Genus Crematogaster - Subgenus Orthocrema
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The Ants of Africa Genus Crematogaster - Subgenus Orthocrema |
| Genus Crematogaster Introduction |
Diagnostic Features - Antennal club 2-jointed. Frontal carinae well developed. Petiole with parallel sides, usually straight or scarcely arcuate, rarely broader posteriorly than anteriorly. Postpetiole entire.
Santschi's (1918d) subgenus description is at
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Described by Bernard (1952) as primarily oriental, small ants, often
soil-inhabiting, considered as the most primitive of the genus by virtue
of the petiole structure.
Key to workers
| 1 |  TL
2.2 mm; with long scapes, surpassing occiput, and convex elongated eyes;
head rectangular, as long as wide; eyes convex, elongated, as long as a
third of the head and placed in the posterior third; scape arcuate
surpassing posterior border of head; pronotum bordered transversely with
distinct anterior angles; propodeal spines about 2/3 as long as basal
interval, recurved apically; thorax with three pairs of erect hairs, one
pair on each node of pedicel; shiny, anterior of cheeks and mesopleuron
finely striate; colour red-brown, appendages and anterior half of gaster
yellowish, rest of gaster blackish |
Zaïre & Gabon - gratiosa |
| -- | Scape not or only just surpassing the occiput, eyes convex or flat | 2 |
| 2 |  Alitrunk
flat to slightly concave; few erect hairs in pairs on alitrunk and
pedicel; long propodeal spines |
3 |
| -- |  Alitrunk
convex; no or only short propodeal teeth |
5 |
| -- | Alitrunk flat to slightly concave; few erect hairs in pairs on alitrunk and pedicel; long propodeal spines | -- |
| 3 | Unicolourous black; TL 3 mm; head regularly and finely longitudinally striate but with median smooth strip; most of rest of body reticulo-punctate; erect pilosity whitish, set out in pairs on each segment of alitrunk and pedicel; shiny black, mandibles and tarsi brown | Kenya - jeanneli |
| -- | Other than unicolourous black | 4 |
| 4 | 
TL 2.3-2.5 mm; head rounded with a faint longitidual median line;
pro-mesonotum with longitudinal carinae but not laterally bordered;
propodeum with a distinctive longitudinally elliptical spiracle with a
sclerotinized border; distinctly bicoloured - head, alitrunk and pedicel
shiny clear yellow but gaster entirely black; very shiny and
unsculptured; |
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Guinea & Cameroun - pulchella |
| -- | TL
2.0-2.6 mm; head wider than long, angles rounded; eyes placed well back;
scape robust and surpassing occiput; club two-segmented; alitrunk
distinctly bordered; propodeum with a small circular spiracle, the
spines long and straight angled upward posteriorly; pubescence fine and
sparse, erect hairs slender and obtuse; few and short on anterior of
head, on alitrunk three pairs of large long hairs placed on lateral
border placed as shown; petiole and postpetiole each with one pair;
gaster with only narrower hairs; smooth and shiny, sides of alitrunk
reticulate, pedicel and gaster finely punctate; colour testaceous
yellow, gaster more brown-red; |
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Cameroun, Gabon and Zaïre - pauciseta |
| -- | TL 2.8 mm; eyes convex but petiole longer; propodeal spines long but not longer than the interval between their bases; body near smooth and shiny, two or three rugae or reticulae effaced on alitrunk dorsum; reddish to yellowish brown, gaster brown (if Forel, 1916: 404, was correct this is a large form of pauciseta) | Tanzania - dolens |
| -- | Alitrunk convex; no or only short propodeal teeth | -- |
| 5 | Head more circular than square; promesonotum marginate and wider in front than long; in dorsal view petiole quadrate and straight-sided; erect hairs quite abundant and slender | 6 |
| -- | Head rectangular; petiole not quadrate in dorsal view | 8 |
| 6 |  Without
propodeal spines; TL 2.2-2.5 mm; scape reaching occiput; reddish-yellow,
head brownish, gaster bright yellow |
Comoro Is - voeltzkowi |
| -- | With short, sharp propodeal spines | 7 |
| 7 |  TL
1.8-2.1 mm; petiole short, wider than long, straight-sided in dorsal
view; colour pale ochreous yellow |
Zimbabwe - rectinota |
| -- |  TL
2.0-2.2 mm; eyes flat, placed posterior of mid-point and about
one-quarter length of face; petiole straight-sided but longer than wide;
colour generally ochreous but posterior border of first gastral segment
and rest of gaster black; pubescence very sparse and yellowish, few
erect hairs |
Kenya - litoralis |
| -- | Head rectangular; petiole not quadrate in dorsal view | -- |
| 8 | Head
longer than wide; TL 2.7-2.8 mm; head rectangular, wider behind; eyes
large in posterior third; pronotum fairly distinctly marginate and with
small longitudinal median carina; metanotal suture shallow; propodeal
spines short; colour dark castaneous-brown, appendages lighter; erect
pilosity sparse and fairly coarse |
South Africa - transvaalensis |
| -- | Head square not longer than wide | 9 |
| 9 | TL 2.8-2.9 mm; body colour all over black; head square; eyes as large as one-fifth of face, placed in posterior third; scape reaches posterior sixth of head; promesonotum with convex profile; cheeks and thorax longitudinally striate; colour black; appendages brownish; | Zimbabwe - boera |
| -- | TL no more than 2.5 mm | 10 |
| 10 |  TL
2.0-2.5 mm; promesonotum narrower and longer not wider in front than
long; colour yellowish anteriorly and no more than reddish-brown |
South Africa - natalensis |
| Promesonotum wider in front than long | 11 | |
| 11 |  TL
2.2-2.4 mm; metanotal groove deep and narrow; sculpturation on pronotum
and lateral mesonotum of distinct fine longitudinal striations;
pubescence of thin decumbent yellowish hairs very scanty; erect hairs
yellowish few on thorax and petiole, more on the gaster, where they are
slightly clavate; shiny; colour piceous; appendages brownish-yellow
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West Africa & Central African Republic - muralti |
| -- |  TL
1-8-2.2 mm; head and alitrunk lightly striated; dark brown to black |
East Africa - ugandensis |
| -- |  TL
2.4-2.8 mm; quite coarsely sculptured; brown to dark brown |
Sudan (Imatong Mts) - molongori |
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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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