Odontomachus ruginodis

Identification
Deyrup and Trager (1985) - Worker: gastral hairs, pronotal striation, inner side of hind femur approximately as in Odontomachus clarus; petiole conspicuously transversely striate on sides and back; color reddish brown to piceous gaster black. Male: each ocellus less than two-thirds as wide as ocello-ocular space, ocelli not on a turret; petiole strongly rugose laterally; propodeum and lateral pronotal spot black, remainder of thorax and head yellow, gaster brown.

The conspicuous striae on the posterior face of the petiole distinguish workers of this species from the similar Odontomachus clarus and Odontomachus relictus, but there are additional species with petiolar striae (e.g., Odontomachus bauri Emery) outside the U.S (Deyrup and Cover 2004).

Distribution
This species occurs sporadically through southern and central Florida, at least as far north as Orlando, and also in the West Indies. Its distribution in South and Central America is unclear because it has been confused with brunneus. Its ability to thrive in disturbed habitats should allow it to invade mainland Neotropical areas, if it is not already present. It is probable that this species will be distributed by commerce to disturbed areas in the Southwest. (Deyrup and Cover 2004)

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Bahamas, Barbados, Bermuda, Costa Rica, Dominican Republic, Ecuador, Greater Antilles, Guatemala, Honduras, Mexico, Panama, Puerto Rico.

It is also found in Ecuador, Guatemala, Honduras, Panama, Costa Rica, United States, Dominican Republic, Puerto Rico, Bermuda and Barbados.

Biology
Deyrup and Cover (2004) - In Florida, this species occurs in disturbed areas, including urban and suburban habitats. It occurs along the beaches in the tropical part of the state. It has not yet been found inland in natural habitats. In Puerto Rico it differs from another sympatric species (perhaps Odontomachus bauri) in its preference for open, sunny areas, especially river bottoms (see below).

The defensive mandible-snapping behavior of ruginodis was studied by Carlin and Gladstein (1989). When a nest is attacked by other ants, the ruginodis workers rush out, snapping at anything that seems a threat. Enemy ants may be dismembered or knocked out of the way by the mandibular strikes. If the mandibles hit a solid object, the ruginodis may itself be flung into the air for a distance of several centimeters. This does not seem to be an escape mechanism, as the worker, upon landing, immediately charges back into the fray. The nest entrance is usually guarded by a single worker, who stands with cocked mandibles near the entrance. If an intruder approaches within striking distance, the mandibles snap shut, responding to signals from the antennae and long sensory hairs at the bases of the mandibles. The heavy apices of the mandibles do not slice into the intruder, but knock it away a distance of about one to fourteen centimeters. Carlin and Gladstein call this the “bouncer defense.”

Puerto Rico
Wheeler (1908): ...found only in open, sunny places in the sandy soil of river bottoms. It is smaller than ..Odontomachus haematodus.., has a paler head, and the petiole is less acuminate above, with a shorter spine.

Nomenclature

 *  ruginodis. Odontomachus haematodus var. ruginodis Smith, M.R. 1937: 828 (w.q.) BAHAMAS. [First available use of Odontomachus haematodes subsp. insularis var. ruginodis Wheeler, W.M. 1905b: 82; unavailable name.] Deyrup, Trager & Carlin, 1985: 192 (m.). Raised to species: Wilson, 1964b: 4. Junior synonym of brunneus: Brown, 1976a: 103. Revived from synonymy: Deyrup, Trager & Carlin, 1985: 192.

Additional References

 * Wheeler, W. M. 1908a. The ants of Porto Rico and the Virgin Islands. Bull. Am. Mus. Nat. Hist. 24: 117-158.