Key to US Brachymyrmex species

Key to workers of Brachymyrmex species known from the United States based on Ortiz-Sepulveda et al. (2019).

1

 * Gaster with sparse pubescence, but with scattered, appressed hairs (Fig. 6 g1)
 * Gaster with dense appressed or decumbent pubescence (Fig. 6 g2)

2

 * Mesonotum bulging dorsally above the pronotum in lateral view (Fig. 6 b1) Brachymyrmex depilis


 * Mesonotum not bulging dorsally above the pronotum in lateral view (Fig. 6 b2)

3

 * Body yellowish Brachymyrmex termitophilus


 * Body dark brown

4

 * Dorsum of the head and mesosoma with light-colored, dense pubescence; gaster with dense appressed pubescence; eye with on average 11 ommatidia along its maximal diameter, head on average long (head length > 0.5 mm) and wide (head width > 0.4 mm) Brachymyrmex cordemoyi


 * Dorsum of the head and mesosoma with less conspicuous dense pubescence; gaster with dense decumbent pubescence; eye with on average nine ommatidia along its maximal diameter, head on average short (head length < 0.5 mm) and narrow (head width < 0.4 mm) Brachymyrmex obscurior

5

 * Body yellowish, usually with a narrow mesonotum (mesonotum width ~ 0.16) and 8–9 ommatidia along the maximum diameter of the eye Brachymyrmex aphidicola


 * Body brownish or dark brown, usually with a wide mesonotum (mesonotum width ~ 0.20 or more) and 10 or more ommatidia along the maximum diameter of the eye

6

 * Scapes surpassing the posterior margin of the head by a length smaller than the maximal diameter of the eye (Fig. 5 d3: A > B); usually with two erect hairs on the pronotum and two on the mesonotum Brachymyrmex patagonicus


 * Scapes surpassing the posterior margin of the head by a length approximately equal to the maximal diameter of the eye (Fig. 5 d3: A ≈ B); usually with more than two erect or decumbent hairs on the pronotum and two erect hairs on the mesonotum Brachymyrmex bruchi