Leptogenys chalybaea

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Leptogenys chalybaea
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Genus: Leptogenys
Species: L. chalybaea
Binomial name
Leptogenys chalybaea
(Emery, 1887)

Leptogenys chalybaea casent0281931 p 1 high.jpg

Leptogenys chalybaea casent0281931 d 1 high.jpg

Specimen Labels

This is a complex of four large bluish species currently revised by Kouichi Arimoto (Kyushu University). In Cambodia and Thailand, workers link their bodies in chains during the retrieval of freshly immobilized large millipedes (Peeters & De Greef 2015). Chains are a striking example of cooperation in ants, and this is the first report of a function during the transport of prey.



Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo (type locality), Indonesia, Malaysia.
Oriental Region: Cambodia, Thailand.

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Daisy chain blue ants killing giant millipede in Cambodia. Video © Stéphane De Greef, used with permission.

Chain behavior in Leptogenys sp. functions for the collective transport of large millipedes (Peeters & De Greef 2015). This bluish species is a swarm raider with a small range of prey: millipedes belonging to four orders, and occasional earthworms. Small prey were carried individually or dragged by a few ants, while chains made it possible to move millipedes weighing up to 16.4 g. Chains (either linear or branched) changed according to obstacles along the way to the nests. Between 2 and 52 workers were observed to drag single prey items, with only a few ants directly grasping the prey. One 15-cm-long millipede was captured rodeo-style after being encircled by 25–30 ants. As it uncurled from a defensive coil, the ants held back except one that tried to sting between its legs. The millipede started thrashing about which caused many ants to attempt stinging.

Workers of Leptogenys sp. assemble in chains to drag a heavy millipede (order Spirostreptida, 15 cm-long, 16.4 g fresh weight). From Siem Reap province, Cambodia. Photograph © Stéphane De Greef, used with permission.

Many species of Leptogenys with large workers occur in Africa and the Neotropics (Bolton 1975; Lattke 2011), while large millipedes are also distributed on these continents. Yet chain behavior has never been reported outside SE Asia, suggesting that its evolution requires a complex combination of traits (Peeters & De Greef 2015). Four other ponerine genera hunt millipedes solitarily, but chains are not used.

Detail of short linear chain used to drag a smaller millipede (order Spirobolida, 1.9 g fresh weight). Photograph © Stéphane De Greef, used with permission.
Single foragers of Leptogenys sp. retrieving a pill millipede (order Sphaerotheriida). Photograph © Stéphane De Greef, used with permission.



The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • chalybaea. Lobopelta chalybaea Emery, 1887b: 432 (w.) BORNEO. Combination in Leptogenys (Lobopelta): Emery, 1911d: 102.