Pictorial key to the ant genera of Illinois

by N.C. Wilkins and S.B. Menke

Fig. 1 Stigmatomma pallipes (antweb.org)

Fig. 2 Tapinoma sessile (antweb.org)

Fig. 3 Tetramorium caespitum (antweb.org)

Fig. 4 Crematogaster cerasi (antweb.org)

1
A Postpetiole absent; waist consisting of a petiole (abdominal segment 2).

 

B In some cases, petiole greatly reduced and node vestigial or absent.

 

C In profile, abdominal segment 3 not markedly smaller in size than segment 4.

 

D Abdominal segment 3 either confluent with or separated from segment 4 by a slight or moderate constriction.
2
1'
AA Postpetiole present; waist consisting of two segments. Following the petiole is the postpetiole (abdominal segment 3), which is much smaller than abdominal segment 4 and separated from it by a strong constriction.
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