The Ants of Africa
Genus Crematogaster - Subgenus Atopogyne
Genus Crematogaster Introduction

Subgenus Atopogyne Forel (1911d: 343)

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.

The true Atopogyne appear to be polymorphic and to have large colonies based on big carton nests.

Key to workers from Africa - some sections of are left as visual groupings rather than fully dichotomous separations. As far as possible the images are of major workers.

Petiole with small but distinct anterior, subventral tooth; propodeal spines long and splayed out in dorsal view
-- Petiole without a subventral tooth
2 {Crematogaster ambigua}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 Congo Basin - ambigua
-- Crematogaster tibialisTL ca 4.0 mm; dirty yellow; with no more than very fine sculpturation
Congo Basin - tibialis
Bicoloured, at least part orange or orange-yellow 4
-- Unicoloured, brown to black 5
4 {short description of image}Body brown, gaster orange; TL 3.7-6.4 mm; major head much wider than long, CI 118, SI 47
West Africa & Congo Basin - clariventris
-- {Crematogaster transiens}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 & Zare - biimpressa
-- Crematogaster resulcataTL 4.3-4.7 mm; 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
South Africa - resulcata
-- {Crematogaster n sp Liberia}Larger, major TL 6.5 mm plus; colour generally red-brown (chestnut) but with posterior two-thirds of gaster much darker; distinguished by a lack of erect hairs and very fine almost unnoticeable pubescence Liberia - new species Liberia
. Essentially unicolorous .
Propodeal spines no more than sharp denticles,  metanotal groove weak 6
-- Propodeal spines distinct and set at top of declivity; metanotal groove quite deeply impressed 7
6 Crematogaster mottaziTL 3.5-5.6 mm; dark chestnut brown (species A? but this seems monomorphic) West Africa & Central African Republic - mottazi
-- Crematogaster kasaiensisTL 2.5-3 mm, head with sides and occiput rounded, the latter weakly so;  (possibly minors only, but not stated, note species A also seems monomorphic); blackish, extremities brownish, tarsi and mandibles apically reddish Zare & Gabon - kasaiensis
-- Crematogaster biemarginataTL 3.3-3.7 mm; orange brown
Cameroun & Zare - biemarginata
-- Crematogaster variegataTL 2.5-3 mm (possibly minors only, but not stated); head, alitrunk and gaster brownish, tarsi and funiculi yellowish
Cameroun & Zare - variegata
. Propodeal spines distinct and set at top of declivity; metanotal groove quite deeply impressed .
{Crematogaster africana propodeum}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 - 8
-- {Crematogaster depressa propodeum}Propodeal spines moderately long and not downturned; spiracle not raised depressa group - 15
Head longer than wide africana-group - 9
-- Head at least as wide as long 10
9 {Crematogaster african major}TL 3.25-5.5 mm; propodeal spiracle prominently raised; matt, dull dark brown-black; numerous erect hairs West Africa & Congo Basin - africana
-- Crematogaster winkleriTL 2.8-4.6 mm; uniform red-brown
Cameroun & Zaire - winkleri
-- Crematogaster batesi majorLarge TL to 7.5 mm; reddish-brown, with reddish appendages; matt and finely sculptured Cameroun - batesi
-- Crematogaster adulteraTL 3.5-5.8 mm; uniform dull yellow-brown;
Congo - adultera

return to key
buchneri group --
10 {Crematogaster buchneri} 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 West Africa & Congo Basin -
-- Head square or nearly so 11
11 Crematogaster laurentiTL no more than 2.6 mm; lightly sculptured; shiny black
Probably not an Atopogyne
Zare (? Nigeria & Guinea) - laurenti
-- TL of smallest > 2.6 mm 12
12 {Crematogaster wasmanni profile}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 West Africa & Congo Basin - wasmanni
-- TL of smallest at least 3.2 mm 13
14 Crematogaster thetaTL 3.4-3.7 mm; less shiny; propodeal spines longer (than laurenti) - close in size and form to the media 2 worker of depressa - below
Zare - theta
return to key depressa group --
15 Propodeal spines short 16
-- Propodeal spines at least as long as width between bases 17
16 {short description of image}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
-- {Crematogaster jullieni}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 West Africa & Congo Basin - jullieni
17 Crematogaster kohliTL 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 18
18 Crematogaster togoensisTL 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 - almost certainly a minima worker of C. depressa Togo - togoensis
-- {Crematogaster cuvierae}TL ca 5.5 mm - 3.0 mm; fine striate sculpturation; colour black with yellowish extremities, dark orange mandibles quite distinctive; yellowish pilosity (type damaged)
West Africa - cuvierae
Contents MYRMICINAE Introduction
2007, 2008, 2009, 2013, 2014, 2015, 2016, 2017, 2018 - Brian Taylor CBiol FRSB FRES
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