Anochetus pubescens

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Anochetus pubescens
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Genus: Anochetus
Species: A. pubescens
Binomial name
Anochetus pubescens
Brown, 1978

Anochetus pubescens casent0136793 profile 1.jpg

Anochetus pubescens casent0136793 dorsal 1.jpg

Specimen labels

Collected in various forest types from the ground, litter and on vegetation.

Identification

This species should probably be counted as belonging to the grandidieri-punctaticeps group because of its modest size, compact build and the proportions of the funicular segments. In some ways, particularly the habitus of the head and mandibles, it resembles Anochetus graeffei.

Keys including this Species

Distribution

Known from Zimbabwe, Comoros, Mayotte and Madagascar.

Distribution based on Regional Taxon Lists

Afrotropical Region: Comoros, Ethiopia, Zimbabwe (type locality).
Malagasy Region: Mayotte.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Not much is known about the the biology of Anochetus pubescens 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.

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

Queens and males have been collected but are undescribed.

Queen

Male

Nomenclature

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

  • pubescens. Anochetus pubescens Brown, 1978c: 607, figs. 10, 16 (w.) ZIMBABWE.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Holotype, worker: TL 4.9, HL 1.13, HW 1.02, ML 0.60, WL 1.45, scape L 0.91, eye L 0.14. mm; CI 90, MI 53.

Castaneous (medium orange-brown); posterior corners of head, antennae and legs lighter, more yellowish-brown; gaster very slightly darker brown.

Resembling the largest specimens of Anochetus grandidieri, but with the following differences:

1) In full-face view, antennal scapes at rest surpass posterior borders of occipital lobes by nearly the apical scape thickness.

2) Eyes, though modest in size, distinctly larger than in grandidieri and related species. There seem to be about 33 ommatidia in each eye.

3) The frontal striation is very fine and close, giving the surface there a sericeous appearance at magnifications of about 25X; it extends all the way to the nuchal carina in a median band, but extends only part way out onto the occipital lobes, which are otherwise smooth and shining.

4) Pronotum densely rugulose-punctate in an ellipse around a very narrow median strip that is nearly smooth, with coarse punctures, and shining. Mesonotum finely transversely striolate, subopaque; propodeal dorsum rugulose in a more or less transverse direction. Gaster smooth and shining, without conspicuous punctures.

5) Erect pilosity largely suppressed, consisting only of a few fine erect hairs on anterior part of head, on mandibles, on underside of gaster, and near posterior margins of the second and succeeding gastric terga. Dorsal surfaces of body with abundant and conspicuous, short, appressed and subappressed pubescence, which also extends to appendages as a short, appressed to decumbent fuzz.

Funiculus rather robust, segments II through VIII thick, scarcely longer than broad; II and III together are slightly shorter than I and II-IV are subequal in length; apical segment very long. The petiolar node, while narrow and sharply tapered as seen from the side, has the tip more blunt (fig. 16) than in grandidieri, and about as in Anochetus punctaticeps.

Type Material

Holotype (Museum of Comparative Zoology) taken in the Vumba Mountains, near Umtali on the eastern border of Rhodesia (now Zimbabwe), 11 March 1969 (W. L. Brown). The specimen came from under a rock in a grassy cleared sloping area along the main road through the mountains; a forest remnant was farther down the slope nearby.

References

  • Brown, W. L., Jr. 1978c. Contributions toward a reclassification of the Formicidae. Part VI. Ponerinae, tribe Ponerini, subtribe Odontomachiti. Section B. Genus Anochetus and bibliography. Stud. Entomol. 20: 549-638 (page 607, figs. 10, 16 worker described)