The Ants of Africa
Contents - Myrmicinae - MYRMICINAE Introduction

Genus Tetramorium Mayr (1855: 423), includes previous Macromischoides, Triglyphothrix and Xiphomyrmex

In Tribe TETRAMORIINI. Synonymy of former genera by (Bolton, 1976, 1980, 1985).

{Tetramorium worker clypeus}Diagnostic Features - Antennae 11- or 12-segmented, with a 3-segmented club. Antennal scrobes absent to feebly present; frontal carinae often extended as a pair of diverging longitudinal rugae. Mandibles with three or four large teeth apically, followed by a variable number of denticulae. Posterior lateral margins of clypeus raised into a ridge bordering the antennal insertions (see image, right, adapted from Arnold, 1917: 272, and my own photography). Pronotum characteristically square-shouldered in dorsal view due to the sharp anterolateral angles. Promesonotal suture absent; metanotal groove usually impressed. Propodeum with a pair of spines or teeth; metapleural lobes present, acute, and may project as a lower pair of spines. Sting with an apicodorsal lamelliform appendage. Femora usually distinctly swollen.

Mayr's (1855) genus definition is at {original description}. Mayr (1861: 61) reiterated his earlier genus description, this is at {original description}.

Erect hairs simple in most species, but divided in many former Triglyphothrix, and bizarre in a few species. The former Macromischoides (or at least African members) do not have the posterior lateral margins of the clypeus raised into a ridge bordering the antennal insertions; are less noticeably square-shouldered; and have a more rounded shape to the head in full face view, plus antennal scapes which surpass the occipital margin.

Of Tetramorium sensu stricto, Bolton (1980) recognised 176 species from sub-Saharan Africa. In his review of the former genus Triglyphothrix, Bolton (1976) described 55 species, 33 being from the Afrotropical region. Initially in 1998, accepting the synonymy of Triglyphothrix with Tetramorium (Bolton, 1985), I selected those with occurrences in one or more West African countries (including more recent findings) and, because of the large number of species, plus the high quality of Bolton's keys (Bolton, 1976, 1980), I drew up a Key to facilitate identification of the species known from West Africa. The list included species known primarily or solely from savannah, as such species sometimes occur in open, drier spaces in the forested areas.

In addition to the species in the key, I listed the three so-far unnamed species found by Belshaw & Bolton (1994b); and seven species known from Gabon or Zaïre - which might be found in West Africa, see, for instance the recent discovery of the previously Angolan species Tetramorium youngi by Belshaw & Bolton (1994b). Unfortunately, Bolton (1976, 1980) gave no indication of what the well-used coding encountered in reports by CRIG and CRIN collectors meant in terms of the fresh revision of the genus. At the end of this page, I have listed such coding and indicate which species seem to be involved. Finally, the names used are those given in Bolton (1995), where species names with an adjective as their root were corrected where necessary to agree in gender with the masculine genus, and where some otherwise published but recent synonymies and revivals were listed.

In 2001, I decided to add species known from the Congo Basin. Although a little clumsy, I modified the key by adding couplets numbered xxA, xxB and so-on, rather than renumbering the entire key and adjusting the many links. This was in two parts.

New style interactive key

With the expansion to cover all the ants of sub-Saharan Africa, I have developed a fresh style of interactive key. This is a departure from the traditional dichotomous key but I am trying it as a way of making the key more visual and comparative. It is compiled largely from the groupings used by Bolton (1976 & 1980) and the synonymisation of Triglyphothrix by Bolton (1985); the names are as in Bolton (1995).

This starts on Tetramorium species-groups 1, which is the first of six pages. The species information is provided on twelve further linked pages (see below for a linked alphabetic list of the species).
The format in summary is -

Primary division (approximates to former sub-genus level)
Secondary division
Tertiary division - only under Tetramorium (Tetramorium)
Quarternary division - only under Tetramorium (Tetramorium)
Sub-division - only under Tetramorium (Tetramorium)
with further separation as necessary
Species-group (note ¤) Diagnostic character(s)
Bolton key couplet number
(1976* or 80)
Diagnostic character(s)
with image if available
Tetramorium xxxx Known distribution

Note ¤
Some groups are further divided into species-complexes.
In some instances, the diagnostic characters used by Bolton (1980) lead to a particular species-group at more than one point.
The final column gives the determination point for individual species when Bolton's dichotomous keys to species are followed. This shows that a few species appear in what seem to be odd places relative to other members of a species-group or species complex, as defined in Bolton's papers. Bolton explains this by noting - that some species-groups are convenience assemblages, apparently solely to avoid having too many species-groups with only one member; and - that his key to species-groups was provisional.
Includes revived species and new species status names as in Bolton (1995: 403).

Unresolved forms

Tetramorium new species (from Nigeria)

Mentioned by Bolton (1985) as being in the British Museum collection, and having entirely trifid hairs but with some 2-4 bifid; 11-segmented antennae, and in antrema-complex. No other details were given.

Tetramorium new species (from Ivory Coast)

Mentioned by Bolton (1985) as being in the British Museum and MHN, Geneva collections, and having entirely trifid hairs; 11-segmented antennae, and in antrema-complex. No other details were given.

Tetramorium new species (weitzeckeri group)

Presumably with 11-segmented antennae and a squamiform petiole. From Ghana primary forest at Kade, Atewa Forest Reserve and secondary forest at Bunso in leaf litter, a total of 30 workers, by Belshaw & Bolton (1994b). Described as Tetramorium intermedium Hita Garcia, Fischer & Peters (2010)

Tetramorium new species (convexum group)

Presumably similar to convexum, in having smooth mandibles. From Ghana secondary forest at Bobiri and primary forest at Esukawkaw Forest Reserve in leaf litter, a total of 5 workers, by Belshaw & Bolton (1994b).

Tetramorium new species (dumezi group)

Presumably similar to dumezi, in having no more than a pair of small triangular teeth or denticles on the propodeum. Two specimens from Ghana, secondary forest at Bunso in leaf litter by Belshaw & Bolton (1994b).

Undetermined species from Ghana , all probably among the named species -

Strickland (1951a) noted that there were a few species which were all soil nesting and of very minor importance on cocoa including an unnamed and uncoded Xiphomyrmex, also:
Tetramorium species 541. Sporadically associated with mealybugs on Ghana cocoa (Strickland, 1951a).

Species listed in Room (1971) from the Mampong Cemetery site. Although, six species, amentete, ataxium, distincta, muralti, sitefrum and versiculum, were listed by Bolton (1980) as collected by Room from Mampong, they are not linkable by derivation. These are:
Tetramorium species L. In cocoa leaf litter. Bigger (1981a) recorded it by pkd from canopy and on the ground (57 workers in one plot) in a single area of Amelonado cocoa at CRIG.
Tetramorium species S. In cocoa leaf litter and nesting in dead wood on the ground.
Tetramorium species T. On open ground under Lantana scrub.
Tetramorium species A15. On mistletoe on cocoa canopy.
Tetramorium species 37. In cocoa leaf litter and on open ground under Lantana scrub; also by Majer (1975) at Kade.
Tetramorium species A 205. In cocoa leaf litter and nesting in dead wood on the ground.

Others listed by Majer (1975, 1976b). Bolton (1980) listed findings by Majer at Kade as including amentete, browni and guineense.
Tetramorium species 1. On cocoa at Kade, by pkd, with five workers in one sample.
Tetramorium species A. On cocoa at Kade, by pkd, with eight workers in one sample. Also in Bigger (1981a) leaf litter only at CRIG, 4-14 workers per one hour search.
Tetramorium species B. On cocoa at Kade, by pkd, with 13-16 workers in each sample, and at CRIG (Bigger, 1981a).
Triglyphothrix species K. On cocoa at Kade, by pkd (apparently not in his later list, 1976b), and at CRIG on leaf litter (42 and 5 in two samples) (Bigger, 1981a). Possibly Tetramorium brevispinosum as that is one of the few former Triglyphothrix recorded above ground.

Others listed by Room (1975). These probably are the four species, convexum, dumezi, elidisum and wadje listed as collected at Aburi by Room in Bolton (1980).
Tetramorium species 15. From cocoa mistletoe (Room, 1975).
Tetramorium species 41. From cocoa mistletoe (Room, 1975).
Tetramorium species 52. From cocoa mistletoe (Room, 1975).
Tetramorium species 63. From cocoa mistletoe (Room, 1975).

Others listed by Bigger (1981a); none of his collections were sighted by Bolton (1980)
Tetramorium species C. Leaf litter (10 workers) and pkd (4) from CRIG.
Tetramorium species G. Leaf litter (9 workers) from CRIG.
Tetramorium species (former Xiphomyrmex species A). Leaf litter (2) from CRIG. See Tetramorium muralti
Tetramorium species (former Xiphomyrmex species B). Leaf litter (3-14 in four samples) from CRIG.
Tetramorium species (former Xiphomyrmex C). Leaf litter (2 and 5) from CRIG.
Tetramorium species (former Triglyphothrix species A). Leaf litter (1-4 in three samples) from CRIG.

Undetermined species from Guinea

Tetramorium shilohense?

Bernard (1952) recorded, under the name T. shiloense Forel, several workers from Guinea, Mt. Nimba, sample area F 110, savanna at Ziéla, which he thought were of this southern species, "ex-race of T. simillimum", of which the subspecies "congolense Santschi" was more northerly. No subspecies of this name is listed in Bolton (1995) nor Wheeler (1922). Tetramorium shilohense itself was given by Bolton (1980) as stat. n., type location Rhodesia (Forel, 1913c), with other records from Malawi, Zambia and Zimbabwe. The new status is somewhat curious as Bernard's comment indicates that it was already established as a full species. Given the distance of its known distribution, I am inclined to think these Mt. Nimba specimens are of either Tetramorium intonsum which is known from savanna in Ivory Coast (Dabou, west of Abidjan), i.e. not too far from Mt. Nimba, or less likely Tetramorium jugatum, which seems a forest species.
Contents MYRMICINAE Introduction
© 2007, 2011 - Brian Taylor CBiol FSB FRES
11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K.