedes, which they grasp with long, bidenticulate-toothed mandibles and paralyze with a long and powerful sting. Prey may be dragged into a nearby nest or larvae may be brought to the paralyzed prey to feed (Trager pers. comm). Members of this genus are sometimes referred to as Dracula ants because queens of some species obtain much of their nutrients from hemolymph of their larvae. The queen, and sometimes workers, puncture the integument of the larvae, which results in a small drop of hemolymph, which is then lapped up. For more about this bizarre behavior, see Alex Wild's online article about the related species Stigmatomma oregonensis (link). Although I rarely encounter more than a few workers at a time, I have seen numerous alates, both male and female, in malaise and Lindgren funnel traps, which gives me the impression that this species is quite common. We routinely collect this ant in wooded areas, and in a current study of Mississippi ants, have already collected it in over one-fourth of the counties in the state. Alates have been collected in mid July.

This species would not typically be considered a pest species and generally would have little or no obvious impact on mankind. However, this species does have the capabililty of stinging, and it is concievable that alate females could get caught in someones clothing and sting them. This sort of thing is know to happen with various ponerine ants, although I do not know of any instances of this species stinging anybody.

Distribution
Ont., Que, south to FL, west to WI, IA, OK, CO, TX, AZ (Smith, D. R., 1979); found in all of the southeastern states including AL, AR, FL, GA, LA, MO, MS, NC, SC, TN.

Literature Cited
Smith, D. R. 1979. In Catalog of Hymenoptera in America north of Mexico. Smithsonian Institution Press, Washington D. C. Vol. 2, pp. 1323-1427.

Links
BugGuide-Amblyopone pallipes - mostly images of live specimens
AntWeb Images
Discover Life Images
Alex Wild Photography - Amblyopone