Ants of Singapore #08 - Strumigenys (cf. koningsbergi)

Strumigenys

Species accounts

Strumigenys cf. koningsbergi

Strumigenys c.f. koningsbergeri

Strumigenys (Myrmicinae : Dacetini) is a small, cryptic, leaf-litter dwelling ant; they are otherwise known as Trap Jaw ants as well.

They are pretty numerous in the leaf litter and also nest in the crevices of dead logs. They are move slowly most of the time, unless when disturbed.

It is said that some species are specialist predators of springtails (Coembolla, which are arthropods with six legs but do not have wings [Entognatha]). Perhaps that is why they require trap-jaw like mandibles as well, to 'capture' these fast moving Coembollas!

Ants of Singapore #07 - Cerapachys (undet.)

Cerapachys

Species accounts

sp. 1

Old World Army Ants Cerapachys sp.

The Old World Army Ants, Cerapachys are a diverse group of ants. Some of these ants are blind (i.e. they have no eye facets), while others are not. The one as shown above has only one eye facet (look at picture below), suggesting a subterranean or nocturnal lifestyle. It was actually seen attacking an earthworm at night, though no photographs to document that.


Cerapachys biroi, one of the species within the genus, is said to be very widespread and is considered a tramp ant [1] and was first described in Singapore by Forel in 1907, suggesting its origins in Asia as well. They are said to practice parthenogenesis [2] because workers can produce diploid eggs. They are also entirely subterranean which also suggests dispersal by exported soil perhaps. This might be an interesting article for those who wish to read more.

Alright, good day ahead.


References

[1] Wetterer et al.. 2012. Worldwide spread of Cerapachys biroi (Hymenoptera: Formicidae: Cerpachyinae). Myrmecological News 17: 1-4.
[2] Kronaeur et al.. 2012. Asexual reproduction in introduced and native populations of Cerapachys biroi. Molecular Ecology 21(21): 5221-5225.

Ants of Singapore #06 - Pheidologeton (diversus)

Pheidologeton

Species accounts

Pheidologeton diversus 

Recently Pheidologeton was synonymised under Carebara (Fisher, 2014). I will still recognize Pheidologeton for the sake of this blog.

Pheidologeton diversus, otherwise known as the Maurauder Ant. 

These ants are commonly seen, in the day and in the night, where there is a dead carcass. They are quick to recruit, and are the dominant insects at a particular dead carcass, often excluding other competitors. Maybe that's why they're relatively common insects.

Dominating at a carcass

They are polymorphic (come in various sizes), and sometimes the minor ants can be seen to be riding on the major ants, a behaviour similar to the leaf cutter ants whose minors ride on the leaves carried by the major workers. Not many are sure why this behaviour is so, but it has been hypothesized that perhaps it prevents phorid flies from laying eggs on their head.

They look similar to the Pheidole ant, another genus but can be distinguished based on the number of antennal clubs (Pheidologeton has 2, Pheidole has 3).

Ants of Singapore #05 - Camponotus (gigas)

Camponotus

Species accounts

Camponotus gigas

Camponotus gigas Latreille, 1802, the Giant Forest Ant in Singapore

The ant above, is none other than the famous Giant Forest Ant (Camponotus gigas), one of the largest species of ants possibly in the world. The Camponotus genus ("Carpenter Ants"), is also a hyperdiverse genus, meaning that there are many species within the genera. Fortunately, these Giant Forest Ants are easily distinguished from the other Camponotus species by their (large) size and red gaster.

They are polymorphic and have majors which are generally larger with a head which is more heart-shaped rather than ovate. They are said to have intraspecific territorial fights at night. They also nest in the base of trees.

Generally though, these ants are docile and they cannot sting (they have no stinging apparatus). It is personally therapeutic to look at them forage ;)

[As a side note, there are many other Camponotus species in Singapore, but am likely to be highlighting only this one for now. It would be interesting to study the temporal niche differentiation for certain species, because some are observed in the night, while others are observed foraging in the day.]

Giant Forest Ant Camponotus gigas female alate in Singapore.

C. gigas worker, found at Kubah National Park, Sarawak with slight variation in the legs (yellow) as compared to the ones in Singapore.

Ants of Singapore #04 - Oecophylla (smaragdina)

Oecophylla

Species accounts

Oecophylla smaragdina

The Weaver Ant, Oecophylla smaragdina

In the Singaporean context, the Asian Weaver Ant Oecophylla smaragdina Fabricius 1775 (subfamily Formicinae) is one of the more conspicuous ants around. These ants are able to bite and inflict some pain on one, if you step on their tiny "toes". Further, the formic acid they spray exacerbates that pain.

They are found mainly in the Indo-Australian region. The subspecies we have in Singapore is orange in colour but there is a green subspecies present in Australia, too. This is what makes their biogeography interesting as well (species independent of the Wallace and Weber lines).

These Weaver ants weave nests with leaves, using their larvae to produce silk thread. They are so adapatable, they can use almost any kind of leaves to build their nests -- even long, palm leaves. I have never witnessed the nest construction but it is said that they form chains extending to the next leaves. A satellite nests can be found in the vicinity of the 'main' nest, which houses the queen.

They are probably scavengers and food-generalists. In addition, they are seen to have an association with honey-dew producing insects, such as treehoppers, planthoppers and even some caterpillars. Perhaps their generalistic behaviour allows them to thrive in various conditions, at forest fringes and even at urban areas. They are able to utilize metal bars as passage ways.

In certain cultures (such as the Thai culture), people eat the Weaver Ants and their larvae fried with egg. It is said to be very delicious!

There are only two extant species, Oecophylla smaragdina and Oecophylla longinoda that are currently extant, with other species that are currently extinct.

I think I can go on and on about them because they are rather well-studied. A good read here.



The Weaver ant is not to be confused with the Yellow Crazy Ant. Here is a photograph of an alate Weaver Ant, with a couple of Yellow Crazy Ant (Anoplolepis gracilipes).

Ants of Singapore #03 - Anoplolepis (gracilipes)

Anoplolepis

Species accounts

Anoplolepis gracilipes

Yellow Crazy Ants, Anoplolepis gracilipes with some planthoppers.

The Yellow Crazy Ant, Anoplolepis gracilipes Smith 1857 (subfamily Formicinae) is considered to be a tramp ant. A tramp ant is one which is very widespread because of its life history characteristics. One example would be that it is polydomous, where ants from different nests can intermingle, thus allowing high densities of ants to live together.

These ants are able to occupy niches within the humid, tropical areas, these ants are pretty conspicuous. Their common name, the Yellow Crazy Ant is indicative of its quick and fast movements when disturbed. On certain islands, these ants are known to dominate and cause certain native species to be affected. One such example is on Christmas Islands, possibly fuelled by biotic interactions with planthoppers.

It is likely that these ants originated from Asia or Africa, its origins are unclear at the moment.

Just as a note: there are only nine species within the genera Anoplolepis.

Ants of Singapore #02 - Myrmoteras (iriodum, arcoelinae)

Myrmoteras 

Myrmoteras is a genera of ants belonging to the subfamily Formicinae. Formicines have an acidopore rather than a sting and can spray formic acid. Myrmoteras is known as a lowland tropical rainforest and montane forest species. What is so unique about these ants is that it has a very long elongated mandible, unlike the many other ants. Further, these mandibles can open 270 degrees. These specimens are by far rare, and little is known about their biology. What made them develop such huge eyes, if they're primarily leaf-litter dwelling, and what are the long mandibles used for? Nests have been found in dead twigs of leaf litter. [1]

Also, about its taxonomy -- there are two subgenera within the genera, namely Myrmoteras and Myagroteras that are geographically separated, and delineated respectively by the Wallace line and Weber's line. They're strictly an Indomalayan genera.

Species accounts

Myrmoteras iriodum

A specimen -- Myrmoteras iriodum collected in Singapore

Myrmoteras cf. arcoelinae

A Myrmoteras cf. arcoelinae found on a leaf of a shrub (surprise, surprise) - not leaf litter where it is usually spotted. This was also observed by Agosti (1992). Found at one of the trails at Kinabalu National Park (1500m) which is a lower montane forest. The individual was moving sluggishly and did not seem aggressive.  Credit and thanks to Chui Shao Xiong for this wonderful photograph!

References
[1] Agosti, D.. 1992. Revision of the ant genus Myrmoteras of the Malay Archipelago (Hymenoptera: Formicidae). Revue sueisse Zoologie 99(2): 405-429.