Anochetus emarginatus

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Anochetus emarginatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Genus: Anochetus
Species: A. emarginatus
Binomial name
Anochetus emarginatus
(Fabricius, 1804)

Anochetus emarginatus casent0217503 p 1 high.jpg

Anochetus emarginatus casent0217503 d 1 high.jpg

Specimen Labels

Synonyms
At a Glance • Ergatoid queen  

 

Identification

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil, Colombia, French Guiana, Grenada, Guyana, Lesser Antilles, Mexico, Suriname, Trinidad and Tobago, Venezuela.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

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Biology

Not much is known about the the biology of Anochetus emarginatus but we can presume that its biology is similar to other Anochetus species. The following account of Anochetus biology is modified from Brown (1968):

Habitat. The places where Anochetus live are varied. Where they penetrate into the temperate zone, most species excavate nests in the earth. Occasionally the nest is dug under a covering rock. In the tropics, many nests are also dug in the soil, but in moist forested areas, a common site is the soil beneath a rotting log or other large mass of rotting wood, with extensions of the nest into the log itself. Another frequent nesting site in tropical forest is in the humus and leaf litter at the base of large trees, particularly between buttress roots. Anochetus species of medium or small size often nest in small pieces of rotting wood or bark, or even small rotting twigs or seeds and nuts lying in or on the forest litter. Some species tend to choose more arboreal nest sites.

Diet. Foraging for living animal prey takes place on the soil surface, within the soil-humus-log mold matrix, or on the trunks, branches and foliage of trees and plants wherever these are available. Fragmentary evidence indicates that most epigaeically foraging tropical Anochetus tend to do their foraging at dusk, at night, or during dawn hours. I found Anochetus africanus walking on tree trunks only at night in the Ivory Coast. Some species, particularly those with red heads or other aposematic coloration, apparently forage in the open more during the day. No systematic comparative study has yet been made of foraging hours for different species.

The food of Anochetus consists principally of living arthropods caught and killed or incapacitated by the ants. The smaller and more delicate species Anochetus inermis has been observed by me in a laboratory nest. The colony came from a piece of rotten wood from the floor of a wet ravine near Bucay in western Ecuador. The colony was fed with small tenebrionid beetle larvae (Tribolium castaneum), comparable in size to the A. inermis workers, and the latter attacked the prey with their mandibles in the familiar snapping manner, but very cautiously and nervously, with stealthy approach, extremely rapid strike, and instant recoil-retreat. After several attacks of this kind, with intervening periods of waiting, during which the beetle larvae fled, rested, or writhed about in distress, an ant would finally attack with its mandibles and hold them closed on the prey for long enough to deliver a quick sting in the intersegmental membrane. After this, the prey appeared to be paralyzed, or at least subdued, and sooner or later was carried off by the ant to the nest, and eventually placed on an ant larva.

Frequent delays and excursions before the prey are finally immobilized and brought to the ant larvae in the nest may well have the function of allowing time for protective allomones of the prey to dissipate. Many tenebrionid adults, including Tribofium, possess potent quinonoid defensive allomones, but the larva is not known to possess quinones in this genus.

Nuptial flight. Although males of different species of Anochetus are commonly taken at light, other species are not. Stewart and Jarmila Peck gave me Malaise trap samples taken in western Ecuador that contained males of several species, but Malaise traps capture both day- and night-flying insects.

Defense. When a nest of any of the larger Anochetus species is breached, some of the workers immediately hide beneath leaves or other objects, while other workers rush about with open jaws, which they snap at foreign objects, or even at leaves and twigs, with an audible tick. On human skin or clothing, a worker will snap her jaws and hold fast to the surface with them, at the same time quickly bringing her gaster around to sting. The sting is long and strong, and to me the effect is shocking and quickly painful.

Most of the smaller and medium-sized Anochetus species feign death when disturbed, crouching flat against the surface, or rolling themselves into a ball and remaining still, often for a minute or more. Only when held do they sting. Their stings can be felt in most cases, but the effect is usually trifling.

Castes

Worker

Nomenclature

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

  • emarginatus. Myrmecia emarginata Fabricius, 1804: 426 (w.) CENTRAL AMERICA. Wheeler, G.C. & Wheeler, J. 1952c: 644 (l.). Combination in Odontomachus: Illiger, 1807: 194; in Stenomyrmex: Mayr, 1862: 711; in Anochetus: Emery, 1890a: 63. Senior synonym of quadrispinosus: Roger, 1862c: 289; of rugosus: Kempf, 1964f: 238. See also: Brown, 1978c: 609.
  • quadrispinosus. Odontomachus quadrispinosus Smith, F. 1858b: 78, pl. 5, figs. 15-17 (w.) BRAZIL. Junior synonym of emarginatus: Roger, 1862c: 289.
  • rugosus. Anochetus (Stenomyrmex) emarginatus r. rugosus Emery, 1890a: 63 (w.) BRAZIL. Mann, 1916: 418 (m.); Wheeler, G.C. & Wheeler, J. 1952c: 645 (l.). [Unresolved junior secondary homonym of Odontomachus rugosus Smith, above.] Junior synonym of emarginatus: Kempf, 1964f: 238.

The following notes on F. Smith type specimens have been provided by Barry Bolton (details):

Odontomachus quadrispinosus

Holotype worker in The Natural History Museum. Labelled “Brazil” and also with a Farren White label. It is probable that this determination is spurious, a secondary labelling by Farren White, who seems to have had a habit of throwing away original data labels and substituting his own. Also in The Natural History Museum are two quadrispinosus workers with the data, “Para 48/133.” Acc. Reg.: “1848 no. 133. Para. Bt of Stevens. Collected by Mssrs Bates & Wallace.” One of these specimens is sublabelled “172.” I suspect that all three together constituted the original syntype series.

Description

References