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.

Key to workers from Africa. Note: With the availability of type images from Antweb, it now (January 2015) has become obvious that several of the Atopogyne "species" and lower forms were described from minor workers. I due course I will try to sort those. The true Atopogyne appear to be polymorphic and to have large colonies based on big carton nests.


Bicoloured, at least part orange or orange-yellow 2
-- Unicoloured, brown to black 3
2 {short description of image}Body brown, gaster orange; TL 3.7-6.4 mm; major head much wider than long, CI 118, SI 47
.
. {Crematogaster clariventris major} 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 - transiens
-- {short description of image}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
-- {Crematogaster n sp Liberia}Smaller TL 3.2-5 mm; colour generally red-brown (chestnut) but with posterior two-thirds of gaster much darker; distinguished by lack of erect hairs and very fine almost unnoticeable pubescence Liberia - new species Liberia
. Essentially unicolorous .
3 {Crematogaster sp A}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 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 (possibly minors only, but not stated, note species A also seems monomorphic); blackish, extremities brownish, tarsi and mandibles apically reddish Zare & Gabon - kasaiensis
. Propodeal spines distinct and set at top of declivity; metanotal groove quite deeply impressed .
5 {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 - 6
-- {Crematogaster depressa propodeum}Propodeal spines moderately long and not downturned; spiracle not raised depressa group - 11
-- buchneri group --
6 {Crematogaster africana head} Head longer than wide; TL 3.25-5.5 mm; propodeal spiracle prominently raised; matt, dull dark brown-black; numerous erect hairs .
. {Crematogaster african major} West Africa & Congo Basin - africana
-- Head at least as wide as long 7
7 {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 -
buchneri
-- Head square or nearly so 8
8 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 9
9 {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 .
. {Crematogaster wasmanni} West Africa & Congo Basin - wasmanni
-- TL of smallest at least 3.2 mm 10
10 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
-- Crematogaster batesi majorLarge TL to 7.5 mm; reddish-brown, with reddish appendages; matt and finely sculptured; (otherwise cf buchneri) Cameroun - batesi
return to key depressa group --
11 Propodeal spines short 12
-- Propodeal spines at least as long as width between bases 13
12 {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 .
. {Crematogaster depressa} West Africa & Congo Basin - depressa
-- {short description of image}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 .
. {Crematogaster jullieni} West Africa & Congo Basin - jullieni
13 {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
-- Sculpturation quite fine to reduced 14
14 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 15
15 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
-- {short description of image}TL ca 5.5 mm - 3.0 mm; fine striate sculpturation; colour black with yellowish extremities, dark orange mandibles quite distinctive; yellowish pilosity .
. {Crematogaster cuvierae} West Africa - cuvierae
Contents MYRMICINAE Introduction
2007, 2008, 2009, 2013, 2014, 2015 - Brian Taylor CBiol FSB FRES
11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K.

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