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.

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 #11)

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 #12) (in part - also #21)

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 #20)

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 #19)

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 #2)

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 #4) (in part - also #21)

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 #7)

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 #6)

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 #4) (in part - also #12)

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