Key to US Hypoponera species

Key to Hypoponera species of the United States based on workers.

1

 * Mesopleuron smooth and shiny, lacking punctures (sculpturing present immediately above mid coxa, but smooth above this) => 2
 * Mesopleuron partly to entirely granulate or punctate => 3

2

 * In profile petiole node less blocky, higher and relatively shorter (PeH 0.30–0.39, LPeI 43–53); in dorsal view node shorter and relatively broader (DPeI 140–165); body larger (HW 0.46–0.60) => Hypoponera punctatissima
 * In profile petiole node more blocky, lower and relatively longer (PeH 0.26–0.30, LPeI 55–61); in dorsal view node longer and relatively narrower (DPeI 120–140); body smaller (HW 0.42–0.50) => Hypoponera ragusai

3

 * Outer surface of the mandibles sinuate, distinctly concave medially; dorsum of mesosoma and gaster with abundant long erect and/or suberect hairs => Hypoponera inexorata
 * Outer surface of mandible straight or nearly so, at most only slightly concave medially; dorsum of mesosoma and gaster lacking erect and suberect hairs, or with at most a few short suberect to decumbent hairs => 4

4

 * Petiole of worker in lateral view narrower dorsally than ventrally, the anterior and posterior faces not parallel; head and body punctate over a smooth and shiny background surface; yellow to yellowish red => Hypoponera opacior
 * Petiole of worker in lateral view not narrowed dorsally, the anterior and posterior faces parallel; head and body punctate-granulate, the background surface not particularly shiny; reddish brown => Hypoponera opaciceps