Key to Neotropical Strumigenys (as Pyramica)

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]]


 * [[Media:Longino 2006b.pdf|Longino, J.T. 2006b. New species and nomenclatural changes for the Costa Rican ant fauna. Myrmecologische Nachrichten. 8:131-143. PDF]]

Bolton noted: The position in the key of Strumigenys xenognatha, known only from the queen, is conjectural. The two Dominican Amber fossil species, Strumigenys electrina and Strumigenys schleeorum, are omitted from the key.

Rigato and Scupola ([[Media:Rigato & Scupola 2008.pdf| Rigato, F. & Scupola, A. 2008. Two new species of the Pyramica gundlachi-group from Ecuador. Biodiversity of South America I. Memoirs on Biodiversity. 1:477-481. PDF]]) also modified this key (beginning at couplet 7) to add the species Strumigenys heterodonta and Strumigenys osellai. Their modifications overlap with those of Sosa Calvo et al. (2010) so the sections they changed are listed on a separate page that is found here: Neotropical Pyramica key modifications.

This key is from a study that included the now synonymized genus Pyramica. Therefore there are two sets of keys for the Strumigenys species from the Neotropical region: the key found below for the group of species once classified as Pyramica and a key Key to Neotropical and Nearctic Strumigenys.

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 * Strumigenys

1

 * Antenna with 4 segments; first funicular segment not separated from the 2-segmented apical club . . . . . 2


 * Antenna with 6 segments; first funicular segment separated from the 2-segmented apical club by two small segments . . . . . 3

2
return to couplet #1
 * Anterior clypeal margin convex in full-face view; lateral margins of clypeus without projecting hairs of any form. Outer margins of fully closed mandibles intersect anterior clypeal margin at the clypeal anterolateral angles. Pronotum marginate dorsolaterally. (Brazil) . . . . . Strumigenys minuscula


 * Anterior clypeal margin broadly concave in full-face view; lateral margins of clypeus with short freely laterally projecting hairs. Outer margins of fully closed mandibles intersect anterior clypeal margin mesad of the clypeal anterolateral angles. Pronotal dorsum rounding broadly into the sides. (Cuba) . . . . . Strumigenys simulans

3
return to couplet #1
 * Mandibles in full-face view sublinear to linear, elongate and narrow; at full closure engaging only in the apical halves or less of their lengths; either with an elongate space between the mandibles or their inner margins convex so that the margins touch, or nearly touch, near the midlength . . . . . 4


 * Mandibles in full-face view either short and stoutly trap-like, or triangular to elongate-triangular; at full closure engaging through most or all of their exposed length, without a space between the mandibles or at most with a diastema basally between basal lamella and first (basal) tooth . . . . . 31

4
return to couplet #3
 * Ventral surface of petiole with a strip or curtain of spongiform tissue. Leading edge of scape without freely projecting broadly spatulate or spoon-shaped hairs, without hairs that are curved toward the base of the scape . . . . . 5


 * Ventral surface of petiole without spongiform tissue. Leading edge of scape with freely projecting spatulate to spoon-shaped hairs, usually at least one curved toward the base of the scape but sometimes all directed anteriorly or curved toward apex of scape . . . . . 7

5
return to couplet #4
 * Antennal scrobe absent. A single preapical denticle present on inner margin of mandible, close to apicodorsal tooth. Dorsolateral margin of head and pronotal humeri without specialised elongate or flagellate hairs. Dorsal surfaces of head, alitrunk and first gastral tergite without standing pilosity of any form. Bulla of metapleural gland almost reaching annulus of propodeal spiracle. (Costa Rica) . . . . . Strumigenys warditeras


 * Antennal scrobe present. More than one preapical teeth or denticles present on inner margin of mandible. Dorsolateral margin of head and pro notal humeri with specialised elongate or flagellate hairs. Dorsal surfaces of head, alitrunk and first gastral tergite with standing pilosity present. Bulla of metapleural gland very small, widely separated from annulus of propodeal spiracle . . . . . 6

6
return to couplet #5
 * Cuticle on side of head within the antennal scrobe smooth and shining. Lateral margin of preocular carina not visible in full-face view. Basalmost preapical tooth on mandible arising proximal of the midlength of the blade. Labrum apically broadly bilobate, the lobes expanding distally. Dorsal surfaces of head and alitrunk smooth and shining. (Bahamas, Cuba) . . . . . Strumigenys nitens


 * Cuticle on side of head within the antennal scrobe reticulate-punctate. Lateral margin of preocular carina visible in full-face view. Basalmost preapical tooth on mandible arising distal of the midlength of the blade. Labrum apically narrowly biconical, the lobes tapering distally. Dorsal surfaces of head and alitrunk reticulate-punctate. (Venezuela, Brazil, Paraguay) . . . . . Strumigenys tanymastax

7
return to couplet #4
 * Dorsum of postpetiole (5 disc) smooth and with weak costulae . . . . . 7b


 * Disc of postpetiole densely reticulate-punctate over most or all of its surface . . . . . 12

Rigato and Scupola (2008) modified this key, beginning at this couplet, to include Strumigenys heterodonta and Strumigenys osellai. Their modifications are found here: Neotropical Pyramica key modifications.

7b
return to couplet #7
 * Cephalic dorsum with 1 or 2 pairs of standing hairs. Apicoscrobal and pronotal humeral hairs present . . . . . 8


 * Cephalic dorsum lacking standing hairs. Apicoscrobal and pronotal humeral hairs absent . . . . . Strumigenys dahlanae

8
return to couplet #7
 * Cephalic dorsum with 2 pairs of filiform standing hairs, one pair near highest point of vertex, the other near the occipital margin. Apicoscrobal and pronotal humeral hairs narrow, filiform. Apical fork of mandible with 2 intercalary denticles that arise from the ventral surface of the apicodorsal tooth, near its base . . . . . 9


 * Cephalic dorsum with a single pair of stoutly remiform standing hairs, located close to the occipital margin. Apicoscrobal and pronotal humeral hairs thick, remiform. Apical fork of mandible with 2 intercalary denticles that arise from the vertical surface between the apicodorsal and apicoventral teeth. (Venezuela, Colombia) . . . . . Strumigenys nubila

9
return to couplet #8
 * Mandible with 2 preapical teeth or denticles. (Colombia) . . . . . Strumigenys xenognatha


 * Mandible with 3 preapical teeth or denticles, sometimes also with an additional tiny preapical denticle located very close to the apex . . . . . 10

10
return to couplet #9
 * Proximal (basal most) of the three preapical mandibular teeth or denticles distinctly longer and broader-based than the median tooth or denticle. (Colombia) . . . . . Strumigenys gemella


 * Median of the three preapical mandibular teeth or denticles distinctly longer and broader-based than the proximal (basal most) tooth or denticle . . . . . 11

11
return to couplet #10
 * Mandibles relatively long, MI 66-70. Inner margin of mandible shallowly concave in full-face view; basal most preapical denticle close to midlength of exposed mandible. Anterodorsal collar of postpetiole present, narrow and lamellate. Basigastral costulae present but short. (Colombia, Ecuador) . . . . . Strumigenys vartana


 * Mandibles relatively short, MI 55-57. Inner margin of mandible shallowly convex in full-face view; basalmost preapical denticle at apical third of exposed mandible. Anterodorsal collar of postpetiole absent. Basigastral costulae absent. (Colombia) . . . . . Strumigenys laevipleura

12
return to couplet #7
 * Inner margin of mandible with a clearly defined submedian tooth or distinctly enlarged denticle at or just distal of the midlength, this tooth or denticle obviously larger than any other preapical dentition that may be present distal to it. Labral lobes long to very long, trigger hairs at apices of lobes short; in ventral view (usually also visible in profile) the trigger hairs at most subequal in length to the lobes, usually obviously shorter . . . . . 13


 * Inner margin of mandible without a tooth or distinctly enlarged denticle at or near the midlength that is obviously larger than any other preapical dentition that may be present distal to it. Labral lobes short or very short, trigger hairs at apices of lobes long; in ventral view (usually also visible in profile) the trigger hairs longer than the lobes . . . . . 22

13
return to couplet #12
 * Pronotal humeral hair long and flagellate. Mesonotum with a single pair of long flagellate hairs. (Panama, Peru, Brazil) . . . . . Strumigenys metopia


 * Pronotal humeral hair sometimes absent, usually present, short-spatulate to filiform, never flagellate. Mesonotum without flagellate hairs . . . . . 14

14
return to couplet #13
 * With head in full-face view the dorsum posteriorly with a thick blunt convexly-arched carina that traverses the highest part of the vertex and curves forward on each side. In profile the carina the highest point of a strongly raised triangular peak, the cephalic dorsum sloping away steeply in front of and behind it. (Costa Rica) . . . . . Strumigenys aethegenys


 * With head in full-face view the dorsum posteriorly without a convexly-arched carina traversing the highest part of the vertex. In profile the outline of the posterior quarter of the cephalic dorsum is not strongly raised into a high triangular . . . . . 15

15
return to couplet #14
 * Scape narrow basally; distal of this the leading edge abruptly expanded and almost lobate at the subbasal angle, the scape distinctly widest at this point. Dorsolateral margin of head without an apicoscrobal hair. Postpetiole swollen in profile, subglobular. (Trinidad, Venezuela, Guiana, Brazil, Paraguay, Argentina) . . . . . Strumigenys crassicornis


 * Scape gradually broadening from base, the leading edge convex but not abruptly expanded at the subbasal angle, the scape widest close to the midlength. Dorsolateral margin of head with an apicoscrobal hair of some form. Postpetiole not swollen nor subglobular in profile . . . . . 16

16
return to couplet #15
 * Mandibles relatively very long, MI 61-67. Masticatory margin of mandible usually with more denticles proximal of the submedian tooth than distal to it. Petiole node in dorsal view as long as broad or nearly so. (Costa Rica, Panama) . . . . . Strumigenys myllorhapha


 * Mandibles relatively much shorter, MI 33-45. Masticatory margin of mandible usually with fewer denticles proximal of the submedian tooth than distal to it, rarely equal. Petiole node in dorsal view distinctly broader than long . . . . . 17

17
return to couplet #16
 * Eye large, its maximum diameter distinctly greater than the maximum width of the scape. Eye in profile with 24 or more ommatidia in total, with 6-7 in the longest row. Larger species with relatively long scapes, HL 0.70-0.72, AL 0.76-0.78, SI 66-67. (Costa Rica) . . . . . Strumigenys pasisops


 * Eye small, its maximum diameter usually distinctly less than the maximum width of the scape; rarely the two subequal. Eye in profile with 14 or fewer ommatidia in total, with 2-4 in the longest row. Smaller species with relatively short scapes, HL 0.41-0.63, AL 0.43-0.64, SI 48-60 . . . . . 18

18
return to couplet #17
 * Inner margin of mandible with only a single enlarged preapical tooth, located close to the midlength; all teeth proximal to this minutely denticulate, without a second equally sized tooth in the basal third of the mandible length . . . . . 19


 * Inner margin of mandible with two enlarged preapical teeth of approximately equal size; the distal located at about the apical third and the proximal in the basal third of the mandible length. (French Guiana) . . . . . Strumigenys auctidens

19
return to couplet #18
 * Head in full-face view relatively broad, CI 74-81; in profile head not strongly dorsoventrally flattened, the maximum depth of the head capsule 0.45-0.52 X HL . . . . . 20


 * Head in full-face view relatively narrow, CI 66-71; in profile head strongly dorsoventrally flattened, the maximum depth of the head capsule 0.35-0.41 X HL . . . . . 21

20
return to couplet #19
 * Erect hairs on first gastral tergite remiform or markedly flattened and expanded apically. Backcurved pair of stout hairs located posteriorly on petiole dorsum thickly remiform. Scape relatively longer, SI 53-60. (Mexico, Belize, Honduras, Nicaragua, Costa Rica, Panama) . . . . . Strumigenys brevicornis


 * Erect hairs on first gastral tergite simple, acute or blunt apically but not remiform nor flattened and expanded apically. Backcurved pair of stout hairs located posteriorly on petiole dorsum slender, scarcely thicker apically than basally. Scape relatively shorter, SI 48-52. (Costa Rica, Panama) . . . . . Strumigenys crementa

21
return to couplet #19
 * Larger species, HL 0.61-0.63, HW 0.41-0.43, AL 0.58-0.60. Outer margin of mandible in full-face view approximately straight to shallowly convex from median tooth to apex. (Brazil) . . . . . Strumigenys stenotes


 * Smaller species, HL 0.50-0.57, HW 0.34-0.39, AL 0.47-0.56. Outer margin of mandible in full-face view conspicuously concave from a point proximal of the median tooth to close to the apex. (Costa Rica, Panama, Colombia, Peru, Brazil) . . . . . Strumigenys zeteki

22
return to couplet #12
 * In full-face view apicoscrobal hair either elongate and fine, or flagellate or looped apically. Pronotal humeral hair long and slender, either filiform, flagellate, or looped. Curved hairs on leading edge of scape slender, narrowly spatulate . . . . . 23


 * In full-face view apicoscrobal hair short and stout, broadly remiform to clavate, or absent. Pronotal humeral hair stout, remiform, spatulate or clavate. Curved hairs on leading edge of scape coarse, very broadly spatulate to spoon-shaped . . . . . 27

23

 * In lateral view, postpetiole lacking ventral spongiform lobe; sometimes a minute vestige visible; mesonotum with a pair of erect hairs . . . . . 23b


 * In lateral view, postpetiole with reduced ventral spongiform lobe but distinct; if lobe very shallow then mesonotum with pair of straggly (i.e., laid out in an irregular, untidy way) flagellate hairs . . . . . 25

23b
return to couplet #23
 * Mandibles long, MI 72–85. Dorsum of pronotum lacking pair of stiff erect hairs . . . . . 23c


 * Mandibles short, MI 58–65. Dorsum of pronotum with pair of stiff erect hairs . . . . . Strumigenys eggersi

23c
return to couplet #23b
 * Inner margin of mandibles with 5–10 preapical denticles of similar size. Metapleuron densely reticulate. Peduncle of petiole short, PI 38–42 . . . . . Strumigenys denticulata


 * Inner margin of mandibles with 3–4 preapical denticles, two distinctly larger than rest. Metapleuron smooth and shining. Peduncle of petiole elongate, PI 48–49 . . . . . Strumigenys mariae

24
no couplet 24, as modified by Sosa Calvo et al 2010.

25
return to couplet #23
 * Ventral spongiform lobe of postpetiole large in profile, almost equal in height to exposed cuticle of side of postpetiole disc. Preapical teeth on inner margin of mandible relatively stout, large and conspicuous. (Jamaica) . . . . . Strumigenys jamaicensis


 * Ventral spongiform lobe of postpetiole small in profile, not approaching height of exposed cuticle of side of postpetiole disc; usually only about half as high or even less. Preapical teeth on inner margin of mandible small and relatively inconspicuous . . . . . 26

26
return to couplet #25
 * Mandibles and scapes relatively short, MI 59-67, SI 57-75; head slightly shorter and broader, CI 77-85. In full-face view outer margins of closed mandibles straight or feebly concave in the median section of their length. Yellow to yellowish brown species. (U.S.A., Bahamas, Cuba, Jamaica, Dominican Republic, Puerto Rico, St Vincent I., Tobago, Trinidad, Mexico, Belize, Nicaragua, Costa Rica, Panama, Venezuela, Colombia, Ecuador, Peru) . . . . . Strumigenys gundlachi


 * Mandibles and scapes relatively long, MI 70-78, SI 84-100; head slightly longer and narrower, CI 72-78. In full-face view outer margins of closed mandibles evenly shallowly convex throughout their length. Black species. (Colombia) . . . . . Strumigenys enopla . . . Strumigenys lojanensis

27
return to couplet #22
 * In profile dorsal surface of alitrunk without standing hairs of any form; all pilosity curved short-spatulate, decumbent to appressed . . . . . 28


 * In profile dorsal surface of alitrunk with at least one pair of mesonotal standing hairs . . . . . 29

28
return to couplet #27
 * Mandibles relatively short, MI < 50, their inner margins strongly convex; preapical denticle closest to apex the longest. Apicoscrobal hair present, short and stout. Median third of leading edge of scape expanded into a broad lobe. (Ecuador, Brazil) . . . . . Strumigenys decipula


 * Mandibles relatively long, MI > 60, their inner margins feebly sinuate, not strongly convex; preapical denticle third or fourth from the apex the longest. Apicoscrobal hair absent. Leading edge of scape convex but median third not expanded into a broad lobe. (Costa Rica, Panama, Ecuador) . . . . . Strumigenys lalassa

29
return to couplet #27

The following (29a-e, with couplet 30 now skipped) is the revised key of Longino (2006) that adds numerous species described after 2000:

29a

 * Ground pilosity of head nearly or quite obsolete; color usually dark brown; mandible with exactly 3 small preapical teeth; erect setae on gastral dorsum filiform . . . . . Strumigenys trieces


 * Ground pilosity abundant and conspicuous on head; color usually light brown to orange; mandible dentition various; erect setae on gastral dorsum remiform, swollen at the tip . . . . . 29b

29b
return to couplet 29a
 * Mandible with only tiny preapical denticles or one relatively larger preapical tooth followed by tiny denticles (Fig. 21); metanotal groove not impressed; size relatively small, HL less than 0.6 mm . . . . . 29c


 * Mandible with two or more relatively large preapical teeth (Figs. 19, 20); metanotal groove impressed or not; size relatively large, HL 0.6 mm or greater . . . . . 29d

29c
return to couplet #29b
 * Promesonotum with a single pair of standing setae (in addition to those at humeri), on mesonotum; setae projecting from leading border of scape relatively thin and strongly curved (Fig. 18); first gastral tergite relatively less sculptured, with variable extent of longitudinal striolation on basal fourth or less; first gastral sternites largely smooth and shining; katepisternum smooth and shining . . . . . Strumigenys oconitrilloae


 * Promesonotum with 4 - 6 pairs of stout remiform standing setae (in addition to those at humeri); setae projecting from leading border of scape broadly fan-shaped, less strongly curved (Fig. 15); first gastral tergite relatively more sculptured, basal fourth or more striatopunctate; first gastral sternite finely reticulate to reticulate-punctate at least basally; katepisternum punctate . . . . . Strumigenys subedentata

29d
return to couplet #29b
 * Katepisternum punctate; metanotal groove not impressed (Colombia) . . . . . Strumigenys connectens


 * Katepisternum smooth and shining; metanotal groove broadly and shallowly impressed, such that promesonotum and dorsal face of propodeum form two separate convexities . . . . . 29e

29e
return to couplet #29d
 * Mandible with exactly 2 small preapical teeth and no denticles (Fig. 19); katepisternum and part of side of propodeum smooth and shining; MeL about 0.7 mm . . . . . Strumigenys paniaguae


 * Mandible with 3 or more preapical teeth (Fig. 20); only a portion of katepisternum smooth and shining, side of propodeum punctate; MeL about 0.6 mm . . . . . Strumigenys cascanteae

30
Couplet 30 is replaced by the revised key of Longino (2006), 29a-e above.

31
return to couplet #3
 * With the head in full-face view the leading edge of the scape with a row of conspicuous projecting curved hairs, of which one or more, distal to the subbasal bend, distinctly curves toward the base of the scape. These hairs may be simple, spatulate, remiform, spoon-shaped or wire-like . . . . . 32


 * With the head in full-face view the leading edge of the scape lacking projecting hairs that distinctly curve toward the base of the scape. Scape edge may have elongate simple straight or flagellate projecting hairs present; or may have entirely anteriorly or apically directed short hairs (hairs simple, narrowly to broadly spatulate, or spoon-shaped); or the edge may be hairless . . . . . 56

32
return to couplet #31
 * Pronotal humeral hair present, may be filiform, flagellate, remiform or clavate; humeral hair always distinctly differentiated from any other pilosity that may be present on the dorsal pronotum . . . . . 33


 * Pronotal humeral hair absent; humerus without a hair that is distinctly differentiated from any other pilosity that may be present on the dorsal pronotum . . . . . 50

33
return to couplet #32
 * Midpoint of anterior clypeal margin not produced into a sharp triangular tooth that projects forward over the mandibles. In full-face view preocular carina visible posterior to level of antennal insertions. Lateral margins of clypeus with a series of anteriorly curved spatulate hairs. Standing hairs absent or present on clypeal dorsum, if present then not all are gently curved posteriorly . . . . . 34


 * Midpoint of anterior clypeal margin produced into a sharp triangular tooth that projects forward over the mandibles. In full-face view preocular carina not visible posterior to level of antennal insertions. Lateral margins of clypeus without anteriorly curved spatulate hairs. Dorsum of clypeus densely clothed with stiff hairs that are all gently curved posteriorly. (Brazil) . . . . . Strumigenys reticeps

34
return to couplet #33
 * Ventral surface of petiole in profile with spongiform tissue reduced to absent; discounting anterior subpetiolar process (if present) usually with a narrow nonspongiform cuticular carina, but if a weakly spongiform strip occurs then its maximum depth is only a fraction of the depth of the peduncle. Disc of postpetiole usually sculptured at least in part, only rarely mostly smooth . . . . . 35


 * Ventral surface of petiole in profile with a deep, conspicuous and very obviously spongiform curtain, its maximum depth at least half that of the peduncle and usually more. Disc of postpetiole completely unsculptured and glassy smooth . . . . . 42

35
return to couplet #34
 * Metapleuron and side of propodeum mostly or entirely smooth and shining . . . . . 36


 * Metapleuron and side of propodeum entirely reticulate-punctate . . . . . 37

36
return to couplet #35
 * Pronotal humeral hair fine, long and flagellate. Dorsolateral margin of head with numerous fine flagellate hairs that freely project laterally. Hairs that curve toward base on leading edge of scape narrow and wire-like, each shaped roughly like a question-mark or a hook. Clypeal dorsum with elevated curved pilosity that is stouter than the pilosity on the dorsum behind the clypeus. (Brazil) . . . . . Strumigenys cincinnata


 * Pronotal humeral hair stout, short and stiffly remiform. Dorsolateral margin of head with curved spatulate to spoon-shaped hairs that project laterally. Hairs that curve toward base on leading edge of scape spatulate and evenly curved. Clypeal dorsum with appressed small spatulate hairs that are not stouter than the pilosity on the dorsum behind the clypeus. (Colombia, Brazil) . . . . . Strumigenys grytava

37
return to couplet #35
 * Mandible with 3 stout teeth distal of the basal lamella, the second of which may be blunt; fourth tooth represented by a broadly rounded low lamella or plate; fifth tooth acute. Scape in dorsal view slender, the broadest point distinctly distal of the midlength. Anterior margin of clypeus very shallowly convex in full-face view. Disc of postpetiole not entirely densely reticulate-punctate . . . . . 38


 * Mandible with 5 acute triangular teeth distal of the basal lamella; teeth 4 and 5 may be about the same length as 1-3 or slightly shorter. Scape in dorsal view broad and flattened, the broadest point proximal of the midlength, at or just distal of the subbasal bend. Anterior margin of clypeus transverse to very shallowly concave in full-face view. Disc of postpetiole entirely densely reticulate-punctate . . . . . 39

38
return to couplet #37
 * Cephalic dorsum behind highest point of vertex with a transverse row of 4 erect stout hairs that are conspicuously different from the ground-pilosity. Pronotal humeral hair elongate and freely projecting, slightly flattened apically and more or less straight. Eye with 3-4 ommatidia in the longest row. (Trinidad, Colombia, Ecuador, Brazil) . . . . . Strumigenys urrhobia


 * Cephalic dorsum behind highest point of vertex without a transverse row of erect stout hairs that are conspicuously different from the ground-pilosity. Pronotal humeral hair broadly spatulate to spoon-shaped and strongly curved. Eye with 5 ommatidia in the longest row. (Brazil, Paraguay) . . . . . Strumigenys emiliae

39
return to couplet #37
 * Cephalic dorsum just in front of occipital margin with a transverse row of 6 small hairs that are only marginally longer and more erect than the ground-pilosity, difficult to see. Pronotal humeral hair very short, clavate. Erect hairs on mesonotum indistinct, scarcely distinguishable from the dense ground-pilosity; on first gastral tergite hairs very short, clavate apically. (Paraguay) . . . . . Strumigenys metrix


 * Cephalic dorsum j ust in front of occipital margin with a conspicuous transverse row of 4-6 erect hairs that are obviously much longer and more erect than the ground pilosity. Pronotal humeral hair elongate, flattened or truncated apically. Erect hairs on mesonotum conspicuously differentiated from the very sparse ground-pilosity, distinct; on first gastral tergite hairs stout and simple, truncated apically . . . . . 40

40
return to couplet #39
 * Basal half or more of first gastral tergite sculptured. Basigastral costulae fine and very numerous, regular and extremely densely packed, appearing as dense uniform costulation. Mesonotum with a single pair of erect hairs. Larger species, HL 0.60-0.64, AL 0.60-0.68. (Venezuela, Colombia) . . . . . Strumigenys orchibia


 * Much less than basal half of first gastral tergite sculptured. Basigastral costulae coarse and sharply defined, distinctly separated and not appearing as dense uniform costulation, the spaces between them smooth or weakly sculptured. Mesonotum with 2-3 pairs of erect hairs. Smaller species, HL 0.50-0.55, AL 0.50-0.56 . . . . . 41

41
return to couplet #40 Venezuela, Peru, Brazil) . . . . . Strumigenys schulzi
 * Petiole node in dorsal view broader than long. (Trinidad, Mexico, Costa Rica, Panama,


 * Petiole node in dorsal view longer than broad. (Venezuela, Colombia) . . . . . Strumigenys castanea

42
return to couplet #34
 * Dorsal (outer) surfaces of hind tibiae and basitarsi with narrowly spatulate curved hairs and in addition each also with 1-3 freely projecting extremely long fine flagellate hairs. Cephalic dorsum behind highest point of vertex with 1-2 pairs of erect long flagellate hairs. Base of first gastral sternite without a pad of dense spongiform tissue though some short clumped pilosity may occur . . . . . 43


 * Dorsal (outer) surfaces of hind tibiae and basi tarsi with curved narrowly spatulate hairs only, without freely projecting long fine flagellate hairs. Cephalic dorsum behind highest point of vertex with 1-2 pairs of erect stout simple or remiform hairs. Base of first gastral sternite with a pad of dense spongiform tissue . . . . . 44

43
return to couplet #42
 * Mandible without a diastema between basal lamella and basal tooth; no gap between basal tooth of mandible and anterior clypeal margin in full-face view with mandibles fully closed. Basal lamella followed directly by 5 larger teeth then 2 smaller teeth. Dorsolateral margins of head with 4 freely laterally projecting flagellate hairs on each side. Scape longer, SI 93. (Mexico) . . . . . Strumigenys tlaloc


 * Mandible with a distinct diastema between basal lamella and basal tooth, diastema longer than height of the basal tooth; a marked gap present between basal tooth of mandible and anterior clypeal margin in full-face view with mandibles fully closed. Basal lamella followed by diastema, followed by 4 larger teeth then 2 smaller teeth. Dorsolateral margins of head with a single freely laterally projecting hair on each side. Scape shorter, SI 80. (Mexico) . . . . . Strumigenys dispalata

44
return to couplet #42
 * With head in full-face view the apicoscrobal hair short and stout, shallowly curved or hooked; apicoscrobal hair contrasts with the much longer hair at the pronotal humerus and the pair on the mesonotal dorsum . . . . . 45


 * With head in full-face view the apicoscrobal hair long and fine, flagellate or looped; apicoscrobal hair similar in length and structure to the hair at the pronotal humerus and the pair on the mesonotal dorsum . . . . . 47

45
return to couplet #44
 * Propodeal spines long, narrowly acutely triagular; lamella below spine reduced to a narrow carina. Eye with 6-7 ommatidia in longest row. Cephalic dorsum close to occipital margin with a transverse row of 4 simple to weakly remiform hairs that are decidedly more erect and much longer than the ground-pilosity. Larger species with longer scapes, HW 0.52-0.59, SI 79-86 . . . . . 46


 * Propodeal teeth short, broadly triangular, lamella below tooth broad, fully engaging the tooth. Eye with 3 ommatidia in longest row. Cephalic dorsum close to occipital margin with a pair of weakly remiform hairs that are only slightly more erect and slightly longer than the ground-pilosity. Minute species with short scapes, HW 0.45-0.46, SI 65-67. (Brazil) . . . . . Strumigenys furtiva

46
return to couplet #45
 * Dorsum of alitrunk and side of pronotum smooth and shining, without punctulate or reticulate-punctate areas. (Brazil) . . . . . Strumigenys sublucida


 * Dorsum of alitrunk blanketed with reticulate-punctate sculpture on all surfaces; side of pronotum reticulate-punctate. (Brazil, Argentina) . . . . . Strumigenys conspersa

47
return to couplet #44 Basal lamella of mandible followed distally by a long edentate second lamella that extends forward about half the exposed length of the fully closed mandible, the two separated only by a minute cleft; mandibles relatively long, MI 27-33. (Dominica, St. Vincent, Grenada, Mexico, Honduras, EI Salvador, Nicaragua, Costa Rica, Panama, Venezuela, Colombia, Ecuador, Peru, Guiana, Brazil, Bolivia). . . . . Strumigenys alberti


 * Basal lamella of mandible immediately followed distally by the tooth-row, without a second lamella that extends forward for half the exposed length of the fully closed mandible; mandibles shorter, MI 19-24 . . . . . 48

48
return to couplet #47
 * Eye small, with only 4 ommatidia in total. Promesonotal dorsum without a median longitudinal carina. Pronotal dorsum entirely smooth and shining. Propodeal dorsum smooth and shining. In full-face view anterior clypeal margin narrowly convex between points where outer margins of fully closed mandibles intersect the clypeal margin. (Costa Rica) . . . . . Strumigenys parsauga


 * Eye larger, with 10 or more ommatidia in total. Promesonotal dorsum with a fine median longitudinal carina through most or all of its length. Pronotal dorsum partially to mostly sculptured. Propodeal dorsum weakly to strongly reticulate-punctate. In full-face view anterior clypeal margin transverse to extremely shallowly convex between points where outer margins of fully closed mandibles intersect the clypeal margin . . . . . 49

49
return to couplet #48
 * Basal tooth-row of mandible consisting only of narrowly triangular high acute teeth. Disc of petiole node in dorsal view as long as broad and with the sides of the node converging anteriorly. (Trinidad, Costa Rica, Panama, Venezuela, Colombia, Peru, Brazil, Paraguay) . . . . . Strumigenys fridericimuelleri


 * Basal tooth-row of mandible consisting of alternating high narrow acutely triangular teeth and lower bluntly rounded broader teeth; tooth 4 from base particularly broad and rounded. Disc of petiole node in dorsal view much broader than long, roughly transversely rectangular, the sides not converging anteriorly. (Bahamas, Cuba, Jamaica, Haiti, Dominican Republic, Trinidad, Mexico, Belize, El Salvador, Nicaragua, Costa Rica) . . . . . Strumigenys nigrescens

50
return to couplet #32
 * Dorsal (outer) surfaces of middle and hind tibiae and basi tarsi with abundant freely projecting sub erect to erect simple hairs that may be short straight and stiff, or flagellate. Mesonotum with abundant suberect to erect hairs dorsally . . . . . 51


 * Dorsal (outer) surfaces of middle and hind tibiae and basi tarsi with decumbent to appressed short spatulate hairs only. Mesonotum hairless or with strongly curved to appressed short spatulate to spoon-shaped hairs dorsally . . . . . 52

51
return to couplet #50
 * Promesonotum, side of alitrunk and disc of postpetiole finely reticulate-punctate. Head in profile incredibly dorsoventrally flattened; at eye level the depth of the head capsule scarcely more than twice the vertical diameter of the eye. Petiole ventrally without a curtain of lamellate or spongiform tissue. (Costa Rica, Panama, Colombia, Ecuador, Peru, Guiana) . . . . . Strumigenys depressiceps


 * Promesonotum and side of alitrunk smooth and shining, disc of postpetiole not reticulate-punctate. Head in profile not strongly dorsoventrally flattened; at eye level the depth of the head capsule distinctly more than twice the vertical diameter of the eye. Petiole ventrally with a lamellate curtain that extends the length of the segment. (Trinidad) . . . . . Strumigenys thaxteri

52
return to couplet #50
 * Dorsal alitrunk smooth or nearly so; pronotum sharply marginate anteriorly, marginate dorsolaterally throughout its entire length. With the head in full-face view and the mandibles fully closed the dorsal surface of each mandible basally with a very distinct sharp transverse edge or rim that extends across the width of the blade, parallel to and in front of the anterior clypeal margin. (Cosmopolitan tramp species) . . . . . Strumigenys membranifera


 * Dorsal alitrunk reticulate-punctate; pronotum not marginate anteriorly nor dorsolaterally. With the head in full-face view and the mandibles fully closed the dorsal surface of each mandible entire basally, without a transverse edge or rim that extends across the width of the blade parallel to the anterior clypeal margin . . . . . 53

53
return to couplet #52
 * First gastral tergite finely and densely striolate-punctulate or striolate-costulate everywhere. Basigastral costulae minute and inconspicuous, restricted to extreme base of tergite and masked by the other dense sculpture. Disc of postpetiole sculptured . . . . . 54


 * First gastral tergite smooth behind the basigastral costulae, the latter distinct and extending at least the basal fifth to quarter of the length of the tergite, not masked by dense sculpture. Disc of postpetiole smooth . . . . . 55

54
return to couplet #53
 * First gastral tergite with suberect to subdecumbent remiform hairs, without appressed small spatulate hairs. Median third of cephalic vertex with short spatulate ground pilosity that is directed medially or anteromedially. Leading edge of scape at subbasal bend rounded. First gastral sternite finely shagreenate or punctulate at least basally and laterally. (U.S.A., Bahamas, Puerto Rico, Antigua, Montserrat, Dominica, Martinique, St Vincent, Trinidad, Mexico, Belize, El Salvador, Costa Rica, Panama, Colombia, Surinam) . . . . . Strumigenys margaritae


 * First gastral tergite with appressed small spatulate hairs only, without standing hairs of any form. Median third of cephalic vertex covered with small scale-like hairs that are closely appressed and arranged in dense longitudinal rows. Leading edge of scape at subbasal bend angulate. First gastral sternite unsculptured. (Peru) . . . . . Strumigenys pholidota

55
return to couplet #53
 * Mesopleuron, metapleuron and side of propodeum smooth and shining. Eye minute, with only 1-2 ommatidia in total. Mandible with a distinct diastema between basal lamella and basal tooth; the latter reduced to a denticle, much shorter than the second tooth. Cephalic dorsum in front of occipital margin without a transverse row of 4 standing hairs that are distinctly differentiated from the ground-pilosity. (Brazil) . . . . . Strumigenys dapsilis


 * Mesopleuron, metapleuron and side of propodeum reticulate-punctate. Eye much larger, with 5-6 ommatidia in the longest row. Mandible without a diastema between basal lamella and basal tooth; the latter about the same size as the second tooth. Cephalic dorsum in front of occipital margin with a transverse row of 4 standing hairs that are distinctly differentiated from the ground-pilosity. (Mexico, Costa Rica, Brazil) . . . . . Strumigenys epinotalis

56
return to couplet #31
 * Lateral head capsule within the antennal scrobe entirely reticulate or reticulate-punctate; without conspicuous broad smooth shining areas . . . . . 57


 * Lateral head capsule within the antennal scrobe mostly or entirely smooth and shining; at least with conspicuous broad smooth shining areas . . . . . 68

57
return to couplet #56
 * Ventral surface of petiole with a longitudinal spongiform or lamellate strip or curtain. Lateral spongiform lobe present on petiole node; in dorsal view the spongiform lobes project freely on each side of the petiole node . . . . . 58


 * Ventral surface of petiole without trace of spongiform tissue. Lateral spongiform lobe absent from petiole node or at most no more than a narrow extension of the posterior collar; in dorsal view without spongiform lobes that project freely on each side of the petiole node . . . . . 64

58
return to couplet #57
 * Midpoint of anterior clypeal margin produced into a sharp triangular tooth that projects forward over the mandibles. In full-face view preocular carina not visible posterior to level of antennal insertions. With head in profile the ventrolateral margin terminating in a large anteroventrally directed triangular tooth just behind the mandibular insertion. Dorsum of clypeus densely clothed with stiff erect hairs that are all gently curved posteriorly. (Brazil) . . . . . Strumigenys reticeps


 * Midpoint of anterior clypeal margin not produced into a sharp triangular tooth that projects forward over the mandibles. In full-face view preocular carina visible posterior to level of antennal insertions. With head in profile the ventrolateral margin not terminating in a tooth behind the mandibular insertion. Standing hairs absent or present on clypeal dorsum, if present then not all are erect and gently curved posteriorly . . . . . 59

59
return to couplet #59
 * Propodeum unarmed, without trace of spines or teeth; propodeal declivity with a lamella present. Scape very short and stout, SI < 60 . . . . . 60


 * Propodeum armed with a pair of acute teeth or spines; propodeal declivity with a lamella that is confluent at its apex with the basal portion of the tooth. Scape long and slender, SI > 80 . . . . . 61

60
return to couplet #59
 * Dorsal alitrunk entirely smooth and shining. Pronotal humeral hair elongate and simple. Mesopleural gland very large. Dorsalmost point of metapleural gland bulla reaches annulus of propodeal spiracle. Base of first gastral sternite with a massive spongiform pad. Basigastral costulae very long, extending over more than half the length of the tergite. (Costa Rica) . . . . . Strumigenys paradoxa


 * Dorsal alitrunk entirely reticulate-punctate. Pronotal humeral hair absent. Mesopleural gland vestigial. Dorsalmost point of metapleural gland bulla widely separated from annulus of propodeal spiracle. Base of first gastral sternite with vestigial spongiform tissue. Basigastral costulae short, restricted to basal quarter of tergite. (Argentina) . . . . . Strumigenys kyidriformis

61
return to couplet #59
 * Disc of postpetiole smooth and shining . . . . . 62


 * Disc of postpetiole densely reticulate-punctate . . . . . 63

62
return to couplet #61
 * Basal lamella of mandible short and subtriangular, not visible at full closure. Funicular segments 2 and 3 together longer than funicular segment 4. Behind clypeus anterior half of cephalic dorsum smooth. Scape very long, SI 105-110. (Brazil) . . . . . Strumigenys browni


 * Basal lamella of mandible very long and narrow, at full closure occupying more than half the exposed length of the masticatory margin. Funicular segments 2 and 3 together shorter than funicular segment 4. Behind clypeus anterior half of cephalic dorsum sculptured. Scape shorter, SI ca 97. (Ecuador) . . . . . Strumigenys doryceps

63
return to couplet #61
 * Metapleuron and side of propodeum entirely reticulate-punctate. Clypeal dorsum with small anteriorly directed spatulate hairs. Fourth (preapical) funicular segment longer than funicular segments 1-3 together; fourth funicular segment broader than fifth (apical) segment. Eyes large and convex, clearly visible in full-face view. (Mexico, Costa Rica, Panama) . . . . . Strumigenys probatrix


 * Metapleuron and side of propodeum smooth and shining. Clypeal dorsum with very long wire-like hairs that project outwards from their bases then curve upwards and back toward their points of origin. Fourth (preapical) funicular segment shorter than funicular segments 1-3 together; fourth funicular segment narrower than fifth (apical) segment. Eyes small, not visible in full-face view. (Trinidad, Venezuela, Brazil) . . . . . Strumigenys hyphata

64
return to couplet #57
 * With head in profile dorsal outline of posterior vertex forming a high narrowly rounded dome, the anterior face of which is very steep; maximum depth of head 0.56 X HL. Propodeal teeth minute, in profile no longer than their basal width. Postpetiole swollen and subglobular. Appressed hairs on first gastral tergite numerous, each arising from a conspicuous pit. (Ecuador) . . . . . Strumigenys umboceps


 * With head in profile dorsal outline of posterior vertex not forming a high narrowly rounded dome with a very steep anterior face; maximum depth of head 0.42-0.47 X HL. Propodeal teeth strong, in profile longer than their basal width. Postpetiole not swollen nor subglobular. Appressed hairs on first gastral tergite sparse, not arising from conspicuous pits . . . . . 65

65
return to couplet #64
 * With head in profile clypeus, at least posteriorly, and all of cephalic dorsum behind clypeus with abundant short stubbly standing hairs. In full-face view lateral margins of occipital lobes with numerous stubbly hairs projecting freely from the surface . . . . . 66


 * With head in profile posterior clypeus and cephalic dorsum behind clypeus without stubbly standing hairs; any hairs present are minute and curved, decumbent to appressed. In full-face view lateral margins of occipital lobes without stubbly hairs projecting from the surface . . . . . Strumigenys microthrix (Costa Rica, Colombia) . . . Strumigenys madrigalae (Ecuador)

66
return to couplet #65
 * Cephalic dorsum at level of frontal lobes with a conspicuous transverse row of 4 erect long straight hairs that are much longer than the short stubbly surrounding pilosity. Promesonotal dorsum with abundant short stubbly erect hairs, as on the cephalic dorsum. (Costa Rica) . . . . . Strumigenys stauroma


 * Cephalic dorsum at level of frontal lobes without a transverse row of hairs that are much longer than the surrounding pilosity. Promesonotal dorsum lacking abundant short stubbly hairs such as are present on the cephalic dorsum . . . . . 67

67
return to couplet #66
 * Anterior clypeal margin transverse in full-face view. Petiole node in dorsal view longer than broad. Mesopleuron punctate, without a broad smooth area. Slightly larger species with shorter scapes, HL 0.60-0. 66, SI 52-56. (Costa Rica) . . . . . Strumigenys cassicuspis


 * Anterior clypeal margin broadly evenly convex in full-face view. Petiole node in dorsal view broader than long. Mesopleuron mostly smooth and shining. Slightly smaller species with longer scapes, HL 0.55-0.58, SI 59-62. (Ecuador) . . . . . Strumigenys necopina

68
return to couplet #56
 * Disc of postpetiole in dorsal view very broadly U-shaped or V-shaped, with an extremely deeply concave anterior face. Spongiform tissue absent from ventral surface of petiole; postpetiole without a ventral spongiform lobe; first gastral sternite without a basal pad or strip of spongiform tissue . . . . . 69


 * Disc of postpetiole in dorsal view not U-shaped or V-shaped, without a deeply concave anterior face. Spongiform tissue present either as a strip or curtain on ventral surface of petiole, or as a ventral lobe on postpetiole, or as a basal pad or strip on first gastral sternite, or in two or all three of these locations . . . . . 76

69
return to couplet #68
 * Pronotal humeral hair absent; pronotal dorsum without standing hairs . . . . . 70


 * Pronotal humeral hair present, simple to weakly flagellate; pronotal dorsum with at least one pair of standing simple hairs . . . . . 71

70
return to couplet #69
 * Dorsum of petiole node broader than long. Head in profile not dorsoventrally flattened, maximum depth of head > 0.55 X HW. In full-face view and with mandibles fully anteriorly and form a narrow inverted V-shape from base to apex. Minute species, HL 0.44-0.46, HW 0.34-0.37, with CI 76-80. (Belize) . . . . . Strumigenys prex (but see the identification section of Strumigenys augustandrewi, a species described after this key was published)


 * Dorsum of petiole node longer than broad. Head in profile extremely dorsoventrally flattened, maximum depth of head < 0.41 X HW. In full-face view and with mandibles fully closed the cuticular margins of the mandibles from which the teeth arise are parallel or even convergent anteriorly. Larger species, HW 0.74-0.84, HW 0.64-0.72, with CI 85-87. (Costa Rica) . . . . . Strumigenys longinoi

71
return to couplet #69
 * Dorsal surfaces of antennal club segments with numerous erect bristle-like hairs that are longer than the maximum width of the segments from which they arise. Vertex of head extensively reticulate-rugulose, only the mid-dorsal strip smooth. Pronotal dorsum with some rugulose sculpture present. (Mexico, Belize, Nicaragua, Costa Rica) . . . . . Strumigenys excisa


 * Dorsal surfaces of antennal club segments without erect long bristle-like hairs. Vertex of head smooth and shining, any sculpture present is restricted to periphery, close to dorsolateral margins. Pronotal dorsum smooth . . . . . 72

72
return to couplet #71
 * With gaster in profile outline of first sternite evenly shallowly arched-convex from behind midlength to junction with postpetiole; outline of sternite visible to base, basal section not overhung by lateral expansion of tergite immediately behind postpetiole. (Costa Rica) . . . . . Strumigenys dontopagis


 * With gaster in profile outline of first sternite convex behind midlength, strongly depressed or concave in basal half to junction with postpetiole; outline of sternites not visible to base as basal section overhung by lateral expansion of tergite immediately behind postpetiole . . . . . 73

73
return to couplet #72
 * Dorsal (outer) surface of hind tibia with a number of erect or suberect freely projecting long fine hairs. Ventrolateral margin of head with a ventrally directed obtuse angle at eye level, the eye occupying the ventral apex of the angle. Behind eye the ventrolateral margin sharply thinly marginate. Clypeal dorsum with short simple hairs that are weakly elevated and curved anteriorly. (Belize) . . . . . Strumigenys asaphes


 * Dorsal (outer) surface of hind tibia with fine hairs that are decumbent or curved back toward the tibial surface. Ventrolateral margin of head evenly convex at eye level, the eye not at the apex of an angle in the margin. Behind eye the ventrolateral margin not sharply thinly marginate. Clypeal dorsum with inconspicuous sparse minute appressed pubscence . . . . . 74

74
return to couplet #73
 * Cephalic dorsum behind clypeus with 6 or more standing simple hairs; usually the dorsal head with numerous standing hairs that are not restricted to zone behind highest point of vertex. (Mexico) . . . . . Strumigenys turpis


 * Cephalic dorsum behind clypeus with 0 - 4 standing simple hairs; usually the dorsal head hairless . . . . . 75

75
return to couplet #74
 * Head in profile with dorsum relatively shallowly evenly convex, maximum depth of head 0.58 X HW and 0.50 X HL. Ventrolateral margin of head in profile shallowly arched in front of eye, the arch not filled in by a thin cuticular lamella. (Mexico, Costa Rica) . . . . . Strumigenys rogata (but see the identification section of Strumigenys erikae, a species described after this key was published)


 * Head in profile with dorsum relatively strongly convex, the vertex high and domed, maximum depth of head 0.68 X HW and 0.60 X HL. Ventrolateral margin of head in profile narrowly high-arched in front of eye, the arch filled in by a thin cuticular lamella. (Mexico, Belize) . . . . . Strumigenys azteca

76
return to couplet #68
 * With the head in full-face view the dorsolateral margin behind the level of the eye with laterally projecting hairs present; at least an apicoscrobal hair but often more along the margin . . . . . 77


 * With the head in full-face view the dorsolateral margin behind the level of the eye without laterally projecting hairs of any form; any hairs that do occur are minute and closely appressed, not at all projecting . . . . . 84

77
return to couplet #76
 * With postpetiole in profile the ventral spongiform lobe either completely absent or reduced to a minute triangular vestige anteriorly on the sternite . . . . . 78


 * With postpetiole in profile the ventral spongiform lobe fully developed, basally extending the length of the sternite and conspicuously convex apically . . . . . 80

78
return to couplet #77
 * With alitrunk in profile the mesonotum with an erect truncated short spine on the midline close to the metanotal groove. Apicoscrobal hair long, fine and flagellate. Ventral spongiform lobe of postpetiole a triangular vestige anteriorly on sternite. (Colombia) . . . . . Strumigenys kompsomala


 * With alitrunk in profile the mesonotum without an erect spine on the midline close to the metanotal groove. Apicoscrobal hair short, stout and straight. Ventral spongiform lobe of postpetiole entirely absent . . . . . 79

79
return to couplet #78
 * Midline of clypeal dorsum raised into a high-arched thick longitudinal crest that extends the entire length of the sclerite. Lateral spongiform lobe of petiole node absent. First gastral sternite without a basal spongiform pad. With head in full-face view preocular carinae not visible, concealed by expanded frontal lobes. (Venezuela, Brazil) . . . . . Strumigenys inusitata


 * Midline of clypeal dorsum not raised into a high longitudinal crest that extends the length of the sclerite. Lateral spongiform lobe of petiole node present and large, extending the entire length of the node. First gastral sternite with a basal spongiform pad. With head in full-face view preocular carinae clearly visible. (Brazil) . . . . . Strumigenys moloch

80
return to couplet #77
 * Dorsal surface of petiole with an erect cuticular lamella that extends along the peduncle and ascends the anterior face of the node, terminating just behind the anterodorsal angle. Dorsolateral margin of propodeum with a tall erect cuticular lamella on each side that is continuous with an extremely broad lamella on the declivity; in profile maximum width of lamella on declivity is equal to the length of the postpetiole disc. (Brazil, Bolivia) . . . . . Strumigenys mirabilis


 * Dorsal surface of petiole without an erect cuticular lamella on the peduncle and anterior face of the node. Dorsolateral margin of propodeum without an erect lamella on each side; lamella on propodeal declivity narrow to cariniform, in profile its maximum width much less than the length of the postpetiole disc . . . . . 81

81
return to couplet #80
 * Anterior clypeal margin narrowly convex in full-face view. Petiole node longer than broad in dorsal view; in profile the dorsal surface of the node longer than the ascending anterior face. Long fine flagellate hairs present in apicoscrobal position, at pronotal humerus and on the mesonotal dorsum . . . . . 82


 * Anterior clypeal margin transverse in full-face view. Petiole node conspicuously broader than long in dorsal view; in profile the node roughly cuneate, the dorsal surface shorter than the ascending anterior face. Long fine flagellate hairs absent from apicoscrobal position, pronotal humerus and mesonotal dorsum . . . . . 83

82
return to couplet #81
 * With head in profile the anterior portion of the clypeus sloping down toward the dorsal margin of the mandible. In full-face view junction of preocular carina with clypeus visible; upper scrobe margin continuous with side of occipital lobe, not detaching from the latter to curve medially on the dorsum. Upper scrobe margin at level of eye with a laterally projecting flagellate hair that is longer than the scape; posterior to this is a flagellate apicoscrobal hair. (Trinidad, Venezuela, Colombia, French Guiana, Brazil) . . . . . Strumigenys villiersi


 * With head in profile the anterior portion of the clypeus curving upwards away from the dorsal margin of the mandible. In full-face view junction of preocular carina with clypeus not visible, concealed by expanded frontal lobes; extreme posterior portion of upper scrobe margin curving medially across dorsum, not continuous with the sides of the occipital lobes. Upper scrobe margin at level of eye without a projecting flagellate hair; a flagellate apicoscrobal hair present. (Brazil) . . . . . Strumigenys rugithorax

83
return to couplet #81
 * Dorsal (outer) surface of hind tibia with suberect to erect hairs present that project freely outward from the surface. Propodeal spiracle with a narrow annulus that does not project posteriorly and does not replace part of the lamella. Head in profile with ventrolateral margin not strongly arched between eye and mandible. Eye with about 20 ommatidia in total. (Argentina) . . . . . Strumigenys lygatrix


 * Dorsal (outer) surface of hind tibia with minute appressed hairs only. Propodeal spiracle with a very broad annulus that projects posteriorly and replaces the upper part of the lamella. Head in profile with ventrolateral margin strongly narrowly arched between eye and mandible; apex of arch higher than level of eye. Eye with 5-6 ommatidia in total. (Cuba) . . . . . Strumigenys convexiceps

84
return to couplet #76
 * Anterior clypeal margin in full-face view transverse to deeply concave; the concavity may be restricted to the central portion of the margin or may extend across its entire width . . . . . 85


 * Anterior clypeal margin in full-face view narrowly and very conspicuously convex . . . . . 97

85
return to couplet #84
 * Ventral surface of petiole with a longitudinal deep continuous crest or curtain of spongiform or translucent lamellar tissue that runs most or all of the length of the segment and is very conspicuous. Mandibles without a conspicuous basal gap between them at full closure; main dentition not of 4 massive teeth . . . . . 86


 * Ventral surface of petiole lacking a continuous longitudinal crest or curtain of spongiform or lamellar tissue; at most with an extremely fine cuticular carina, or a minute lobe present behind the midlength that is surmounted by a thin triangular lamella. Mandibles with a conspicuous basal gap between them at full closure; main dentition of 4 massive teeth that immediately follow the basal gap . . . . . 88

86
return to couplet #85
 * Pronotum (at humeri) and mesonotum each with a pair of long flagellate hairs. First gastral tergite with fine standing hairs present all over its surface. With head in profile the dorsum in front of the occipital margin evenly convex both longitudinally and transversely. Dorsum of propodeum and petiole node sculptured, the latter not margined anteriorly with spongiform tissue . . . . . 87


 * Pronotum and mesonotum without flagellate hairs. First gastral tergite without standing hairs except at the extreme base. With head in profile the dorsum in front of the occipital margin with a broad concave depression that extends across almost the entire width of the head. Dorsum of propodeum and petiole node smooth, the latter margined anteriorly with dense spongiform tissue. (Brazil) . . . . . Strumigenys perissognatha

87
return to couplet #86
 * With head in full-face view and the mandibles fully closed the cuticular margins of the mandibles from which the rows of teeth arise are strongly divergent anteriorly and form a marked inverted V-shape; counting from the base teeth 3 and 4 distinctly longer than teeth 1 and 2. Head in profile not dorsoventrally flattened; dorsal outline of the clypeus angled down at about 45 degrees to the line of the vertex. (Colombia, Brazil) . . . . . Strumigenys beebei


 * With head in full-face view and the mandibles fully closed the cuticular margins of the mandibles from which the rows of teeth arise are approximately parallel; counting from the base teeth 3 and 4 are no longer than teeth 1 and 2. Head in profile remarkably dorsoventrally flattened; dorsal outline of the clypeus not angled down from the line of the vertex. (Brazil) . . . . . Strumigenys substricta

88
return to couplet #85
 * Ventral spongiform lobe of postpetiole conspicuous in profile, prominently lobate and with a rounded convex ventral margin . . . . . 89


 * Ventral spongiform lobe of postpetiole vestigial to absent in profile, at most represented by a minute anteroventral process, without a convex ventral margin. . . . . . 95

89
return to couplet #88
 * Pronotal humeral hair present, filiform or flagellate. Mesonotum with a pair of standing hairs. Anterodorsal angle of petiole in profile not overhanging anterior face of node . . . . . 90


 * Pronotal humeral hair absent. Mesonotum without standing hairs. Anterodorsal angle of pe tiole in profile acute, prominent and slightly overhanging anterior face of node. (Brazil) . . . . . Strumigenys deinomastax

90
return to couplet #89
 * Basigastral costulae longer than maximum length of postpetiole disc. Dorsum of petiole node coarsely reticulate-punctate . . . . . 91


 * Basigastral costulae much shorter than maximum length of po stpetiole disc, sometimes vestigial. Dorsum of petiole node not coarsely reticulate-punctate . . . . . 92

91
return to couplet #90
 * Eye with 4 ommatidia in total. With postpetiole in profile the ventral spongiform lobe conspicuous, only slightly smaller than the lateral lobe. First gastral tergite with short curved hairs. Minute species, HL 0.44, HW 0.41. (Colombia) . . . . . Strumigenys teratrix


 * Eye with 8-10 ommatidia in total. With postpetiole in profile the ventral spongiform lobe minute, only a fraction of the size of the lateral lobe. First gastral tergite with long fine flexuous to flagellate hairs. Larger species, HL 0.56-0.60, HW 0.50-0.54. (Paraguay) . . . . . Strumigenys siagodens

92
return to couplet #90
 * With petiole node in dorsal view the lateral lobes tiny and inconspicuous, represented only by minute oblique cuticular denticles at the extreme posterolateral angles; not laminate and translucent, not spongiform. (Costa Rica, Panama, Venezuela) . . . . . Strumigenys wheeleri (=Strumigenys tumida)


 * With petiole node in dorsal view the lateral lobes distinct, bluntly triangular to rounded, laminate and translucent or spongiform; not reduced to minute denticles that are restricted to extreme posterolateral angles . . . . . 93

93
return to couplet #92
 * Petiole node in dorsal view broader than long. Basigastral costulae vestigial to absent. Width of one lateral postp etiolar lobe in dorsal view less than one-quarter the width of the disc. Ventral lobe of postpetiole narrow and shallow, its attachment restricted to anterior half of sternite. (Venezuela) . . . . . Strumigenys halosis


 * Petiole node in dorsal view at least as long as broad. Basigastral costulae short but sharply developed and distinct. Width of one lateral postpetiolar lobe in dorsal view distinctly more than one-quarter the width of the disc. Ventral lobe of postpetiole broad and deep, its attachment spanning almost the entire length of the sternite. . . . . . 94

94
return to couplet #93
 * Hairs on first gastral tergite short and fine, stiff and straight or only very feebly curved. Occipital margin of head deeply concave in full-face view. Pronotum, mesonotum, or both with fine dense superficial sculpture. Smaller species, HL 0.43-0.48, HW 0.40-0.44. (Venezuela, French Guiana, Brazil) . . . . . Strumigenys glenognatha


 * Hairs on first gastral tergite long and fine, strongly arched, flexuous or subflagellate. Occipital margin of head almost transverse in full-face view. Pronotum and mesonotum mostly or wholly glassy smooth. Larger species, HL 0.55-0.59, HW 0.48-0.54. (Colombia) . . . . . Strumigenys raptans

95
return to couplet #88
 * Postpetiole without any trace of a ventral spongiform lobe. Disc of petiole node in dorsal view distinctly broader than long, broadest at the prominent anterolateral angles and the sides converging posterior to the angles. (Brazil, Paraguay). . . . . . Strumigenys xenochelyna


 * Postpetiole retaining an anteroventral vestige of the ventral spongiform lobe. Disc of petiole node in dorsal view slightly broader than long to longer than broad, but not broadest at the anterolateral angles and the sides not converging posterior to the angles . . . . . 96

96
return to couplet #95
 * First gastral tergite with short simple erect hairs present. Apical half of first gastral tergite with fine superficial reticular patterning. Propodeum armed with a pair of narrow elongate spines that in profile are much longer than their basal width. (Brazil) . . . . . Strumigenys hadrodens


 * First gastral tergite with elongate fine curved to flagellate hairs present. Apical half of first gastral tergite glassy smooth. Propodeum armed with a pair of triangular teeth that in profile are scarcely longer than their basal width. (Brazil) . . . . . Strumigenys appretiata

97
return to couplet #84
 * Disc of petiole node in dorsal view very conspicuously broader than long. Petiole node in profile triangular to cuneate, with a very narrowly rounded dorsum. (Brazil, Argentina) . . . . . Strumigenys lilloana


 * Disc of petiole node in dorsal view longer than broad. Petiole node in profile elongate, its dorsal surface longer than its anterior face . . . . . 98

98
return to couplet #97
 * Pronotal humeral hair present; humerus angular in dorsal view. Pronotal dorsum sharply marginate anteriorly and laterally. With petiole in profile the dorsal length of the node only slightly greater than the height of its anterior face. With head in full-face view and mandibles fully closed the basal lamella occupying less than one-quarter of the exposed length of the masticatory margin . . . . . 99


 * Pronotal humeral hair absent; humerus rounded in dorsal view. Pronotal dorsum not marginate anteriorly, angular or broadly rounded laterally. With petiole in profile the dorsal length of the node much greater than the height of its anterior face. With head in full-face view and mandibles fully closed the basal lamella occupying half or more of the exposed length of the masticatory margin . . . . . 100

99
return to couplet #98
 * Dorsum of clypeus in profile with a short acute anteromedian spine that is slightly inclined anteriorly. Frontal carina in full-face view with two large translucent fenestrae posterior to a small fenestra that is directly above the antennal insertion. (Brazil) . . . . . Strumigenys dentinasis


 * Dorsum of clypeus in profile flat anteromedially, without a spine. Frontal carina in full-face view with a single small semitranslucent fenestra posterior to a small fenestra that is directly above the antennal insertion. (Brazil) . . . . . Strumigenys comis

100
return to couplet #98
 * With head in full-face view preocular carinae not visible, concealed by the lateral expansion of the frontal lobes. Frontal carinae very broad, with translucent fenestrae present. Dorsum of propodeum and petiole node smooth and shining. Dorsum of mandibles finely and very densely sculptured and matt. (Brazil) . . . . . Strumigenys abditivata


 * With head in full-face view preocular carinae exposed, not concealed by the frontal lobes. Frontal carinae narrow, without translucent fenestrae. Dorsum of propodeum and petiole node finely reticulate-punctate. Dorsum of mandibles smooth and shining. (Brazil, Argentina) . . . . . Strumigenys splendens