Key to Neotropical and Nearctic Strumigenys

This worker key is based on: Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028 and contains modifications by [[Media:Sosa Calvo et al 2010.pdf|Sosa-Calvo, J., T.R. Schultz, and J.S. LaPolla. 2010. A review of the dacetine ants of Guyana (Formicidae: Myrmicinae). Journal of Hymenoptera Research. 19(1):12-43. PDF]]

Bolton noted in regards to this key: Strumigenys precava and Strumigenys silvestrii are keyed twice as their intercalary dentition varies from a single small denticle to absent.

This key is from a study that included the now synonymized genus Pyramica. Therefore there are a three keys for the New World Strumigenys species. The key found below, a key to the Neotropical Pyramica and a key to the Nearctic Pyramica.

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 * Strumigenys

1

 * Antenna with 4 segments; the first funicular segment followed directly by the 2-segmented club . . . . . 2


 * Antenna with 5 or usually 6 segments; the first funicular segment separated from the 2-segmented club rarely by one, usually by two, much smaller segments . . . . . 3

2
return to couplet #1
 * Ventral surface of petiole with a spongiform strip or curtain. Leading edge of scape with all hairs curved or inclined toward the apex of the scape. Dorsum of head and promesonotum with scale-like to orbicular hairs. Mandible with a spiniform preapical tooth. (Pantropical tramp species) . . . . . Strumigenys emmae


 * Ventral surface of petiole without spongiform tissue. Leading edge of scape with one to several hairs that distinctly curve toward the base of the scape. Dorsum of head and promesonotum with fine simple hairs. Mandible with 2 minute preapical denticles that are extremely small and difficult to see, under low magnifications appearing edentate. (Brazil) . . . . . Strumigenys quadrua

3
return to couplet #1
 * Leading edge of scape with all hairs curved or inclined toward the apex of the scape; without hairs that curve toward the base of the scape, without a series of hairs at right-angles to the long axis of the scape shaft . . . . . 4


 * Leading edge of scape either with one to many hairs that distinctly curve toward the base of the scape, or rarely with hairs that are at right-angles to the long axis of the scape shaft; never with all hairs obviously curved or inclined toward the apex of the scape . . . . . 37

4
return to couplet #3
 * Mandibles without intercalary teeth or denticles that arise between apicodorsal and apicoventral teeth of apical fork, nor arise from dorsal base of apicoventral tooth . . . . . 5


 * Mandible with 1 or 2 intercalary teeth or denticles that arise between apicodorsal and apicoventral teeth of apical fork, or arise from dorsal base of apicoventral tooth . . . . . 10

5
return to couplet #4
 * Ventrolateral margin of head with a strongly developed preocular notch immediately in front of the eye, anterior portion of eye detached from side of head. Mandible with 2 distinct acute preapical teeth, both in the distal third of the length; proximal preapical tooth longer than the distal. (Cosmopolitan tramp species) . . . . . Strumigenys rogeri


 * Ventrolateral margin of head straight to shallowly concave in front of the eye but without a preocular notch, anterior portion of eye not detached from side of head. Mandible with a single preapical tooth or with a distal tooth and a minute proximal denticle located near the midlength . . . . . 6

6
return to couplet #5
 * First gastral tergite dorsolaterally sharply marginate throughout its length. Propodeal declivity with a broad spongiform lamella. (Costa Rica, Panama, Venezuela, Colombia) . . . . . Strumigenys marginiventris


 * First gastral tergite without dorsolateral margination. Propodeal declivity with a narrow carina . . . . . 7

7
return to couplet #6
 * Postpetiole sculptured across entire disc. First gastral tergite with sculpture present other than basigastral costulae . . . . . 8


 * Postpetiole smooth across most or all of disc. First gastral tergite smooth except for basigastral costulae . . . . . 9

8
return to couplet #7
 * Petiole with a narrow ventral spongiform crest. Disc of postpetiole longitudinally costulate. First gastral tergite finely and densely longitudinally striolate-costulate for half or more of its length. Hairs on first gastral tergite long and flagellate, very fine. Mandible with a preapical tooth, without an additional minute denticle just proximal of midlength. (Venezuela, Colombia, Peru, Bolivia) . . . . . Strumigenys interfectiva


 * Petiole without trace of ventral spongiform tissue. Disc of postpetiole reticulate-punctate. First gastral tergite superficially reticulate-punctate posterior to basigastral costulae. Hairs on first gastral tergite short and curved, simple to weakly remiform. Mandible with a preapical tooth and additionally with a minute denticle, that may be difficult to see, just proximal of midlength. (Mexico) . . . . . Strumigenys manis

9
return to couplet #7
 * Hairs on first gastral tergite fine and flagellate. Pronotal dorsum reticulate-punctate with faint superimposed longitudinal rugulae. Metapleuron and side of propodeum punctate or reticulate-punctate, at least in part. (Costa Rica, Panama, Colombia, Ecuador) . . . . . Strumigenys longispinosa


 * Hairs on first gastral tergite stiff and bristle-like. Pronotal dorsum strongly longitudinally rugulose, not reticulate-punctate. Metapleuron and side of propodeum glassy smooth. (Colombia) . . . . . Strumigenys incuba

10
return to couplet #4
 * Mandibles without, or with only one, preapical tooth or denticle . . . . . 11


 * Mandible with 2 preapical teeth or denticles . . . . . 15

11
return to couplet #10
 * Preapical dentition consisting of single tooth on one or both mandibles; preapical tooth conspicuously dentiform and located close to apicodorsal tooth . . . . . 12


 * Preapical dentition absent from both mandibles or single minute denticle present; if the latter denticle located close to midlength, not near apicodorsal tooth . . . . . 14

12
return to couplet #11
 * First gastral tergite very densely clothed with long fine flagellate hairs. Dorsolateral margin of head with 2 freely laterally projecting long flagellate hairs, one at level of eye, other apicoscrobal . . . . . Strumigenys lanuginosa


 * First gastral tergite with stout curved hairs that are remiform or apically spatulate or simple erect standing hairs. Dorsolateral margin of head without projecting flagellate hairs or with single hair, in apicoscrobal position . . . . . 13

13
return to couplet #12
 * Scape strongly dorsoventrally flattened and very broad; in full-face view maximum width of scape greater than maximum width of mandible. First gastral tergite unsculptured. Pronotal humeral hairs stiff and stout. With head in profile highest point of vertex without erect hairs . . . . . Strumigenys platyscapa


 * Scape subcylindrical; in full-face view maximum width of scape less than maximum width of mandible. First gastral tergite with sculpture present other than basigastral costulae. Pronotal humeral hairs elongate or flagellate. With head in profile highest point of vertex with pair of erect hairs . . . . . 13b

13b
return to couplet #13
 * Ventral surface of postpetiole with large and distinct spongiform lobe. Propodeal spines long. Mandibles with asymmetrical preapical dentition (left mandible without trace of preapical dentition, right mandible with small slender preapical tooth located close to apicodorsal tooth and slightly smaller than intercalary tooth) . . . . . Strumigenys idiogenes


 * Ventral surface of postpetiole without spongiform lobe or crest. Propodeal spines short. Mandibles with symmetrical preapical dentition (both mandibles with small preapical tooth located close to apocidorsal tooth) . . . . . Strumigenys royi

14
return to couplet #11
 * Pronotal humeral hair long and fine, sub flagellate to flagellate; mesonotum with a pair of flagellate hairs. Pronotum with longitudinal rugulae superimposed on reticulate-punctate sculpture. MI 65 or more, SI 85 or more. (Mexico, Belize, Honduras, Nicaragua, Costa Rica) . . . . . Strumigenys ludia


 * Pronotal humeral hair stiff and more or less straight, simple, truncated or somewhat flattened apically; mesonotum without flagellate hairs. Pronotum reticulate-punctate only. MI 55-60, SI 72-75. (U.S.A., Mexico, Belize) . . . . . Strumigenys boneti

15
return to couplet #10
 * Inner margin of mandible in full-face view with a longitudinal raised translucent cuticular carina or flange that arises immediately behind the proximal preapical tooth and extends almost to the mandibular base . . . . . 16


 * Inner margin of mandible in full-face view without a longitudinal raised translucent cuticular carina arising behind the proximal preapical tooth . . . . . 21

16
return to couplet #15
 * Apex of mandible with one intercalary tooth or denticle between apicodorsal and apicoventral teeth. Propodeum merely angulate between dorsum and declivity or at most with a denticle; base of declivity without an acutely triangular lobe. First gastral tergite smooth and basigastral costulae vestigial or absent, when present extremely short, much shorter than length of postpetiole disc. (Brazil) . . . . . Strumigenys cultrigera


 * Apex of mandible with 2 intercalary teeth or denticles between apicodorsal and apicoventral teeth. Propodeum strongly dentate or spinose between dorsum and declivity; base of declivity with an acutely triangular lobe or short spine. First gastral tergite sculptured or smooth but basigastral costulae conspicuous, at least equal to length of postpetiole disc . . . . . 17

17
return to couplet #16
 * First gastral tergite behind apices of basigastral costulae smooth and shining . . . . . 18


 * First gastral tergite behind apices of basigastral costulae very finely and densely longitudinally striolate-costulate everywhere . . . . . 19

18
return to couplet #17
 * Petiole, postpetiole and first gastral tergite with conspicuous long fine straggly flagellate hairs present. (French Guiana, Brazil) . . . . . Strumigenys tococae


 * Petiole, postpetiole and first gastral tergite without flagellate hairs. (Costa Rica, Panama) . . . . . Strumigenys extirpa

19
return to couplet #17
 * Ventral surface of petiole with a minute longitudinal cuticular carina but without a crest or curtain of spongiform tissue. First gastral tergite with conspicuous appressed spatulate hairs that are similar in size to those on the cephalic dorsum. Smaller species, HL 0.80-0.84. (Venezuela) . . . . . Strumigenys usbensis


 * Ventral surface of petiole with a conspicuous spongiform crest or curtain. First gastral tergite with inconspicuous minute appressed pubescence, without spatulate hairs such as are present on the cephalic dorsum. Larger species, HL 0.92-1.06 . . . . . 20

20
return to couplet #19
 * Apicoscrobal hair present, simple. Propodeal tooth and acute propodeal lobe at base of declivity about equal in length or the former only very slightly longer than the latter. Lateral lobe of petiole in profile thick and dense, coarsely spongiform. (Venezuela) . . . . . Strumigenys anthocera


 * Apicoscrobal hair absent. Propodeal tooth much longer than the acute propodeal lobe at base of declivity. Lateral lobe of petiole in profile narrow and lamellate, only weakly spongiform. (Costa Rica, Panama) . . . . . Strumigenys fairchildi

21
return to couplet #15 appears as a pale elongate streak or as an oval patch . . . . . 22
 * Bulla of femoral gland located close to midlength on dorsum of each leg; each bulla


 * Bulla of femoral gland located in apical quarter of dorsum of each leg; each bulla usually appears as a pale oval patch, less commonly as a short streak . . . . . 29

22
return to couplet #21
 * Mandibles relatively short, MI < 75; preapical dentition crowded into about the apical one-fifth of the exposed mandible length. In full-face view outer margins of mandibles approximately parallel at full closure. First gastral tergite with a combination of conspicuous appressed small spatulate hairs and larger suberect short stout clavate hairs. (Costa Rica, Colombia, Brazil) . . . . . Strumigenys borgmeieri


 * Mandibles relatively long, MI > 85; preapical dentition not crowded into apical one-fifth of the exposed mandible length. In full-face view outer margins of mandibles diverge anteriorly at full closure. First gastral tergite without a combination of appressed spatulate hairs and suberect clavate hairs; usually with at least a few flagellate hairs present but rarely with minute fine appressed hairs only. . . . . . 23

23
return to couplet #22
 * In full-face view the distal preapical tooth of the mandible is closer to the proximal preapical tooth than it is to the apicodorsal tooth. (Colombia, Guiana, Brazil) . . . . . Strumigenys dolichognatha


 * In full-face view the distal preapical tooth of the mandible is closer to the apicodorsal tooth than it is to the proximal preapical tooth . . . . . 24

24
return to couplet #23
 * First gastral tergite with short pointed hairs that are closely appressed and pubescence-like; without long erect finely filiform or flagellate hairs. Disc of postpetiole and dorsum of petiole node densely clothed with recurved spatulate hairs. (Brazil) . . . . . Strumigenys rehi


 * First gastral tergite with long erect finely filiform or flagellate hairs at least in the basal quarter; without short pointed appressed hairs though some inconspicuous minute pubescence may be present. Disc of postpetiole and dorsum of petiole node without spatulate hairs . . . . . 25

25
return to couplet #24
 * First gastral tergite with long erect finely filiform or flagellate hairs not restricted to basal third, such hairs also arise posterior to this. Mesonotum with a pair of stiff erect hairs . . . . . 26


 * First gastral tergite with long erect finely filiform or flagellate hairs restricted to basal third, such hairs absent posterior to this. Mesonotum without stiff erect hairs . . . . . 27

26
return to couplet #25
 * Mandibles relatively long, MI > 120. Upper scrobe margin with 2 remiform hairs that project dorsolaterally; cephalic dorsum with 2 pairs of erect remiform hairs. Basigastral costulae short, in dorsal view no longer than thickness of posterior spongiform collar of postpetiole at its midpoint. (Colombia) . . . . . Strumigenys monstra


 * Mandibles relatively short, MI 100 or less. Upper scrobe margin with 1 remiform hair that projects dorsolaterally; cephalic dorsum with 1 pair of erect remiform hairs. Basigastral costulae long, in dorsal view much longer than thickness of posterior spongiform collar of postpetiole at its midpoint. (Brazil, Bolivia) . . . . . Strumigenys sublonga

27
return to couplet #25
 * Pronotal humeral hair stiff and freely projecting, approximately straight, simple or slightly expanded apically. Apicoscrobal hair present, stiff, projecting dorsolaterally or dorsally . . . . . 28


 * Pronotal humeral hair short and broadly spatulate, curved posteriorly and closely applied to the surface. Apicoscrobal hair absent. (Costa Rica) . . . . . Strumigenys deletrix

28
return to couplet #27
 * Mandibles enormously elongate, MI > 130. Propodeum in profile with upper lobe of declivity elongate and narrow, subspiniform, almost as long as lower lobe. Petiole node in profile with height of anterior face less than dorsal length; in dorsal view node about as long as broad. (Brazil) . . . . . Strumigenys diabola


 * Mandibles shorter, MI 120 or less. Propodeum in profile with upper lobe of declivity a mere angle or very short triangle, much shorter than lower lobe. Petiole node in profile with height of anterior face greater than dorsal length; in dorsal view node distinctly broader than long. (Trinidad, Mexico, Belize, Honduras, Nicaragua, Costa Rica, Panama, Venezuela, Colombia, Peru, Surinam, Brazil, Paraguay) . . . . . Strumigenys cordovensis

29
return to couplet #21
 * First gastral tergite blanketed with very fine dense longitudinal striolate sculpture; first gastral sternite also sculptured. (Brazil) . . . . . Strumigenys mandibularis


 * First gastral tergite glassy smooth behind basigastral costulae; first gastral sternites unsculptured . . . . . 30

30
return to couplet #29
 * Large species with short stout mandibles, HW > 0.90, MI 50 or less. Disc of postpetiole inflated and massive, much longer than broad and disproportionately large (length of disc 0.40-0.50). (Costa Rica, Panama, Venezuela, Colombia, Ecuador, Guiana) . . . . . Strumigenys godmani


 * Smaller species with longer narrower mandibles, HW < 0.85, MI > 50. Disc of postpetiole not inflated, not disproportionately large (length of disc < 0.30), disc usually broader than long, at most slightly longer than broad . . . . . 31

31
return to couplet #30
 * Preapical dentition of mandible consisting of a small distal tooth and a somewhat more proximal minute denticle, both located within the apical quarter of the mandible length. Pronotal humeral hair fine and flagellate. Mesonotum with flagellate hairs present. Basigastral costulae at least as long as disc of postpetiole. (Brazil) . . . . . Strumigenys vilhenai


 * Preapical dentition of mandible consisting of two conspicuous spiniform teeth, the proximal of which is not located within the apical quarter of the mandible length. Pronotal humeral hair stout and stiff. Mesonotum without flagellate hairs. Basigastral costulae very short or absent, much shorter than disc of postpetiole . . . . . 32

32
return to couplet #31
 * Propodeal declivity with a rounded lamella but otherwise unarmed, without a triangular lobe, tooth or spine at either top or bottom of the declivity. (Venezuela, Colombia) . . . . . Strumigenys hemidisca


 * Propodeal declivity with a triangular lobe, tooth or spine either at top or at bottom of declivity, or at both top and bottom of declivity . . . . . 33

33
return to couplet #32
 * Propodeal declivity with an angular lobe or tooth at base of declivity only; without a lobe, tooth or spine at upper limit of declivity. (Jamaica, Mexico, Guatemala, Belize, Honduras, Costa Rica, Panama, Colombia, Ecuador) . . . . . Strumigenys biolleyi


 * Propodeal declivity with an angular lobe or tooth at base of declivity, and with a lobe, tooth or spine at upper limit of declivity . . . . . 34

34
return to couplet #33
 * With petiole in profile the lateral spongiform lobe narrow, merely an extension of the posterior collar down the side of the node; lobe does not extend forward along side of node toward its anterior face. Mandibles relatively longer, MI > 85. (Brazil) . . . . . Strumigenys sanctipauli


 * With petiole in profile the lateral spongiform lobe large, obviously more than a mere extension of the posterior collar down the side of the node; lobe extends forward along side of node toward its anterior face. Mandibles relatively shorter, MI < 75 . . . . . 35

35
return to couplet #34
 * With alitrunk in profile the propodeal declivity deep, upper and lower propodeal teeth or lobes widely separated and linked by a narrow cuticular carina, the upper and lower teeth or lobes never appear merely as slightly higher triangular peaks at either end of the carina. CI 69-77, MI 59-64, SI 90-106. (Brazil, Argentina) . . . . . Strumigenys saliens


 * With alitrunk in profile the propodeal declivity shallow, upper and lower propodeal teeth or lobes closely approximated, linked by a broad lamella, the upper and lower teeth or lobes frequently appear as slightly higher triangular peaks at either end of the short wide lamella. CI 76-85, MI 53-57, SI 82-88 . . . . . 36

36
return to couplet #35
 * First gastral tergite with very few (often merely a single transverse row of 4) long fine sub flagellate to flagellate standing hairs that are restricted to the extreme base of the sclerite. Cephalic dorsum with 2-3 pairs of erect hairs. (Trinidad, Venezuela, Peru, Brazil, Bolivia) . . . . . Strumigenys planeti


 * First gastral tergite with numerous long fine subflagellate to flagellate standing hairs that arise over the entire sclerite. Cephalic dorsum with a single pair of erect hairs, located posteromedially. (Venezuela, Peru, Brazil, Bolivia, Argentina) . . . . . Strumigenys prospiciens

37
return to couplet #3
 * Mandible without intercalary teeth or denticles that arise between the apicodorsal and apicoventral teeth, nor that arise from the dorsal base of the apicoventral tooth . . . . . 38


 * Mandible with 1 or 2 intercalary teeth or denticles that arise between the apicodorsal and apicoventral teeth, or that arise from the dorsal base of the apicoventral tooth . . . . . 62

38
return to couplet #37
 * Mandible without preapical teeth or denticles of any form . . . . . 39


 * Mandible with 1 or 2 preapical teeth or denticles . . . . . 43

39
return to couplet #38
 * Hairs on first gastral tergite short, either simple stiff and erect, or stoutly remiform, or expanded and blunted apically, but never flagellate nor ribbon-like . . . . . 40


 * Hairs on first gastral tergite elongate, flagellate or ribbon-like, never simple and stiff, nor remiform, nor expanded and blunted apically . . . . . 42

40
return to couplet #39
 * Disc of postpetiole glassy smooth. Cephalic dorsum with two pairs of erect hairs, one pair close to occipital margin, the other near highest point of vertex. Basigastral costulae extremely short, vestigial. Hairs on first gastral tergite simple. (Costa Rica) . . . . . Strumigenys consanii


 * Disc of postpetiole mostly or entirely punctate or reticulate-punctate. Cephalic dorsum with one pair of erect hairs, close to occipital margin. Basigastral costulae fine but conspicuous. Hairs on first gastral tergite stoutly remiform or expanded and blunted apically . . . . . 41

41
return to couplet #40
 * With gaster in profile standing hairs on first tergite stoutly remiform. Disc of postpetiole completely covered with dense coarse reticulate-punctate sculpture. (Trinidad, Belize, Costa Rica, Venezuela) . . . . . Strumigenys spathula


 * With gaster in profile standing hairs on first tergite thick, gradually increasing in width from midlength to apex. Disc of postpetiole punctate but not completely covered with coarse reticulate-punctate sculpture. (Venezuela) . . . . . Strumigenys tachirensis

42
return to couplet #39
 * Hairs on first gastral tergite flagellate, not flattened and ribbon-like through most of their length. (Trinidad, Mexico, Guatemala, Belize, Honduras, Nicaragua, Costa Rica, Panama, Venezuela, Colombia, Ecuador, Peru, Guiana, Surinam, Brazil, Bolivia, Paraguay) . . . . . Strumigenys elongata


 * Hairs on first gastral tergite flattened and ribbon-like through most of their length, narrowly flagellate only in the apical section. (Costa Rica, Venezuela) . . . . . Strumigenys pariensis

43
return to couplet #38
 * Ventrolateral margin of head in front of eye, and side of head above it, deeply concave; margin and side appear excavated or constricted in oblique dorsal view. In full-face view mandible abruptly narrowed just before the apex by a sudden oblique divergence of the inner margin; a small preapical tooth arises on this short oblique section . . . . . 44


 * Ventrolateral margin of head in front of eye, and side of head above it, not deeply concave; margin and side do not appear excavated or constricted in oblique dorsal view. In full-face view mandible not abruptly narrowed just before the apex, the inner margin without a suddenly divergent oblique section; distal preapical dentition a spiniform tooth or a denticle that does not arise from an oblique surface . . . . . 45

44
return to couplet #43
 * Entire side of alitrunk reticulate-punctate or at most with a smooth patch on mesopleuron. Pronotal humeral hair arises from a long conical tubercle. Basigastral costulae longer than disc of postpetiole. Mandible without a denticle proximal of the preapical tooth. (Costa Rica, Panama, Venezuela, Colombia, Ecuador, Peru, Guiana, Brazil, Bolivia) . . . . . Strumigenys precava


 * Entire side of alitrunk smooth and shining. Pronotal humeral hair does not arise from a long conical tubercle. Basigastral costulae shorter than disc of postpetiole. Mandible with a denticle proximal of the preapical tooth. (Ecuador) . . . . . Strumigenys formicosa

45
return to couplet #43
 * Mandibles very long, MI > 100. Distal preapical tooth strongly elevated, arching dorsally well above plane of mandible. Scape broadest in the apical third of its length. (Venezuela, Colombia, Brazil) . . . . . Strumigenys trudifera


 * Mandibles much shorter, MI < 75. Distal preapical tooth not strongly elevated above plane of mandible. Scape broadest proximal of, or close to, its midlength . . . . . 46

46
return to couplet #45
 * With head in profile preocular carina extends back almost to apex of scrobe, well beyond level of minute eye. Petiole node in dorsal view much longer than broad. Entire side of alitrunk finely reticulate-punctate. Bulla of femoral gland proximal of midlength on dorsum of middle leg, very conspicuous. Scape relatively long, SI 111-112. (Brazil) . . . . . Strumigenys smilax


 * With head in profile preocular carina terminates at level of minute eye. Petiole node in dorsal view at most as broad as long, usually broader than long. Pleurae and side of propodeum smooth, at least in part. Bulla of femoral gland distal of midlength on dorsum of middle leg or inconspicuous. Scape shorter, SI < 100 . . . . . 47

47
return to couplet #46
 * In full-face view upper scrobe margin with a row of 4–5 broadly spatulate to spoon-shaped hairs that are curved posteriorly . . . . . Strumigenys perparva


 * In full-face view upper scrobe margin with row of simple or spatulate to spoon-shaped hairs that are all curved anteriorly . . . . . 48

48
return to couplet #47
 * Cephalic dorsum with two pairs of short erect hairs, one pair close to occipital margin, the other close to highest point of vertex. Ventral surface of petiole with curtain or fringe of spongiform tissue, or at least with spongiform lobes linked by carina. If spongiform tissue reduced to angular anteroventral process present, then dorsolateral margin of head with two freely laterally projecting short flagellate hairs, one at level of the vestigial eye, the other the apicoscrobal . . . . . 49


 * Cephalic dorsum without or with one pair of short erect hairs, when one is present it is close to occipital margin. Ventral surface of petiole without spongiform tissue, sometimes with rounded or angular anteroventral cuticular process. Dorsolateral margin of head without projecting flagellate hairs or with single hair, in apicoscrobal position . . . . . 52

49
return to couplet #48
 * Distal preapical tooth conspicuous and obviously spiniform, located markedly proximal of the apicodorsal tooth and at about right angle to long axis of the mandible. Distal preapical teeth of opposing mandibles so long that their apices meet or even slightly overlap when mandibles fully closed. Mandibles always with small denticle just proximal of the inner midlength . . . . . 50


 * Distal preapical tooth small, thorn-like and not obviously spiniform, located very close to the apicodorsal tooth and inclined toward it. Distal preapical teeth of opposing mandibles so short that their apices are widely separated when mandibles fully closed. Mandible usually without trace of denticle proximal to inner midlength but rarely vestigial denticle visible . . . . . Strumigenys timicala

50
return to couplet #49
 * Leading edge of scape at subbasal bend with projecting convex cuticular lamella; lamella originates close to scape base and terminates just distal of the bend. Distal preapical tooth about same distance from proximal preapical denticle as it is from apicodorsal tooth . . . . . Strumigenys nastata


 * Leading edge of the scape at subbasal bend without projecting convex cuticular lamella. Distal preapical tooth closer to apicodorsal tooth than it is to proximal preapical denticle . . . . . 51a

51a
return to couplet #50
 * Leading edge of antennal scape with spoon-shaped or narrowly spatulate hairs. In full-face view upper scrobe margin with row of spatulate to spoon-shaped hairs. Cephalic ground-pilosity spoon-shaped or spatulate . . . . . 51


 * Leading edge of antennal scape with simple or filiform hairs. In full-face view, upper scrobe margin with a row of simple or filiform hairs. Cephalic ground-pilosity multifurcated . . . . . Strumigenys waiwai

51
return to couplet #51a
 * With gaster in profile standing hairs on first tergite simple and stiff, erect and straight. (Costa Rica) . . . . . Strumigenys perdita


 * With gaster in profile standing hairs on first tergite strongly remiform to clavate, curved or inclined posteriorly. (Costa Rica) . . . . . Strumigenys calamita

52a
return to couplet #48
 * Mandible with minute inconspicuous denticle close to midlength . . . . . Strumigenys acarai


 * Mandible with 1 or 2 very conspicuous spiniform preapical teeth, distal one in apical third, proximal one close to midlength . . . . . 52

52
return to couplet #52a
 * Mandible with 2 very conspicuous spiniform preapical teeth, the distal in the apical third, the proximal close to the midlength. (Brazil) . . . . . Strumigenys ascita


 * Mandible with a single spiniform preapical tooth, in the distal third, or with a tooth in this position and a denticle, that may be minute and difficult to see, close to the midlength . . . . . 53

53
return to couplet #52
 * Basigastral costulae longitudinal, variable in length but always well defined and more or less regularly spaced . . . . . 54


 * Basigastral costulae transverse to strongly oblique, fine and densely crowded. (Ecuador) . . . . . Strumigenys obliqua

54
return to couplet #53
 * Hairs on first gastral tergite short and stout, broadly spatulate or remiform; elongate slender fine hairs absent or restricted to a transverse row at extreme apex of sclerite . . . . . 55


 * Hairs on first gastral tergite elongate and slender, finely filiform to flagellate, or flexuous; short stout spatulate or remiform hairs entirely absent . . . . . 56

55
return to couplet #54
 * Preapical tooth of mandible widely separated from apicodorsal tooth, the distance between them greater than the length of the preapical tooth. Apicoscrobal hair absent. Pronotal humeral hair short and spatulate, recurved. First gastral tergite with narrowly spatulate hairs. (Paraguay) . . . . . Strumigenys epelys


 * Preapical tooth of mandible very close to apicodorsal tooth, the distance between them less than the length of the preapical tooth. Apicoscrobal hair present, stoutly remiform and short. Pronotal humeral hair elongate, stiffly remiform. First gastral tergite with stout remiform hairs. (Bahamas, Cuba, Dominican Republic, Brazil, Argentina) . . . . . Strumigenys silvestrii

56
return to couplet #54
 * Ground-pilosity of cephalic dorsum, from about level of eye to close to occipital margin, short and straight, stubbly, suberect in profile. Erect short simple hairs present on pronotal dorsum. Petiole node in dorsal view almost as long as broad; in profile height- of anterior face of node less than length of dorsum of node (excluding posterior collar). Propodeal teeth absent. (Paraguay) . . . . . Strumigenys insolita


 * Ground-pilosity of cephalic dorsum, from about level of eye to close to occipital margin, spatulate to narrowly spoon-shaped, strongly curved to reclinate in profile. Erect simple hairs absent from pronotal dorsum. Petiole node in dorsal view much broader than long; in profile height of anterior face of node equal to or greater than length of dorsum of node (excluding posterior collar) . Propodeal teeth present even if very short and mostly linked to propodeal lamella . . . . . 57

57
return to couplet #56
 * Pilosity of first gastral tergite consists solely of widely spaced erect long flagellate or flattened-flagellate hairs; without closely applied short fine soft simple hairs that are curved medially or posteromedially . . . . . 58


 * Pilosity of first gastral tergite entirely or almost entirely of short soft extremely fine simple hairs that are gently curved and strongly inclined medially or posteromedially; a few longer more erect but still extremely slender hairs may be present . . . . . 61

58
return to couplet #57
 * Flagellate hairs o n first gastral tergite slender, fine and simple throughout their lengths. Similar fine hairs present on dorsa of petiole and postpetiole. Mesonotum without a pair of erect flagellate hairs . . . . . 59


 * Flagellate hairs on first gastral tergite thick or flattened and ribbon-like through most of their lengths, slender and simple only in the apical section. Similar flattened or ribbon-like hairs present on dorsa of petiole and postpetiole. Mesonotum with a pair of erect flagellate hairs . . . . . 60

59
return to couplet #58
 * Mandibles relatively long, MI 67. Apicoscrobal hair elongate, fine and simple, directed dorsally or dorsolaterally. Basigastral costulae medially exceeding one-third the length of the tergite. (Colombia) . . . . . Strumigenys dyseides


 * Mandibles relatively short, MI 55. Apicoscrobal hair absent. Basigastral costulae medially less than one-third the length of the tergite. (Brazil) . . . . . Strumigenys gytha

60
return to couplet #58
 * Disc of postpetiole densely punctate to reticulate-punctate. On dorsum of hind femur the gland bulla closer to apex than to midlength of segment. (Colombia, Brazil) . . . . . Strumigenys ruta


 * Disc of postpetiole glassy smooth. On dorsum of hind femur the gland bulla closer to midlength than to apex of segment. (Colombia, Ecuador) . . . . . Strumigenys skia

61
return to couplet #57
 * With petiole in profile the lateral spongiform lobe minute to vestigial, at most the lobe represented by a small expansion of the apex of the posterior collar so that most of cuticle of posterolateral portion of node is exposed. (Surinam, Brazil, Paraguay) . . . . . Strumigenys carinithorax


 * With petiole in profile the lateral spongiform lobe large and conspicuous, extending forward and down the side of the node so that most of cuticle of posterolateral portion of node is concealed by spongiform tissue. (Trinidad, Brazil, Peru) . . . . . Strumigenys schmalzi

62
return to couplet #37
 * Apical fork of mandible with a single intercalary tooth or denticle that arises between the apicodorsal and apicoventral teeth, or arises from dorsal surface of the apicoventral tooth . . . . . 63


 * Apical fork of mandible with two intercalary teeth or denticles that arise between the apicodorsal and apicoventral teeth; frequently represented by a distinct intercalary tooth accompanied by a less conspicuous or minute denticle . . . . . 81

63
return to couplet #62
 * With alitrunk in profile base of propodeal declivity with an acute triangular tooth or spine; top of declivity also with a tooth or spine present . . . . . 64


 * With alitrunk in profile base of propodeal declivity with a rounded lobe or thin lamella, without an acute tooth or spine; top of declivity with a tooth or spine present . . . . . 66

64
return to couplet #63
 * First gastral tergite very finely and densely longitudinally striolate-costulate and opaque. Apicoscrobal hair, pronotal humeral hair and standing hairs on mesonotum all flagellate. Entire body dull yellow to brownish-yellow, the gaster not contrasting with the head and alitrunk . . . . . 65


 * First gastral tergite glassy smooth. Apicoscrobal hair, pronotal humeral hair and standing hairs on mesonotum all stiff, simple to weakly remiform. Head and alitrunk reddish brown to brown, gaster blackish brown to black, the two contrasting. (St Vincent I., Grenada, Belize, El Salvador, Costa Rica, Panama, Venezuela, Colombia, Brazil, Bolivia) . . . . . Strumigenys smithii

65
return to couplet #64
 * Mandible with two small preapical teeth, the distal somewhat longer than the proximal. (Trinidad, Costa Rica, Panama, Brazil, Bolivia) . . . . . Strumigenys trinidadensis


 * Mandible with a single inconspicuous preapical denticle. (Ecuador) . . . . . Strumigenys vivax

66
return to couplet #63
 * With head in full-face view the upper scrobe margin with a series of projecting spoon-shaped hairs that are strongly curved posteriorly. (Brazil, Argentina) . . . . . Strumigenys ogloblini


 * With head in full-face view the upper scrobe margin without projecting spoon-shaped hairs that are curved posteriorly; hairs may be absent from margin but are usually present, spatulate and curved anteriorly, or rarely simple and erect . . . . . 67

67
return to couplet #66
 * Dorsal surfaces of head and promesonotum densely clothed with squamate to orbicular hairs, without standing hairs of any form. Mandible with 2 preapical teeth, both spiniform, set very close together and close to the apex. Hairs on leading edge of scape delta-shaped. (Mexico, Panama, Colombia) . . . . . Strumigenys deltisquama


 * Dorsal surfaces of head and promesonotum with fine, non-squamate pilosity that includes some standing hairs. Mandible either without preapical teeth, or with one preapical tooth, situated close to apex; sometimes also with a more proximally situated minute denticle. Hairs on leading edge of scape simple to narrowly spatulate, not delta-shaped . . . . . 68

68
return to couplet #67
 * Side of head in front of eye deeply concave, with a scooped-out appearance; head in full-face view appearing pinched-in and constricted in front of eyes. Preocular carina in profile terminates well in front of level of eye, not extending back above eye nor running obliquely to anterior margin of eye . . . . . 69


 * Side of head in front of eye not deeply concave, the head in full-face view not appearing constricted in front of eyes. Preocular carina in profile extending back above eye or running obliquely to anterior margin of eye . . . . . 71

69
return to couplet #68
 * First gastral tergite with very long fine erect flagellate hairs. Pronotal humeral hair very long and flagellate, arising from a long conical tubercle. Dorsal (outer) surface of hind tibia with apically curved strongly spatulate hairs that are almost reclinate. (Costa Rica, Panama, Venezuela, Colombia, Ecuador, Peru, Guiana, Brazil, Bolivia) . . . . . Strumigenys precava


 * First gastral tergite without long fine erect flagellate hairs. Pronotal humeral hair short and filiform, not arising from a long conical tubercle. Dorsal (outer) surface of hind tibia with apically inclined short stiff hairs that are straight and simple . . . . . 70

70
return to couplet #69
 * First gastral tergite smooth and glossy behind basigastral costulae. Hairs on first gastral tergite short and sparse, stiff and erect. (Brazil) . . . . . Strumigenys princeps


 * First gastral tergite finely and very densely longitudinally striolate-costulate everywhere. Hairs on first gastral tergite short and dense, soft and decumbent. (Brazil) . . . . . Strumigenys thomae

71
return to couplet #68
 * Mesopleuron, metapleuron and side of propodeum entirely reticulate-punctate, without smooth shining areas anywhere on lateral alitrunk . . . . . 72


 * Mesopleuron, metapleuron and side of propodeum not entirely reticulate-punctate, at least a smooth shining area on the katepisternum . . . . . 73

72
return to couplet #71
 * First gastral tergite smooth and shining behind basigastral costulae. Disc of postpetiole finely longitudinally costulate. Propodeal declivity with a weak carina, lacking a distinct lamella. Mesonotum with a pair of erect flagellate hairs. MI 63, SI 85. (Mexico) . . . . . Strumigenys eversa


 * First gastral tergite reticulate-punctate to reticulate-shagreenate behind basigastral costulae. Disc of postpetiole reticulate-punctate. Propodeal declivity with a conspicuous lamella. Mesonotum without erect hairs. MI 45, SI 68. (Mexico) . . . . . Strumigenys xochipili

73
return to couplet #71
 * With propodeum in profile the lamella on the declivity broad, its posterior (free) margin straight to convex, not paralleling the concave curve of the declivity . . . . . 74


 * With propodeum in profile the lamella on the declivity narrow, or reduced to a carina, or absent; when present its posterior (free) margin concave and paralleling the concave curve of the declivity . . . . . 77

74
return to couplet #73
 * Cephalic dorsum with 2 pairs of erect fine long flagellate hairs; anterior pair arises close to highest point of vertex, posterior pair arises close to occipital margin. (panama) . . . . . Strumigenys lacacoca


 * Cephalic dorsum with 2 pairs of erect stout stiff hairs that are simple, narrowly spatulate or weakly remiform; anterior pair arises close to highest point of vertex, posterior pair arises close to occipital margin . . . . . 75

75
return to couplet #74
 * Promesonotum in dorsal view predominantly to entirely reticulate-punctate; if any costulate sculpture is present it is feeble and distinctly secondary to the reticulate-punctate component. (Costa Rica) . . . . . Strumigenys micretes


 * Promesonotum in dorsal view predominantly to entirely longitudinally costulate or largely smooth; if any reticulate-punctate sculpture is present it is feeble and distinctly secondary to the costulate component . . . . . 76

76
return to couplet #75
 * Preapical tooth of mandible distinct, its length equal to at least half the distance separating it from the apicodorsal tooth. Disc of postpetiole smooth. Head relatively broad and scapes shorter, CI 79-83, SI 81-89. (Mexico, Honduras) . . . . . Strumigenys emeryi


 * Preapical tooth of mandible absent or reduced to a minute denticle whose length is very much less than half the distance separating it from the apicodorsal tooth. Disc of postpetiole longitudinally costulate. Head relatively narrow and scapes longer, CI 71-74, SI 94-102. (Costa Rica, Panama, Venezuela) . . . . . Strumigenys humata

77
return to couplet #73
 * Disc of postpetiole finely densely and evenly reticulate-punctate. Mandible without trace of a preapical tooth close to apicodorsal tooth . . . . . 78


 * Disc of postpetiole mostly or entirely smooth, at most with a few weak costulae dorsolaterally. Mandible with a small but conspicuous preapical tooth close to apicodorsal tooth . . . . . 79

78
return to couplet #77
 * Ventral surface of petiole without spongiform tissue or at most with a minute lobe at extreme posteroventral angle. Metapleuron entirely reticulate-punctate. Pronotal dorsum with weak rugulae present. Head broader and scape shorter, CI 76-82, SI 80-88. (Costa Rica) . . . . . Strumigenys sevesta


 * Ventral surface of petiole with a thin spongiform strip from level of spiracle to posteroventral angle. Metapleuron with an extensive smooth area. Pronotal dorsum entirely reticulate-punctate, without rugular sculpture. Head narrower and scape longer, CI 71, SI 100. (Ecuador) . . . . . Strumigenys moera

79
return to couplet #1
 * Ventral surface of petiole with spongiform tissue present at least beneath the node and frequently extending the length of the segment. Cephalic dorsum with a pair of erect hairs near highest point of vertex and another pair near occipital margin. Eye of moderate size, with 15 or more ommatidia in total. Larger species, HW 0.44-0.52 . . . . . 80


 * Ventral surface of petiole without trace of spongiform tissue. Cephalic dorsum without a pair of erect hairs near highest point of vertex, with a pair near occipital margin. Eye minute, usually with 4 ommatidia in total. Small species, HW 0.33-0.37. (Bahamas, Cuba, Dominican Republic, Brazil, Argentina) . . . . . Strumigenys silvestrii

80
return to couplet #79
 * Mesonotal pair of standing hairs long and flagellate. Apicoscrobal hair flagellate. Petiole node in dorsal view broader than long. Head somewhat broader and scape shorter, CI 75-80, SI 79-86. (U.S.A., Costa Rica) . . . . . Strumigenys nevermanni


 * Mesonotal pair of standing hairs simple and stiff. Apicoscrobal hair stiff and simple. Petiole node in dorsal view slightly longer than broad. Head somewhat narrower and scape longer, CI 71, SI 92. (Costa Rica) . . . . . Strumigenys diaptyxis

81
return to couplet #62
 * Ventral surface of petiole with a fringe or curtain of spongiform tissue that extends the length of the segment. Hairs on first gastral tergite long and very fine, filiform to flagellate. Cephalic ground-pilosity and hairs on leading edge of scape fine and simple . . . . . 82


 * Ventral surface of petiole entirely lacking spongiform tissue or at most with a tiny lobe posteriorly. Hairs on first gastral tergite stout, remiform to weakly clavate. Cephalic ground-pilosity and hairs on leading edge of scape curved-spatulate . . . . . 83

82
return to couplet #81
 * With head in full-face view upper scrobe margin from frontal lobe to apex expanded laterally as a broad cuticular flange that is as broad as the maximum width of the scape. Larger species HL 0.63-0.70, HW 0.52-0.62. (Brazil, Argentina) . . . . . Strumigenys hindenburgi


 * With head in full-face view upper scrobe margin from frontal lobe to apex with a fine narrow cuticular rim that at its broadest is only a fraction of the maximum width of the scape. Smaller species HL 0.52-0.58, HW 0.42-0.48. (Mexico, Costa Rica, Venezuela, Peru, Brazil) . . . . . Strumigenys cosmostela

83
return to couplet #81
 * Pronotal humeral hair long, fine and flagellate . . . . . 84


 * Pronotal humeral hair short and stiff, simple to weakly remiform . . . . . 85

84
return to couplet #83
 * Mesonotum with a pair of standing hairs that are either simple filiform, remiform, or flattened apically. Apicoscrobal hair stiff, remiform or flattened apically. Mandible without a minute denticle proximal of the preapical tooth. With head in profile postbuccal groove deeply incised. (U.S.A., Bahamas, Cuba, Haiti, Puerto Rico, Mexico, Guatemala, Nicaragua, Costa Rica, Venezuela, Colombia, Ecuador, Surinam, Brazil, Bolivia, Paraguay, Argentina) . . . . . Strumigenys louisianae


 * Mesonotum with a pair of standing hairs that are long, fine and flagellate. Apicoscrobal hair flagellate. Mandible with a minute denticle proximal of the preapical tooth. With head in profile postbuccal groove obtuse and shallow. (Guatemala) . . . . . Strumigenys mixta

85
return to couplet #83
 * Cephalic dorsum with two pairs of erect hairs, one pair located close to occipital margin, the other just in front of highest point of vertex. With head in profile postbuccal groove obtuse and shallow. (Costa Rica) . . . . . Strumigenys dubitata


 * Cephalic dorsum with a single pair of erect hairs, located close to occipital margin. With head in profile postbuccal groove deeply incised. (Venezuela, Brazil, Bolivia, Argentina) . . . . . Strumigenys infidelis