Polyrhachis
Temporal range:
Polyrhachis gracilior
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Camponotini
Genus: Polyrhachis
F. Smith, 1857
Type species
Formica bihamata
Species
Diversity[1]
477 species
Synonyms

Cephalomyrma Karavaiev, 1935
Dolichorhachis Mann, 1919
Evelyna Donisthorpe, 1937
Florencea Donisthorpe, 1937
Irenea Donisthorpe, 1938
Johnia Karavaiev, 1927
Morleyidris Donisthorpe, 1944

Polyrhachis is a genus of formicine ants found in the Old World with over 600 species.[2] The genus is yet to be comprehensively resolved and contains many varied species including nest-weavers (e.g. Polyrhachis dives), swimming workers (e.g. Polyrhachis sokolova), soil (e.g. Polyrhachis proxima) and tree-dwellers (e.g. Polyrhachis bicolor). First fossil record of this genus was P. annosa from Miocene.

General morphology

Size: Workers range in size approx 5–10mm in length. Eyes developed, no ocelli. Antennae have 12 segments. Antennal insertions situated far from posterior margin of clypeus. Mesosoma of most species have spines on one or more of its pronotal, mesonotal or propodeal components. Petiole armed with spines or teeth. First gastral tergite well developed, longer in dorsal view than exposed parts of the following terga together. Opening at gastral apex for release of venom lacking a radial fringe of hairs.[3]

Ecology

Polyrhachis species include an array of nesting types ranging from terrestrial, soil based nests to arboreal nests. As a result, the nest architectures also vary with some species displaying a high level of complexity to nest building, utilising larval silk to weave nest materials together. Such nest weaving is more commonly associated (and indeed more complex) in ants of the genus Oecophylla.

Polyrhachis do not have a stinger but an acidipore that can spray formic acid. When attacking, this is often sprayed in combination with biting thus making the acid more effective against the subject of the attack. Polyrhachis that do not possess a metapleural gland seem to utilise the antibiotic properties of their formic acid and when it cannot be used, ants are more likely to succumb to parasite infection [4]

Some species are found to be social parasites of different ant genera; Polyrachis lemalidens is a good example. They live in the Korean Peninsula, China and other parts of northeastern Asia. Their nuptial flight occurs during late September to late November depending on the climate. After flight queen dealates search for host colonies. Usually Camponotus japonicus is the host but especially in Korea, their main host is Camponotus atrox. Korean antkeepers say that they even take on to Formica japonica and Camponotus quadrinotatus. Once they find a host colony, they attack small workers hanging out and 'copying' their pheromones. After doing that multiple times to multiple ants, they sneak into the nest and keep 'copying.' Then whether they hibernate or not, they eventually go to the Host Queen's chamber. Then they become tiny vampires, literally. They take onto the queen, bites its neck subduing it, sucks blood, 'Copy' pheromone. And eventually and literally cuts the neck of the host queen. This process usually lasts for 2–4 days but can last over 2 weeks. After that is much the same to other social parasites.

Other species exhibiting social parasitism include Polyrhachis lama and Polyrhachis loweryi, which intrude other ants colonies of different subfamilies, some permanently living within the host colonies.[5][6][7]

Selected species

References

  1. ↑ Bolton, B. (2014). "Polyrhachis". AntCat. Retrieved 17 July 2014.
  2. ↑ "Genus: Polyrhachis". antweb.org. AntWeb. Retrieved 29 September 2013.
  3. ↑ Hung, ACF (1967). "A Revision of the Ant Genus Polyrhachis at the Subgeneric Level (Hymenoptera: Formicidae)". Transactions of the American Entomological Society. 93 (4): 395–422.
  4. ↑ Graystock, Peter; Hughes, William O. H. (2011). "Disease resistance in a weaver ant, Polyrhachis dives, and the role of antibiotic-producing glands". Behavioral Ecology and Sociobiology. 65 (12): 2319–2327. doi:10.1007/s00265-011-1242-y. S2CID 23234351.
  5. ↑ Iwai, H.; Mori, M.; Kono, N.; Tomita, M.; Arakawa, K. (2022). "Molecular Evidence of Chemical Disguise by the Socially Parasitic Spiny Ant Polyrhachis lamellidens (Hymenoptera: Formicidae) When Invading a Host Colony". Frontiers in Ecology and Evolution. 10: 915517. doi:10.3389/fevo.2022.915517.
  6. ↑ Maschwitz, U.; Go, C.; Dorow, W. H. O.; Buschinger, A.; Kohout, R. J. (2003). "Polyrhachis loweryi (Formicinae): A guest ant parasitizing Rhytidoponera sp. (Ponerinae) in Queensland, Australia". Insectes Sociaux. 50 (1): 69–76. doi:10.1007/s000400300011. S2CID 22494816.
  7. ↑ "Polyrhachis lama, Biology". AntWiki. Retrieved 2022-07-24.
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