Key to Proceratium species in the southeastern United States (from Brown 1979 and Baroni Urbani and de Andrade 2003)
1   

Petiole rectangular; anterior border of clypeus unarmed, straight; palp formula 2,2

....2
  Petiole convex; anterior border of clypeus subconvex, rectangular, or triangular; palp formula 3,2 or 4,3
...4
2(1)    Larger size, total length (TL) greater than 3.7 mm and HW > 0.75 mm; frontal area broader than 1/3 of the maximum HW
  Smaller size, TL < 3.5 mm and HW < 0.75 mm; frontal area at most slightly more than 1/4 of the maximum HW
...3
3(2)

Frontal area about 1/4 of HW, frontal carinae gently diverging posteriorly; hairs on gaster and petiole of two types: (1) short and (2) long; type (1) hairs dense, type (2) hairs sparse and shorter than in silaceum

 

Frontal area broader than 1/4 of HW, frontal carinae strongly diverging on the two anterior thirds; hairs on gaster and petiole of two types: (1) short and (2) long; type (1) hairs less dense, and type (2) hairs denser and longer than in crassicorne

4 (1)   Scapes not reaching the margin of vertex; first segment of funiculus approximately 1/5 longer than broad; funicular segments 2-10 about as long as broad or slightly broader than long; mid basitari shorter than fore basitarsi; first tergite of gaster strongly angulate on the curvature
...5
  Scapes reaching or surpassing the margin of vertex; first segment of funiculus about 1/2 longer than broad; funicular segments 2-10 longer than broad; mid basitarsi as long or longer than fore basitarsi; first tergite of gaster at most weakly angulate on the curvature
5(4) Gaster short and opaque, with short dense hairs
  Gaster longer and shinier, with longer, sparser hairs