Key to Afrotropical Tetramorium simillimum species group

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This worker key is based on Bolton (1980)[1]

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NOTE: Four species were not included in the original key:

1

  • Eyes relatively large, maximum diameter 0.29 x HW at least, usually greater, and longest row of facets in the eye containing 10 or more ommatidia. Ventral surface of head behind buccal cavity commonly with 2-4 elongate hooked or "J"-shaped hairs . . . . . 2
  • Eyes relatively smaller, maximum diameter 0,27 x HW at most, usually less, and longest row of facets in the eye containing 7-8 ommatidia at maximum. Ventral surface of head behind buccal cavity without elongate hooked or"J"-shaped hairs . . . . . 7

2

return to couplet #1

3

return to couplet #2

  • Propodeum armed with a pair of broad blunt triangular teeth. Ground-sculpture of head between the rugulae feeble, the surfaces glossy. Petiole node in dorsal view transverse, much broader than long...... Tetramorium luteolum
Tetramorium luteolum casent0901216 p 1 high.jpg
Tetramorium luteolum casent0901216 d 1 high.jpg
  • Propodeum bluntly angular, without projecting teeth. Ground-sculpture of head between the rugulae a very distinct fine reticulate-punctulation, the surfaces matt and dull. Petiole node in dorsal view about as broad as long..... Tetramorium berbiculum
Tetramorium berbiculum casent0901214 p 1 high.jpg
Tetramorium berbiculum casent0901214 d 1 high.jpg

4

return to couplet #2

  • Base of first gastral tergite with a band of shagreening or of reticulate-punctate sculpture . . . . . 5
  • Base of first gastral tergite unsculptured except for hair pits . . . . . 6

5

return to couplet #4

  • Eyes very large and set well forward on the head, their maximum diameter 0.37-0.39 x HW. In profile the maximum diameter of the eye more than 3 times greater than the distance separating the anterior margin of the eye from the mandibular insertion at their closest approach ..... Tetramorium oculatum
MCZ-ENT00512615 Tetramorium oculatum hal 5.jpg
MCZ-ENT00512615 Tetramorium oculatum had 5.jpg
  • Eyes much smaller and set at about the midlength of the head, their maximum diameter 0.29-0.32 x HW. In profile the maximum diameter of the eye about equal to the distance separating the anterior margin of the eye from the mandibular insertion at their closest approach..... Tetramorium argenteopilosum
Tetramorium argenteopilosum casent0249012 p 1 high.jpg
Tetramorium argenteopilosum casent0249012 d 1 high.jpg

6

return to couplet #4

  • Antennal scapes longer, SI 80-87. Metapleural lobes triangular and acute..... Tetramorium bevisi
Tetramorium bevisi casent0280858 p 1 high.jpg
Tetramorium bevisi casent0280858 d 1 high.jpg
Tetramorium krynitum casent0901213 p 1 high.jpg
Tetramorium krynitum casent0901213 d 1 high.jpg

7

return to couplet #1

  • Frontal carinae long and strongly developed throughout their length, running unbroken almost to the occipital margin and forming the dorsal borders of the broad and distinctive antennal scrobes; the carinae always more strongly developed than the remaining cephalic sculpture . . . . . 8
  • Frontal carinae feeble or reduced, either fading out posteriorly or uniformly weak, sometimes broken or interrupted and usually not more strongly developed than the remaining cephalic sculpture; antennal scrobes vestigial to absent . . . . . 14

8

return to couplet #7

  • Dorsum of head with spaces between longitudinal rugulae smooth or only superficially sculptured, without a dense blanketing reticulate-punctulation or a coarse granular mat . . . . . 9
  • Dorsum of head with spaces between longitudinal rugulae blanketed by a dense reticulate-punctulation or by a coarse granular mat . . . . . 11

9

return to couplet #8

  • Scapes relatively long, SI 90-93. Dorsum of head with only 5 weak longitudinal rugulae between the frontal carinae at the level of the eyes ..... Tetramorium buthrum
Tetramorium buthrum casent0280864 p 1 high.jpg
Tetramorium buthrum casent0280864 d 1 high.jpg
  • Scapes relatively short, SI 74-83. Dorsum of head with 8-10 longitudinal rugulae between the frontal carinae at the level of the eyes . . . . . 10

10

return to couplet #9

Tetramorium anxium casent0235786 p 1 high.jpg
Tetramorium anxium casent0235786 d 1 high.jpg
Tetramorium mossamedense casent0249029 p 1 high.jpg
Tetramorium mossamedense casent0249029 d 1 high.jpg

11

return to couplet #8

  • Sides of head immediately behind eyes with a single stout projecting hair, directed anteriorly at an angle of about 45°..... . . . . . 11a
  • Sides of head immediately behind eyes without such a hair, either hairless or with a number of minute decumbent to appressed hairs . . . . . 12

11a

Tetramorium delagoense casent0134755 profile 1.jpg
Tetramorium delagoense casent0134755 dorsal 1.jpg


(Added by K. Gómez, not in the original keys)

11b

MCZ-ENT00512619 Tetramorium zambezium hal 6-3.jpg
MCZ-ENT00512619 Tetramorium zambezium had 6-3.jpg
Tetramorium intextum casent0280857 p 1 high.jpg
Tetramorium intextum casent0280857 d 1 high.jpg

(Added by K. Gómez, not in the original keys)

12

return to couplet #11

  • With the head in full-face view the sides behind the eyes with a number of very short fine curved decumbent to appressed hairs which are directed anteriorly. Hairs on first gastral tergite dense, at least as long as the maximum width of the hind tibia..... Tetramorium rhetidum
Tetramorium rhetidum casent0235779 p 1 high.jpg
Tetramorium rhetidum casent0235779 d 1 high.jpg
  • With the head in full-face view the sides behind the eyes without hairs. Hairs on first gastral tergite sparse, shorter than the maximum width of the hind tibia . . . . . 13

13

return to couplet #12

  • Yellow to yellowish brown species, sometimes with gaster darker than head and alitrunk. Mandibles lightly shagreened or feebly striate..... Tetramorium simillimum
Tetramorium simillimum casent0005830 profile 1.jpg
Tetramorium simillimum casent0005830 dorsal 1.jpg
  • Uniform blackish brown species. Mandibles smooth with scattered pits..... Tetramorium bothae
Tetramorium bothae casent0249011 p 1 high.jpg
Tetramorium bothae casent0249011 d 1 high.jpg

14

return to couplet #7

  • Basal one-third or more of first gastral tergite strongly sculptured, punctulate or densely shagreened . . . . . 15
  • First gastral tergite unsculptured or at most with a narrow band of faint punctulation at the extreme base . . . . . 16

15

return to couplet #14

  • With the head in full-face view the sides between the eye and the long hair at the occipital corner with 2 freely projecting stout hairs. Scapes longer, SI 86-90. Eyes with 7 ommatidia in the longest row..... Tetramorium ghindanum
Tetramorium ghindanum casent0909146 p 1 high.jpg
Tetramorium ghindanum casent0909146 d 1 high.jpg
  • With the head in full-face view the sides between the eye and the long hair at the occipital corner without projecting hairs. Scapes shorter, SI 74. Eyes with 9 ommatidia in the longest row ..... Tetramorium nefassitense
Tetramorium nefassitense casent0909147 p 1 high.jpg
Tetramorium nefassitense casent0909147 d 1 high.jpg

16

return to couplet #14

  • Median longitudinal strip on dorsum of head unsculptured and shining, without rugulose or punctulate sculpture ..... Tetramorium poweri
Tetramorium poweri casent0280861 p 1 high.jpg
Tetramorium poweri casent0280861 d 1 high.jpg
  • Median longitudinal strip on dorsum of head with longitudinal rugulae and usually also with punctulate ground-sculpture. . . . . 17

17

return to couplet #16

18

return to couplet #17

  • Longitudinal rugulae on dorsum of head weak, very fine and narrow, not strongly developed: the rugulae superimposed upon a finely reticulate-punctulate or granular ground-sculpture, SI range 79-87..... Tetramorium caldarium
Tetramorium caldarium casent0003150 profile 1.jpg
Tetramorium caldarium casent0003150 dorsal 1.jpg
  • Longitudinal rugulae on dorsum of head strongly developed, sharp, broad and very conspicuous; the spaces between the rugulae unsculptured or at most with only the faintest superficial ground-sculpture. SI range 74-80 ..... Tetramorium mossamedense (part)
Tetramorium mossamedense casent0249029 p 1 high.jpg
Tetramorium mossamedense casent0249029 d 1 high.jpg

19

return to couplet #17

Tetramorium pusillum casent0280862 p 1 high.jpg
Tetramorium pusillum casent0280862 d 1 high.jpg

20

return to couplet #19

  • Larger species, HW 0.52-0.56, SI 84-91. Propodeum armed with a pair of short triangular teeth..... Tetramorium altivagans
Tetramorium altivagans P casent0249018.jpg
Tetramorium altivagans D casent0249018.jpg
  • Smaller species, HW 0.44; SI 77. Propodeum without teeth, the dorsum and declivity separated only by a prominent angle..... Tetramorium nigrum
Tetramorium nigrum casent0217208 p 1 high.jpg
Tetramorium nigrum casent0217208 d 1 high.jpg

References

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