Genus Crematogaster - Subgenus Atopogyne
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The Ants of Africa Genus Crematogaster - Subgenus Atopogyne |
| Genus Crematogaster Introduction |
Diagnostic Features Antennae 11-jointed. Frontal carinae well developed. Promesonotal suture impressed, metanotum carinate in front. Propodeal spines often curved downwards. Petiole broadened in front, usually oval or at least rounded at the anterior angles. Postpetiole impressed behind.
Forel (1911d) erected the subgenus to separate depressa and julienni, together with the European species he described as hellenica (Forel, 1911d: 342; type location Greece; now regarded as a subspecies of Crematogaster (Atopogyne) lorteti Forel, 1910e: 435, type location Syria). His definition was - Subgenus, characterised by the depressed head, being rectangular or trapezoidal; with straight mandibles, with a long terminal border, and elongated thorax, narrowed anteriorly; specially so in the female. On hellenica, he noted that it was easily distinguished from jullieni by the head being smooth (except anteriorly) and from depressa by its shorter mandibles with the entire terminal border with teeth.
Bernard (1952) noted the subgenus members as generally large and striated, the most common of the genus and the greatest nuisances in plantations; 21 species were known from Africa.
Key to workers from Africa
| 1 | Bicoloured, at least part orange or orange-yellow | 2 |
| -- | Unicoloured, brown to black | 3 |
| 2 |  Body
brown, gaster orange; TL 3.7-6.4 mm |
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| . |  |
West Africa & Congo Basin - clariventris |
| -- |  Smaller
TL 3.2-5 mm; colour like clariventris, generally blackish but
with gaster somewhat darker (red-brown?); mesonotum with carina
projecting forward less than clariventris; petiole narrow and
scarcely wider anteriorly |
Cameroun & Zaïre - transiens |
| -- |  Head
distinctly wider than long; pronotum from above regularly rounded;
mesonotum higher than pronotum with promesontal suture distinct;
propodeal dorsum only two-fifths the length of the declivity; head and
alitrunk yellowish-red-brown; gaster brown-black with base lighter; TL
4.3-4.7 mm |
South Africa & Gabon - resulcata |
| . | Essentially unicolorous | . |
| 3 |  Propodeal
spines no more than sharp denticles, set part way down declivity;
metanotal groove weak |
4 |
| -- | Propodeal spines distinct and set at top of declivity; metanotal groove quite deeply impressed | 5 |
| 4 |  TL
3.5-5.6 mm; dark chestnut brown (species A? but this seems monomorphic) |
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| . |  |
West Africa & Central African Republic - mottazi |
| -- |  TL
2.5-3 mm (possibly minors only, but not stated, note species A also
seems monomorphic); blackish, extremities brownish, tarsi and mandibles
apically reddish |
Zaïre & Gabon - kasaiensis |
| . | Propodeal spines distinct and set at top of declivity; metanotal groove quite deeply impressed | . |
| 5 |  Propodeal
spines with prominent raised spiracle at base (with distinct margin);
the spines usually fairly short and distinctly downturned (long in one
species) |
buchneri group - 5 |
| -- |  Propodeal
spines moderately long and not downturned; spiracle not raised |
depressa group - 11 |
| -- | buchneri group | -- |
| 6 | 
Head longer than wide; TL 3.25-5.5 mm; propodeal spiracle prominently
raised; matt, dull dark brown-black; numerous erect hairs |
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| . |  |
West Africa & Congo Basin - africana |
| -- | Head at least as wide as long | 7 |
| 7 | 
Head wider than long; TL up to 6.5 mm; mesonotum with high central
carina; propodeal spiracle lower; colour reddish-brown, appendages
darker; silky gloss appearance; sparse yellowish decumbent hairs |
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| . |  |
West Africa &
Congo Basin - buchneri |
| -- | Head square or nearly so | 8 |
| 8 | TL no more than 2.6 mm; lightly sculptured; shiny black | Zaïre - laurenti |
| -- | TL of smallest > 2.6 mm | 9 |
| 9 |  TL
2.8-3.5 mm; head square with rounded posterior corners, sides convex,
widest at level of eyes, in lateral view distinctly flattened; head with
dense fine striations, also on pronotum dorsum, rest of alitrunk and
petiole finely rugo-reticulate; dark chestnut brown; overall with fine
yellowish pubescence and quite numerous long erect hairs |
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| . |  |
West Africa & Congo Basin - wasmanni |
| -- | TL of smallest at least 3.2 mm | 10 |
| 10 | TL 3.4-3.7 mm; less shiny; propodeal spines longer (than laurenti) | Zaïre - theta |
| -- | Large TL to 7.5 mm; reddish-brown, with reddish appendages; matt and finely sculptured; (otherwise cf buchneri) | Nigeria - batesi |
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depressa group | -- |
| 11 | Propodeal spines short | 12 |
| -- | Propodeal spines at least as long as width between bases | 13 |
| 12 |  TL
3.4-7.3 mm; mandible of largest with reduced teeth; head near square
with fairly straight posterior margin; dark brown-black; dense pilosity |
. |
| . |  |
West Africa & Congo Basin - depressa |
| -- |  TL
3.2-5.5 mm; mandible with five teeth; short propodeal spines; short
petiole; head and alitrunk with dense fine striations; colour black,
apical areas rust; quite abundant long greyish hairs |
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| . |  |
West Africa & Congo Basin - jullieni |
| 13 | TL 3.2-4.0 mm; mandibles with four teeth; strongly sculptured with dense reticulation underlying strong striation; colour black, appendages brown; matt; dense short pilosity and overall pubescence | Zaïre - ambigua |
| -- | Sculpturation quite fine to reduced | 14 |
| 14 | TL 2.5-2.7 mm; propodeal spines as long as basal width and sharp; very black, shiny, almost no erect hairs and little pubescence | West Africa & Congo Basin - kohli |
| -- | Sculpturation of fine striations, not shiny | 15 |
| 15 | TL 3-4 mm; head slightly longer than wide; colour black, antennal club and tarsi dirty-yellow; short yellow decumbent hairs and some longer erect yellow hairs - seemingly like a minor of C. depressa | Togo - togoensis |
| -- |  TL
3.0 mm; fine striate sculpturation; colour black with yellowish
extremities; yellowish pilosity - seemingly like a minor of C.
depressa |
Ghana - cuvierae |
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MYRMICINAE Introduction | © 2007, 2008 - Brian Taylor CBiol
FIBiol FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. |
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