Key to Pogonomyrmex queens of South American

This key is based on: Johnson, R.A. 2015. A taxonomic revision of South American species of the seed-harvester ant genus Pogonomyrmex (Hymenoptera: Formicidae). Part I. Zootaxa. 4029:1–142.

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1

 * Ergatoid (wingless) . . . . . 2


 * Winged (including brachypterous) . . . . . 10

2
return to couplet #1
 * Queens small (HW < 1.30 mm); mesoscutum, mesoscutellum, and posterior surface of petiolar node rugoreticulate; in profile, mesosoma discontinuous between the metanotum and propodeum . . . . . Pogonomyrmex naegelii (in part - also )


 * Queens larger (HW > 1.40 mm); mesoscutum, mesoscutellum, and posterior surface of petiolar node usually rugose, rarely rugoreticulate; in profile, mesosoma continuous or nearly so between metanotum and propodeum . . . . . 3

3
return to couplet #2
 * Anterior clypeal margin with small medial tooth; anterior surface of petiolar node striate . . . . . Pogonomyrmex mayri


 * Anterior clypeal margin entire, lacking a medial tooth; anterior surface of petiolar node usually smooth and shining, never striate . . . . . 4

4
return to couplet #3
 * Fine, dense, incised striae (usually longitudinal) cover anterior one-third or more of first gastral tergum . . . . . rastratus-group (in part - also ) (in part - also )


 * First gastral tergum smooth and shining to moderately coriarious, weakly shining, lacking striae except occasionally at base . . . . . 5

5
return to couplet #4
 * Queens larger (HW > 2.40 mm); in dorsal view, petiolar node only slightly longer than wide, anterior margin broadly rounded; in dorsal view, postpetiole wider than long . . . . . Pogonomyrmex bispinosus


 * Queens smaller (HW < 2.35 mm); in dorsal view, petiolar node notably longer than wide, anterior margin spatulate to angulate; in dorsal view, postpetiole longer than wide . . . . . 6

6
return to couplet #5
 * Eyes large (OI > 27.5); posterior surface of petiolar node and dorsum of postpetiole weakly coriarious, posterior surface of petiolar node sometimes with few longitudinal rugae; in profile, apex of petiolar node usually angulate with a small crest along anterior margin; propodeal spiracles circular or nearly so . . . . . brevibarbis-group (in part - also )


 * Eyes small (OI < 26.0); posterior surface of petiolar node and/or dorsum of postpetiole with transverse rugae; in profile, apex of petiolar node usually rounded to subangulate and lacking a small crest along anterior margin; propodeal spiracles narrowly ovate . . . . . 7

7
return to couplet #6
 * Anterior margin of clypeus concave; gaster blackish to black; psammophore well-developed, consisting of long hairs along basolateral margin of head. . . . . Pogonomyrmex laticeps (in part - also )


 * Anterior margin of clypeus flat to weakly convex; gaster tannish-brown, reddish-brown, or brown; psammophore poorly-developed, consisting of short to medium-length hairs scattered across ventral side of head (cunicularius-group) . . . . . 8

8
return to couplet #7
 * In profile, petiolar node rounded; inferior propodeal spines wider than high, broadly rounded; first gastral tergum smooth and polished, strongly shining . . . . . Pogonomyrmex cunicularius


 * In profile, petiolar node angulate; inferior propodeal spines about as wide as high, acuminate; first gastral tergum moderately to strongly coriarious, dull to weakly shining . . . . . 9

9
return to couplet #8
 * Sculpturing on dorsum of mesosoma and posterior surface of petiolar node weak to moderately strong, irregularly rugose to moderately rugoreticulate; body concolorous tannish-red . . . . . Pogonomyrmex pencosensis


 * Sculpturing on dorsum of mesosoma and posterior surface of petiolar node coarse, rugoreticulate to vermiculate; bicolored, mesosoma and petiolar node medium to dark orangish-brown to reddish-brown, rest of body lighter . . . . . Pogonomyrmex serpens

10
return to couplet #1
 * Queens small (HW < 1.35 mm); psammophore poorly-developed, consisting of scattered short hairs on ventral side of head . . . . . 11


 * Queens larger (HW > 1.40 mm); psammophore well-developed, consisting of numerous, long hairs along basolateral margin of head . . . . . 12

11
return to couplet #10
 * Cephalic dorsum, mesoscutum, mesoscutellum, and posterior surface of petiolar node at least partly rugoreticulate to vermiculate; hairs short, all hairs on mesosoma, posterior surface of petiolar node, dorsum of postpetiole, and gaster shorter than MOD . . . . . Pogonomyrmex naegelii (in part - also )


 * Cephalic dorsum, mesoscutum, and mesoscutellum with regular to weakly irregular longitudinal rugae, posterior surface of petiolar node granulate-punctate; hairs longer, longest hairs on mesosoma, posterior surface of petiolar node, dorsum of postpetiole, and gaster > MOD . . . . . Pogonomyrmex abdominalis

12
return to couplet #10
 * Fine, dense, incised striae (usually longitudinal) cover anterior one-third or more of first gastral tergum . . . . . rastratus-group (in part - also ) (in part - also )


 * First gastral tergum smooth and shining to moderately coriarious, weakly shining, lacking striae except occasionally at base . . . . . 13

13
return to couplet #12
 * Queen larger (HW > 2.90 mm); cephalic dorsum with scattered foveae (use >50x magnification); part to all of cephalic dorsum with longitudinal striae; antennal scapes short, extending beyond eye less than one-third the distance from posterior margin of eye to posterior corner of head (coarctatus-group) . . . . . 14


 * Queens small (HW < 2.70 mm); cephalic dorsum lacking scattered foveae; cephalic dorsum with prominent longitudinal rugae; antennal scapes longer, extending beyond eye by more than one-half the distance from posterior margin of eye to posterior corner of head . . . . . 17

14
return to couplet #13
 * Fine striae cover only part of cephalic dorsum, areas lacking striae shining to strongly shining . . . . . 15


 * Fine striae cover cephalic dorsum, entire dorsum weakly shining . . . . . 16

15
return to couplet #14
 * Queens larger (HW > 3.6 mm); cephalic dorsum mostly lacking fine striae; inferior propodeal spines poorly-developed, wider than tall, broadly rounded . . . . . Pogonomyrmex coarctatus


 * Queens smaller (HW < 3.1 mm); most of cephalic dorsum covered by moderately dense striae; inferior propodeal spines well-developed, triangular, apex bluntly angulate to acuminate . . . . . Pogonomyrmex marcusi

16
return to couplet #14
 * In profile, lateral lobe of clypeus massively enlarged with narrow gap (much less than width of antennal scape) between clypeal lobe and frontal lobe; concolorous ferruginous orange to orange-red . . . . . Pogonomyrmex lobatus


 * In profile, lateral lobe of clypeus not enlarged with broad gap (similar to width of antennal scape) between clypeal lobe and frontal lobe; bicolored, head dark red to reddish-black, gaster blackish . . . . . Pogonomyrmex micans

17
return to couplet #13
 * Brachypterous; in dorsal view, pronotum large and well-developed; mesoscutum poorly-developed, anterior margin barely surpassing humeral shoulders of pronotum; in profile, the pronotum rises at an approximately 45° angle to meet the mesoscutum . . . . . 18


 * Wings fully-developed; in dorsal view, pronotum small, poorly-developed; mesoscutum well-developed, anterior margin extending to or near pronotal collar; in profile, the pronotum rises nearly vertically to meet the mesonotum . . . . . 20

18
return to couplet #17
 * Gaster dark ferruginous orange . . . . . . Pogonomyrmex mendozanus


 * Gaster black . . . . . 18

19
return to couplet #18
 * Head and mesosoma dark reddish-black, gaster black . . . . . Pogonomyrmex laticeps (in part - also )


 * Concolorous black except for reddish area encircling eye . . . . . Pogonomyrmex tinogasta

20
return to couplet #17
 * Posterior surface of petiolar node and dorsum of postpetiole smooth and shining to moderately coriarious, weakly shining, rarely with few longitudinal or transverse rugae; head, mesosoma, and gaster concolorous dark brown to black; inferior propodeal spines well-developed, acuminate; propodeal spiracles circular or nearly so . . . . . brevibarbis-group (in part - also )


 * Posterior surface of petiolar node and usually dorsum of postpetiole with numerous transverse rugae; color variable, usually orangish or orange and black but never concolorous dark brown to black; inferior propodeal spines poorly-developed, tips usually subangulate to broadly rounded; propodeal spiracles narrowly ovate . . . . . 21

21
return to couplet #20
 * Transverse rugae cover dorsum of postpetiole; lateral margins of propodeal declivity lacking numerous fine, delicate hairs . . . . . rastratus-group (in part - also ) (in part - also )


 * Transverse rugae on dorsum of postpetiole lacking, discontinuous, or only present on lateral margins, faint to absent medially; numerous fine, delicate hairs usually present along lateral margin of propodeal declivity . . . . . 22

22
return to couplet #21
 * Superior propodeal spines present . . . . . Pogonomyrmex uruguayensis


 * Superior propodeal spines absent . . . . . Pogonomyrmex inermis