Key to Afrotropical Tetramorium species groups

This key is based on Bolton 1980 adding the decem group following Hita & Fisher (2014), and the species on the former genus Rhoptromyrmex under the globulinode group

The species belonging to the former Triglyphothrix genus are redistributed into other groups (Bolton, 1985 ) was synonymyzed with Tetramorium and their species groups have been retained here except for two species. Species belonging to this non-group (!) can be distinguished by the presence of abundant bifid or triphid queate distributed all over the body.

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 * Tetramorium
 * Tetramorium species groups
 * Afrotropical Tetramorium species groups

1

 * Branched hairs present on some or all of the surfaces of head, mesosoma, petiole, postpetiole and gaster ..... groups ericae, osiris, inezulae, gabonense (Key to species)
 * Branched hairs absent .....2

2
return to couplet .....1
 * Head heart shaped in full-face view. Ventral margin of petiole convex and keel-like. Anterior clypeal margin strongly arcuate and prominent. Eyes behind midlenght of sides of head ..... globulinode group (Key to species)


 * Head not heart shaped in full-face view. Ventral margin of petiole never convex and keel-like. Anterior clypeal margin not strongly convex nor prominent. Eyes only rarely behind midlenght of sides of head .....3

3
return to couplet .....2


 * Antennae with 10 segments => decem group (Key to species)


 * Antennae with 11 or 12 segments .....4

4
return to couplet .....3


 * Antennae with 11 segments .....5


 * Antennae with 12 segments .....7

5
return to couplet .....4


 * Petiole squamiform or represented in profile by a high, narrow node ….. weitzeckeri group (Key to species)


 * Petiole strongly nodiform .....6

6
return to couplet .....5


 * Dorsal (outer) surface of hind tibiae only with fine pubescence. Hairs on first gastral tergite directed towards midline, at least in part …. angulinode group
 * Dorsal (outer) surface of hind tibiae only with long projecting hairs. Hairs on first gastral tergite not directed towards midline….. tortuosum group (Key to species)

7
return to couplet .....4


 * SI 100 or more .....8


 * SI < 100 .....12

8
return to couplet .....7


 * Frontal carinae extending back well beyond the level of the posterior margins of the eye .....9
 * Frontal carinae ending at or in front the level of the eyes .....10

9
return to couplet .....8


 * Maximum diameter of eye 0,25 x HW at minimum, usually greater. Longest row of facets with at least 9 ommatidia. Petiole node high and quite narrow in profile …..setigerum group (in part)


 * Maximum diameter of eye 0,24 x HW at maximum, usually smaller. Longest row of facets with 7-8 ommatidia. Petiole node long and low in profile …..flabellum group (in part)

10
return to couplet .....8
 * Petiole node in profile long and low, in dorsal view usually longer than broad.....11
 * Petiole node in profile high and narrow, in dorsal view distinctly broader than long …..aculeatum group (Key to species)

11
return to couplet .....10


 * Lateral portions of clypeus prominent as a tooth or crest on each side in full face view. When viewed from above and behind, the lateral parts of the clypeus rise to a high peak in front of the antennal insertions and then slope steeply down towards the median portion of the clypeus …..sericeiventre group


 * Lateral portions of clypeus not strongly modified as above …..setigerum group (part)

12
return to couplet .....7


 * Eyes very small or minute. Maximum diameter < 0,17xHW, less than maximum width of scape. Commonly only 1-5 facets altogether, but always with 5 or less ommatidia in the longest row …..shilohense group


 * Eyes larger. Maximum diameter >0,20xHW, greater than maximum width of scape, with more than 5 facets in the longest row .....13

13
return to couplet .....12
 * Petiole, and sometimes also postpetiole, squamiform…..squaminode group


 * Petiole not squamiform.....14

14
return to couplet .....13
 * Lamellate appendage of sting spatulate or linear…..grassii group


 * Lamellate appendage of sting dentiform, triangular or pennant shaped .....15

15
return to couplet .....14


 * Frontal carinae short, ending in front of the level of the posterior margins of the eyes .....16
 * Frontal carinae long, reaching back well beyond the level of the posterior margins of the eyes, usually approaching or even reaching the occipital margin .....19

16
return to couplet .....15


 * Either anterior clypeal margin with a broad deep indentation medially or ventral surface of head with ammochetae hairs present or both …..solidum group


 * Anterior clypeal margin entire and ventral surface of head without ammochetae hairs .....17

17
return to couplet .....16
 * Hairs on dorsal alitrunk and/or first gastral tergite short, stout, and blunt apically …..simillimum group (part)


 * Hairs on dorsal alitrunk and/or first gastral tergite fine and acute apically, or hairs absent from both these surfaces .....18

18
return to couplet .....17
 * Mandibles striate …..caespitum group


 * Mandibles smooth …..convexum group

19
return to couplet .....15
 * Anterior clypeal margin with a median notch or impression, even if small .....20
 * Anterior clypeal margin entire, without a trace of median notch or impression .....24

20
return to couplet .....19


 * Occipital region of head with a rugoreticulum …..bicarinatum group


 * Occipital region of head at most with a few anastomoses, without a rugoreticulum .....21

21
return to couplet .....20
 * Propodeum with a pair of small triangular teeth or denticles …..dumezi group (part)


 * Propodeum with a pair of spines .....22

22
return to couplet .....21
 * Dorsal surfaces of petiole and postpetiole unsculptured or at most with only vestigial traces of sculpture …..camerunense group (part)


 * Dorsal surfaces of petiole, postpetiole or both distinctly sculptured .....22

22
return to couplet .....21
 * Node of postpetiole in dorsal view longer than broad…..camerunense group (part)


 * Node of postpetiole in dorsal view broader than long…..capense group

24
return to couplet .....19
 * Propodeum armed with a pair of elongate spines .....25
 * Propodeum at most with a pair of short, triangular teeth; sometimes only with a pair of denticles, most rarely unarmed .....28

25
return to couplet .....24
 * Dorsal (outer) surface of hind tibiae with erect or suberect hairs or pubescence .....26
 * Dorsal (outer) surface of hind tibiae without erect or suberect hairs or pubescence .....27

26
return to couplet .....25
 * Occipital region of head with a rugoreticulum …..quadridentatum group (part)


 * Occipital region of head without a rugoreticulum …..camerunense group (part)

27
return to couplet .....25
 * Either the anterior and dorsal faces of the petiole node in profile meeting in a smooth curve without a developed anterodorsal angle, or the eyes large with maximum diameter >0,30 x HW …..quadridentatum group (part)


 * Anterior and dorsal faces of the petiole node in profile meeting in an angle, a defined anterodorsal angle present. Eyes smaller< 0,26 x HW…..flabellum group (part)

28
return to couplet .....24
 * Mandibles longitudinally striate and the anterior and dorsal faces of the petiole node meeting in a smooth continuous convexity, without an anterodorsal angle …..quadridentatum group (part)


 * Mandibles smooth or striate. If the latter, then a distinct anterodorsal angle developed which separates anterior and dorsal faces of the petiole node .....29

29
return to couplet .....28
 * Mandibles usually sculptured. Hairs on dorsal alitrunk short, stout and blunt when present; if absent, then the eyes large, maximum diameter > 0,29 x HW or more …..simillimum group (part)


 * Mandibles usually smooth. Hairs on dorsal alitrunk fine and acute when present; if present, then eyes with maximum diameter < 0,29 x HW …..dumezi group (part)