''Megaponera analis'' is the sole species of the genus ''Megaponera''. They are a strictly termite-eating (termitophagous) ponerine ant species widely distributed in

Sub-Saharan Africa Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and ...

and most commonly known for their column-like raiding formation when attacking

termite Termites are a group of detritivore, detritophagous Eusociality, eusocial cockroaches which consume a variety of Detritus, decaying plant material, generally in the form of wood, Plant litter, leaf litter, and Humus, soil humus. They are dist ...

feeding sites. Their sophisticated raiding behaviour gave them the common name Matabele ant after the Matabele tribe, fierce warriors who overwhelmed various other tribes during the 1800s. With some individuals reaching up to in length, ''M. analis'' is one of the world's largest ants. In 2014, the

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

''analis'', in Latin "anus-related", chosen by Latreille, replaced ''foetens'' "stinking", given by

Johan Christian Fabricius Johann Christian Fabricius (7 January 1745 – 3 March 1808) was a Danish zoologist, specialising in "Insecta", which at that time included all arthropods: insects, arachnids, crustaceans and others. He was a student of Carl Linnaeus, and is co ...

in 1793, because

Guillaume-Antoine Olivier Guillaume-Antoine Olivier (; 19 January 1756, Les Arcs near Toulon – 1 October 1814, Lyon) was a French entomologist and naturalist. Life Olivier studied medicine in Montpellier, where he became good friends with Pierre Marie Auguste Br ...

had given the same name ''Formica foetens'' to another species in 1792. Both names allude to the fact that the mandibular gland of this ant releases

dimethyl disulfide Dimethyl disulfide (DMDS) is an organic chemical compound with the molecular formula . It is a flammable liquid with an unpleasant, garlic-like odor resembling that of "leaking gas". The compound is colorless, although impure samples often appea ...

and

dimethyl trisulfide Dimethyl trisulfide (DMTS) is an organic chemical compound and the simplest organic trisulfide, with the chemical formula CH3SSSCH3. It is a flammable liquid with a foul odor, which is detectable at levels as low as 1 part per trillion. Occurren ...

, which smell like human faeces.

Taxonomy

''Megaponera'' is a genus of ponerine ant first defined by

Gustav Mayr Gustav L. Mayr (12 October 1830 – 14 July 1908) was an Austrian Entomology, entomologist and professor in Budapest and Vienna. He specialised in Hymenoptera, being particularly known for his studies of ants.Latreille, 1802, the sole species belonging to the genus to date. In 1994 William L. Brown Jr. synonymised the genus under ''

Pachycondyla ''Pachycondyla'' is a Ponerinae, ponerine genus of ants found in the Neotropics. Distribution ''Pachycondyla'' is currently distributed from southern United States to northern Argentina, but some fossil species (e.g. ''Pachycondyla eocenica, P. ...

'' even though he lacked phylogenetic justification, thereby changing the name from ''Megaponera foetens'' to ''Pachycondyla analis''. In 2014 Schmidt and Shattuck revived ''Megaponera'' back to full genus status due to both molecular and morphological evidence. Since ''foetens'' was a

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

incorrectly used, the name for the species as of June 2014 is ''Megaponera analis''.

Subspecies of ''Megaponera analis''

Due to its very wide distribution throughout Africa, it is likely that there are many more

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

of ''M. analis'' than those recognised at the moment – some of which may warrant elevation to full species status. The five currently recognised subspecies of ''M. analis'' are: *''M. analis'' subsp. ''amazon'' ( Santschi, 1935):

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

*''M. analis'' subsp. ''crassicornis'' ( Gerstäcker, 1859):

Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...

*''M. analis'' subsp. ''rapax'' ( Santschi, 1914b):

Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...

*''M. analis'' subsp. ''subpilosa'' ( Santschi, 1937):

Angola Angola, officially the Republic of Angola, is a country on the west-Central Africa, central coast of Southern Africa. It is the second-largest Portuguese-speaking world, Portuguese-speaking (Lusophone) country in both total area and List of c ...

*''M. analis'' subsp. ''termitivora'' ( Santschi, 1930):

DRC The Democratic Republic of the Congo (DRC), also known as the DR Congo, Congo-Kinshasa, or simply the Congo (the last ambiguously also referring to the neighbouring Republic of the Congo), is a country in Central Africa. By land area, it is t ...

Morphology

The size of worker ants varies between , with larger workers making up to 50 percent of the

colony A colony is a territory subject to a form of foreign rule, which rules the territory and its indigenous peoples separated from the foreign rulers, the colonizer, and their ''metropole'' (or "mother country"). This separated rule was often orga ...

. Though it was often suggested that the larger ants also function as gamergates, they were never observed laying fertile eggs, a function solely reserved to the ergatoid queen. Even though ''M. analis'' is often referred to as dimorphic, with a major and minor caste, they actually exhibit polyphasic allometry in worker sizes. The variations among the ants are mostly in size and pubescence (with minors having less), although differences in the

mandibles In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

have also been observed, with minors having smoother mandibles compared to majors.

Range and habitat

''Megaponera analis'' occurs throughout sub-Saharan Africa from 25° S to 12° N. Its nests are generally subterranean, up to deep, and often located next to trees, rocks, or abandoned termite hills. While the nest itself may have more than one entrance, it comprises only one chamber in which the eggs, larvae, cocoons, and the queen are located. Frogs of the species ''

Phrynomantis microps ''Phrynomantis microps'' is an African frog with many interesting adaptations to the savannah. These frogs are also called the Accra snake-necked frog. They are found across Western and Central Africa. One of its distinguishing features is the pe ...

'' are sometimes found in the nests, and have evolved a skin secretion that inhibits the ants aggression.

Behaviour

Raiding behaviour

The raiding activity of ''M. analis'' focuses on dawn and dusk between 6:00–10:00 and 15:00–19:00, with approximately three to five raids occurring per day. There are also observations of a third raiding activity window during the night between 22:00–2:00, although this phase has been poorly studied. ''M. analis'' raids focus solely on termites from the subfamily Macrotermitinae and generally consist of 200 to 500 ants. The general foraging pattern of ''M. analis'' starts with scout ants searching an area of approximately around the nest for termite foraging sites. This searching phase can last up to one hour, and if it is unsuccessful the scout returns to the nest by a circuitous route. If a scout ant finds a potential site, it will start to investigate it without getting into contact with the termites or entering the galleries, before returning by the quickest route to recruit its nestmates to conduct a raid. While the quickest route is often also the shortest, this is not always the case. Scouts have been observed to use deviations on open terrain (like paths) on which they can run twice as fast to reduce travel time on average by 35%. Although the scout ant is observed to lay a

pheromone trail Trail pheromones are semiochemicals secreted from the body of an individual to affect the behavior of another individual receiving it. Trail pheromones often serve as a multi purpose chemical secretion that leads members of its own species towards a ...

on the return journey to the nest, the other ants seem to be unable to follow this trail without the help of the scout. The scout ant therefore leads the raid from the front, with the other ants following in a column-like formation. Recruitment time varies between 60 and 300 seconds, with all castes taking part in a raid. During the outward journey towards the termites, all ants are laying a pheromone trail, making it much easier for them to find their way back to the nest later without having to rely on the scout ant. Approximately before contact with the termites, the raiding column stops and agglomerates until all the ants in the column have arrived, forming a sort of circle around the raid leader (the scout). Afterwards the ants rush forward towards the termites in an open formation and overwhelm their prey. During the attack, a division of labour can be observed. While the majors focus mostly on breaking up the protective layer over the foraging galleries of the termites, the minors rush into the galleries to kill the termites through the created openings. After a foraging site has been exploited, the ants congregate at the same place they waited earlier, with the majors carrying the termites, and return to the nest in a column-like formation. These raids are always a single event and ants do not return independently to re-exploit a former raiding site, although the possibility of the scout ant remembering a site and reinvestigating it in the future for a possible second raid cannot be excluded.

Colony size and reproduction

Colony size varies, depending on the location and age of the colony, from 440 to 2300 adult ants. Little is known about the reproduction of ''M. analis''. The

alate Alate (Latin ''ālātus'', from ''āla'' (“wing”)) is an adjective and noun used in entomology and botany to refer to something that has wings or winglike structures. In entomology In entomology, "alate" usually refers to the winged form of ...

males of ''M. analis'' are often observed leaving and entering the nests of established colonies by using pheromone trails from previous raids as guides to the nest. Since ''M. analis'' colonies are obligate termite hunters, a queen could not establish a nest on her own, since she could not conduct a raid against termites without a standing army of worker ants. It is therefore assumed that new colonies are always created through colony fission, with the new queen taking a number of the workers of the old colony with her to create a new colony.

Helping behaviour

Cooperative self defence

While cooperative defence of the nest is well known in ants, cooperative self-defence outside of the nest is much less so. When ''M. analis'' ants are attacked by driver ants ( ''Dorylus'' sp.) outside of the nest, they cooperate with one another in an attempt to defend themselves by checking each other's extremities for enemy ants and removing any that are clinging to their legs or antennae.

Saving injured individuals

During battles against termites some of the ants get injured. The termite soldiers are able to bite off extremities or cling on to ant bodies after their death. These ants have evolved a unique mechanism to deal with this increased foraging cost. The battle-injured ants "call" for help with a pheromone in their mandibular gland (consisting of two chemical compounds:

and

), attracting nestmates, who then start to investigate the injured nestmate, pick her up, and carry the injured ant back to the nest. By doing so, they reduce their mortality rate from 32% to close to zero. Inside the nest the clinging termites get removed. If they have lost one or two legs, the ants adapt to four or five legged locomotion to compensate for it, allowing them to reach running speeds similar to a healthy ant. These injured ants are then capable again of performing colony tasks and are even observed in future raids against termites. A model calculated this rescue behaviour to allow a colony to be 28.7% larger than a colony that would not show this behaviour (due to the energy saved by not having to replace the injured workers with new healthy replacements). This is the only invertebrate species known to show such a behaviour towards injured individuals. The rescue behaviour is also limited to only lightly injured ants (loss of 1-2 limbs); heavily injured ants (that have lost 3 or more limbs) are left behind on the hunting ground. The mechanism with which this is regulated is believed to be relatively simple and based on a two-step process: after an ant is injured the first step is for it to try standing normally on its legs again ("return to an idling position"). Step two is to call for help and cooperate with the responding helpers, but if step one cannot be achieved, then step two will not occur. Heavily injured ants are therefore in a constant loop trying to achieve step one, making it a very simple mechanism of only rescuing ants that are still useful for the colony.

Wound-care behavior

Observations inside the nest have revealed that these ants treat the wounds of their injured nest-mates, making them the first recorded non-human species to consistently take care of the wounds of other individuals. Nest mates grab the damaged limb of the injured ant in their mandibles and hold it in place with their front legs. They then start to "lick" the wound for numerous minutes. This treatment occurs predominantly within the first hour after injury. Without treatment, the typical mortality rate of injured ants is 80%. Wounds often get infected by opportunistic pathogens on the soil surface entering the wound. A major, lethal pathogen in this regard for ''M. analis'' is ''Pseudomonas aeruginosa''. Wounds exposed to this pathogen lead to a mortality of close to 90%. Infected ants signal their infected wounds through changes in their cuticular hydrocarbon profile, allowing nestmates to recognise infected wounds and treat them accordingly. This second, therapeutic care phase also includes the application of the secretions from the metapleural gland, which harbor over 100 antimicrobial compounds and proteins. This specialised antimicrobial wound care allows the ants to successfully treat infected wounds, allowing the injured ants to recover from their injuries. See also:
Science Magazine summary video of rescue behaviour

National Geographic: report about the helping behaviour

Science Magazine summary video of wound treatment

National Geographic: report about the wound treatment

Gallery

References

External links

Antweb: further information about ''M. analis''Arkive: further information about ''M.analis'' Antwiki: further information about ''M.analis''
* ttp://www.antcat.org/catalog/442768 AntCat: online catalog for the ants of the worldbr> Hymenoptera online: further taxonomic information Encyclopedia of Life
{{Taxonbar, from1=Q7122109, from2=Q21322148 Ponerinae Hymenoptera of Africa Insects described in 1802 Monotypic ant genera