Genus Crematogaster - Subgenus Crematogaster
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|
The Ants of Africa Genus Crematogaster - Subgenus Crematogaster |
| Genus Crematogaster Introduction |
Diagnostic
Features - Antennae 11-jointed. Frontal carinae well developed.
Petiole broadened in front and trapezoidal, sometimes truncated or rounded
at the anterior angles, sometimes oval. Postpetiole grooved, or sometimes
merely impressed.
Bernard (1952) wrote "We arrive, alas, at the group with the most confused systematics, with 68 described species, most eastern (Africa)". He went on to comment how these are the most evolved Crematogaster in biological terms, some with very complicated carton nests and (?reduced) larvae with elongated exudation organs (notably Crem. rivai, from Erithrea). As with the genus as a whole, there was a need for revision "truly hardly possible today". In addition to the specific findings listed below, he noted the Mt. Nimba, Guinea, collections had yielded indeterminable males.
Santschi (1913a) considered Cremastogaster of the group tricolor-menileki,
providing a key; this is at 
;
tricolor now is regarded as a subspecies of castanea.
Substantive species separated were degeeri (from Madagascar), menileki,
alulai, impressa, amabilis, foraminiceps,
castanea (with 14 subspecies); excisa, neuvillei
and vulcania. Other useful keys are that for southern Africa by
Arnold (1920a), Menozzi (1930b) for Somalia, and Collingwood (1985) for
Saudi Arabia.
I came across several of these small brown to black species which seemed quite variable within themselves; but I attempted to select the most consistent characters in separating them into 'species'.
Key to workers, based mainly on historical sources and original
descriptions
Note - dichotomy not used where unnecessarily artificial.
Crematogaster santschii and Crematogaster trautweini now reverted to subgenus Oxygyne.
| ° | Queen only described | Angola - ancipitula |
| ° | Nomen nudum no known description | Zaïre - charon |
| ° | Details inadequate + queen | South Africa + ? Sierra Leone - cicatriculosa |
| ° | Queen only known | Cameroun - homeri |
| ° | Seems more likely to be a species of Cr. (Sphaerocrema), i.e. postpetiole entire, without median longitudinal groove | WC - nigrans |
| . | . | . |
| 1 |  TL
3.3-3.7 mm; antennae exceptionally long, reaching as far back as the
petiole, scape surpassing occiput by at least one-third its own length:
colour brownish red-yellow, front of head and petiole paler, gaster dark
brown |
South Africa - schultzei |
| -- | Antennae of usual length | 2 |
| 2 | Maxillary palp with 5 segments; all brown or lighter, red-brown or yellow-brown | 3 |
| -- | Maxillary palp with three/four segments | 8 |
| 3 | Propodeum spines limited to triangular teeth | 4 |
| -- | Propodeum spines sharp and elongated | 5 |
| 4 |  TL
3.5-4.4 mm; segments 3-5 of funiculus wider than long; head
(particularly on genae) and alitrunk strongly sculptured; brightly
coloured wine-red, with gaster near black |
East Africa & Saudi Arabia - mimosae |
| -- |  TL
4.5-5.3 mm; pronotum profile distinctly humped; gaster with superficial
sculpture and coarse pubescence; colour red-brown, gaster darker, may be
overall dark |
East & north east Africa and wider - aegyptiaca |
| -- | Propodeum spines sharp and elongated | -- |
| 5 | Alitrunk profile relatively flat without a raised section or keel on the mesonotum; quite finely striated on head and lateral alitrunk | 6 |
| -- | Alitrunk profile curved or humped anteriorly, with a raised section or keel on the mesonotum; more coarsely sculptured, especially on lateral alitrunk | 7 |
| 6 | TL 3.5-3.6 mm; petiole in dorsal view almost quadratic, not much wider anteriorly than posteriorly (similar to mimosae); head rounded-square, wider than the alitrunk; propodeal spines half as long as interbase distance; colour brown to red-brown; pedicel and gaster more yellow-brown | Cameroun - inconspicua |
| -- | TL 2.5-3.8 mm or less; petiole trapezoidal, widest in front; propodeum at same level of mesonotum but with a deep metanotal groove; head near matt with fine longitudinal striation (near smooth in type); alitrunk with weak sculpturation | West Africa & Congo Basin & ?S Africa - censor |
| 7 |  TL
3.5-5.5 mm; true senegalensis is brown rather than red and
vice-versa; gaster brilliant with fine sparse pubescence; |
type form - senegalensis |
| -- |  TL
3.5-5.5 mm; a confusing description of varieties suggests overlap with
aegyptiaca - the East African "senegalensis"
is rather redder, without the contrasting gaster; gaster dullish; head
much more coarsely scluptured |
East African form - senegalensis |
| -- | Maxillary palp with three/four segments | -- |
| 8 |  Maxillary
palp with three segments, antennal club of four segments; colour
uniformly castaneous brown; TL 3.5-4.0 mm |
Ethiopia & Somalia - rivai |
| -- | Maxillary palp with four segments, antennal club of three segments | 9 |
| 9 |  TL
2.8-3.8 mm; head distinctly longer than wide, parallel-sided; eyes small
and flat; scapes very short; propodeum with acute denticles; colour
black |
Zimbabwe - nigronitens |
| -- |  Head
near square, sides usually convex |
10 |
| 10 | Petiole other than triangular (parallel-sided or pyriform) - see 11 below | 11 |
| -- |  Petiole
essentially triangular |
12 |
| 11 |  TL
4.6-5.5 mm; petiole pyriform; posterior border with raised prominence;
scape extending well beyond occipitum; colour ferruginous-red, gaster
darker brown to black |
South Africa - melanogaster |
| -- |  TL
3.0-3.5 mm; petiole parallel-sided; scape extending beyond occiput;
propodeum rounding from dorsum into declivity, with no more than small
denticles; colour piceous |
South Africa - constructor |
| -- | Petiole essentially triangular | -- |
| 12 |   TL
3.3-3.5 mm; post-petiole distinctly wider than petiole; no pilosity;
overall very polished and shiny; colour black, antennal club
yellowish-red |
South Africa & Zaïre - santschii -reverted to subgenus Oxygyne |
| -- | Post-petiole not wider than petiole | 12 |
| 13 | Propodeum with no more than blunt tubercles or minute sharp denticles | 14 |
| -- | Propodeum with distinct sharp teeth or spines | 18 |
| 14 | Propodeum with no more than blunt tubercles | 15 |
| -- | Propodeum with distinct but very short teeth | 16 |
| 15 |  TL
3.5-4.2 mm; head smooth and shiny, with sparse fine punctures; propodeum
with no more than rounded tubercles; body red-brown, darker posteriorly |
dubiously recorded from sub-Saharan Africa - inermis |
| -- |  Limited
details; TL 2.5-3.8 mm; head square; mesonotum marginate; propodeal
spines absent or no more than tubercles denticles; dark brown or
red-brown, head lighter |
Madagascar & Mauritius - sewelli |
| 16 |  TL
3.4-4.1 mm; head, alitrunk and petiole dull; scapes short, not reaching
occiput; propodeum with minute denticles; colour brownish black |
East & southern Africa - delagoensis |
| -- | Colour brown or lighter | 17 |
| 17 |  TL
3.5 mm; head, alitrunk and pedicel brown, gaster yellowish |
Congo - ochraceiventris |
| -- |  TL
3.5-3.9 mm; head broader than long; sides convex, occipitum impressed;
scapes reaching occiput; alitrunk dorsum flattish, sides marginate;
propodeal spines short & conical; petiole broader than long;
shining, with feeble striation on head, alitrunk laterally and dorsal
pronotum; brown ferruginous |
Sudan - latuka |
| -- |  TL
2.8-4.0 mm; overall reddish-yellow; gaster lighter; propodeum with
distinct but minute spines |
Sudan - marnoi |
 |
Propodeum with distinct sharp teeth or spines | -- |
| 18 |  Pronotum
convex and mostly emarginate |
19 |
| -- |  Pronotum
distinctly marginate and flat, if not concave |
tricolor-menileki group of Santschi (1912); Arnold group C - 35 |
| 19 |  At
least some funiculus joints wider than long |
Arnold group A - 20 |
 All
joints of funiculus as long as or longer than wide |
25 | |
| -- | Arnold Group A | -- |
| 20 | With very wide heads, sides highly convex | 21 |
| -- | With head near square | 21 |
| 21 |  TL
4.0-4.2 mm; bicoloured, gaster black, remainder ferruginous red, quite
densely sculptured but shiny |
Kenya - kachelibae |
| -- |  TL
3.5-4.0 mm; overall colour dark brown or darker, anterior margins
brownish-red; alitrunk dull, closely and longitudinally rugulose |
Zimbabwe - rufigena |
| . |  |
Tanzania (closest to rufigena) |
| -- |  TL
3.8-4.0 mm; colour ferruginous-red or reddish raw umber, posterior of
head, alitrunk dorsum and apex of gaster darker to mahogany; essentially
smooth and shiny, sides of alitrunk longitudinally striate; clothed all
over with distinctive long, silky white pubescence; montane species |
South Africa - monticola |
| -- | Head near square | -- |
| 22 | Propodeal spines long | 23 |
| -- | Propodeal spines short | 24 |
| 23 |  TL
3.6-4.5 mm; overall matt, with quite dense puncturation between very
fine striate sculpture; general colour very dark red-brown; no erect
hairs but short, dense golden pubescence on gaster |
Niger - chopardi |
| -- |  TL
not given; head only slightly wider than long; propodeal spines long and
thin, at least 0.25 mm; body unicolorous dark brown to black |
Somalia & Saudi Arabia - affabilis |
| 24 |  TL
4.0-4.5 mm; sculpturation of head and alitrunk essentially striate to
rugose; gaster shiny but finely rugulose; colour dirty reddish-brown |
East & southern Africa - capensis |
| -- | TL 3.6-4.2 mm; head rectangular scarcely longer than wide; propodeal spines moderately long, straight divergent and oblique; dull only clypeus and legs shiny, most of head and alitrunk reticulate-punctate, gaster nitidulous; colour dark dusty-red, gaster brown | South Africa & Zaire - opaciceps |
| -- |  TL
3.5-4.0 mm; head wider than long; petiole not much wider than long;
alitrunk paler than head or gaster; propodeal spines at least 0.2 mm;
colour piceous, with reddish pubescence, alitrunk and mandibles |
primarily eastern Africa - chiarinii |
|
All joints of funiculus as long as or longer than wide | -- |
| 25 | Head very superficially sculptured and fairly shiny, at least on posterior two-thirds | 26 |
| -- |  Head
dull and closely sculptured except for median narrow longitudinal streak
on vertex |
Arnold group B (gerstaeckeri group) - 30 |
| 26 | Small species TL no more than 3.0 mm; propodeal spines set well down declivity; petiole with small but distinct antero-ventral tooth | 27 |
| -- | Larger species, TL 3.0-5.0 mm | 28 |
| 27 |  Small
species TL no more than 3.0 mm, colour black or piceous; Acacia gall-inhabiter |
east and southern Africa - gallicola |
| -- |  Propodeal
spines thick; base colour yellow-brown, head darker, apex of gaster near
black |
north-east Tanzania - rauana |
| 28 |  TL
2-4 mm; colour, at least head, yellowish or brown; lateral margins of
mesonotum bevelled; nests under bark? |
. |
| . |  |
West Africa and (? ssp omniparens) South Africa - brunneipennis |
| -- | Colour of alitrunk essentially reddish | 29 |
| 29 |  TL
3.0-3.6 mm; colour ferruginous-red, head piceous, appendages dull
ferruginous; pubescence very fine and short; head as wide as long, with
convex sides, strongly rounded posterior corners and near straight
occiput; funiculus segments 3-6 wider than long; head microscopically
reticulate, near smooth, alitrunk with reticulate sculpture; Acacia
inhabiter |
East & southern Africa - nigriceps |
| -- |  TL
3.0-5.0 mm; head distinctly reddish, gaster darker; head wider than
long; petiole not much wider than long; head and alitrunk pale
unicolorous red; propodeal spines 0.15 mm or less, reduced to tubercles;
weakly sculptured; occiput dull; second funiculus segment shorter than
third; Acacia inhabiter |
. |
| . |  |
Pan-African - acaciae |
| -- | TL 3.8-4.5 mm; gaster black but with narrow yellow borders; rest of body essentially red-brown but posterior of head darker; shiny and smooth; few erect hairs but quite long, abundant white pubescence | Namibia - gutenbergi |
|
Arnold group B - gerstaeckeri group with sculptured head | -- |
| 30 | Propodeal spines scarcely more than sharp denticles, relatively short scapes and funiculi | 31 |
| -- | Propodeal spines at least moderately long; scapes and funiculi longer | 32 |
| 31 |  TL
3.0-3.5 mm; colour dark-brown, anterior of head sometimes paler; head
more strongly striate than godfreyi (ssp. of sjostedti) |
East & southern Africa - arnoldi |
| -- |  TL
3.2-4.0 mm; mesonotum marginate with subdentate prominence at anterior
end; colour reddish-brown, alitrunk and pedicel paler; fairly abundant
long, decumbent, pale whitish-yellow pubescence all over, especially on
gaster (Arnold comparison with bulawayensis, ssp of gerstaeckeri) |
East & southern Africa - desperans |
| -- |  TL
3.6-5.0 mm; very little pilosity or pubescence; sculpturation overall
fine, whole ant with a slight gloss; colour variable piceous brown to
black |
. |
| . |  |
East & southern Africa - sjostedti and varieties inc. bulawayensis |
| -- | Propodeal spines at least moderately long; scapes and funiculi longer | -- |
| 32 |  TL
3.0-3.5 mm; colour yellow-brown |
Somalia - aloysiisabaudiae |
| -- | Colour at least dark brown | 33 |
| 33 | TL 3.3-3.6 mm; very wide head and long scapes surpassing occiput by 1.5 times own width; head, thorax and sides of petiole densely reticulate-punctate and submatt, on sides of head reticulo-striate post-petiole and gaster feebly shagreened and shiny; no erect hairs except at apices; colour brownish-black, appendages and articulation of pedicel red-brown, base of gaster reddish-brown | Zimbabwe - retifera |
| -- | Head square or slightly longer than wide | 34 |
| 34 |  TL
2.6-3.7 mm; colour dark-brown to black, scape dark red-brown, appendages
reddish; ssp atriscapus with head more strongly puncturate than
type; distinct puncturation on lateral alitrunk, also on dorsum and
sides of pedicel segments |
Ethiopia & Zaire - ruspolii |
| -- |  TL
3.2-4.0 mm; colour dark brown to black |
. |
| . |  |
northern sub-Saharan savanna - gerstaeckeri |
| -- |  TL
3.5-5.2 mm; head about one-seventh longer than wide, sides moderately
convex, occiput straight; scape barely reaches occiput, funiculus with
segments 2-4 at least as long as wide; propodeal spines thin and acute,
usually about half as long as interval between bases; dull, very closely
striate longitudinally on head more coarsely on alitrunk, gaster shiny
and smooth; pilosity scanty but fairly long and yellowish; moderate,
decumbent, pale yellowish pubescence; colour dark brown to black. |
South Africa - peringueyi |
| -- |  TL
3.5-5.0 mm, dimorphic; head square, wider than the alitrunk; quite
strongly sculptured with striations; promesonotum convex not marginated;
colour dark brown, appendages lighter, antennal club pale to white |
Cameroun & Congo Basin - impressiceps |
| -- |  TL
3.6 mm; eyes relatively large; alitrunk profile convex almost flat,
mesonotum with a slight carina but metanotal groove hardly interrupting
the profile; propodeal spines one-third down declivity, long, acute and
upward pointing; no subpetiolar spine; pilosity and erect hairs sparse;
lateral alitrunk and pedicel spiculate; colour dark brown-black |
Crematogaster (Cr.) species F970 |
|
Arnold Group C - pronotum distinctly marginate, mesonotum variable; profile flat or slightly convex | -- |
| 35 | Propodeum with short acute denticles | 36 |
| -- | Propodeum with at least moderately long spines | 43 |
| 36 |  TL
3.0-4.0 mm; colour black, gaster may be brownish, shiny, moderately
pilous |
Kenya - vulcania |
| -- | Colour primarily brown or lighter | 37 |
| 37 | TL 2.3-2.8 mm; cf excisa; colour pitch brown, head and gaster duller; noticeable whitish pubescence on head and gaster; largely smooth, except genae and antennal bases finely striate and alitrunk dorsum finely reticulo-granulate, dorsum of petiole microscopically reticulate; segments 2-6 of funiculus longer than wide; promesonotum laterally bordered, less concave than concava | West Africa & Congo Basin - coelestis |
| -- | TL generally > 2.8 mm | 38 |
| 38 | TL < 3.5 mm | 39 |
| -- | TL > 3.5 mm | 40 |
| 39 |  TL
2.7-3.3 mm; near solers, neuvillei and ilgii;
pro-mesonotum convex only slightly sculptured; few yellowish erect
hairs, sparse pubescence; colour dull reddish-brown, head and gaster
darker. This and the following three seem likely to be synonymous with
alulai as the senior name |
Ethiopia - alulai |
| -- |  TL
2.8 mm; scape narrow reaching posterior border of head, eyes large, oval
and moderately prominent; pronotum smooth and shining, convex, margined
anteriorly and laterally, anterior angles and sides rounded; metanotal
groove deep and well marked; mesonotum with striae on dorsal surface;
lateral mesonotum finely punctate; propodeal spines short, sharp and
projecting outwards and slightly downwards, marked angle at junction of
dorsum and declivity of propodeum; clothed with fine, short, decumbent
hairs; colour smooth and shining yellowish-brown |
? sp A1 - West Africa & Congo Basin - painei |
| -- | TL 3 mm; scapes reaching occiput; head near square with only slight convexity of sides; eyes slightly elongated, about 1/4 length of head, set in middle of sides; alitrunk as impressa, laterally raised from promesonotal suture to anterior margin; metanotal groove deep and lateral borders of propodeum raised, spines about 1/3 as long as interval between bases, slightly curved upwards; a few whitish erect hairs on head and gaster, pale pubescence; alitrunk dorsum finely reticulate, faintly striate on propodeum dorsum; clear yellow-brown, apex of gaster darker | Gabon - incorrecta |
| -- | TL ?; pro- and mesonotum margined and flatter; propodeal spines stouter; metanotal groove deeper than alulai | Eastern & Southern Africa - ilgii |
| 40 | TL 3.5-4.0 mm | 41 |
| -- | TL 4.0 mm or more | 42 |
| 41 |  TL
3.5-3.8 mm; scape almost reaching occiput; glabrous; head and alitrunk
clear red, gaster brownish |
? sp T¹ - pan-African - excisa |
| -- |  TL
3.6 mm; in profile alitrunk slightly convex, mesonotum with a vertical
rear face descending into a slightly impressed metanotal groove,
propodeal spines near halfway down declivity, stout, acute and
triangular; no subpetiolar spine; lateral alitrunk reticulo-striate,
markings faint on the pronotum; pilosity sparse and erect hairs few;
colour black, shiny |
Crematogaster (Cr.) species 3 |
| 42 |  TL
3.9-5.0 mm; colour clear brown, gaster chestnut, glabrous |
East and southern Africa - neuvillei |
| -- | TL 4.0 mm; head with almost straight sides; pronotum with well defined marginal line; mesonotum emarginate, with median prominence; propodeum with broad triangular teeth, hardly longer than basal width; longer narrower petiole with anterior ventral tooth; erect hairs absent on alitrunk and petiole; head reddish-brown, rest brownish red-yellow, appendages brown | Namibia - solers |
|
Propodeal spines more than 2.5 times the width of their base | -- |
| . | NOTE - the separation of the so-called subspecies, varieties, stirps, etc. of Cr. impressa is a confused mess with the original authors ignoring quite basic features such as sculpturation and colour | . |
| 43 | Head almost all smooth and fairly shiny (may be finely striate at least anteriorly) | 44 |
| -- | Head entirely sculptured | 46 |
| 44 | TL 4.0-4.2 mm; posterior part of petiole parallel sides and sides concave; colour light-brown, head yellowish | museisapientiae ssp of castanea |
| -- | Petiole with straight sides, not narrowing suddenly in the middle | 45 |
| 45 | TL 3.3-3.4 mm; scape well short of occiput; propodeum striated, spines short; colour essentially black | West Africa & Congo Basin - impressa |
| -- |  TL
3.7-4.0 mm; propodeum not striated, spines longer; colour essentially
brownish |
Pan-African - menilekii |
| . | Head entirely sculptured | . |
| 46 |  TL
3.4-3.9 mm; head globose; scapes not reaching occiput; very little
pilosity or pubescence; head and alitrunk dull and closely reticulate,
petiole and gaster shiny; generally reddish brown, gaster darker |
Zimbabwe - misella |
| -- | Alitrunk densely striated and matt; pronotum sometimes concave | 47 |
| 47 | With abundant erect pilosity (montane species) | 48 |
| -- | Erect pilosity sparse or absent | 49 |
| 48 | TL 4.0-4.5 mm; head densely and finely striate, with fine interspersed puncturation; with abundant relatively long pubescence; colour dark brown, apex of gaster almost black; alpine 2700 m and above | East Africa - amabilis |
| -- |  TL
3.4-4.3 mm; head more irregularly striate, with large hair pits,
especially on the occiput; colour brown-yellow; subalpine 1700 m |
Kenya & Zaïre - foraminiceps |
| . | With little or no erect pilosity | . |
| 49 | At least bicolored with part of the body distinctively lighter than the rest | 50 |
| -- | Essentially unicolorous | 51 |
| 50 |  With
the posterior of the gaster darker than the rest of the head and body,
and, the base of the gaster lighter than the other parts |
eastern Africa - tricolor |
| -- | Based on cacozela - TL 4.0-4.5 mm; head square, eyes occupy one-third of face; funiculus segments 3-7 as wide as long; pronotum laterally bordered, but promesonotal suture straight and not curved; propodeal spines about a quarter to a third longer than the dorsum of propodeum; lateral alitrunk reticulo-punctate; mostly shiny; colour yellowish-red, gaster black, appendages also dark | Pan-African - werneri |
| . | Essentially unicolorous | . |
| 51 | TL 2.6-3.5 mm; head square; scapes just exceeding occiput; alitrunk flat, propodeal spines fine, short and directed upward; head and alitrunk dull, head anteriorly sharply and closely striate, alitrunk and petiole finely reticulo-punctate; black, appendages dark brown | South Africa - orobia |
| -- | TL > 3.5 mm | 52 |
| 52 |  Head
subovate; frontal carinae short, not reaching anterior level of the
eyes; scapes short; generally no more than brown or brown-red, with
gaster darker brown |
Pan-African - castanea and its numerous varieties |
| -- | Head in full face view square; scapes reaching or almost reaching the occiput; base colour dark red-brown to black | 53 |
| 53 |  TL
3.5-4.0 mm; head square; scapes reach occiput; antennal club 3-segmented
but apical two segments slender; pronotum bordered, slightly convex;
submatt, most of head, declivity of propodeum and gaster shiny, sides of
mesonotum densely punctate; pedicel segments finely reticulate; colour
dark red-brown, posterior of head darker, gaster yellow ochre to yellow
brown; appendages yellow to orange |
. |
| . |  |
West Africa - stigmata |
| -- |  TL
2.8-4.0 mm; petiole with quite rounded sides; in profile promesonotum
flat and slight carination of the mesonotum; metanotal groove deeply
impressed, mesonotum with a vertical posterior face; propodeal spine one
third down the declivity, stout and moderately long; subpetiolar spine
short and blunt; lateral mesonotum, propodeum and pedicel spiculate,
some specimens with faint striations; pilosity sparse, erect hairs few,
most on the head and gaster; colour dark brown/black, shiny. |
. |
| . |  |
Cango Basin & Nigeria - acis |
| -- | TL 4.0 mm; head square; frontal carinae reaching posterior third of eyes; eyes feebly convex filling third quarter of face; scapes just surpassing occiput; funiculus segments 3-5 wider than long; pronotum with distinct but rounded margination, slightly concave (cf andrei - impressa); dorsum of head shiny, anterior finely striated, alitrunk finely and densely striated on the dorsum, partly replaced by fine puncturation which dominates the lateral alitrunk, also on pedicel, gaster shiny but with microscopic reticulation; black, appendages dark red, apex of gaster yellowish | Ivory Coast - vidua |
 |
MYRMICINAE Introduction | © 2007, 2008 - Brian Taylor CBiol
FIBiol FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. |
href="crematogastersg.htm"
