Asian Army Ants Pheidologetons

There are 42 identified species of the ant genus previously tagged as Pheidologeton if the recorded account is correct. Personally I have encountered at least 8 species. Some members of ant forums and sites have robbed many of the photos and images from here and brazenly claimed it as their own making up stories too (shameless). If you do a google image search you will find them.

By the way Carebara Pheidologetons are not considered as army ants but as marauder ants possibly because they are not disciplined enough. Fact is with effect from September 1, 2014, Pheidologetons are from the scientific perspective not even Pheidologetons anymore (as a genus of ants) but Carebara. This is just as for a good while now Oligomyrmex was no longer Oligomyrmex (as a genus of ants) but Carebara.

But for me, Pheidologetons (for the purpose of my identification to differentiate it from Carebara and Oligomyrmex) are characterized by the large variations in the morphology of the worker caste as well as by a significantly bulkier (larger head) as a ratio to body in the gyne similar to those of the Pheidole genus. Oligomyrmex are characterized by a dimorphic worker caste while those of Carebara are monomorphic. Gyne of both Oligomyrmex and Carebara typically have smaller and less bulky head as a ratio to body size, similar to those of Monomorium and Solenopsis. But of course from the point of view (i.e. perspective) of the experts these are insignificant, too insignificant to take into consideration for genera classification purposes.

On the other hands, Leptogenys, Aenictus and Dorylus are considered army ants because they are equally not disciplined (I am just seriously kidding). For the specifications on what constitute army ants please refer to the defining experts.

Pheidologeton Diverus.

A male alate of Pheidologeton diversus.

An alate gyne of Pheidologeton diversus.

Lateral view of Pheidologeton diversus alate gyne.

Mating Pheidologeton diversus.

Mating Pheidologeton diversus.

A mated dealated gyne of Pheidologeton diversus. This gyne measure all of 20mm (length).

A mated dealated gyne of Pheidologeton diversus. This gyne measure all of 20mm (length).

A mated dealated gyne of Pheidologeton diversus. This gyne measure all of 20mm (length).

A mated dealated gyne of Pheidologeton diversus. This gyne measure all of 20mm (length).

A mated dealated gyne of Pheidologeton diversus. This gyne measure all of 20mm (length).

This glob is usually the first batch of 'download' from a mated gyne once she has sealed herself in her newly dug nest.

Here the gyne places her first batch of eggs gently on the underside of her abdomen.

And keep them there until the brood is too big and spilled over (below).

The spill.

The spill.

Eggs hatch in six to seven days.

Eggs hatch in six to seven days.

Eggs hatch in six to seven days.

Around 25 days after mating the first worker eclosed.

two months old colony moving nest in designated container

The Nest.

A new nest at slightly over a month old.

The eggs, the larvae  and pupae of Pheidologeton diversus in various stages of growth.

A young larva of probably a gyne - long and slim still. It is too early in the colony growth for it to produce reproductive so the appearance of a reproductive larva at this stage is indicative of an abnormal condition (of two much feeding of high protein food). The reproductive larva would be a female because males are only produced under slightly different conditions.

Pheidologeton hangs their larvae from the ceiling of their nest chambers (photo above) and stacks their pupa and pre-pupa larvae on the floor of the nest chambers (image below).

An eclosing major worker of Pheidologeton is cleaned off its molt by her siblings.

The larva of a major worker or super major.

The pupa of a mega super major worker. Beside it is its smaller sibling a super major worker.

The same mega super major worker almost to eclosion. Once eclosed this ant will be among largest worker in this nest.

The whole nest at four months old.

The nest compacting due to exposure. A super major worker and another slightly larger. The gyne is in the centre of the nest.

Four sizes of major worker with the mega super major just beside the gyne in the midst of the nest. Polymorphism among the major workers in this genus is progressive. This nest does not have the largest size mega super major yet. Food availability determines the speed of growth and size of nest. Pheidologeton diversus foraging columns rarely stretches much beyond a hundred or so feet. That kind of restrict how large (in numbers) the nest can grow.

The nest with a larva of a gyne (top of nest)

Unusual for such a small nest to begin producing alates. A possible reason is having plenty of high protein food. This nest at over three months was given a large quantity of protein rich food to maximized growth. In the wild such condition are abnormal.

The nest fully compacted in response to exposure as the enclosed container is opened.

The gyne moving reluctantly into her new nest. She doesn't like the transparency of the nest. I suppose no genteel discerning lady would.

A major worker and a worker.

Some workers and a super major worker.

A super major worker with a mega super major worker. The larger still partially in its callow's colour.

The mega super major worker from the pupa shown in previous photos above.

 Wild nest under a fallen tree. This nest has not reached full maturity yet indicative from the small number of mega super majors and the small quantity of brood. 

Pheidologeton affinis: A brown species

This Pheidologeton species is brown both the major and minor workers.

The minor worker

A mega super major worker with a minor worker.

Two mega super major worker, one slightly larger than the other.

This super major worker the largest worker in this Pheidologeton nest is all of 12mm long when it is no longer a 'food store.'

A minor major worker.

Another minor major.

Here a major minor worker.

Two major minor of differring sizes.

Pheidologeton sp1.

This species is much smaller than the common Pheidologeton diversus and is less agressive.

 
 The worker (minor).

 The super major worker. This is largest worker.

Being smaller, they are also less aggressive.

Pheidologeton queen with minor workers. In this species the "waist" of the queen is very pronounced.

 

Pheidologeton queen with minor workers.

Species Comparison.

The male and female of Pheidologeton diversus (the larger species) and another Pheidologeton species (sp2).

Close-up comparison of the two species. Pheidologeton diversus is nearly twice as large.

Queen or gyne of Pheidologeton sp2.

 Queen of Pheidologeton sp2.

A third species.. This species has the longest and largest gaster in proportion to its body.

Measuring at 20mm (tip of mandible to tip of gaster) this gyne is much smaller than Pheidologeton diversus but almost the same length.

Here is the male alate badly mangled by the gyne after mating. This is the first species that I have come across in which the dealate gyne attacks the male.

Queens (i.e. the mated alates) of 4 different species of Carebara Pheidologeton.

Young nest of sp3 not more three months old.

Pheidologeton sp.

This species is much smaller than Pheidologeton diversus. 

This species being smaller is not as agressive. It has a nice yellowish brown almost red color.

Major workers of Pheidologeton sp.

This species of Pheidologeton has a nice color. A minor worker besides one of the majors.

One of the medium size worker with a minor worker of an yellowish brown Pheidologeton species.

 Two minor workers of Pheidologeton sp.

The largest worker - the mega super major worker beside it is a yellow minor worker trying to retrieve a buried pupa of a reproductive. Of all the species recorded in this post, this semi-replete major has the largest gaster enlargement.

Minor workers of this yellowish brown species of Pheidologeton are just barely 2 millimeters while the largest mega super major is 10 millimeters when food storing gaster is not filled.

 Gyne of this species is 18 millimeters.

Workers of various sizes attending to the larvae of reproductives. 

Close up of some of the smaller workers of this yellowish brown species of Pheidologeton.

Queen of Pheidologeton sp. in a young nest. This species is polygynous.

Pheidologeton sp5.

This fifth species of Pheidologeton is the smallest recorded so far. The dealated gyne (newly mated gyne) measured at only 15 millimeters. The minor workers at 2 millimeters is not much smaller than the other smaller species recorded above.

Workers of Pheidologeton sp5.

The pupa of a super major worker.

Pheidologeton sp.

 The mega super major and minor workers of Pheidologeton sp. This species has workers (minor and major) around the same size as P. diversus but are mostly subterranean in their foraging.

Major and minor workers of Pheidologeton sp.

Pheidologeton sp

This species of Carebara/Pheidologeton is a small size species and is sensitive. The colony has five queens but yet to reach its matured size but was getting too large for me to maintain so I induced the production of alates just so I can photograph them before letting the colony go back into the wild.

Pheidologeton / Oligomyrmex / Carebara

The defunct type for Carebara use to be a large oversize (compared to the monomorphic workers) queen with a huge hump of a thorax and small to tiny monomorphic workers. The oversize thorax is more that just for flight as they are not particular good fliers, no different from Pheidologeton's. While Pheidologeton typically raise a brood of around fifty workers in incubation before foraging workers bring back food to feed the growing brood, Carebara typically raise over a hundred workers before the first workers began foraging. Oligomyrmex brood during incubation are typically just around ten workers or more (depending on the species).

Oligomyrmex were type by dimorphic workers from very tiny to small and queens that not particularly different from (macro perspective) those of Monomorium and Solenopsis, with the gaster is on the larger side.

Pheidologeton were typed by large queens with large heads (in proportion to the rest of the body) similar to those of the Pheidole genus, and large super majors in a diverse morphology of the worker caste. Of these three Carebara genera, Pheidologeton exhibit aggressive hunting-foraging of army ants while some (or should be many) Oligomyrmex are thief ants the same also being true of Carebara. Of course now we no longer have these separations and they are all just Carebara the thieving and scavenging marauder ants.

A Oligomyrmx Pheidologeton Connection?

 Minor workers. At slightly over two millimeters the minor workers while smaller than the larger Pheidologeton sub genus (or group) such as P. diversus and P. affinis, is as large or slightly larger than those of the smaller Pheidologeton species.

 Major worker is slightly below 4 millimeters (TL) around the same size to those of some of the larger Oligomyrmex species. But unlike the similar size Oligomyrmex which aren't aggressive, this species is as aggressive as Pheidologeton. 

Minor workers are aggressive like those of Pheidologeton (Carebara) with a sting that is more painful than those of Pheidologeton's minor workers. The pain intensity and also the surface damage caused is very similar to those of Solenopsis geminata (I actually have a slight allergic reaction to their stings something that hasn't happened with Solenopsis, Odontoponera, Aenictus, Leptogenys, etc.). Unlike Pheidologeton this species which sits between Oligomyrmex and Pheidologeton ignores most animal food that Pheidologeton readily takes.

The gyne at over 1 centimeter is not as corresponding large when compare to the minor workers (at slightly over 2 millimeters) as those of Pheidologeton and the classic monomorphic Carebara. Mature colony size is somewhere between those of Solenopsis geminata and those of Pheidologeton.

The males (drones) are around 8 millimeters. So here in this species the workers do not differ much between this and Oligomyrmex (in  photo below) but the alates are very dissimilar as well as the predatory behavior with Oligomyrmex hardly aggressive and can be considered as timid (from the context of when the nest incubation chambers are exposed).

Carebara (Oligomyrmex defunct) major and minor workers.

Notes To Ant Keepers

After receiving several queries I thought it might be helpful to add this short discussion here.

Firstly Pheidologeton is no longer Pheidologeton but a junior synonym for Carebara according to the latest paper (Sept 1, 2014 C.E.) by Georg Fischer, Frank L Azorsa and Brian Fisher. This is exactly as Oligomyrmex was no longer Oligomyrmex but a junior synonym of Carebara from sometime back (Ettershank 1966, Bolton & Belshaw 1993).

Secondly Pheidologeton though also known as Asian army ants were never ever army ants in the strictest sense but marauder ants.

For the moment I will keep the current label for both Pheidologeton and Oligomyrmex to differentiate them from other monomorphic Carebara.

According to some documentations there are some 42 species and sub species of Pheidologeton. According to the latest Myrmecology paper the Pheidologeton genus is basically the Carebara genus from both the perspective of morphology as well as from genetic lineage as per the Darwinian Evolutionary Tree of life (so called).

Unlike other species of the now expanded Carebara genus the now defunct Pheidologeton genus are more sensitive and requires a stricter set up parameter to get a founding queen to successfully rear up a new colony. Of this previously Pheidologeton genus, P. diversus and P. affinis are the least sensitive and therefore easiest to rear from a new founding queen. 

Basically a newly mated queen should be housed in a sufficiently size container with some or an all clay type soil nesting media. Keep the container at room temperature (tropical temperature of around 30 degrees Celsius, without air conditioning) with sufficient soil moisture. Leave the nest undisturbed or minimally disturbed for a month to six weeks. At the end of six weeks the colony should have foraging workers that should be fed with food that have sufficiently high protein content.

Smaller species of the defunct polymorphic Pheidologeton genus are more sensitive and to successfully rear them from foundress queen I would suggest a larger container with more clay soil content. As a further precaution avoid, do not transfer newly founded colonies into new housing until there are a significantly large numbers of major workers.

See also:
Pheidologeton sp5

Taxonomy:

Kingdom – Animalia

Phylum – Arthropoda

Subphylum – Hexapoda

Class – Insecta

Subclass – Pterygota

Infraclass – Neoptera

Order – Hymenoptera

Suborder – Apocrita

Infraorder – Aculeata

Superfamily – Vespoidea

Family – Formicidae
Subfamily – Myrmicinae
Tribe – Pheidologetonini

Genus – Pheidologeton / Carebara

Last Updated: 2021 08 02
First Posted: 2009 09 23

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