Key to US Odontomachus species

Key to United States species of Odontomachus based on workers, modified from MacGown et al. (2014).

1

Petiole with conspicuous transverse striae (Fig. A) => 2
Petiole smooth, lacking transverse striae, or with at most, only a few feeble striae basally (Fig. B) => 3

Large, HL usually greater than 2.5 mm, WL usually greater than 3.0 mm; transverse striae on petiolar node conspicuous anteriorly, laterally, and posterobasally, but reduced or lacking on remainder of posterior region; metasternum with paired, elongate, slender, spiniform processes present (Fig. A) (it may be necessary to remove one hind leg including coxa to see this character) (Gulf Coast) => Odontomachus haematodus

Head of Odontomachus haematodus worker

Profile of Odontomachus haematodus worker

Smaller, HL usually less than 2.5 mm, WL usually less than 2.75 mm; petiole with coarser striae on the posterior side, finer striae basally on the sides and front; metasternum with notched ridge, but not projecting as elongate spiniform processes (Fig. B) (peninsular Florida) => Odontomachus ruginodis

Head of Odontomachus ruginodis worker

Profile of Odontomachus ruginodis worker

Pubescence on first tergite of gaster extremely fine and dense, spaces between hairs less than 1/3 as wide as length of hairs (Fig. A) (Georgia to Mississippi) => Odontomachus brunneus

Head of Odontomachus brunneus worker

Profile of Odontomachus brunneus worker

Pubescence on first tergite of gaster sparse, spaces between hairs at least 1/2 as wide as length of hairs (Fig. B) => 4

Basalar lobe striate, ovate in shape (Fig. A) (endemic to sand ridges of south-central peninsular Florida) => Odontomachus relictus

Head of Odontomachus relictus worker

Profile of Odontomachus relictus worker

Basalar lobe mostly smooth, spheroid (Fig. B) (west of the Mississippi River) => 5

Large, HL > 2.5 mm, WL > 3.0 mm; propleurae almost entirely striate or otherwise roughened (Fig. A); cervical lobe of pronotum wider than long in dorsal view with width measured from the posterior inflection points; scapes long (SL/HW = 1.11-1.15); dorsomedian process of petiole in anterior view spiniform, long, thick at base, and poorly differentiated from rest of node (Fig. C) (Sonoran Desert, Arizona, Mexico) => Odontomachus desertorum

Head of Odontomachus desertorum worker

Profile of Odontomachus desertorum worker

Smaller, HL ≤ 2.2 mm, WL ≤ 2.8 mm; propleurae almost entirely smooth and shining, with sculpture restricted to portions of lateral margins (Fig. B); cervical lobe of pronotum longer than wide in dorsal view with width measured from the posterior inflection points; scapes shorter (SL/HW = 0.99-1.07); dorsomedian process of petiole in anterior view either stoutly conical or spiniform, short, narrow at base, and strongly differentiated from rest of node (Fig. D, E) (Louisiana, southwest United States, north and central Mexico) => Odontomachus clarus

Head of Odontomachus clarus worker

Profile of Odontomachus clarus worker

MacGown, J.A., Boudinot, B., Deyrup, M. & Sorger, D.M. 2014. A review of the Nearctic Odontomachus (Hymenoptera: Formicidae: Ponerinae) with a treatment of the males. Zootaxa 3802(4): 515-552.