Anochetus modicus

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

Anochetus modicus casent0217508 p 1 high.jpg

Anochetus modicus casent0217508 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of this species.

Identification

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

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

Check distribution from AntMaps.

Distribution based on specimens

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The above specimen data are provided by AntWeb. Please see Anochetus modicus for further details

Biology

Not much is known about the the biology of Anochetus modicus 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

Queen

Nomenclature

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

  • modicus. Anochetus modicus Brown, 1978c: 582 (w.q.m.) BORNEO. Imai, Kubota, et al. 1985: 47 (k.).

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

Description

This species is similar to several species of the risii group; in fact, it is as nearly average a form for the group as one could hope to find. The very short, straplike, mesonotal disc is one distinctive feature; the mandibles are longer than in Anochetus brevis, and its much more restricted frontal striation will distinguish modicus from Anochetus strigatellus; the smooth, shining pronotum separates it from the similar-sized Anochetus incultus. Probably A. modicus will be found eventually to be a widespread species in wet upland forests of the Sunda islands.

Worker

Holotype: TL 5:9, HL 1.45, HW 1.25, ML 0.84, WL 1.90, scape L 1.17, eye L 0.21 mm; CI 86, M.I 58.

Color rich, bright, brownish-red; corners of head, mandibles, antennae, legs, petiole and gastric apex lighter, more yellowish. A member of the Anochetus risii group in habitus, mandibular form and armament, and body sculpture, but differing from Anochetus risii, apart from smaller size and darker color, in the relatively shorter mandibles, scapes and eyes, as well as the following:

1. Scapes surpass posterior margins of occipital lobes by an amount less than the length of the first funicular segment.

2. Mesonotal disc reduced to a mere smooth, transversely straplike, raised strip, 4 times or more wider than long, limiting the strong longitudinal costulae of the metanotal saddle anteriorly.

3. Petiolar node smooth, moderately stout, almost perfectly erect, narrowly rounded at apex, but more broadly so than in risii, and not nippled; as seen in side view outline, both anterior and posterior slopes gently convex; base of petiole horizontally costulate. and with a brief anterior peduncle.

Body shining. Frontal striation weak, extending only a short way beyond frontal carinae caudad, not fanning out widely, leaving most of central vertex smooth and shining. Pronotum smooth and shining, the only distinct sculpture, aside from occasional faint traces of lateral striae, and some piligerous punctures, is the usual transverse striation of cervix, becoming coarser, more costulate, on base of anterior slope of pronotal disc. Meso- and metapleura smooth and shining. the former with distinct transverse suture. Propodeal dorsum transversely costulate, the costulae irregular and about 30 in number, with 4-5 more on declivity. Gaster smooth and shining, narrowed behind basal segment, but not noticeably constricted.

Long, fine, erect and inclined hairs fairly numerous and generally distributed over dorsal surfaces, undersides of head and gaster, anterior side of front coxae, and scapes and legs; up to 0.25 mm long on pronotum and gastric dorsum, but mostly not much over 0.1 mm elsewhere. Pubescence fine, mostly restricted to appendages.

Worker variation, paratypes: Of the 9 workers available, 5, including the holotype, are from Moaratoa I., Borneo; 3 are from Tjibodas, Java; and 1 is from the Cuernos Mts., Negros I., Philippines. The combined measurements and indices for these are: TL 4.8-5.9, HL 1.21-1.45, HW 1.06-1.29, ML 0.71-0.87, WL 1.50-1.80, scape L 1.01-1.21, eye L 0.16-0.21 mm; CI 84-90, MI 58-62. The Moaratoa workers average larger (TL 5.7-5.9, HL 1.40-1.45, HW 1.22-1.24 mm; CI 86-90, MI 58), but have slightly shorter trunks (WL 1.73-1.74) than do the Javanese workers (WL 1.77-1.80), even though in other dimensions the latter are smaller: TL 5.5-5.7, HL 1.37-1.40, HW 1.15-1.18 mm; CI 84-86, MI 58-62.

The single Philippine worker is small (TL 4.8, HL 1.21, HW 1.06, WL 1.50 mm; CI 88, MI 59) and pale brownish-red in color, with the head slightly darker. Its petiolar node is a little more slender in side view than in the other 2 series.

While the Moaratoa series has fairly regular transverse costulation of the propodeal dorsum, the Tjibodas sample has the propodeal dorsum covered with mainly disoriented rugulation, showing only weak and partial organization into transverse costulae.

Queen

Paratypes: Two specimens, one a callow alate taken with the Moaratoa series, the other a dealate taken alone in the Cuernos Mts. of Negros I. at 4000 ft. (about 1220 m). Moaratoa I.: TL 6.9, HL 1.54, HW 1.40, ML 0.84, WL. 2.00, scape L. 1.17, eye L 0.32 mm; CI 91, MI 55. Cuernos Mts., Philippines: TL. 5.9, HL 1.31, HW 1.22, ML 0.78, WL 1.88, scape L 1.10, eye L 0.29 mm; CI 93, MI 60.

The Moaratoa queen is winged (forewing L about 4 mm) and dull, light reddish-brown in color (callow); the Philippine specimen is dealate and light brownish-yellow. Pronotum and mesonotum smooth and shining (faint traces of diagonal striation on side of pronotum in Moaratoa queen).

Male

Single specimen mounted on same pin with worker from Cuernos Mts., Philippines: TL 4.4, HL 0.71, HW (including eyes) 0.92, ML (closed mandibles) 0.11, WL 1.62, forewing L 3.3 mm.

Color dark brown, gaster slightly paler, especially toward apex; antennae tan; legs, mouthparts and genital capsule sordid yellowish. Eyes taking up about 2/3 of sides of head. Lateral ocelli separated from eye by about 0.2 mm, and distant from anterior ocellus by about the diameter of the latter. Mandibles small, cuneiform as seen from above, acute, with conspicuous circular white basin at base.

Trunk robust, with convex dorsum and pleura; notauli obsolete, except for shallow longitudinal sulcus at rear of scutum; scutellum prominent, hemispherical; metanotum short, convex; propodeum convex, dorsum rounded into declivity; its spiracle very small, elliptical. Petiolar node subsquamiform; bluntly cuneiform as seen from side, with both anterior and posterior slopes slightly convex; sides convex, and apex rather broadly rounded as seen from in front. Gaster almost imperceptibly constricted after postpetiolar segment.

Terminalia unremarkable; pygidium folded, lightly sclerotized, and thus forming a barely acute beak; hypopygium narrow-linguiform, tapered to a truncate apex, its ventral surface convex. Parameres broadly subcuneiform in side view, with rounded apices; outer surfaces convex; bent slightly mesad just beyond their midlength as seen from dorsal view. Aedeagus thick; volsellae each with digitus and cuspis.

Tibial apices each with two spurs on middle and hind legs, of which the mesial spur of the hind leg is large and broadly pectinate. Hind wing with a well-developed anal lobe.

Entire body weakly to moderately shining, mostly smooth, with numerous fine piligerous punctures; additional fine shagreening around the periphery of the scutum, on anterolateral faces of propodeum, etc.

Virtually the entire, normally-exposed body surface and appendages covered with a short, dense, pubescence-like investiture, decumbent on extremities of appendages, but becoming erect or suberect on mesonotum and elsewhere. A few longer (but still short and fine) hairs on ocellar triangle (otherwise nearly bare, and very smooth), on anterior cheeks, on metanotum, on apex of petiolar node, and toward gastric apex.

Type Material

Holotype worker Museum of Comparative Zoology and 4 paratype workers with one callow alate queen from Moaratoa lsl[and], Borneo, [E.] Mjöberg. I have not been able to find a locality with this exact name on maps, charts, or gazetteers of the Borneo area. Moara in Malay means mouth of river. The most similar island name I located is Maratua Island, for an atoll including a hill in the Celebes Sea southeast of Tarakan, off the east coast of Kalimantan Timur (Indonesian Borneo), but I am not at all certain whether this is the same as Mjöberg's locality. Other paratypes (MCZ) are 3 workers from Tjibodas, Java, 1400 m (without collector's name, but one specimen carrying the label jumping ant; also the single worker with one male from Chapman's Camp, at about 1100 m in the Cuernos Mts., near Dumaguete, Negros Oriental, Philippines (J. W. Chapman). A single dealate queen also comes from 4000 ft. (about 1220 m) in the Cuernos Mts. (Chapman).

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 582, worker, queen, male described)
  • Imai, H. T.; Kubota, M.; Brown, W. L., Jr.; Ihara, M.; Tohari, M.; Pranata, R. I. 1985. Chromosome observations on tropical ants from Indonesia. Annu. Rep. Natl. Inst. Genet. Jpn. 35: 46-48 (page 47, karyotype described)