The Genus Crematogaster (Cocktail ants)
|Typical ‘carton’ nest built by Crematogaster ants; this one in the hedgerows near Albertinia|
There are about 43 species in Southern Africa, of which the most common are the Black Cocktail ant (Crematogaster peringueyi),the Brown Cocktail ant (Crematogaster melanogaster) and the Red Cocktail ant (Crematogaster castanea), which occurs along the south and east coasts and up into the northern interior of South Africa. The genus in Africa is in a fairly severe taxonomic mess, but includes a large number of forest species as well as thorn-dwelling species in savanna habitats.
Crematogaster peringueyi (Emery, 1895):
Black cocktail ant
Crematogaster melanogaster (Emery, 1895):
Brown cocktail ant
Crematogaster castanea (F. Smith, 1858):
Red cocktail ant
Size: Some confusion exists around the size of the ants. Some of the species are quite variable; C. peringueyi can vary [but not in the same nest, please note – these variations are in separate colonies] from 3.5 to 5 mm in length.
Some useful photos of C. peringueyi can be found at these links:
A couple of good photos of C. castanea are at these:
Crematogaster transvaalensis (Forel, 1894):
Small black cocktail ant
This is the only Southern African Crematogaster that belongs to the sub-genus Orthocrema. Based on characteristics not visible to the naked eye, the classification essentially places this small species amongst the most ‘primitive’ of the genus. Usually found under stones in subterranean nests, the species does not build the carton nests associated with the genus.
The workers are all the same size and measure about 2.5 to 2.8 mm; the colonies are small. The bodies are black with limited pilosity, with brown to reddish mandibles and brown legs.
The name means ‘from the Transvaal’, a complete misnomer as, although never common, the ants are widespread from the Western Cape fynbos to Limpopo.
Crematogaster orobia (Santschi, 1919)
Matroosberg cocktail ant
A small species (workers from 2.6 to 3.2 mm), the ants are black with dark brown mandibles, clypeus and tarsi [lower legs]. Fairly hairless; gaster smooth and shiny. At a microscopic level the petiole joint is more complex than in C. transvaalensis, but otherwise C. orobia is hard to tell apart from its distant cousin. However, the ant is rare and has only been found in the Western Cape at altitudes above 1500 m, so if you find black Crematogaster under stones anywhere above the Western Cape snowline they will with 99% certainty be C. orobia, not C. transvaalensis.
Survive invasive species:
Linepithema humile : Argentine ants : No
Pheidole megacephala : House ants : unknown
Lepisiota capensis : Small Black ants : unknown