Key to Afrotropical Tetramorium weitzeckeri-group species

The Tetramorium weitzeckeri-group species are primarily Afrotropical (one species occurs in both the Afrotropical and Malagasy regions). They were revised in 2010. Hita Garcia, F.; Fischer, G.; Peters, M. K. 2010. Taxonomy of the Tetramorium weitzeckeri species group (Hymenoptera: Formicidae) in the Afrotropical zoogeographical region. Zootaxa 2704:1-90.

This key is for all of the species in the Tetramorium weitzeckeri group except Tetramorium mpala. The species in this group can be divided into three species complexes. There is a key to these complexes on the T. weitzeckeri species group page. There is also a key to the species of the Tetramorium weitzeckeri species complex that includes T. mpala.

1

 * Antennal scrobe well developed and usually deep, with distinct, and often sharp, margin all around, frontal carinae curve down ventrally between posterior eye level and posterior margin of head to form the posterior and ventral margins of the antennal scrobe (Fig. 2A), in few species posterior margin weak but visible; sculpturation on cephalic dorsum often reduced, generally 3 or fewer rugae present between frontal carinae, in few species up to 5 or 6, never more. (T. muralti complex) . . . . . 2


 * Antennal scrobe developed, but shallow, never with a sharp margin all around, frontal carinae almost reach posterior margin of head and function as dorsal margin of antennal scrobe, ventral margin of antennal scrobe never differentiated (Fig. 2B); sculpturation on cephalic dorsum never reduced, always at least 7 (generally distinctly more) longitudinal rugae present between frontal carinae. (T. edouardi and T. weitzeckeri complexes) . . . . . 9

2
return to couplet #1
 * Species with characteristic bicoloration: head, petiole, postpetiole, and gaster very dark brown to black, strongly contrasting with white to yellow mesosoma and appendages (Fig. 3A). (Ghana, Ivory Coast, Nigeria) . . . . . . Tetramorium flavithorax


 * Head, mesosoma, and gaster uniformly coloured (Fig. 3B) . . . . . 3

3
return to couplet #2
 * Dorsum of mesosoma with 3 to 7 strong and unbroken longitudinal rugae (Fig. 4A) . . . . . 4


 * Dorsum of mesosoma with reduced sculpture, at most with weak partial rugulation on pronotum or mesonotum, but generally completely smooth and shiny (Fig. 4B) . . . . . 5

4
return to couplet #3
 * Antennal scape short (SI 65 - 70); petiolar node squamiform, strongly transverse and thin, in dorsal view between 2.5 to 3 times wider than long (DPeI 257 - 300); dorsum of mesosoma usually with 3, rarely 4, strong longitudinal rugae medially (Fig. 5A). (Cameroon, Gabon) . . . . . Tetramorium trirugosum


 * Antennal scape of moderate size (SI 74 - 81); petiolar node thickly squamiform, in dorsal view either less than twice as wide as long or only faintly more (DPeI 179 - 211); dorsum of mesosoma with 6 or more longitudinal rugae (Fig. 5B). (Ghana) . . . . . Tetramorium intermedium

5
return to couplet #3
 * Anterior clypeal margin always entire and convex (Fig. 6B) . . . . . 6


 * Anterior clypeal margin with a distinct median impression of variable size (Fig. 6A) . . . . . 7

6
return to couplet #5
 * Cephalic dorsum between frontal carinae with 3 longitudinal rugae, rugae between median ruga and frontal carinae often interrupted but always present (Fig. 7A); postpetiole rounded cuneiform, never with sharp dorsal transverse margin, in dorsal view never more than twice as wide as long (DPpI 173 -192). (Cameroon, Central African Republic, D.R. Congo, Gabon, Ghana, Ivory Coast) . . . . . Tetramorium muralti


 * Cephalic dorsum with 1 unbroken median longitudinal ruga between frontal carinae, rarely traces of short rugulae present anteriorly near posterior clypeal margin or posteriorly near posterior margin of head (Fig. 7B); postpetiole strongly cuneiform with sharp dorsal transverse margin, in dorsal view distinctly more than twice as wide as long (DPpI 216 - 263). (Angola, Cameroon, Central African Republic, D.R. Congo, Gabon, Ghana) . . . . . Tetramorium susannae

7
return to couplet #5
 * Metanotal groove impressed(Fig. 8A); postpetiole in lateral view strongly rounded dorsally and relatively low, only 1.25 times higher than long (LPpI 77 - 83), in dorsal view usually less than 1.5 times wider than long (DPpI 143 - 151) (Kenya) . . . . . Tetramorium kakamega


 * Metanotal groove never impressed (Fig. 8B); postpetiole in lateral view not strongly rounded dorsally, usually cuneiform, between 1.3 to 1.6 times higher than long (LPeI 62 - 73), in dorsal view between 1.5 and 1.8 times wider than long (DPpI 153 - 182) . . . . . 8

8
return to couplet #7
 * Petiolar node thickly squamiform, in dorsal view less than twice as wide as long (DPeI 188 - 196) (Fig. 9A); in lateral view weakly above twice as high as long (LPeI 47 - 50); colour uniformly reddish brown to brown. (D.R. Congo) . . . . . Tetramorium akengense


 * Petiolar node moderately squamiform, in dorsal view distinctly above twice as wide as long (DPeI 225- 268) (Fig. 9B); in lateral view between 2.3 to 2.8 times higher than long (LPeI 36 - 44); colour uniformly very dark brown to black. (Cameroon, Central African Republic, Gabon, Ghana, São Tomé & Principe, Togo, Ivory Coast) . . . . . Tetramorium occidentale

9
return to couplet #1
 * Petiolar node in profile distinctly squamiform (LPeI 25 - 43) (Fig. 10A), shape in dorsal view always elliptical, and usually distinctly much more than twice as wide as long (DPeI 219 - 367). (T. weitzeckeri complex) . . . . . 10


 * Petiolar node in profile high nodiform (LPeI 50 - 80) (Fig. 10B), shape in dorsal view never elliptical, more an irregular polygon with rounded corners, and generally less than 1.5 times wider than long (DPeI 110 - 154). (T. edouardi complex) . . . . . 18

10
return to couplet #9
 * First gastral tergite without standing hairs (Fig. 11A) . . . . . 11


 * First gastral tergite with standing hairs (Fig. 11B) . . . . . 14

11
return to couplet #10
 * Mesosoma with abundant long, erect hairs (usually 7 to 8 pairs of hairs) (Fig. 12A). (South Africa, Swaziland) . . . . . Tetramorium sepultum


 * Mesosoma usually without long, erect hairs, in 1 species with up to 4 pairs of hairs at most (Fig. 12B) . . . . . 12

12
return to couplet #11
 * Whole mesosoma with very distinct reticulate-punctate ground sculpturation underlaying a fine, mostly longitudinal rugulation (Fig. 13A). (Burundi) . . . . . Tetramorium bendai


 * Mesosoma either mostly unsculptured or rugulose, but never with distinct reticulate-punctate ground sculpturation as above (Fig. 13B) . . . . . 13

13
return to couplet #12
 * Dorsum of mesosoma, especially of pronotum, unsculptured and shiny (Fig. 14A). (Madagascar, Comoros, Mauritius, Mayotte, Tanzania, Zambia, Zimbabwe, Namibia, South Africa) . . . . . Tetramorium humbloti


 * Most of mesosomal dorsum longitudinally rugulose (Fig. 14B). (Kenya) . . . . . Tetramorium tanaense

14
return to couplet #10
 * Dorsum of head with conspicuous reticulate-punctate ground sculpturation (Fig. 15A); propodeal spines always long to very long (PSLI 28- 43) (Cameroon, Central African Republic, D.R. Congo, Gabon, Ghana, Guinea, Ivory Coast, Liberia, Nigeria) . . . . . Tetramorium guineense


 * Dorsum of head without conspicuous reticulate-punctate ground sculpturation (Fig. 15B); propodeal spines variable, medium sized to very long (PSLI 17 - 45) . . . . . 15

15
return to couplet #14
 * Distinctly bicoloured species, head and mesosoma orange to reddish brown, petiole, postpetiole and gaster very dark brown to black (Fig. 16A). (Central African Republic, Kenya, Uganda) . . . . . Tetramorium snellingi


 * Whole body either uniformly brown to black or bicoloured with gaster, and often head, of lighter colour than mesosoma, petiole, and postpetiole (Fig. 16B) . . . . . 16

16
return to couplet #15
 * Generally bicoloured species with gaster, appendages, and head yellowish brown contrasting with reddish brown mesosoma, petiole, and postpetiole; mesosomal sculpturation partly reduced, dorsum generally with weak rugulation only, lateral mesosoma to great extent unsculptured (Fig. 17A). (São Tomé & Principe) . . . . . Tetramorium renae


 * Uniformly coloured species, generally dark brown to black; mesosoma dorsally and laterally strongly longitudinally rugose (Fig. 17B) . . . . . 17

17
return to couplet #16
 * Larger species (HW 0.772 - 0.933, HL 0.789 - 0.944, SL 0.600 - 0.744, WL 0.911 - 1.206); propodeal spines long to very long and spinose (PSLI 32 - 45) (Fig. 18A); open habitat species. (Angola, Eritrea, Kenya, Namibia, South Africa, Sudan, Swaziland, Tanzania, Zambia, Zimbabwe) . . . . . Tetramorium weitzeckeri


 * Smaller species (HW 0.644 - 0.744, HL 0.678 - 0.761, SL 0.467 - 0.539, WL 0.778 - 0.911); propodeal spines moderate to long, triangular-elongate to spinose, but never as long as above (PSLI 23- 29) (Fig. 18B); rain forest species. (Angola, Cameroon, Central African Republic, D.R. Congo, Equatorial Guinea, Gabon, Kenya, Nigeria, Uganda, Sudan) . . . . . Tetramorium boltoni 

18
return to couplet #9
 * Mesosoma, petiole, postpetiole, and first gastral tergite without standing hairs (Fig. 19A). (Tanzania) . . . . . Tetramorium mkomazi


 * Mesosoma, petiole, postpetiole, and first gastral tergite with standing hairs, may be simple or bizarre but always present(Fig. 19B) . . . . . 19

19
return to couplet #18
 * Pilosity bizarre (pectinate, pinnate, clavate, or broad, flattened, and appressed) (Fig. 20A) . . . . . 20


 * Pilosity simple, never bizarrely modified as above (Fig. 20B) . . . . . 22

20
return to couplet #19
 * Pilosity broad, flattened, and appressed, especially on first gastral tergite (Fig. 21A). (Cameroon, D.R. Congo, Kenya, Rwanda, Sudan, Tanzania, Uganda) . . . . . Tetramorium zonacaciae


 * Pilosity pectinate, pinnate, or clavate, but never broad, flattened and appressed (Fig. 21B) . . . . . 21

21
return to couplet #20
 * Pilosity pectinate, pinnate. (Angola, Kenya) . . . . . Tetramorium pinnipilum


 * Pilosity clavate, especially on first gastral tergite. (Angola) . . . . . Tetramorium rogatum

22
return to couplet #19
 * Eyes relatively small (OI 21 - 22), bicoloured species, gaster significantly much darker than remaining body (Fig. 22A) . . . . . 23


 * Eyes relatively large (OI 23 - 30), uniformly coloured species (Fig. 22B) . . . . . 24

23
return to couplet #22
 * Mandibles unsculptured, smooth and shiny. (D.R. Congo) . . . . . Tetramorium schoutedeni


 * Mandibles with longitudinal striation, sometimes fine but always present. (Cameroon, Gabon, Zambia) . . . . . Tetramorium philippwagneri

24
return to couplet #22
 * Median area of clypeus unsculptured, smooth and shiny (Fig. 23A). (Tanzania) . . . . . Tetramorium robertsoni


 * Clypeus with distinct median longitudinal ruga and 1 or 2 additional lateral rugae on each side (Fig. 23B) . . . . . 25

25
return to couplet #24
 * Antennal scapes larger (SI 85 - 92); eyes smaller (OI 23 - 26); head relatively longer (CI 87 - 91) (Fig. 24A); in profile metanotal groove not impressed; coloration reddish brown. (Cameroon, Ghana, Nigeria) . . . . . Tetramorium rubrum


 * Antennal scapes shorter (SI 76 - 83); eyes larger (OI 26 - 30); head relatively shorter (CI 90 - 95) (Fig. 24B); in profile metanotal groove distinctly impressed; usually of very dark brown to nearly black colour. (Burundi, D.R. Congo, Ethiopia, Kenya, Tanzania, Uganda) . . . . . Tetramorium edouardi