Anochetus tua

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

Anochetus tua casent0217514 p 1 high.jpg

Anochetus tua casent0217514 d 1 high.jpg

Specimen Labels

The type specimens were collected from "hill forest."

Identification

Brown (1978) - A. tua takes its name from the Malay word meaning elder or senior, and also meaning darker in color, in reference to its size and hue. Among the larger risii group species with long mandibles, only [[Anochetus risii and Anochetus agilis might be confused with tua, especially A. agilis, with its even more slender head, elongate body, and variable petiolar shape, But the sculptural differences, which are about the same as for the comparison against A. risii, and the much darker color of mature workers, will serve to distinguish A. tua with ease.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

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

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 tua 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 of this species are unknown.

Nomenclature

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

  • tua. Anochetus tua Brown, 1978c: 580, figs. 1, 29 (w.) WEST MALAYSIA.

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 8.2, HL 1.77, HW 1.47, ML 1.22, WL 2.54, scape L 1.68, eye L 0.32 mm; CI 83, MI 69.

A moderately larger (longer) relative of Anochetus risii, with the following additional differences from that species:

1. Color much darker: body dark reddish-brown to piceous, appearing black to the naked eye (trunk and petiole lighter reddish-brown in presumably partly teneral paratype examples); posterior and often anterior corners of head reddish; gastric apex, mandibles, antennae and legs predominantly light ferruginous to dull yellow.

2. Sculpture more extensive and coarser. Frontal striation occupies most of the central vertex, and faint traces sometimes even reach the nuchal carina on each side of the midline; «occipital» lobes and sides of head behind eyes smooth and shining. Pronotum completely sculptured and opaque to subopaque, though sculpture may be weak discad, consisting here of fine, indefinite rugulosity with shagreening, mostly inverted U- or V-like in pattern; front of pronotum transversely costulate, the costulae continuing around onto the sides of the pronotum as fine reticulo-striation. Mesonotum irregularly transversely striolate, the sculpture more or less effaced mesad. Mesopleura mainly smooth and shining, with traces of rugulae toward the ends; metapleura shining, with traces of oblique costulation and some shallow punctures. Petiolar node very finely reticulate, but moderately shining. Coxae and gaster smooth and shining. Mandibles, legs and antennae very finely punctulate-shagreened, moderately shining to nearly opaque.

3. Petiolar node thicker, not pointed above, but narrowly rounded, and only slightly laterally compressed toward the apex.

4. Mandibles long and in general shaped like those of risii, but the series of denticles springing from the inner ventral margins sharper and more prominent (fig. 1) as the distinction between dorsal and ventral margins tends to disappear apicad along the shaft. The denticles also tend to be spaced farther apart, and most of them are visible, even in full-face view. Intercalary denticle small, sharp when unworn and situated near the end of the ventral tooth as in risii, but often broken off or worn to a blunt remnant.

The paratypes, aside from color variation already mentioned, vary moderately in dimensions: TL 7.6-8.2, HL 1.73-1.80, HW 1.44-1.48, ML 1.16-1.21, WL 2.42-2.56, scape L 1.65-1.72, eye L 0.31-0.33 mm; CI 82-83, MI 67-68. Variation occurs in size, number and spacing of the denticles on the inner mandibular borders, and details of sculpture on head and trunk vary in minor ways.

Type Material

Holotype Museum of Comparative Zoology and 6 paratype workers (MCZ, The Natural History Museum) from Malaysia, Pahang: Fraser's Hill, ca 1300 m, wet hill forest, 16 August 1967, R. H. Crozier, No. CJ 16.

Etymology

A. tua takes its name from the Malay word meaning elder or senior, and also meaning darker in color, in reference to its size and hue.

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 580, figs. 1, 29 worker described)