Ants of Kenya

This webpage is the regional project page for Kenya. A list of species can be found here Kenya

The most recent study to assess the Kenyan ant fauna is: Hita Garcia, F.; Wiesel, E.; Fischer, G. 2013. The ants of Kenya (Hymenoptera: Formicidae) - faunal overview, first species checklist, bibliography, accounts for all genera, and discussion on taxonomy and zoogeography. Journal of East African Natural History 101:127-222. DOI: 10.2982/028.101.0201 This webpage is based on this publication. There are 596 species in 63 genera from 12 ant subfamilies known from Kenya.

Generic Diversity Table
The following table provides an accounting of the number of species for each genus. The last column of the table, Taxonomic Status, provides some idea of the taxonomic status of the genera. Good means that the number of species given here is likely a good estimate of the generic diversity, fair means revisionary work is needed but the genus is not likely to be much more diverse and poor indicates there remains much uncertainty in regards to the number of species for the genus. More information about each genus is also given in the text that follows this table. Links are provided that will easily move between the table and text for each entry.

Genera are organized by subfamily (listed in alphabetical order), and are listed in alphabetical order within each subfamily. The ordering of the rows can be changed to show other arrangements by clicking on a heading.

Generic Accounts
Genera are organized by subfamily (listed in alphabetical order), and are listed in alphabetical order within each subfamily.

Aenictus
The Old World genus Aenictus is distributed in the Afrotropical, Palaearctic, Oriental and Indo-Australian regions (Gotwald, 1982, 1995; Shattuck, 2008). Currently, it comprises 148 species worldwide, of which 40 are found in the Afrotropical region (Shattuck, 2008; Bolton, 2012). In Kenya there are six valid species, two subspecies and three unidentified morphospecies from Kakamega. These species numbers should however be regarded with caution, since the taxonomy of this genus is in a state of confusion. Most species were described on the basis of a single unassociated caste or sex. This might indicate that the real number of species is significantly lower since it is very likely that the unknown castes from an already described species were not adequately recognised but described as different species. Emery (1910) provided a list of the then known fauna, and some species or unknown sexual forms were described some decades ago (Gotwald & Cunningham-van Someren, 1976; Gotwald & Leroux, 1980; Campione et al., 1983). Nevertheless, no modern taxonomic revision is available for the Afrotropical region, and without keys the identification to species level is often difficult or impossible.

Aenictus are small, blind, monomorphic army ants that live in colonies with hundreds or thousands of workers and seem to be specialised predators of ants or other social insects (Wilson, 1964; Gotwald, 1982, 1995). Despite the large colony size, they are generally inconspicuous due to their hypogaeic lifestyle and appear to be comparatively rare on a local scale (Shattuck, 2008). Like other army ants, they display nomadism, and migrate to new nesting sites after depletion of prey colonies in their environment. Furthermore, Aenictus possesses specialised dichthadiiform queens with an increased egg-laying ability and new colonies arise through colony fission (Gotwald, 1982, 1995).

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Aenictogiton
The genus Aenictogiton is of extraordinary interest within the Afrotropical region. The genus occurs in Central, South, and East Africa, and is biogeographically limited to the Afrotropical region (Brown, 1975; Parr et al., 2003; Hita Garcia et al., 2009). Material of Aenictogiton is generally scarce, and consists solely of male specimens. Brown (1975) already stated the complete lack of knowledge concerning the female castes, which, despite intensive search efforts, have not been discovered until the present day. The known species richness appears comparatively small, with just seven described species (Brown, 1975), although a good number of unidentifiable and possibly undescribed specimens located in several museum collections await taxonomic examination and possibly description as new species. The taxonomy of the genus can be regarded as unsatisfactory since it was never revised after the initial species descriptions (Emery, 1901; Forel, 1913; Santschi, 1919b, 1924). The only Kenyan species is an unidentified male-based morphospecies recorded from the Kakamega Forest.

The biology of this enigmatic genus remains an almost complete mystery. Brown (1975) mentioned the possibility that these ants are subterranean or otherwise strongly cryptobiotic; we fully agree since no foraging worker nor any trace of a colony could ever be found. Phylogenetic and morphological affinities to the army ant genus Dorylus suggest an army-ant-like lifestyle, although there is no current evidence for this. However, most males were collected from light traps close to forest localities, indicating that Aenictogiton might prefer forested habitats.

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Stigmatomma
The genus Stigmatomma is of global distribution and holds currently around 60 described species (Yoshimura & Fisher, 2012). Since Brown (1960) it was considered to be a junior synonym of Amblyopone Erichson, but it was recently revived to genus rank (Yoshimura & Fisher, 2012). In the Afrotropics it seems to be relatively species-poor with only three described species (Brown, 1960; Gotwald & Levieux, 1972), but it should be mentioned that more than 13 undescribed forms exist in several museum collections (Brian Fisher, personal communication). Two unidentifiable and possibly undescribed species are known from the Kenyan coast. Although Brown (1960) reviewed the genus (as Amblyopone) on a global basis, he did not provide a revision of the Afrotropical fauna. One species was described later, but outside of a generic framework (Gotwald & Levieux, 1972). As a consequence, the genus is in need of a modern taxonomic revisionary work.

Members of this genus, as most amblyoponines, are specialised predators, which are thought to hold several ancestral anatomical and behavioural character states (Fisher, 2003). Stigmatomma species are known to live a hypogaeic lifestyle as predators of chilopods (Gotwald & Levieux, 1972) and in addition, are known as "dracula ants" that feed on their own larvae (Fisher, 2003; Saux et al., 2004). Queens can be observed to perform a form of non-destructive cannibalism by cutting a hole in the larval integument to feed on the exuding hemolymph. This however does not seem to harm the larvae, which continue growing and eventually emerge as normal adults.

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Cerapachys
The genus Cerapachys is widely distributed across the World's tropics and subtropics, although most of the 146 known species occur in the Old World (Brown, 1975; Bolton, 2012). Although treated by Brown (1975) on a global base, the taxonomy of this genus is far from satisfactory, especially for the Afrotropical region. Brown (1975) listed around 20 described species from this region and presented an identification key to the worker caste, but postponed a formal revision until more material would become available. He also presented some doubts on the species status of some species, and mentioned the existence of several undescribed species. Unfortunately, since then no more works on Afrotropical Cerapachys have been published. Consequently, the identification to species level with Brown's (1975) key is often unreliable. At present, we recognise eight valid species and two morphospecies for Kenya.

Cerapachys ants are specialised predators of other ants that conduct raids to attack prey nests. They retrieve captured larvae and pupae, less commonly also adults, to their own colony and store them as food (Hölldobler, 1982; Brown, 1975). Wilson (1958) and later Brown (1975) raised the question of whether Cerapachys and other members of the subfamily are nomadic, and proposing that nomadism might have evolved as special adaptation in ant-hunting cerapachyines in order to avoid depletion of prey. Members of this genus can be encountered in a variety of habitats ranging from humid rainforests to arid savannah grasslands or semi-deserts, and nests are generally constructed in the ground or in rotten wood (Brown, 1975).

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Simopone
Simopone is distributed in the Afrotropical, Malagasy, Oriental, and Indo-Australian regions and it holds 38 described species (Brown, 1975; Kutter, 1976, 1977; Bolton & Fisher, 2012), of which most are found in the Afrotropical and Malagasy regions. In their recent revision of the genus Bolton and Fisher (2012) list 18 species for the Afrotropical region. Currently, three species are known to occur in Kenya, which are only known from the Kakamega Forest. On the basis of the recent revision by Bolton and Fisher (2012), the taxonomy of the genus is in an excellent condition, and very good identification keys are now available for workers and queens.

Simopone seem to be rare, arboreal ants and presumably nocturnal (Bolton, 1973a; Brown, 1975; Kutter, 1977; Bolton & Fisher, 2012). Knowledge on the natural history of most species is very limited, but from some species it is known that they are specialised predators of other ants (Brown, 1975; Bolton & Fisher, 2012).

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Sphinctomyrmex
Although Sphinctomyrmex occurs in the tropics of the New and Old World, only 22 described species are known and these are mainly distributed in Australia (Brown, 1975; Bolton, 2012). Brown (1975) listed just two valid species for the Afrotropical region, but mentioned another three undescribed species. Unfortunately, the two described species are only known from males and the other species mentioned by Brown remain undescribed until today. Additionally, in Kenya two unidentified and probably new worker-based species were sampled in the Kakamega Forest. As a consequence, it is not possible to identify any worker-based Sphinctomyrmex from the Afrotropical region, and a modern taxonomic revision that associates workers, queens, and males is highly desirable. Unfortunately, knowledge on the ecology of the African species is fairly limited. They appear to be rare ants that nest in the ground or rotten wood and were mainly collected from the leaf litter (Bolton, 1973a; Brown, 1975). Some species from Australia seem to be comparatively army-ant-like and have more or less dichthadiiform queens; these species perform mass raids on other ants and are presumably nomadic (Brown, 1975; Buschinger et al., 1990).

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Axinidris
Axinidris is endemic to the Afrotropical region, and seems to be zoogeographically mostly restricted to the Guineo-Congolian rainforest belt from West Africa to the Kakamega Forest in Western Kenya, with few species occurring also in Eastern or Southern Africa (Snelling, 2007). A total of 21 species are known (Bolton, 2012). Interestingly, all eight species known from Kenya are only found in the Kakamega Forest in Western Kenya (Snelling, 2007; Hita Garcia et al., 2009) and four of these are also endemic to this rainforest. This genus is in an almost perfect taxonomic situation, with a revision by Shattuck (1991) and a more recent one by Snelling (2007), allowing easy identification to species.

The genus Axinidris is an arboreal genus with an omnivorous diet (Shattuck, 1991; Snelling, 2007) and its members seem to prefer moist rainforest habitats where they nest in hollow, living or dead stems, or in rotten wood (Snelling, 2007).

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Tapinoma
The genus Tapinoma comprises 64 described species that are distributed worldwide (Bolton, 2012). The Afrotropical region holds 13 described species (Robertson, 2000). There are four valid species and two subspecies known from Kenya and we found two additional morphospecies from Arabuko Sokoke. Species level identification of African species is generally problematic due to the lack of any modern taxonomic revisionary works.

Most Tapinoma species are arboreal and some live in close associations with myrmecophyte plants (Wheeler, 1922; Bolton, 1973a). In addition, they seem to be generalised foragers (Brown, 2000).

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Technomyrmex
Technomyrmex is of moderate size with 93 described species, which are distributed throughout all tropical and sub-tropical zones, mainly in the Afrotropical, Oriental and Indo-Australian regions (Bolton, 2012). Around one third of them occur in sub-Saharan Africa, from which 25 are endemic to this region (Bolton, 2007), and, at present, we recognise nine valid and one undescribed species from Kenya. Recently, Bolton (2007) revised the genus for the West Palaearctic and Afrotropical regions and presented a key to the worker caste.

The majority of Technomyrmex species nest and forage arboreally or sub-arboreally and even the few species that nest in soil or leaf litter forage on trunks and in the canopy (Bolton, 2007). Some specialised myrmecophilous plants have been reported to house Technomyrmex species (Hölldobler & Wilson, 1990), but to what extent this might be true for the Kenyan species remains unknown. The diet mainly consists of hemipteran honeydew, though most species also feed on dead or living arthropods or their brood (Bolton, 2007).

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Dorylus
This genus is distributed throughout the Old World tropics and subtropics, but the majority of species are found in the Afrotropical zoogeographical region (Gotwald, 1982, 1995). The taxonomic condition of Dorylus, especially for the African continent, can be classified as chaotic and useless for identification purposes. On a global basis, 59 species and 68 subspecies are recognised (Bolton, 2012), although the taxonomic validity of many of these taxa is highly questionable. The problem is that most descriptions were based on a single caste, and careful examination of taxa in order to find evidence for conspecificity among these is very rare (Schöning et al., 2008). Also, no modern taxonomic revision is available, which dramatically increases the difficulties to identify Dorylus to species level. Nevertheless, identification to subgenus level can be well performed with the keys provided in Gotwald (1982). At present, we recognise around 15 species, seven subspecies and two morphospecies from Kenya but this number will likely change with future taxonomic modifications and new discoveries.

The army ant genus Dorylus is mostly known for the spectacular swarm raids performed by some epigaeic species, mostly belonging to the subgenus Anomma, better known as "driver ants". These species perform huge swarm raids along the ground and lower vegetation with hundreds of thousands of blind, polymorphic workers to hunt down a great variety of prey taxa in large quantities, predominantly invertebrates (Gotwald, 1982, 1995). However, many more species within the genus live and hunt hypogaeicly and these army ants are generally less visible than their epigaeic relatives (Berghoff et al., 2002). Hypogaeic species hunt in columns and many species are known to be specialised predators of other social insects, such as termites or other ants (Darlington, 1985; Gotwald, 1982, 1995; Schöning & Moffett, 2007). Almost all species of Dorylus, like other army ant genera, live in monogynous colonies with dichthadiiform queens that have a massive egg-laying capacity, e.g. three to four million eggs per month in “driver ant” queens (Raignier & van Boven, 1955). In addition, Dorylus colonies migrate in irregular intervals to new nesting sites and new colonies emerge through colony fission (Gotwald, 1982, 1995).

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Acropyga
Despite their cryptic lifestyle Acropyga, are found in all zoogeographical regions and at present 40 species are known (LaPolla, 2004a; Bolton, 2012). The genus was recently globally revised and just three species are recognised from the Afrotropical region (LaPolla, 2004a; LaPolla & Fisher 2005). LaPolla and Fisher (2005) drew attention to this seemingly depauperate Afrotropical Acropyga diversity, especially when compared with the over a dozen species known from the Oriental and Neotropical regions. Whether this low diversity is typical for the Afrotropics or just a sampling artefact due to insufficient collecting still remains unclear. All three Afrotropical species can be well identified with the key provided in LaPolla & Fisher (2005). Only one species, Acropyga silvestrii , which is widespread in the whole Afrotropical region, is known from Kenya (Hita Garcia et al., 2009).

Acropyga are usually small, cryptic, slow-moving ants that live a hypogaeic lifestyle predominantly in forest habitats (Prins, 1982; LaPolla & Fisher, 2005). The genus is also well known for its close association with mealybugs that are tended for their honeydew on underground plant roots (LaPolla et al., 2002). This relationship is so close that virgin queens take along a mealybug between their mandibles when they leave their birth nest to establish a new colony. (LaPolla et al., 2002; LaPolla & Fisher, 2005).

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Anoplolepis
Anoplolepis is a relatively small genus with only nine valid species (Bolton, 2012), which are predominantly distributed in the Afrotropical region, with fewer species in the Malagasy and Oriental regions and some introduced in other regions. Only one species is listed from Kenya, namely Anoplolepis custodiens, which shows a wide distribution range from Southern Africa to Kenya and Somalia (Prins, 1982). This species is also known as the "common pugnacious ant" because of its aggressiveness and fast movements. It is very common in South African orchards and vineyards (Prins, 1982) where it was early regarded as a pest (Arnold, 1922). There is no modern revision available for this genus on an Afrotropical basis, although Prins (1982) presented a taxonomic treatment for the South African species. Unfortunately, he only provided a key to the queen and male castes.

These formicines are epigaeic and active ants that forage on the ground or the vegetation. Their diet is comparatively variable since they feed on a variety of small arthropods but also on honeydew produced by aphids or coccids (Prins, 1982).

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Camponotus
Camponotus is an extremely large and complex, globally distributed genus. At present, more than 1000 species and nearly 500 subspecies belonging to 45 subgenera are described (Bolton, 2012) and it could well be the largest ant genus of all. Robertson (2000) listed around 150 species for the Afrotropical region and we recognise around 48 Kenyan species, subspecies, and morphospecies. However, all these species counts do not likely represent the "real" number of species found in nature. The enormous species richness, high levels of intraspecific and geographic variation and polymorphism render the taxonomy of Camponotus one of the most complex and difficult. Revisionary studies on Camponotus are generally confined to species groups and / or small geographical regions (e.g. Robertson & Zachariades, 1997; Snelling, 2006; McArthur, 2007; Shattuck & Janda, 2009). The Afrotropical species were treated by several authors in the past (Wheeler, 1922; Emery, 1925a; Santschi, 1926a; Bernard, 1953), but none of these authors tried to fully revise the genus. The only modern treatment for this region is the revision of a small species group restricted to Southern Africa by Robertson & Zachariades (1997). The majority of species, however, remain in a state of taxonomic confusion and would strongly benefit from a modern revision.

These ants live in a variety of habitats and microhabitats and the sheer size of the genus makes any characterisation of their biology challenging. In the Afrotropical region they are almost ubiquitous, occurring from humid rainforests to arid savannahs and from the ground to the canopy. Nests are built in the ground, in rotten branches or twigs, or rarely into living wood (Bolton, 1973a) and most species possess a highly generalistic diet.

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Lepisiota
The genus Lepisiota is distributed in the Old World and with 81 described species of moderate size (Bolton, 2012). The Afrotropical region harbours 45 species (Robertson, 2000; Bolton, 2012) and we list eight valid species and one subspecies from Kenya. However, these species counts have to be taken with caution since there are 21 additional unidentified morphospecies from the country, as well as several dozen more morphospecies from other Afrotropical localities located in museum collections (F.H.G. & G.F., unpublished data). The taxonomy of this genus is in an awful condition because it was never revised for the region. Forel (1892) provided a key to a few then known species but the usefulness of this key is limited since it covers only a minor fraction of the current diversity. Later, Wheeler (1922) and then Emery (1925b) published diagnoses and catalogues of the genus, although none of them attempted a full revision. No further taxonomic works were published since then and a modern revision of Lepisiota would strongly improve the taxonomic understanding of Afrotropical formicines. The "real" number of Kenyan species is very likely to be less than the 29 listed here. It is very difficult to assign names to morphospecies and this situation can only be improved by examining type material.

Generally, Lepisiota nest in rotten wood, in the ground, or in standing trees, and can be considered as generalised foragers (Bolton, 1973a; Brown, 2000). They are especially abundant in less forested habitats, such as grasslands, savannahs or woodlands.

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Nylanderia
Although it reaches its highest diversity in the tropics, Nylanderia is distributed worldwide and holds currently more than 130 species (LaPolla et al., 2011a). The taxonomic history of the genus can be characterised as changeful and unstable. Nylanderia was originally described as a subgenus of Prenolepis, then either treated as a subgenus of Paratrechina (Emery, 1925b), as a good genus (e.g. Wheeler, 1936a), or until lately as a synonym of Paratrechina (Trager 1984). This unsatisfying situation was changed by LaPolla et al. (2010a) who raised Nylanderia to genus rank on the basis of molecular data, and clarified the taxonomic and phylogenetic situation within the Prenolepis genus group. Recently, LaPolla et al. (2011b) revised the Afrotropical Nylanderia fauna and provided a key to species. Four valid species are known from Kenya.

Nylanderia are able to live in a variety of habitats, ranging from deserts to rainforests (LaPolla et al., 2011a). They nest in leaf litter, soil, or in rotten wood, and most species are epigaeic, generalist foragers (LaPolla et al., 2011a).

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Oecophylla
Currently, only two species of Oecophylla “weaver ants” are known: one from the Oriental and Indo-Australian regions and another one from the Afrotropics. The “red tree ant”, Oecophylla longinoda, occurs in the latter region, and is spread throughout the whole of sub-Saharan Africa (Weber, 1949c). Despite the large popularity of the genus (Hölldobler & Wilson, 1990), its taxonomy is in a very disappointing condition since it has not yet benefited from a modern taxonomic revision. Both species together contain 12 subspecies (Bolton, 2012), and it is unclear whether some of these merit species status or should just be regarded as junior synonyms. Oecophylla longinoda and one subspecies, Oecophylla longinoda textor, are listed for Kenya, and we cannot rule out that the status of both names might change in the future. It is possible that O. longinoda textor represents a good species, but it could also just be a synonym of the nominal species.

The weaver ant O. longinoda is one of the most popular and well-studied ants from the Afrotropical region (Hölldobler & Lumsden, 1980; Hölldobler & Wilson, 1990). It is one of the dominant species in African forest canopies and is especially known for its “weaver ant” ability to bind tree leaves into nest compartments with silk spun by larvae (Hölldobler & Lumbsen, 1980). One colony with more than 500,000 individuals can built hundreds of nests in several trees, which are aggressively defended against other conspecific colonies or other ants (Hölldobler, 1979; Hölldobler & Wilson, 1990). They are predacious and hunt large insect prey, not only in the canopy but also in the surrounding vegetation or on the ground and in addition, they tend honeydew-producing insects to supplement their diet (Weber, 1949c; Hölldobler & Lumbsen, 1980).

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Paraparatrechina
Paraparatrechina is biogeographically restricted to the tropics of Africa, Asia and Australia (LaPolla et al., 2010a). Thirty species are known from these regions, of which ten occur in the Afrotropical region and three in Kenya (LaPolla et al., 2010b). The genus, originally described as a subgenus of Paratrechina Motschoulsky, and last treated as a synonym of Paratrechina (Trager, 1984), was raised to genus rank in 2010 (LaPolla et al., 2010a). The taxonomy of the Afrotropical fauna was revised by LaPolla et al. (2010b).

The Afrotropical species can be found in rainforests and forest clearings, in the leaf litter or in rotten logs, and some species presumably live in the vegetation or the canopy (LaPolla et al., 2010b). Paraparatrechina are generalistic feeders and often live in trophobiotic relationships with hemipterans (LaPolla et al., 2010a).

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Paratrechina
The genus Paratrechina contains the single worldwide occurring tramp species Paratrechina longicornis, which is a successful invader predominantly distributed throughout the World’s tropics and subtropics, but is also found in many temperate localities as an indoor pest (Wetterer, 2008). The recent phylogenetic and taxonomic treatments on the Prenolepis genus group (LaPolla et al., 2010a, b) included several modifications at genus level that rendered Paratrechina monotypic and re-elevated Nylanderia and Paraparatrechina. Since P. longicornis is the single species in the genus, the identification is straightforward with the key to genera published in LaPolla et al. (2010a).

This species is well known as a household, greenhouse, and agricultural pest and seems to prefer semi-natural or disturbed habitats (Wetterer, 2008). It often enhances the population of phloem-feeding hemipterans that can cause serious damage to plants and it can reduce the arthropod diversity of particular habitats (Wetterer, 1999, 2008).

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Phasmomyrmex
Phasmomyrmex is a very species-poor genus with only four species, which are all restricted to the Afrotropical region (Bolton, 2012). The few species were described independently from each other in different genera, and their respective genus affiliations remained unstable until they were finally considered to be congeneric (Bolton, 1995, 2003). Surprisingly, despite the small number of species and known specimens, no one has yet attempted a modern taxonomic treatment. Only one unidentified and most probably new species was found in Kenya (in Hita Garcia et al., 2009 mistakenly listed as Phasmomyrmex wolfi).

Unfortunately, the knowledge on the biology of Phasmomyrmex is very limited, but most species appear to be arboreal, living and nesting in trees.

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Plagiolepis
Plagiolepis, with 57 valid species (Bolton, 2012), is a genus of moderate size. It is restricted to the tropical and temperate regions of the Old World and 18 species occur in the Afrotropical region (Robertson, 2000). Five valid species are listed for Kenya, as well as an additional morphospecies from Kakamega. No modern revision or a key to species exist, which is a serious obstacle for the identification of Plagiolepis species.

Unfortunately, also very little is known about the biology of the Afrotropical species. They are small formicines nesting on trees, rotten wood, twigs, or in the soil (Bolton, 1973a).

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Polyrhachis
This genus is one of the largest within the subfamily Formicinae with currently 614 listed species, which occur in the Old World’s tropics and subtropics, except in the Malagasy region (Bolton, 1973b, 2012). The central distribution of the genus is certainly in the Oriental and Indo-Australian regions whereas it plays a less important role in the Afrotropical region. The latter region holds only 43 valid species (Bolton, 1973b; Robertson, 2000) and we list nine for Kenya, with an additional morphospecies. A revision of the Afrotropical species with a good key to the worker caste was provided by Bolton (1973b).

Due to its sheer size Polyrhachis has a diverse ecology. They live in different forests or savannahs (Bolton, 1973b), and nest in trees, in or on the ground, in plant cavities, or within rock crevices (Robson & Kohout, 2007). Some species are weaver ants and build pavilions with larval or spider silk, while other species are social parasites of other ants and live within the colonies of their hosts (Maschwitz et al., 2003). Many species live in trophobiotic relationships with aphids or coccids (Liefke et al., 1998), but there are many species without trophobiotic partners that feed on floral and extra-floral nectarines, sugary saps of fruits and trees, on dead or living insect prey, or get their electrolytes in form of vertebrate excrements.

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Tapinolepis
Tapinolepis is a small, species-poor genus with just 14 species restricted to the Afrotropical and Malagasy regions (Bolton, 2012). Until the last decade Tapinolepis was regarded as a synonym of Anoplolepis, but was reinstated as a good genus by Bolton (2003). Revisions or keys treating Tapinolepis as a genus have not been published yet. Only one morphospecies sampled in Nairobi is known from Kenya.

Unfortunately, the biology of the Afrotropical species is completely unknown.

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Leptanilla
Over 40 species of Leptanilla are known (Bolton, 2012), which are largely distributed in the Old World tropics and subtropics (Baroni Urbani, 1977; Bolton, 1990; Lopez et al., 1994). Baroni Urbani (1977) revised the genus on a global basis, and he recognized three species from the Afrotropical region. However, the Afrotropical material was comparatively scarce, and from two species only the male caste is known. The real species number for this region will probably turn out to be higher with several undescribed species located in museum collections (Bolton, 1990). Furthermore, sampling methods that specifically target hypogaeic insects (Normand, 1911; Lopez et al., 1994) might very likely discover more species of these cryptic ants. One unidentified species was recently recorded from a Western Kenyan rainforest (Hita Garcia et al., 2009), but it is still unclear if this might be an undescribed species or the worker caste of a male-based species.

The members of this genus are all very small, pale, subterranean ants that are rarely collected, especially the worker and queen castes. Leptanilla species nest and forage in the ground, and seem to be specialised predators of geophilomorph centipedes (Masuko, 1990). Additionally, the queens of some species are known to feed on their larvae, but unlike amblyoponine queens they do not damage the larval integument. Instead the larvae possess a specialised duct organ on the fourth abdominal segment from which the queens can gain the larval haemolymph (Bolton, 1990; Masuko, 1990). Leptanilla displays several behavioural similarities to army ants since all known queens are dichthadiiform, several species are known to be migratory, and foraging is performed in groups.

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Atopomyrmex
Atopomyrmex is endemic to the Afrotropical zoogeographical region and with only three species is a relatively small genus. Nevertheless, the distribution of the genus extends to much of Sub-Saharan Africa, and one species, Atopomyrmex mocquerysi, is known from Kenya. The genus was revised by Bolton (1981a) who recognised two species, and a third was later described by Snelling (1992). Species identification can be easily performed with the species key from Bolton (1981a) and the diagnostic notes in Snelling (1992).

The members of the genus are highly polymorphic, arboreal ants that nest in living wood (Bolton, 1981a; Kenne et al., 2009). From one species it is known that its wood-excavating nest activities cause the tree branches to dry out (Kenne et al., 2009). Atopomyrmex ants forage in the vegetation or on the ground and their diet is variable since it can consist of honeydew or small arthropods. In addition, they seem to prefer the canopy stratum of secondary forests or woodlands, but are only rarely encountered in old growth forests (Kenne et al, 2009; F.H.G. & G.F., unpublished data).

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Baracidris
The genus Baracidris is very species-poor with just three described species, which are endemic to the Afrotropical region (Bolton, 1981a; Fernández, 2003; Bolton, 2012). One species, Baracidris pilosa, is known to occur in Kenya, although the only existing specimen was destroyed during transport from one museum to another (see Fernández, 2003). Therefore, it is strongly desirable to rediscover and collect more material of this genus. The genus was revised by Bolton (1981a), who recognised two West African species and later Fernández (2003) described a third species from Uganda and Kenya and updated the species key from Bolton's previous work.

Not much is known about the natural history of these rare ants. All three species seem to inhabit forest habitats and were mainly collected from leaf litter (Fernández, 2003).

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Calyptomyrmex
Calyptomyrmex is a comparatively small genus with 37 described species (Bolton, 2012) distributed throughout the Afrotropical, Malagasy, Oriental and Indo-Australian regions (Baroni Urbani, 1975; Bolton, 1981b; Shattuck, 2011). Sixteen species are known from the Afrotropical region (Bolton 1981b) and six occur in Kenya. Interestingly, almost all specimens were collected in the Kakamega Forest. The taxonomy of the genus was revised by Bolton (1981b) who included a good key to the worker caste.

Species of this more cryptic genus are typically found in the leaf-litter stratum or in the soil of forest habitats. They forage individually or in small groups of two or three workers and in several species the foragers "play dead" if disturbed and remain motionless for a while (Bolton, 1981b; F.H.G., personal observations). A remarkable characteristic of most Calyptomyrmex is their possession of bizarre, often extremely so, pilosity, which can be scale-like, spatulate, clavate, or teardrop-like. At present, there is no explanation for these very specialised forms of pilosity.

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Cardiocondyla
This genus occurs worldwide with 67 species (Bolton, 2012) and possesses several successful tramp species (Seifert, 2003). At present, the Afrotropical fauna consists of 11 described species (Rigato, 2002). Three valid species are known from Kenya of which two are known to be invasive (Heinze et al., 2006) and two further morphospecies were found in the Kakamega Forest. The taxonomic situation for the Afrotropical region is in a relatively good condition, with a revision and keys for the whole region (Bolton, 1982; Rigato, 2002).

Cardiocondyla are often inconspicuous ants because they usually nest subterraneously and live in relatively small colonies of up to a few hundred individuals (Heinze et al., 2006). Most species prefer anthropogenically or naturally disturbed open and arid habitats (Seifert, 2003). Foraging is commonly performed solitarily and most species are omnivorous. One interesting aspect of the biology of the genus is the rare presence of long-living ergatoid males that mate intranidally and usually kill other ergatoid males in order to monopolise matings (Heinze & Hölldobler, 1993; Seifert, 2003; Heinze et al., 2006).

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Carebara
The taxonomy of Carebara has seen great improvements on both generic and regional levels during the last decade (Fernández, 2004, 2006, 2010). Of high importance was Fernández' (2004) synonymisation of the former genera Afroxyidris, Oligomyrmex and Paedalgus under Carebara. Nonetheless, the taxonomy of the genus in the Afrotropics is to a great extent either outdated or fragmentary. Santschi (1914) and Wheeler (1922) treated parts of Oligomyrmex and Carebara. Weber (1950) revised the then known members of Oligomyrmex, and provided a species key for the major caste. Also, there is a key available for species formerly classified as Paedalgus (Bolton & Belshaw, 1993). However, the works of Santschi (1914), Wheeler (1922), and Weber (1950) are very outdated and the whole genus, with 160 species (Bolton, 2012), would benefit highly from an updated revision. We list ten species and one subspecies of Carebara under its recent definition for Kenya, but there are also eight morphospecies and most of them are probably undescribed.

Most species in this genus are small, cryptic, hypogaeic ants that nest in the soil, the leaf litter or in termite mounds. The latter is important since some species seem to be lestobiotic (Bolton & Belshaw, 1993). Some species show an extreme size dimorphism between the tiny worker and the very large queen caste that led to the theory that young queens transport workers to the new nest site to assist with the foundation of a new colony (Arnold, 1916; Wheeler, 1936b). However, on the basis of observations on queens of one species, Lepage & Darlington (1984) and later Robertson and Villet (1989) did not find any evidence for this theory.

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Cataulacus
The genus is of Palaeotropical distribution with its main diversity centred in the Afrotropical region where 35 species from the global total of 65 exist (Bolton, 1974a, 2012). Of these, 15 are known from Kenya. Most seem to be restricted to the rainforest habitats in Western Kenya around Kakamega, but this could also be a sampling artefact. The taxonomy of the genus is in a fairly good condition since it was first revised by Bolton (1974a) on a global scale, additional species added later by Snelling (1979) for the Afrotropical region and then Bolton (1982) presented an updated revision with more new species and a species-level key.

Most species of this genus are forest-inhabitants while only a minority live in more open and arid habitats. All nest and forage on trees or in the vegetation and several species are known to be trophobiotic, while one species was observed to prey on termites (Arnold, 1917; Bolton, 1974a). Interestingly, many members of this genus often co-occur with more dominant and aggressive ant species from the genera Crematogaster and Oecophylla but are usually well-protected by their heavily armoured exterior or dropping-off behaviour (Bolton, 1974a; Yanoviak et al., 2008).

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Crematogaster
The ant genus Crematogaster is one of the most species-rich and widely distributed genera worldwide, with approximately 470 valid species and 300 subspecies (Bolton, 2012). Despite its cosmopolitan distribution, most species are found in the tropics. More than 130 taxa are scattered across the whole Afrotropical region. The extreme species richness together with the high intraspecific and geographical variability provides serious obstacles for the taxonomic understanding of this genus. Thus, it is not surprising that revisionary treatments are very scarce and have been thoroughly avoided in the past. Some regional faunas have been revised on genus or subgenus level (Buren, 1959; Longino, 2003; Hosoishi & Ogata, 2008, 2009; Blaimer, 2010, 2011), but the Afrotropical Crematogaster fauna remains in great need of a taxonomic revision. Therefore, species level identifications of most Kenyan species are comparatively problematic and only possible through comparisons with well identified reference or type material. We list 22 species, 18 subspecies and 12 morphospecies for Kenya, but the "real" number of species is very likely to be lower than their sum of 52.

In tropical regions, most members of this genus are arboreal (Longino, 2003), although a minority of species nest and forage on the ground (Quinet et al., 2009; Hosoishi et al., 2010). Crematogaster can be found in a diversity of habitats, such as forests, woodlands, savannahs or shrublands (Blaimer, 2010) and they often play a dominant, aggressive and territorial role within the local ant fauna (Longino, 2003). Concerning their food sources, most Crematogaster seem to be highly generalistic and omnivorous (Longino, 2003), although the most important resource for many species is homopteran honeydew.

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Cyphoidris
This is a relatively rare and small genus with just four described species, all of which are restricted to tropical Africa (Bolton, 1981a). Only one species, Cyphoidris spinosa, is known from the Kakamega Forest. The taxonomy of Cyphoidris was treated in Bolton (1981a). The identification to species level is comparatively easy with the identification key presented by Bolton (1981a).

The biology of these four species is relatively mysterious except that they prefer the leaf litter stratum in Equatorial rainforests.

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Decamorium
The ant genus Decamorium is known only from the Afrotropical zoogeographic region, and is, with just two valid species, relatively species-poor (Bolton, 1976). Only one described species, Decamorium decem, is found in Kenya, although we also found one potentially undescribed species from the Kenyan coast. The genus was revised by Bolton (1976) who provided diagnostic information to separate the two then known species.

Both known species seem to be specialised termite predators that nest in rotten wood in the leaf litter (Bolton, 1973a, 1976; Longhurst et al., 1979).

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Dicroaspis
Dicroaspis is a minute genus endemic to the Afrotropical region. In his revision of the genus Bolton (1981b) recognised only two valid species and suggested that even these might be variations of the same form. A further, unidentified species was found in the Kakamega Forest (Espira, 2001), which represents the only record of Dicroaspis in Kenya.

The biology of this genus remains to a great extent unknown, although collection data suggests that these ants live in the leaf litter of rainforests.

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Melissotarsus
Melissotarsus is an extremely rarely encountered genus with only four described species distributed in the Afrotropical and Malagasy regions (Bolton, 2012). Two of them are listed for Kenya. The Afrotropical species were revised by Bolton (1982) who also provided a good species identification key.

These ants are special in several ways. They build their nests in healthy wood by tunnelling through the living tissue beneath the surface (Bolton, 1982; Fisher & Robertson, 1999; Belshaw & Bolton, 1994) and are rarely encountered outside of their nests, which could be the main reason for their relative scarcity in museum collections (Bolton, 1982). Also, they live in close association with symbiotic coccids that are kept inside the nest and furthermore, the adults are able to produce silk, which is used to close exit holes or to seal cracks (Fisher & Robertson, 1999).

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Meranoplus
This genus contains 81 species (Bolton, 2012) and is distributed throughout the Old World tropics but its main diversity is centred in Australia (Andersen, 2006). Only a few species occur in the Oriental region or in Africa. Of the eight Afrotropical species, most are restricted to Southern Africa, while only two have a wide distribution across Africa and are also found in Kenya (Bolton, 1981b). For the Afrotropical region the taxonomy of the genus is in a good state due to the revision of Bolton (1981b), which includes an effective species identification key.

The African species of this genus nest in the ground, in rotten wood, or under stones (Bolton, 1981b). Foraging is performed primarily on the ground or in the leaf litter whereas only very few species may additionally climb up trees or shrubs (Bolton, 1981b). Anderson (2006) indicated that the Australian species of this genus are either omnivorous, opportunistically feeding on seeds, or specialised granivores. When disturbed they show a special ‘faking-death’ behaviour. They retract their antennae into the scrobes, tuck their legs under the promesonotal shield and remain motionless (Hölldobler, 1988).

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Messor
The genus is of moderate size with approximately 110 known species (Bolton, 2012), which are distributed across the Holarctic, Afrotropical, and Oriental regions, with its highest diversity found in the Palaearctic region. The Afrotropical region holds a comparatively small proportion of 13 species, of which four occur in Kenya (Bolton, 1982; Ferrer & Collingwood, 1993). The then known species were revised by Bolton (1982), who also provided a key to the medium-sized and large workers. However, the key does not cover all species, since Messor ferreri Collingwood was described later from Kenya (Ferrer & Collingwood, 1993).

Messor is a genus of primarily granivorous ants that play an important role in seed dispersal. These ants are commonly encountered in savannahs, grasslands, or even more arid habitats like semi-deserts and deserts (Bolton, 1982).

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Microdaceton
Microdaceton is a relatively species-poor genus with only four described species that are endemic to the Afrotropical region (Bolton, 2000, 2012). Of these, two species occur in Kenya (Bolton, 2000; Hita Garcia et al., 2009). The taxonomy of Microdaceton, as well as for the whole tribe Dacetini, is in a fairly good condition, since it was well revised in recent decades (Bolton, 1983, 1999, 2000). All African species are easy to identify with the species level key provided by Bolton (2000).

Species of this genus are relatively uncommon dacetine ants that nest in the leaf litter stratum. Apart from this no other information about their biology is known so far.

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Monomorium
Monomorium is a comparatively large and widely distributed genus. Currently it holds a total of 384 valid species (Bolton, 1987, 2012; Heterick, 2006). Bolton (1987) listed 145 species for the Afrotropical region, though the synonymisation of four African species (Heterick, 2006) reduced the species count to 141. Presently, 33 described species are known from Kenya and we also found five potentially undescribed morphospecies. Despite the seemingly well-treated taxonomy of the genus in several parts or zoogeographic regions of the world (e.g. Bolton, 1987; Collingwood & Agosti, 1996; Heterick, 2001, 2006), the genus definition of Monomorium is far from satisfactory (Heterick, 2006). Future taxonomic work at genus-rank level might split up the genus into smaller, better-defined genera. However, under the current genus definition, the species level key from Bolton (1987) allows a proper identification of most Afrotropical and Kenyan species.

Considering the wide distribution and species richness, it is not surprising that Monomorium are found in many terrestrial habitats and microhabitats. Astonishingly, very little is known of the natural history of most species (Ettershank, 1966). Feeding habits of most species seem to be generalistic, or more rarely granivorous. Several species are lestobiotic or parasitic and in addition, some species belong to the most successful and broadly distributed ant tramps (Ettershank, 1966; Bolton, 1987).

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