Macrotermes carbonarius

Macrotermes carbonarius is a large black open foraging termite found throughout Southeast Asia. It is a member of Macrotermitinae (fungus growing termites) subfamily within the higher termites, Termitidae. It has a rather distinct behaviour of 'paving' its foraging trails with soil and fecal pellets. It is the open air foraging species of Macrotermitinae and the only black Macrotermes species of this region.

Identification
M. carbonarius has a dimorphic true worker caste, a dimorphic soldier caste and a single reproductive imago caste.

They are rather easily distinguished from Macrotermes and other termites of their region due to their large size, well developed curved mandibles of the soldiers and dark-brown to jet-black colouration of each caste.

Keys including this species

Termites (Isoptera) of Thailand

Distribution
M. carbonarius is widely distributed on the Malay Peninsula, Thailand, Cambodia, Myanmar and Borneo.

Nest
Mound:

The mounds of Macrotermes carbonarius are normally irregular and conical in shape, large, conspicuous and variable in height, typically being about 1m - 3m in diameter and can range from 0.3m - 1m in height, although they can reach heights of up to 3m.

They are built from clay, soil and sand gathered from below ground. The mound walls are remarkably thick, typically being 100mm - 180mm (10cm - 18cm). Within the mound fungus combs are typically located above and below ground level. They lack a clear ventilation system.

Within the mound is a bell shaped chamber with walls of 20cm - 40cm in thickness, housing the royal chamber, food stores, fungus combs, nursery and brood chamber, the latter of which contains a soil network.

Developmental pathways


Developmental pathways of Macrotermes carbonarius.

Swarming
M.carbonarius flies during November to January with the vast majority occurring in November and sporadic flights from December to January. Flights occur on days with low humidity and avoid rain. Flights are very short in duration (around 10min) but massive in number. Alates fly short distances without the aid of wind, presumably to increase the chance of pairing.

Defense
Soldiers posses a hyaline tip, and a minute fontanelle. Like most other Macrotermitinae there does not seem to be much use for the fontanelle and frontal glands and the primary chemical weapon is from the salivary glands. On the other hand the labial glands of M. carbonarius are very well developed.

In the event of a shallow breach of the mound, a few major soldiers rush out accompanied by minor soldiers while workers work to seal the damage. This is typical Macrotermes species.

A peculiar defensive strategy is displayed however when the breach extends to deeper into the mound, soldiers gather and line the perimeters, at first few soldiers begin hammering their heads, eventually every soldier within the vicinity follows suite. The end result is a synchronized rhythmic rattling noise in quick successions of thrice separated by intervals of two seconds.

The soldiers of this species are very aggressive.

Foraging
Macrotermes carbonarius forages during the dry season and take place during late evening, at night or during early morning. If conditions are favourable however such as in areas with low amounts of direct light foraging may persist much longer than normal.

Foraging tunnels: Unlike other Macrotermes species, M. carbonarius does not have an extensive dense underground network of tunnels. Instead it constructs only large tunnels (6cm - 35cm from the soil surface and 2.5cm - 13cm wide), these large tunnels have a flat smooth plastered flood and either terminate with or without an exit hole. There can be as many as 10 of these tunnels radiating from the nest and they can be up to 33 metres in distance. It is not known how these tunnels are constructed however as with other Macrotermes sp. digging is probably delegated to the minor workers.

As with other Macrotermes species, storage pits for food can be found within the tunnels, in the case of M. carbonarius however, these are only temporary and probably used very briefly as food is mainly stored and found in the lowest parts of the mound.

Open air foraging behaviour: Major workers open up exit holes (1.5cm - 3cm in diameter) from smaller of branching tunnels. This was subsequently followed by the exit of minor soldiers, if no predators are encountered another 10 - 20 minor and major soldiers followed and spearheaded the columns towards the foraging sites. After the establishment of a rudimentary trail major workers would follow and construct the paved trail with soil and fecal matter while soldiers continued the advance or started lining themselves on the side of the foraging trails. Paved tracks are roughly 2cm - 4cm in width.

Upon reaching the foraging site soldiers and workers would fan out, workers harvesting food while soldiers encircled the perimeters,

Diet
Workers harvest leaf litter, dried grass and twigs. M.carbonarius has a preference for recently fallen leaves.

Fungus combs: Like all other Macrotermitinae, M. carbonarius cultivates fungus within the genus Termitomyces. Fungal spores are transmitted via mushrooms that sprout from the termite mound and picked up by the workers. (horizontally)

Unlike most other members of Macrotermes, M. carbonarius does not add material to its combs after construction and its combs do not resemble those of other Macrotermes. The comb construction and consumption can be divided into three phases: newly constructed comb (appearance dark, no fruiting bodies), maturing of fungus (appearance dark, fruiting bodies), consumption of fungus (appearance light coloured, no fruiting bodies).

Pseudacanthotermes also constructs and consumes fungus combs in this fashion.

Role in ecosystem
M. carbonarius is the primary consumer of recently felled leaf litter in areas where it is located.

Interactions with other organisms
Parasites: The larvae of M. carbonarius soldiers is parasitized by the endoparasitoid Verticia fasciventris.

Interactions with humans
M. carbonarius is a pest of crops and wooden structures, especially on land that was rainforest.

Castes
Photo sources: Biodiversity of Singapore Photos and Info on Ants and Termites of Malaysia

Nomenclature
worker:  Typical to Macrotermitinae, the major workers posses rather proportionately large rounded heads and a smaller abdomen.

Major worker: Can be distinguished easily from other termites in the region due to the aforementioned large rounded heads, their jet black tergites and head capsule coupled with their lighter coloured sternites and yellow/straw coloured appendages (legs and palpae). Fontanelle distinct, present on centre of head.

Minor worker: Compared to the major workers, head is not proportionately large. Lighter in colour typically appearing as a uniform dark brownish colour. Fontanelle distinct, present on centre of head. Appendages (legs, palpae and antennae) are straw coloured.

soldier:  Typical to Macrotermitinae, the major soldiers have proportionately very large heads, often times for the major soldiers the head capsule is roughly equal to the size of their body, this is true for M. carbonarius as well.

Major soldier: Head capsule sub rectangular, tapering, head jet black in colour while anterior of head (around the clypeus) is orange in colour, dorsally flat and ventrally convex from profile view; fontanelle minute, almost indistinguishable, situated anteriorly; Mandibles large, slender and curved upwards and inwards, hooked at ends; labrum with trilobed hyaline tip, orange in colour (same colour with anterior portion of head); pronotum concave, trapezoid in shape, black with orange-yellow highlights in centre, not wider than head; abdominal tergites and sternites black, membrane straw coloured; legs long and yellow in colour. Roughly 18mm in length.

Minor soldier: Like Major soldier but smaller in size.