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Iridomyrmex
Iridomyrmex is a genus of ants called rainbow ants (referring to their blue-green iridescent sheen) first described by Austrian entomologist Gustav Mayr in 1862. He placed the genus in the subfamily Dolichoderinae of the family Formicidae. It has 79 described species and five fossil species. Most of these ants are native to Australia; others are found in Asia and Oceania, and they have been introduced to Brazil, New Zealand, and the United Arab Emirates. Fossil species are known from China, France, and the United States.
These ants are known to be an ecologically dominant and important group of ants, but they are sometimes regarded as pests because they disturb soil and enter human houses. Farmers in rural Australia place animal carcasses on meat ant (I. purpureus) mounds as a method of disposing of them; meat ants consume the carcass and reduce it to bones in a matter of weeks. Meat ants also engage in ritualised fighting, which helps prevent casualties and solve territorial disputes between neighbouring colonies. The largest members of this genus are those of the I. purpureus species group, measuring 8 mm (0.31 in).
After their nuptial flight, queen ants may establish a colony by themselves, by budding, or cooperatively, where a subset of the colony migrates to a new location or when multiple queens help find a suitable nesting spot, but they display intolerance to each other when workers are present. The eggs take 44 to 61 days to fully develop into adults. Ants of the genus live in a wide variety of habitats and nest in soil in numbers that range from a few hundred individuals to over 300,000 in a single colony. Depending on the species, nests are large mounds covered in pebbles with multiple entrances, while others live above ground in twig nests. In some cases, ants dwell in several nest sites connected by paths; some of these nests can extend to 650 m (2,130 ft) in length. Some species associate with caterpillars and butterflies that provide the ants with secretions and honeydew, and I. bicknelli pollinates orchids. These ants are predators and scavengers; they hunt for prey to feed their young. Notably, these ants are immune to the toxins of the cane toad and feed on the juveniles. Predators such as spiders, birds, lizards, and other ants prey on Iridomyrmex ants.
The separation of the genus Iridomyrmex from its most recent common ancestor began around 12 million years ago. Its sister group, Froggattella, has only two species, even though both genera are the same age. In comparison to other Indo-Australian genera in the subfamily Dolichoderinae, the clade of which it is a part, is 23 million years old, meaning that it is rather young. However, the fossil species that have been found are from the Eocene and Oligocene. The following cladogram shows the phylogenetic position of Iridomyrmex among the Indo-Australian genera:
The genus Iridomyrmex was first described by Austrian entomologist Gustav Mayr in 1862, but it had no designated type species until 1903. By then, the type species was designated as Formica detecta, a synonym of Iridomyrmex purpureus. The genus was placed in the subfamily Dolichoderinae in 1878, the same year the subfamily was established. Since the establishment of the genus, it suffered taxonomic misunderstanding due to the gradual development of unrelated ants being designated into the genus by early researchers who failed to identify features that would make them distinct from the genus Iridomyrmex.
Myrmecologist William Brown Jr., was perhaps the first person to question the monophyly of the genus, mentioning that the Argentine ant, a former member of Iridomyrmex, differed from the rest of the genus. The first proper revisions of the genus began in the 1990s, and 91 species were transferred to six genera; only 62 species remained after these revisions. These species were placed into the genera Anonychomyrma, Doleromyrma, Linepithema, Ochetellus, Papyrius and Philidris. In 2011, the genus was revised again, and 79 species and five extinct species were now present, 31 of which were newly described. Four species were placed in different genera while 25 species and subspecies were classified as synonyms. According to one source, 350 Australian Iridomyrmex species may be present.
The scientific name of the genus, Iridomyrmex, meaning "rainbow ant", refers to their blue-green iridescent sheen. The word Irido, meaning "rainbow", derives from Ancient Greek, and myrmex, another Greek word, means "ant".
[extinct species are marked with †]
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Iridomyrmex
Iridomyrmex is a genus of ants called rainbow ants (referring to their blue-green iridescent sheen) first described by Austrian entomologist Gustav Mayr in 1862. He placed the genus in the subfamily Dolichoderinae of the family Formicidae. It has 79 described species and five fossil species. Most of these ants are native to Australia; others are found in Asia and Oceania, and they have been introduced to Brazil, New Zealand, and the United Arab Emirates. Fossil species are known from China, France, and the United States.
These ants are known to be an ecologically dominant and important group of ants, but they are sometimes regarded as pests because they disturb soil and enter human houses. Farmers in rural Australia place animal carcasses on meat ant (I. purpureus) mounds as a method of disposing of them; meat ants consume the carcass and reduce it to bones in a matter of weeks. Meat ants also engage in ritualised fighting, which helps prevent casualties and solve territorial disputes between neighbouring colonies. The largest members of this genus are those of the I. purpureus species group, measuring 8 mm (0.31 in).
After their nuptial flight, queen ants may establish a colony by themselves, by budding, or cooperatively, where a subset of the colony migrates to a new location or when multiple queens help find a suitable nesting spot, but they display intolerance to each other when workers are present. The eggs take 44 to 61 days to fully develop into adults. Ants of the genus live in a wide variety of habitats and nest in soil in numbers that range from a few hundred individuals to over 300,000 in a single colony. Depending on the species, nests are large mounds covered in pebbles with multiple entrances, while others live above ground in twig nests. In some cases, ants dwell in several nest sites connected by paths; some of these nests can extend to 650 m (2,130 ft) in length. Some species associate with caterpillars and butterflies that provide the ants with secretions and honeydew, and I. bicknelli pollinates orchids. These ants are predators and scavengers; they hunt for prey to feed their young. Notably, these ants are immune to the toxins of the cane toad and feed on the juveniles. Predators such as spiders, birds, lizards, and other ants prey on Iridomyrmex ants.
The separation of the genus Iridomyrmex from its most recent common ancestor began around 12 million years ago. Its sister group, Froggattella, has only two species, even though both genera are the same age. In comparison to other Indo-Australian genera in the subfamily Dolichoderinae, the clade of which it is a part, is 23 million years old, meaning that it is rather young. However, the fossil species that have been found are from the Eocene and Oligocene. The following cladogram shows the phylogenetic position of Iridomyrmex among the Indo-Australian genera:
The genus Iridomyrmex was first described by Austrian entomologist Gustav Mayr in 1862, but it had no designated type species until 1903. By then, the type species was designated as Formica detecta, a synonym of Iridomyrmex purpureus. The genus was placed in the subfamily Dolichoderinae in 1878, the same year the subfamily was established. Since the establishment of the genus, it suffered taxonomic misunderstanding due to the gradual development of unrelated ants being designated into the genus by early researchers who failed to identify features that would make them distinct from the genus Iridomyrmex.
Myrmecologist William Brown Jr., was perhaps the first person to question the monophyly of the genus, mentioning that the Argentine ant, a former member of Iridomyrmex, differed from the rest of the genus. The first proper revisions of the genus began in the 1990s, and 91 species were transferred to six genera; only 62 species remained after these revisions. These species were placed into the genera Anonychomyrma, Doleromyrma, Linepithema, Ochetellus, Papyrius and Philidris. In 2011, the genus was revised again, and 79 species and five extinct species were now present, 31 of which were newly described. Four species were placed in different genera while 25 species and subspecies were classified as synonyms. According to one source, 350 Australian Iridomyrmex species may be present.
The scientific name of the genus, Iridomyrmex, meaning "rainbow ant", refers to their blue-green iridescent sheen. The word Irido, meaning "rainbow", derives from Ancient Greek, and myrmex, another Greek word, means "ant".
[extinct species are marked with †]
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