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

Odontomachus clarus, top view of a worker (click image to enlarge).
Photo courtesy of http://www.antweb.org/

Introduction
Ants in this genus differ from other ponerine ants found in the United States by the unique head shape; peculiar mandibles, which are elongate and inserted near the center of the clypeus (see photo above); the large tapering petiole; and the large size of the workers. Members of this genus are commonly called trap-jaw ants due to their elongate mandibles, which can be opened to 180°, then snapped rapidly together on prey. These ants are amazing in their ability to control and time the mandibular movement. When necessary, an ant can forcibly close the mandibles against a surface or other organism and actually propel itself away for up to several inches! Remarkable behavior. Additionally, they can use the mandibles for much more sensitive movements such as caring for larvae or nest building.

Odontomachus clarus is typically considered to be a southwestern US species and was only recently discovered to occur in Louisiana (Adams et al. 2010). According to Deyrup and Cover (2004), this species nests under rocks or in grasses associated with arid and mesic habitats.

Taxonomic History (from Bolton, 2012)
Described as Odontomachus clarus by Roger (1861); treated as a subspecies of O. haematodus (Emery 1911); revived as a species by Taylor and Wilson (1962).

Identification

Workers: Bicolored with head, alitrunk, and petiole reddish brown, gaster brownish-black, and legs yellowish brown. Length approximately 9 mm. Pronotum with transverse striae posteriorly. Petiole slightly rugose basally on sides, smooth on back. Inner side of hind femur glabrous at base. Basalar lobe smooth. Fine appressed pubescence on first gastral tergite distributed at least ½ their own length; Other US species differ in the density of gastral pubescence, smoothness of the posterior side of the petiole, and smoothness of the basalar lobe in workers.

Males: Ocelli smaller than the space between lateral ocelli and eye, not raised on turrets; pronotum with fine striations; and head and body dark brown. (Deyrup et al. 1985, Deyrup and Cover 2004).

This species is similar to O. relictus, which has basalar lobes striate in workers and large raised ocelli in males.

Biology and Economic Importance
Similar to other members of this subfamily, Odontomachus workers have a prominent sting(er), and have the ability to inflict a relatively painful sting.

According to Mark Deyrup (pers. com.), this may actually be a species complex with at least two species involved.

According to AntWeb data this species has been collected in agricultural areas, xerophyl scrub, juniper scrub, oak-pine-juniper woodland, juniper woodland, oak-pine forest, Ocotillo-acacia desert, rocky slope, riparian woodland, and riparian woodland/desert scrub habitats.

Distribution
O. clarus has been reported in Mexico, Arizona, New Mexico, Texas, and Louisiana (MEM records, Adams et al. 2010; Deyrup and Cover 2004). 

Literature Cited
Adams, B. J., X. Chen, and L. M. Hooper-Bui. 2010. Odontomachus clarus Roger (Hymenoptera: Formicidae) Reported in Kisatchie National Forest, Louisiana. Midsouth Entomologist 3: 104-105. [Available online: http://midsouthentomologist.org.msstate.edu/pdfs/Vol3_2/Vol3_2_006.pdf]

Bolton, B. 2012. Bolton World Catalog Ants. accessed on October 2012. [Available online: http://www.antweb.org/world.jsp]

Deyrup, M. and S. Cover. 2004.  A new species of Odontomachus ant (Hymenoptera:  Formicidae) from inland ridges of Florida, with a key to Odontomachus of the United States.  Florida Entomologist 87: 136-144.

Deyrup, M., J. Trager, and N. s 1985. The genus Odontomachus in the southeastern United States (Hymenoptera: Formicidae). Entomological News 96: 188-195.

Emery, C. 1911e. Hymenoptera. Fam. Formicidae. Subfam. Ponerinae. Genera Insectorum 118:1-125.

Taylor, R. W. and Wilson, E. O. 1962 ("1961"). Ants from three remote oceanic islands. Psyche (Cambridge) 68:137-144.

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