Jumper ant

Appearance

This ant is a large species, some workers can grow to over 15 mm in length. They have a distinctive pattern of orange-red and black which distinguishes them from other "Myrmecia" species.

Ants of genus "Myrmecia" are generally referred to as "bulldog ants" and "M. nigrocincta", like other species in the genus, has elongated mandibles. "M. nigrocincta" ants are primarily black and orange-red in colour. They have mandibles which are either black or yellow depending on where the ants are found. The gaster, head, legs and mesonotum are black while the pronotum, propodeum, petiole and post-petiole are red. The ant has linear ridges along the front of its head. It also has apical spurs on the tibia of both its middle leg and hind leg. The legs are thin and become more slender away from the body. "M. nigrocincta" can be distinguished from other species in the genus "Myrmecia" by the bi-coloured thorax and post-petiole which are yellowish-red and black and the yellowish-red node.

The workers are 13 to 15 millimetres long, the males 16 to 17 millimetres while the female is 17 to 19 millimetres. The development of the queen's wings is rudimentary and the stubby, reduced wings render the queen flightless.

Naming

The species was first described by Frederick Smith in 1858.

Distribution

Abundant in eastern Australia, "M. nigrocincta" ants prefer temperate bushlands, and are usually located in dry to semi-dry forests and sclerophyll woodlands. The species is found in the eastern states of Australia, mostly on the coastal plains where much suitable dry forest habitat can be found. They prefer tropical climates and warm temperatures. They can also be found in other types of habitat at elevations ranging from 80 - 1,220 metres.

"M. nigrocincta" colonies have been recorded from Cairns, Atherton, Mackay, Mt. Tamborine, Brisbane, Blackall Range and Fletcher in Queensland. In New South Wales, this ant occurs in Lismore, Dorrigo, Armidale and Sydney, while in Victoria it is found in Trafalgar and Millgrove. Several colonies have also been recorded in South Australia.

Behavior

"M. nigrocincta" is an accomplished jumper with leaps ranging from 76 to 102 millimetres. It has good vision and can be observed running amongst plants and leaves, occasionally jumping from one branch to another. It is mostly found foraging on plants, trees, and other vegetation, but it sometimes forages on the ground. It propels its jumps by a sudden extension of its middle and hind legs.

"M. nigrocincta" ants are diurnal and do not hibernate. They are omnivores, and feed on other insects including caterpillars and spiders, as well as honey water. M. nigrocincta has been observed to prey on the larvae of imperial hairstreak butterflies, even jumping while carrying them. Predators of "M. nigrocincta" include spiders, birds, lizards, mammals and other predatory invertebrates, including assassin bugs and redbacks. The ants have been recorded visiting flowers of "Eucalyptus regnans" and "Senna acclinis" and are considered as a possible pollination vector for "E. regnans" trees. Although "Senna acclinis" is self-compatible, the inability of "M. nigrocincta" to appropriately release pollen would restrict capacity to effect pollination.

These ants live in nests in sandy soil which sometimes have a mound, which resembles a molehill. "M. nigrocincta" ants labor to conceal their nests using twigs and leaves. Depending on the type of habitat in which the colony is located, they decorate the nest with plant material and gravel. Other materials that are used to camouflage "M. nigrocincta" colonies include dry leaves, rocks, vegetation, and twigs. Nests are beside a clump of grass or bush or at the base of a tree.

The colonies of "M. nigrocincta" ants are monogyne, i.e. they have only one queen per colony. The queen is semi-claustral, meaning that during the founding of the new colony, the queen has to forage so that she has enough food to raise her brood. Colonies have between 400 and 1200 individuals and are thus considered to be "large" colonies. "M. nigrocinta" is known to enslave "Leptomyrmex" and other species of ants.

The worker and scout "M. nigrocincta" ants use pheromones for communication. They are quick to defend their nests and may react aggressively even to a shadow crossing their nest. Wheeler describes the reaction of "M. nigrocincta" to the disturbance of their nest as "they bound out of their small mound nest in a series of short hops like Lilliputian cavalry galloping to battle." The ants aggressively defend their colony, causing multiple bites and wilingly sacrificing themselves to protect the queen and the colony."M. nigrocincta" is a gamergate species, which allows female workers to be fertile, and these are then able to reproduce in both queenless and queenright colonies. This means a colony which loses its queen can still thrive in the absence of the queen. In laboratory colonies of "M. nigrocincta" where there was no queen present, worker-laid eggs were reared to mature males, showing that workers are highly fertile. The average life expectancy of an adult worker "M. nigrocincta" ant is 1.1 to 1.2 years, with a maximum expectancy of 1.3 years. Larvae collected from "M. nigrocincta" are 4.7mm in length but increase to 9.7mm when matured.

"M. nigrocincta" possess the gamergates gene which allows workers to reproduce, either in the presence of a queen or in a colony where the queen is missing. Life expectancy of a worker ant is over one year. They are known to enslave ants of other species as workers for their colony, and they are aggressive when attacking intruders.

Defense

"M. nigrocincta" ants have highly venomous stings which are painful and produce intense burning sensations. The sensations last for many days and the sting itches. If left untreated, the sting may develop into an ulcer. The venom of a closely related species, "M. pilosula", is amongst the strongest of the Formicidae and contains active ingredients such as acid and alkaline phosphatases, hyaluronidase, as well as phospholipases A2 and B. In a 2011 Australian ant allergy venom study, the objective of which was to determine what native Australian ants were associated with ant sting anaphylaxis, it was shown that 265 of the 376 participants taking part of the study reacted to the sting of several "Myrmecia" species. Of these, 176 reacted to the "M. pilosula", 15 to "M. nigrocincta", three to "M. ludlowi", and 56 to other "Myrmecia" ants. The study concluded that four main groups of Australian ants were responsible for causing anaphylaxis. Besides "Myrmecia" species, these included the green-head ant.