Key to Nearctic and Neotropical Proceratium Species

The following key to workers is based on Baroni Urbani, C., de Andrade, M.L. (2003) The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali, Monografie, 36, 1–492.

1

 * Mid tibiae without pectinate spur . . . . . 2


 * Mid tibiae with a pectinate spur . . . . . 12

2
return to couplet #1
 * Propodeal dorsum with a swelling covered by short hairs only . . . . . 3


 * Propodeal dorsum without swelling and covered by short and long hairs . . . . . 6

3
return to couplet #2
 * Gaster entirely sculptured . . . . . 4


 * Gaster sculptured only over the posterior half or less . . . . . 5

4
return to couplet #3
 * Head and mesosoma reticulate-foveolate and granulate. Propodeal swelling broad and low. Ecuador . . . . . Proceratium ecuadoriense


 * Head and mesosoma granulate. Propodeal swelling narrow and high. Colombia . . . . . Proceratium colombicum

5
return to couplet #3
 * Petiole 1/5 longer than broad. Postpetiole shorter than 1/2 of the gastral tergite I. Postpetiole and gaster more convex. Colombia . . . . . Proceratium catio


 * Petiole at most 1/8 longer than broad. Postpetiole slightly longer than 1/2 of the gastral tergite I. Postpetiole and gaster less convex. Brazil . . . . . Proceratium brasiliense

6
return to couplet #2
 * Mid basitarsi with hairs shorter than 1/2 of the basitarsal length . . . . . 7


 * Mid basitarsi with at least one hair about 1/2 of the mid basitarsal length . . . . . 8

7
return to couplet #6
 * Postpetiole shorter than 1/2 of the length of the first gastral tergite. TL ≥ 3.70 mm. Dark ferrugineous-brown. Dominican Republic . . . . . Proceratium taino


 * Postpetiole about 1/2 of the length of the first gastral tergite. TL ≤ 3.00 mm. Light brown. Cuba . . . . . Proceratium cubanum

8
return to couplet #6
 * Area between the basal and declivous faces of the propodeum with a transverse carina angulate or denticulate laterally . . . . . 9


 * Area between the basal and declivous faces of the propodeum with at most very superficial traces of transverse carina . . . . . 10

9
return to couplet #8
 * Postpetiole anterolaterally convex. IGR < 0.21. TL > 2.8 mm. Mexico . . . . . Proceratium mexicanum


 * Postpetiole anterolaterally angulate. IGR > 0.23. TL < 2.5 mm. Dominican amber . . . . . Proceratium poinari

10
return to couplet #8
 * Mesosoma gently convex in profile. Postpetiole in dorsal view more convex and slightly angulate anterolaterally. Integumental sculpture impressed. Costa Rica, ?Mexico . . . . . Proceratium convexiceps


 * Mesosoma more elongate in profile. Postpetiole in dorsal view more rectangular and angulate anterolaterally. Body sculpture more superficial . . . . . 11

11
return to couplet #10
 * TL ≥ 3.80mm. WL ≥ 1.05 mm. Costa Rica, Panama . . . . . Proceratium panamense


 * TL < 3.60 mm. WL ≤ 0.95 mm. Honduras, Costa Rica, Panama, Colombia, Venezuela, Texas?, Ecuador? . . . . . Proceratium micrommatum

12
return to couplet #1
 * Petiole rectangular. Anterior clypeal border unarmed, straight. Palp formula 2,2 . . . . . 13


 * Petiole convex. Anterior clypeal border subconvex, rectangular or triangular. Palp formula 3,2 or 4,3 . . . . . 16

13
return to couplet #12
 * TL > 3.7 mm. Frontal area broader than 1/3 of the maximum HW. United States . . . . . Proceratium croceum


 * TL < 3.5 mm. Frontal area at most slightly more than 1/4 of the maximum HW, or, if the frontal area is 1/3 of the maximum HW (mancum), then the mid and hind basitarsi with hairs about ½ of their length . . . . . 14

14
return to couplet #13
 * Posterior half of the head dorsum and anterior half of the mesosoma smooth and minutely punctate. Mid basitarsi with hairs 2/3 of their length and hind basitarsi with hairs 1/2 of their length. Mexico, Belize, Guatemala, Honduras, Costa Rica, and Colombia . . . . . Proceratium mancum


 * Posterior half of the head dorsum and anterior half of the mesosoma with marked sculpture. Mid basitarsi with hairs at most 1/4 of their length. United States and Canada . . . . . 15

15
return to couplet #14
 * Frontal area about 1/4 of HW and the carinae gently diverging posteriorly. Standing hairs on the postpetiole and gaster sparse and short. United States . . . . . Proceratium crassicorne


 * Frontal area broader than 1/4 of HW and the carinae strongly diverging on the two anterior thirds. Standing hairs on the postpetiole and gaster denser and longer. Southern Canada and United States . . . . . Proceratium silaceum

16
return to couplet #12
 * Eyes composed by a single convex facet. Frontal carinae broad and strongly diverging posteriorly. Erect hairs dense and long. Sculpture densely granulate-foveolate . . . . . 17


 * Eyes absent or composed of an agglomeration of minute ommatidia at most. Frontal carinae narrow and gently diverging posteriorly. Erect hairs absent, or, at most, sparse and short. Sculpture at most reticulate-punctate and granulate . . . . . 20

17
return to couplet #16
 * Fore tibiae without thick basal spine. Palp formula 3,2 . . . . . 18


 * Fore tibiae with a thick basal spine. Palp formula 4,3 . . . . . 19

18
return to couplet #17
 * Clypeus surrounding the antennal sockets, subrectangular and protruding anteriorly. Propodeal dorsum with a median swelling. Colombia . . . . . Proceratium transitionis


 * Clypeus not surrounding the antennal sockets, reduced medially and triangular. Propodeal dorsum without swelling. Venezuela . . . . . Proceratium lattkei

19
return to couplet #17
 * Sides of the propodeum with an obtuse angle. Ventral process of the petiole at most shortly triangular. Postpetiole about 1/4 shorter than the first gastral tergite. Costa Rica . . . . . Proceratium goliath


 * Sides of the propodeum with a tooth. Ventral process of the petiole distinct and spiniform. Postpetiole about 1/7 shorter than the first gastral tergite. Mexico . . . . . Proceratium tio

20
return to couplet #16
 * Propodeal suture impressed. Clypeus anteromedially triangular. Propodeal sides without lamellae. Long hairs subdecumbent or decumbent, rare on the antennae and absent from the legs. United States (California) . . . . . Proceratium californicum


 * Propodeal suture absent. Clypeus anteromedially rectangular. Propodeal sides with lamellae. Long hairs suberect and distributed on the whole body . . . . . 21

21
return to couplet #20
 * Scapes much short of the vertexal margin. First funicular joint about 1/5 longer than broad. Funicular joints 2-10 about as long as broad or slightly broader than long. Mid basitarsi shorter than fore basitarsi. First gastral tergite strongly angulate on the curvature . . . . . 22


 * Scapes reaching or surpassing the vertexal margin. First funicular joint 1/2 longer than broad. Funicular joints 2-10 longer than broad. Mid basitarsi as long as or longer than fore basitarsi. First gastral tergite at most weakly angulate on the curvature . . . . . 23

22
return to couplet #21
 * Gaster short, opaque, with dense and short hairs. United States . . . . . Proceratium pergandei


 * Gaster longer, shinier, with sparse and longer hairs. United States . . . . . Proceratium chickasaw

23
return to couplet #21
 * Scapes surpassing the vertexal margin. TL ≥ 5.5 mm. United States . . . . . Proceratium creek


 * Scapes reaching the vertexal margin. TL < 5.0 mm. United States (Texas) and Northern Mexico . . . . . Proceratium compitale