Key to Tetraponera of India

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This worker key is based on: Bharti, H. and Akbar, S.A. 2014. Tetraponera periyarensis, a new pseudomyrmecine ant species (Hymenoptera: Formicidae) from India. Asian Myrmecology. 6:43–48.

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1

  • Head with three distinct ocelli; in dorsal view pronotal humeri appearing subangulate; head densely punctate, and lacking extensive shiny interspaces between the punctures; large species, (HW 1.14 – 2.07 mm) . . . . . 2
  • Head almost always lacking ocelli, very rarely with two or three faint ocelli (in a few large workers of T. nigra); pronotal humeri varying from narrowly to broadly rounded, but not subangulate; head usually less densely punctate and with conspicuous shiny interspaces between the punctures; size variable (HW 0.49 – 1.48 mm) . . . . . 4

2

return to couplet #1

  • Larger species (HW 1.62 – 2.07 mm), with smaller eyes (REL 0.27 – 0.34 mm) . . . . . 3
  • Smaller species (HW 1.14 – 1.51 mm), with larger eyes (REL 0.43 – 0.49 mm) . . . . . Tetraponera pilosa
Tetraponera pilosa casent0217596 h 1 high.jpg
Tetraponera pilosa casent0217596 p 1 high.jpg

3

return to couplet #2

  • Body bicoloured, the dark head and gaster contrasting with orange-brown mesosoma (the latter infuscated in some populations). Median lobe of clypeus longer and narrower, smooth and shining. Humeral corners of pronotum angulate . . . . . Tetraponera rufonigra
Tetraponera rufonigra casent0106099 profile 1.jpg
  • Body uniformly black. Median lobe of clypeus shorter and broader, with distinct punctures. Humeral corners of pronotum bluntly angled . . . . . Tetraponera periyarensis
Bharti & Akbar 2014-2Tetraponera-periyarensis hal.jpg

4

return to couplet #1

  • Mandible slender, with three teeth on the masticatory margin, and 1 – 2 denticles on the basal margin; basal margin of mandible much longer than masticatory margin; posteroventral margin of petiole in the form of a thin, ventrally protruding hood, which is distinctly separated from the helcium venter, when the postpetiole is in its normal horizontal position; mesosternum densely pubescent; abdominal tergite IV sparsely pubescent, the appressed hairs separated by their lengths or more; relatively small species (HW 0.49–0.93 mm) . . . . . 5
  • Mandible more robust, with four teeth on the masticatory margin, and 0 – 1 denticles on the basal margin; basal margin of mandible subequal to, or shorter than, masticatory margin; posteroventral margin of the petiole closely associated with the helcium venter, although it may be flanked by ventrolateral flanges; most of the mesosternum devoid of pubescence; abdominal tergite IV usually densely pubescent; size variable (HW 0.63–1.48 mm) . . . . . 6

5

return to couplet #4

  • Larger species (HW 0.62–0.93 mm, usually > 0.70 mm); body predominantly black, although petiole, postpetiole and limb appendages may be lighter in colour; propodeum typically low and broad, such that PDI 0.91–1.09 mm; the propodeum is inflated and prominently raised; pronotal margin varying from sharp-to soft-edged, and maximum width of the pronotum generally occurring below the margin . . . . . Tetraponera allaborans
Tetraponera allaborans casent0103239 profile 1.jpg
  • Smaller species (HW 0.49 – 0.64 mm), body yellow or orange-brown coloured; propodeum notably tall (lateral view) and slender (posterior view), such that PDI 1.12 – 1.24 mm; pronotal margin usually relatively soft-edged and occurring at the point of maximum width of the pronotum . . . . . Tetraponera modesta
Tetraponera modesta casent0281872 p 1 high.jpg

6

return to couplet #4

  • Larger species (HW 0.95 – 1.48), with long legs (LHT/HL 0.80 – 0.97 mm); standing pilosity common, MSC 6-71 (usually > 10) and CSC 10-40, the cephalic hairs scattered over the dorsal surface of the head and often grading into shorter, suberect pubescence; mesopropodeal impression flanked laterally by raised prominences (containing the metanotal spiracles) but otherwise more or less open, not bounded by lateral ridges that enclose a pit-like depression (a shallow pit present in T. binghami) . . . . . 7
  • Smaller species, on average (HW 0.63 – 1.44 mm); if HW > 0.92 mm, then standing pilosity less common (MSC 0-22, CSC 0-4) and the sparse cephalic hairs arranged in pairs on the dorsum of the head, distinct from the much shorter, appressed pubescence; legs generally shorter (LHT/HL 0.58 – 0.86 mm, rarely > 0.80 mm); mesopropodeal impression partly or entirely flanked laterally by raised ridges that enclose a pit-like depression . . . . . 9

7

return to couplet #6

  • Head elongate (CI 0.70 – 0.77 mm) and petiole very slender (PLI 0.34 – 0.43 mm) . . . . . Tetraponera binghami
Tetraponera binghami casent0281873 p 1 high.jpg
  • Head broader (CI 0.76 – 0.94 mm, usually > 0.80 mm); petiole shape variable but if CI <0.80 mm (a few individuals of T. nigra) then petiole more robust (PLI > 0.50 mm) . . . . . 8

8

return to couplet #7

  • Petiole long and slender, PLI 0.38 – 0.47 mm, PL/HL 0.74 – 0.92 mm; mesosoma, petiole and postpetiole, when viewed in profile, with scattered standing pilosity accompanied by, and often grading into, a dense mat of shorter suberect hairs, present on all dorsal surfaces . . . . . Tetraponera attenuata
Tetraponera attenuata casent0217587 p 1 high.jpg
  • Petiole shorter and higher, PLI 0.52 – 0.64 mm, PL/HL 0.57 – 0.72 mm; mesosoma, petiole and postpetiole, when viewed in profile, with standing pilosity and underlying suberect pubescence variably developed (and variably distinguishable), but at least the promesonotum and the anterior peduncle of petiole lacking a dense mat of short suberect hairs . . . . . Tetraponera nigra
Tetraponera nigra casent0103313 profile 1.jpg

9

return to couplet #6

  • Petiole with a pair of acute, posteroventral teeth, formed from ventrolateral extensions of the petiolar sternite; pronotum with dense punctate sculpture on its anterior quarter which contrasts with the shiny (and less densely sculptured) posterior half of head and with the more sparsely punctuate posterior regions of the pronotum; scapes shorter than eye length (SI2 0.83 – 0.98 mm) . . . . . Tetraponera nitida
Tetraponera nitida casent0172004 profile 1.jpg
  • Petiole lacking a pair of posteroventral teeth; pronotal sculpture variable but punctures more evenly distributed not concentrated solely on the anterior quarter (although they may be sparse medially) and usually not occurring in a density that contrasts strongly with that of the posterior half of the head; scapes longer than eye length (SI2 1.02-1.55 mm) . . . . . Tetraponera aitkenii
Tetraponera aitkenii casent0907455 p 1 high.jpg