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.

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 two sets of keys that treat two sets of Strumigenys species. The species of the Neotropics were split among three keys: the key found below, a key to the Nearctic Pyramica and a key to the Neotropical 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 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
 * Mandible without intercalary teeth or denticles that arise between the apicodorsal and apicoventral teeth of the apical fork, nor arise from the dorsal base of the apicoventral tooth . . . . . 5


 * Mandible with 1 or 2 intercalary teeth or denticles that arise between the apicodorsal and apicoventral teeth of the apical fork, or arise from the dorsal base of the 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
 * Mandible 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 of a single tooth on one or both mandibles; preapical tooth conspicuously dentiform and located close to the apicodorsal tooth . . . . . 12


 * Preapical dentition absent from both mandibles or a single minute denticle present; if the latter the denticle is located close to the midlength, not near the 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, the other apicoscrobal. (Bahamas, Cuba, Mexico, Costa Rica, Panama, Venezuela, Colombia) . . . . . Strumigenys lanuginosa


 * First gastral tergite with stout curved standing hairs that are remiform or apically spatulate. Dorsolateral margin of head without projecting flagellate hairs or with a 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 hair stiff and stout. With head in profile highest point of vertex without erect hairs. (Costa Rica) . . . . . Strumigenys platyscapa


 * Scape subcylindrical; in full-face view maximum width of scape less than maximum width of mandible. First gastral tergite finely reticulate-punctate everywhere. Pronotal humeral hair fine and flagellate. With head in profile highest point of vertex with a pair of erect hairs. (Costa Rica) . . . . . Strumigenys idiogenes

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