Crematogaster (Atopogyne) africana Mayr

Type location Cameroun (Cremastogaster africana nov. spec., Mayr, 1895: 142, worker; Santschi, 1937g: 78, queen), from Kriegsschiffhafen (Warship harbour), by H. Brauns - see below

Mayr's (1895) description is at ; with that of schumanni at . Emery (1899e) provided a drawing of the thorax profile of the major (top right) and noted how it could be distinguished from buchneri by having a prominently raised spiracle below the propodeal spine; this is at . Santschi's (1937g) description of the type queen (plus that of stanleyi) is at . Mayr's (1902) description of variegata is at . Forel's (1910e) description of biemarginata is at . Forel's (1911e) description of alligatrix is at . Forel's (1913h) description of brieyi is at . Santschi's (1915c) description of stanleyi is at . Santschi's (1921c) description of thoracica is at . Wheeler's (1922) description of tibialis is transcribed below. Santschi's (1937g) description of stolonis is at .

Nigeria specimens (Taylor, 1979: 35) - WORKER. Size very variable TL 3.23-5.51 mm; largest HL 1.46, HW 1.43, SL 1.00, PW 0.78
Colour generally dark brown-black. Dense pilosity, erect hairs abundant, postpetiole with 10-12 long hairs. Mandible of largest worker with a nearly straight masticatory margin. Alitrunk profile convex interrupted by a low mesonotal carina and a depression to a shallow metanotal groove. Propodeal spines short, acute and down turned. Postpetiole with the lower anterior corners rounded.

Santschi (1915c) described variety stanleyi as - WORKER - TL 2.8-3.8 mm; differs from type by its really black colour; with the funiculi and tarsi brown; and extreme sides of genae and apex of mandibles red yellow; length less variable; spines and pedicel as africana. Specimens from Congo, Mindouli, by A. Weiss, 1907. Santschi noted that with the type the colour is more brown and the length more variable.

Sexual forms are shown on Crematogaster africana sexuals.

The photomontage of the type minor worker is collated from http://www.antweb.org/specimen.do?name=casent0919658

This and the minor worker of Cameroun 97, below, are an exact match.

The photomontage of a cotype minor worker is collated from http://www.antweb.org/specimen.do?name=casent0908617

Oxford University Museum specimens

Largest worker

The photomontages are of workers collected in Cameroun - south-western tropical coastal forest area between Edéa and Campo (McKey Wolbachia project, Cameroon 97) . These are typical of africana as I encountered and drew in Nigeria.

Wheeler (1922) included the following description of tibialis: The photomontage is collated from http://mcz-28168.oeb.harvard.edu/mcz/FMPro?-DB=Image.fm&-Lay=web&-Format=images.htm&Species_ID=20846&-Find
WORKER - Length 3.5 mm. Pale castaneous. Propodeum, postpetiole, and posterior half of gaster of a deeper castaneous tint, passing to reddish brown. A spot on the vertex and the appendages dark. brown, the tibiae and metatarsi blackish, the tarsi and the'extremity of the thorax reticulate, the propodeum more finely, with some fine longitudinal rugae on the whole basal surface. Sides of the mesonotum regularly reticulate-punctate, Sides of the pronotum more shining and of the propodeum longitudinally striate. Petiole finely reticulate; gaster finely shagreened, almost smooth. The pubescence is rather well developed on the head, the gaster, and the appendages, sparse on the thorax. The hairs are very sparse, except around the mouth and at the tip of the gaster. Head square, with rather convex sides and straight posterior border. Eyes at the middle of the sides. Frontal area short, feebly impressed behind. Frontal carinae developed. Clypeus slightly convex, with rather arched anterior border. Mandibles striate-punctate, with four blackish teeth. The pronotum forms with the basal surface of the mesonotum a plane surface with a contour like that of C. castanea Smith. Sides of the basal surface of the mesonotum blunt, not marginate, with the anterior eminence scarcely indicated. Promesonotal suture little or not at all impressed. Sides of the pronotum marginate. Declivity of mesonotum oblique, feebly concave from right to left, above with marginate sides. Metanotal furrow moderately deep. Dorsum of propodeum trapezoidal, its length equal to its width anteriorly in the small worker. It is convex in front, more feebly behind. The spines are as short as a fifth of the interval between their bases, which is concave. They are directed backward and slightly outward. Declivity as long as two-thirds of the basal surface and forming with it an angle of about 145°. Petiole trapezoidal, as broad as long, and as broad as the propodeum. Last antennal joint reddish. A fine and dense striation disposed as in africana (Mayr) but more or less effaced on the front, vertex and occiput, where the reflection is more shining than silky, Propodeum transversely striate-rugose. Petiole smooth, postpetiole and gaster very finely shagreened, almost shining. The head is, moreover, punctate as in africana and much less smooth in the individuals with large head. The head, which varies in size independently of the rest of the body, which is almost invariable, is sometimes longer than broad and scarcely emarginate behind, sometimes broader than long, strongly concave behind and with convex sides. Eyes more posterior than in africana. Frontal area narrow, strongly impressed and shining. Mandibles punctate, feebly striate. Metanotal impression stronger than in africana, the pronotum less marginate anteriorly. Mesonotum carinate, more elongate and with the declivous surface much less abrupt than in africana, with longer propodeal spines, even longer than in the variety variegata (Mayr) and a little farther apart. Petiole and postpetiole as in africana (notes sent to Wheeler by Santschi).
Numerous workers taken at the village of Mosekowa between Walikale and Lubutu by Dr. Bequaert from the peculiar pouches of Macaranga saccifera (Bequaert, 1922, p Part IV) growing in the Rain Forest. As only adult ants and no brood were found in the pouches, Dr. Bequaert does not regard them as true nests. The openings of the pouches were not closed with fibrous carton. Bequaert (p 454) also recorded them from stipules of an Uragoga species; and from Barteria deweverei (p 441).

Bionomics & distribution notes

Wheeler (1922) listed various other findings including the nominate from Ghana (at Aburi, R. Buchholz), Nigeria (Old Calabar) and Cameroun (Duala, von Rothkirch). Bequaert (1922, p 413) found workers of ssp tibialis inside the nectary containing leaf stipules of Macaranga saccifera at Mosekowa, Zaïre.

Forel (1909b) noted E. André had asked him to identify Crematogaster from Congo collected by Father Hermann Kohl and Professor Laurent, botanist, from in the stems of plants. These included this species, sample No. 21, from Kisangani [Stanleyville] in the hollow twigs of Cuviera angolensis. Forel (1911f) reported alligatrix (as ssp of buchneri) from Zaïre, Kasai, Kondué by Luja. Later, Forel (1915c) reported alligatrix as collected at St. Gabriel, Kisangani, Zaïre, by Kohl, with a carton nest attached to the trunk of a mango tree. Forel (1916) described camena as very close to variegata but darker, somewhat larger and with shorter subdentiform propodeal spines, plus a sharper pronotal carina and a deeper metanotal groove.

Bernard (1952) listed it as very common in tropical Africa; Forel and Santschi had created many races and varieties "without great value". Among the subdivisions from Guinea the Mt. Nimba surveys had found the typical form - 4 alate queens from Nion, Mount Tô (1900 m), a male at Yalanzou and several workers from Yanlé and Zouépo forest; also ssp schumanni (small and shiny) from Yanlé and Kéoulenta forest leaf litter; and ssp fickendeyi (medium sized, matt and shagreened) the most widespread form at Zouépo, Nion, forest at 1000 m, crests, etc.- but see kohli below.

A relatively common dominant species in Nigeria, building large carton nests on certain species of large forest trees (e.g. Silk Cottons, Ceiba pentranda and Bombax costatum) [clickable thumbnail photo right]. Rarely nests on cocoa. Forages very widely over trees adjacent to nest tree and will cross the ground between trees. Can cause some loss of production in cocoa by removing flowers, the extent of this loss and the reason for the activity is not known. On CRIN cocoa at Onipe 1/1 it occurred on 12.8% of cocoa trees, and on 7.7% under forest shade (W20), and in cocoa surveys (where it was not separated from Cr. depressa) it was found on 10-12% of trees (Taylor, 1977; Taylor & Adedoyin, 1978). Earlier from CRIN, perhaps on >10% of cocoa in pkd collections from two cocoa blocks, W13/2 and W18/1 (Booker 1968).

In Ghana, mentioned by Donisthorpe (1945b) as collected by H.E. Box (25.xii.1944) from Cola species in fringing forest in the savannah-forest belt of North Ashanti, 10 km north of Wenchi. It was listed by Strickland (1948 - as africanum, 1951a, b), who described it as generally not very common, but dominant in cocoa farms where Canthium trees were present (more than 5/ha), for example at Bunso (where Canthium had been planted at 10/ha) africana occurred on over 40% of cocoa. Bolton (1970-71) listed it as one of the six most common Crematogaster species on cocoa (simply at CRIG or in Ghana is not clear). Leston (1973) also regarded it as a dominant. Later collected by Room (1971) from all parts of the Mamfe-Mampong cocoa farm, his report includes reference to it nesting in cocoa canopy. It also occurred in 32 of his 168 canopy samples at other farms; 30 of those samples, however, were from trees selected for its presence as a dominant. Room also reported its occurrence as the commonest of all insects on cocoa mistletoe - with 62,511 workers from 445 of 630 samples of the mistletoe/cocoa junction, and 122 of 175 samples of mistletoe plants (Room, 1972a, b, 1975). In the first of those papers, Room described its special relation with the pseudococcid, Cataenococcus loranthi (Strickland), the most prevalent of mealybugs on cocoa mistletoe. He noted, however, that Cr. africana was particularly common in the study area, the Akwapim Hills, and that other dominants were relatively scarce there. Bigger (1981a) also referred to its special relationship with Planococcoides njalensis on Canthium subcordatum.

It was among the dominant species studied at Nko'emvon in Cameroun by Jackson (1984), occurring on 25% of the trees in one cocoa plot and negatively associated with Oecophylla longinoda and Tetramorium aculeatum. She described it as preferring dense canopy but did not mention its nest sites. In a study of terrestrial foragers, she found it in large numbers in two heavily shaded grid squares (each being 1 of 12 sampling areas in the study plot).

The photomontage is of a major worker from Ghana, collected by S Sky Stephens, 2006.