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.

Bolton noted in regards to this key: Note: 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.

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
 * Disc of postpetiole smooth or with weak longitudinal costulae in parts, never densely reticulate-punctate . . . . . 8


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

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