Key to Strumigenys of India

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This worker key is based on: Bharti, H. & Akbar, S.A. 2013. Taxonomic studies on the ant genus Strumigenys Smith, 1860 (Hymenoptera, Formicidae) with report of two new species and five new records including a tramp species from India. Sociobiology 60, 387-396 (DOI: 10.13102/sociobiology.v60i4.387-396).

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1

  • Antennae with 4 segments; first funicular segment not separated from the 2-segmented apical club . . . . . 2
  • Antennae with 6 segments; first funicular segment separated from the 2-segmented apical club by one or two small segments . . . . . 3

2

return to couplet #1

  • Cephalic dorsum with small orbicular hairs. Mandibles with 2 teeth at apex (apical fork) and a preapical tooth; not serially dentate and engage only at apical third (Pantropical tramp species) . . . . . Strumigenys emmae
Strumigenys emmae casent0005894 profile 1.jpg
  • Cephalic dorsum with spatulate hairs. Mandibles with 5-7 triangular teeth; serially dentate and engage through all of their visible length (India, Nepal, Thailand, Malaysia (West Malaysia), Singapore) . . . . . Strumigenys nepalensis
Pyramica nepalensis casent0102623 profile 1.jpg

3

return to couplet #1

  • In full face view mandibles elongate and narrowed, sublinear to linear and when fully closed the mandibles engage only in the apical third or less of their length . . . . . 4
  • In full face view mandibles triangular to elongate-triangular, and when fully closed the mandibles engage through the apical half or more of their length, with a basal gap at most . . . . . 19

4

return to couplet #3

  • Apex of each mandibular blade with a single, long tooth at the dorsal apex subtended by a series of minute denticles; always lacking true apical fork. Labral lobes long and conical, visible between the mandibles in full-face view even when the mandibles are closed; Eyes reduced or absent . . . . . 5
  • Apex of each mandibular blade armed with an apical fork of 2-3 spiniform teeth set in a vertical series, with or without intercalary denticles between the spiniform fork teeth. Labral lobes not long and conical, not visible between the mandibles when the latter are closed; Eyes more or less well developed . . . . . 6

5

return to couplet #4

  • With 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 sub-basal bend, distinctly curves toward the base of the scape. Dorsum of head without orbiclar hairs, without any standing pilosity. Eyes absent (India, Nepal) . . . . . Strumigenys hemisobek
Strumigenys hemisobek casent0900139 p 1 high.jpg
  • With head in full-face view the leading edge of the scape lacking projecting hairs that curve toward the base of the scape. Clypeal dorsum with orbicular hairs. Eyes present (Bhutan, India) . . . . . Strumigenys nannosobek
Strumigenys nannosobek casent0900137 p 1 high.jpg

6

return to couplet #4

  • Apex of mandible with three short-spiniform teeth arranged in an oblique series (series extremely oblique so that lowermost tooth has migrated onto ventral surface and appears as a ventrally-arising preapical tooth in full-face view); with 2 intercalary denticles or small teeth, arising between apicomedian and apicoventral teeth . . . . . 7
  • Apex of mandible with two spiniform teeth arranged in a vertical or near-vertical series; with 0-3 intercalary denticles or small teeth, which when present arise between the apicodorsal and apicoventral teeth or from dorsal surface of apicoventral tooth near its base . . . . . 8

7

return to couplet #6

  • With mesosoma in dorsal view, pronotal humeral hair absent. First gastral tergite not entirely sculptured (Sri Lanka, Bhutan, India) . . . . . Strumigenys lyroessa
Strumigenys lyroessa casent0280737 p 1 high.jpg
  • With mesosoma in dorsal view, pronotal humeral hair present, projecting laterally; hair clavate, short and stout. First gastral tergite entirely sculptured (India) . . . . . Strumigenys hostilis
Strumigenys hostilis casent0900770 p 1 high.jpg

8

return to couplet #6

  • Preapical dentition of each mandible of two articles; with one tooth and a denticle (Cosmopolitan tramp species) . . . . . Strumigenys rogeri
Strumigenys rogeri casent0005897 profile 1.jpg
  • Preapical dentition of each mandible with a single article; a single prominent tooth . . . . . 9

9

return to couplet #8

  • Dorsal (outer) surface of hind basitarsus with one or more freely projecting filiform or flagellate hairs that are very long and suberect to erect; this specialised pilosity may also be present on the middle basitarsus and the middle and hind tibiae . . . . . 10
  • Dorsal (outer) surface of hind basitarsus without freely projecting long filiform or flagellate hairs; any pilosity present is simple to spatulate and usually decumbent to appressed; projecting long fine simple hairs absent from middle basitarsus and from middle and hind tibiae . . . . . 17

10

return to couplet #9

  • With mesosoma in profile, the propodeal declivity equipped with a simple carina or at most a narrow cuticular flange; carina or narrow flange does not subtend the ventral margin of the tooth for most or all of its length; posterior (free) margin of carina or narrow flange concave, close to and parallel with the edge of the declivity . . . . . 11
  • With mesosoma in profile, the propodeal declivity equipped with a broad and conspicuous lamella; the propodeal tooth may be replaced by the lamella or completely buried in the lamella, or the lamella may subtend the ventral margin of the tooth for most or all of its length; posterior (free) margin of lamella may be convex, straight or irregular but is not narrowly concave, nor is it close to and parallel with the edge of the declivity . . . . . 12

11

return to couplet #10

  • Anterior clypeal margin with a deep narrow median notch or impression that is narrowly U-shaped or V-shaped. Scape relatively long, SI > 80. Apical segment of funiculus long and narrow, spindle-shaped, basally tapering to a very narrow neck at its articulation with the preapical segment (India, Nepal, Bhutan, Thailand, China, Japan, Wallis Is) . . . . . Strumigenys exilirhina
Strumigenys exilirhina casent0102650 profile 1.jpg
  • Anterior clypeal margin transverse or broadly evenly shallowly concave across its entire width, without a deep median notch. Scape relatively short, SI < 80. Apical segment of funiculus not long and narrow, not spindle-shaped, not or only moderately tapering basally to its articulation with the preapical segment (India) . . . . . Strumigenys aduncomala
Strumigenys aduncomala casent0912867 p 1 high.jpg

12

return to couplet #10

  • With mesosoma in profile, dorsum of pronotum without standing hairs apart from the humeral hair . . . . . 13
  • With mesosoma in profile, dorsum of pronotum with usually one other pair of standing hairs as well as the humeral hair; rarely with more than one pair . . . . . 14

13

return to couplet #12

  • Dorsal mesosoma entirely smooth and shining, devoid of reticulate-punctate sculpture. The body pilosity predominated by long flagellate hairs (India) . . . . . Strumigenys smythiesii
Strumigenys smythiesii casent0280742 p 1 high.jpg
  • Dorsal mesosoma partially to entirely reticulate-punctate. The body pilosity mixed consists of spatulate, flagellate, stiff as well as simple hairs. (Sri Lanka, India, Malaysia (Sarawak, Sabah), Singapore, Indonesia (Sumatra, Krakatau, Java, Lombok, Seram, Flores, Sulawesi, Kai Besar, Aru, Tanimbar, Timor), Philippines (Mindanao, Luzon, Palawan), Papua New Guinea, Solomon Is, Vanuatu, Fiji Is, Samoa, Tonga, Marshall Is, Society Is, Caroline Is, Marquesas Is, Hawaii; also in Austral region) . . . . . Strumigenys godeffroyi
Strumigenys godeffroyi casent0060226 profile 1.jpg

14

return to couplet #12

  • Head in full-face view with a freely laterally projecting long flagellate hair present on dorsolateral margin at or very close to the occipital corner. Apicoscrobal hair also present, also long and flagellate, of the same form and length as the hair at the occipital corner . . . . . 15
  • Head in full-face view with dorsolateral margin at occipital - corner without a freely laterally projecting long flagellate hair (short simple or curved hairs may occur). Apicoscrobal hair present or absent, when present may be simple or flagellate but is always different in form and length from the hair at the occipital corner . . . . . 16

15

return to couplet #14

  • Cephalic ground-pilosity and pilosity that fringes upper scrobe margins simple and extremely fine. Hairs on leading edge of scape fine and simple. Head narrower and mandibles shorter, CI 77, MI 34. (India) . . . . . Strumigenys habropilosa
Strumigenys habropilosa casent0102656 profile 1.jpg
  • Cephalic ground-pilosity and pilosity that fringes upper scrobe margins broadly spatulate. Hairs on leading edge of scape spatulate. Head broader and mandibles longer, CI 86, MI 39. (India) . . . . . Strumigenys hypoturba
Strumigenys hypoturba casent0102609 profile 1.jpg

16

return to couplet #14

  • Head in profile, the pair of standing hairs that straddle the midline near the occipital margin disproportionately long, either flagellate or erect basally and with their apical sections abruptly angled or hooked anteriorly, or even looped (India, Bhutan, Thailand, China, Taiwan, Malaysia, Indonesia) . . . . . Strumigenys nanzanensis
Strumigenys nanzanensis casent0280740 p 1 high.jpg
  • Head in profile, the pair of standing hairs that straddle the midline near the occipital margin short and stiff, straight to feebly curved and usually slightly inclined anteriorly; apical sections not abruptly angled or hooked anteriorly (India) . . . . . Strumigenys peraucta
Strumigenys peraucta casent0900812 p 1 high.jpg

17

return to couplet #9

  • Pronotal humeral hair present; may be simple, clavate, remiform or flagellate . . . . . 18

18

return to couplet #17

  • Mesosoma in profile, the propodeal declivity equipped with a simple cuticular carina or at most a narrow crest; posterior (free) margin of carina or crest narrowly concave, close to and paralleling the concave shape of the edge of the declivity. Mandibular dentition consists of 2 spiniform teeth with 1 intercalary denticle. A single preapical tooth present near the apex, short (India) . . . . . Strumigenys fixata
Strumigenys fixata casent0102651 profile 1.jpg
  • Mesosoma in profile, the propodeal declivity equipped with a broad lamella; posterior (free) margin of lamella broadly convex. Mandibular dentition consists of an intercalary tooth with two denticles between it and the apicoventral tooth; usually there is also a denticle between the intercalary tooth and the apicodorsal spiniform fork tooth (India, Bhutan) . . . . . Strumigenys virgila
Strumigenys virgila casent0900829 p 1 high.jpg

19

return to couplet #3

  • 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 sub-basal bend, distinctly curves toward the base of the scape. These hairs may be spatulate, remiform, spoon-shaped or broadly clavate apically; basal stem of each hair (which may be short) erect or suberect with respect to the long axis of the scape . . . . . 20
  • Head in full-face view the leading edge of the scape lacking projecting hairs that curve toward the base of the scape. Scape edge may have elongate simple straight projecting hairs present, or entirely apically directed short hairs that may be simple, narrowly to broadly spatulate, or spoon-shaped; in some species the leading edge may be hairless . . . . . 21

20

return to couplet #19

  • Pilosity of head without any standing hairs at the highest point of the vertex. Dorsum only having minute appressed pubescence which is very sparse. Cephalic dorsum without a pair of erect hairs. Eyes rudimentary represented by a small black pigmented spot situated in middle of antennal scrobe away from ventral scrobe margin posteriorly (India) . . . . . Strumigenys mukkaliensis
  • Pilosity of head represented by a single pair of standing hairs at the highest point of the vertex. Otherwise the dorsum only having minute appressed pubescence which is very sparse and difficult to see. Eyes prominent represented by 2-3 ommatidia situated at the ventral scrobe margin (Cosmopolitan tramp species) . . . . . Strumigenys membranifera
Pyramica membranifera casent0173252 profile 1.jpg

21

return to couplet #19

  • Petiole node in profile long and low; either anterior face of node much shorter than the long dorsum, or the anterior face shallowly sloped and grading evenly into the peduncle so that the entire segment is subclavate. Petiole node in dorsal view long and narrow, much longer than broad and equal in length to the disc of the postpetiole. (India) . . . . . Strumigenys assamensis
Strumigenys assamensis casent0900133 p 1 high.jpg
  • Petiole node in profile short and relatively high; either anterior face of node at least subequal in length to the dorsum, or the anterior face steeply sloped and meeting the peduncle through an obtuse but marked angle, or both. Petiole node in dorsal view short and broad, as long as broad and shorter in length to the disc of the postpetiole . . . . . 22

22

return to couplet #21

  • With the head in full-face view and the mandibles fully closed the dorsal surface of each massively triangular mandible has, near its base, a very distinct sharp transverse rim that extends across the width of the mandible (India, Nepal) . . . . . Strumigenys podarge
Strumigenys podarge casent0900142 p 1 high.jpg
  • With the head in full-face view and the mandibles fully closed the dorsal surface of each mandible, near its base, is without a sharp transverse rim that extends across the width of the mandible; if dorsum of mandible slightly depressed basally then mandible is linear, not triangular . . . . . 23

23

return to couplet #22

  • With head in full-face view the fully closed mandibles narrow or elongate-triangular, with teeth present only on distal half of exposed length of inner margin; proximal half of inner margin edentate and forming a long diastema between basal tooth and basal lamella; a large space present basally between the opposed mandibles through which the apices of the labral lobes are visible (India, Japan, Taiwan, Malaysia (West Malaysia), Singapore, Indonesia (Java, Bali, Lombok)) . . . . . Strumigenys mutica
Strumigenys mutica casent0280715 p 1 high.jpg
  • With head in full-face view the fully closed mandibles triangular, with teeth present along entire length of exposed inner margin; proximal half of inner margin dentate, without a long diastema between basal tooth and basal lamella; without a large space basally through which the apices of the labral lobes are visible (India, China, Thailand, Singapore, Malaysia (West Malaysia, Sarawak, Sabah), Brunei, Indonesia (Kalimantan, Sumatra, Java, Bali, Sulawesi), Philippines (Luzon), Papua New Guinea) . . . . . Strumigenys mitis
Strumigenys mitis casent0900120 p 1 high.jpg