This paper begins with a Dinoponera literature summary.

LITERATURE SUMMARY

Taxonomy and Biogeography: The ponerine ant genus Dinoponera is restricted to the Neotropics. Kempf (1971, 1972) described seven species and two subspecies native to various savanna, dry forest, and wet forest habitats.

Individual and Colony Reproduction: Haskins and Zahl (1971) described reproduction in D. grandis, Overal (1980) reported colony founding by D. gigantea, and Dantas de Araujo et al. (1990) studied reproduction in D. quadriceps. Unlike most ants having morphologically distinct queens, Dinoponera reproduces via inseminated workers, called gamergates in a review by Peeters (1993).

New nests are formed by colony splitting and migration. When colonies move to new sites, workers either carry nestmates or closely follow one another in tandem. Hölldobler and Wilson (1990) note that such ants seem to rely relatively little on odor trails for group recruitment to nest sites or food. Instead, chemical markings are used mainly for individual orientation.

Nests and Colony Population: Dinoponera australis nests are rather deep below ground, with up to 15 large chambers, each big enough to hold the entire colony, which at most contains 30 large workers (Paiva 1993). Dinoponera quadriceps nests contained 40-92 workers and 1-10 gamergates per colony (Dantas de Araujo et al. 1990).

Defensive Behavior: Schmidt (1990) reported that D. grandis sting pain intensity was comparable to that of the honey bee, and had a 2-10 minute duration.

Captive Husbandry: Paiva (1993) noted laboratory D. australis colonies housed in Gypsy nests. Mendez (pers. comm.) maintained a captive D. gigantea colony for several years in both hydrostone and natural soil nests; mating was observed in the nest, and the ants' diet included "pinkie" or newborn mice. Morgan (1993) detailed captive care of D. longipes.

BIOLOGY OF DINOPONERA LONGIPES

Taxonomy: Voucher specimens preliminarily were identified as D. longipes Emery. However, slight anatomical differences suggest that the specimens may in fact represent a new undescribed Dinoponera species near longipes (Cover pers. comm.).

Habitat: ACEER habitat predominantly is primary, non-seasonal, upland rainforest. This region is characterized by mostly large mature trees and open understory. Heavy rainfall occurs throughout the year, though the ground surface is well drained. Temperatures near the forest floor are relatively stable and generally remain near 24° C.

Nest Site: Twenty-two D. longipes nests were found along a 810 m survey baseline (Morgan 1993). Nest position seemed independent of the area's variable topography. Nests were placed around, between or under plant bases or roots, but their location seemed unrelated to any particular plant species Most nests seemed heavily shaded by overhead vegetation, though at least two nest mounds received dappled sunlight at mid-day. Most nests also were found in sparse understory vegetation and lightly littered ground. Overall, the nest site pattern suggested that some degree of spacing (avg.=35 m) was maintained between nests.

Nest Architecture: The majority of nests exhibited slight to well-developed earthen mounds. These apparently were formed from an accumulation of excavated, rain-compacted soil, and seemed to be most noticeable when surrounding terrain was fairly level, or when vegetation provided structural support and protection from rain erosion.

Two nests were excavated; one of these appeared relatively large while the other was small. The large nest had 21 surface openings roughly scattered over the ground throughout a 2.1 x 0.6 m area. Most nest opening tunnels gently angled downward, and broadly interconnected with nine subterranean chambers. These were horizontally oriented, roughly linearly aligned, and all shallowly positioned, generally about 30 cm from the surface.

Nest chambers were round or oval; most were 10-15 cm wide, but two were about 25 cm wide at their longest axis. The chambers tended to be slightly domed and about 3-4 cm high from floor to ceiling. Some chamber floors were lightly covered with a layer of what appeared to be dry vegetation bits. Several spot temperature measurements made at the nest surface and within nest chambers were similar. These generally ranged closely to 24°C both during the day and at night.

The small nest had a single surface opening surrounded by freshly excavated soil. The opening accessed a 13 cm deep vertical tunnel leading to a single subterranean chamber. The chamber was oval, horizontally positioned, and measured about 10 x 13 cm wide, and about 3 cm high from floor to ceiling.

Nest Population: The large nest contained 120 females (all morphological workers, hence no distinct queen (Fig. 1)), 5 winged males, 57 cocooned pupae, six large larvae, over 30 small to medium-sized larvae, and 25 eggs. The male presence suggests that this colony was reproductively mature. The small nest held 7 morphological worker females and 11 eggs. The absence of brood other than eggs suggests that this nest contained an incipient or very young colony.

Food items too large to carry are first cut into pieces. The mandibles are serrated and seem adapted for cutting in two very different ways. Against large items, they are pushed open and used like a curved saw blade with back and forth head movements. Against narrow objects,

Food includes both invertebrates (mostly insects) and various vertebrates. Invertebrates eaten included Dictyoptera (roaches, mantids), Phasmatoptera (stick insects), Orthoptera (crickets, grasshoppers, katydids), Isoptera (giant termites), Neuroptera (dobsonflies), Hemiptera (back swimmers, giant water bugs), Homoptera (cicadas), Coleoptera (mealworms), Diptera (flesh flies), Lepidoptera (waxworms), Hymenoptera (male Paraponera, honey bees), Arachnida (orb spiders), Chilopoda (centipedes), and Annelida (earthworms).

Similarly, if nest chambers are opened or otherwise disrupted, the ants carry their brood to secure areas. Observation nest chamber temperatures generally remained close to 24°C, but when one chamber was slowly warmed, the colony began to move out as the temperature approached 27°C.

Once settled in a nest, workers often partially cover and hide, or sometimes reduce or temporarily block nest openings with mulch. This behavior perhaps helps camouflage nest openings, or makes them more defensible.

Fecal droplets are used to line nest chamber walls, and to a lesser degree, crevices and spaces outside observation nest boxes, and possibly contain chemical cues for forager orientation or nest recognition. The droplets are applied as a dark gray liquid but soon dry and blacken.

Hatchling larvae are tiny and coiled, while older larvae are grublike and exhibit long flexible necks. Larvae obviously feed while being held or carried

Two repeatedly observed behavioral interactions between nestmates are probably dominance

HUSBANDRY AND DISPLAY

The Insectarium rearing room is maintained at 24-27°C, 40-60% relative humidity, and illuminated primarily with fluorescent lights on a 16-hour day cycle.

Laboratory Housing: Stable shelves support observation nest boxes contained within standard sized glass aquaria. Observation nests consist of cast hydrostone (gypsum cement) chambers and tunnels covered with glass, allowing overhead viewing. Except during observation, viewing glass is covered by opaque plastic sheets to darken nest interiors. The hydrostone was tinted with mortar color to provide natural color and to facilitate evaluation of water content, since colored hydrostone appears markedly darker when damp. Moisture lost through evaporation is replaced by occasionally dribbling water onto hydrostone nest surfaces.

Various standard size glass aquaria contain either nest boxes or serve as foraging areas.

The large wild-caught colony currently is housed in three interconnected aquaria off exhibit for laboratory study. Tanks are connected to one another via two 3.75 cm diam x 15 cm long, clear plastic tubes positioned horizontally; these tubes are used by the ants like tunnels. Two tanks serve as nesting areas and are nearly filled by four observation nest boxes. These contain 2-4 chambers each for a total of 10 nest chambers. Nest boxes are not directly interconnected with one another and colony members travel openly between them. To help maintain nest humidity, the surrounding cypress bark mulch is kept moist.

Food, Water and Cleaning: In the foraging area tank, a flat brick provides a stable, elevated, mulch-free area for dish placement. A petri dish, regularly supplied with fresh drinking water, is routinely visited by the ants. A wide variety of both invertebrate and small vertebrate prey items are provided from Insectarium surplus. Mulch in the foraging area tank is kept dry to retard decomposition of old discarded or uneaten prey items. Ants place colony trash at the foraging tank's far end, facilitating regular large debris removal. Every 2-3 months, the old mulch containing fine debris is replaced with fresh clean mulch. An oily material, possibly related to fecal droplet application, slowly accumulates as a film on the underside of observation nest viewing glass. Periodically, viewing glass is temporarily removed and wiped clean.

Display and Publicity: The small wild-caught colony was established in an observation nest later incorporated into an Insectarium public display tank. The exhibit depicts a naturalistic habitat with the ground surface cut away to show the nest interior. Insectarium visitors may see dinosaur ants outside their nest foraging for food, or within their nest consuming prey and caring for brood.

Acknowledgments:

The Cincinnati Zoo and Botanical Garden supported this work in part. The ACEER Scientific Advisory Board approved the research program. International Expeditions, Explorama Lodge, and ACEER staff generously facilitated logistics. International Rainforest Workshop participants assisted fieldwork. U.S. and Ohio Departments of Agriculture approved importation permits. Insectarium staff Milan Busching, Karen Creamer & Theresa Austing assisted captive husbandry. Joyce Turner created artwork. Kathy Beil-Morgan provided helpful manuscript comments.

REFERENCES

COVER, S. (pers. comm.): Department of Entomology., MCZ Labs., Harvard University, Cambridge, MA.

DANTAS DE ARAUJO, C.Z.; LACHAUD, J.-P.; and Fresneau, D. (1990): Le système reproductif chez une ponérine sans reine: Dinoponera quadriceps Santschi. Behav. Proc. 22:101-111.

HASKINS, C.P. and ZAHL, P.A. (1971): The reproductive pattern of Dinoponera grandis Roger (Hymenoptera, Ponerinae) with notes on the ethology of the species. Psyche 78(1-2):1-11.

HÖLLDOBLER, B. and WILSON, E.O. (1990): The Ants. Cambridge, MA: Belknap Press of Harvard Univ. Press., 732 pp.

KEMPH, W.W. (1971): A preliminary review of the ponerine ant genus Dinoponera Roger (Hymenoptera, Formicidae). Studia Entomologica, n.s., 14(1-4): 369-394.

KEMPH, W.W. (1972): Catálogo abreviado das formigas da Região Neotropical (Hymenoptera: Formicidae). Studia Entomolgica, n.s., 15(1-4): 3-344.

MENDEZ, R. (pers. comm.): Exhibit Consultant, Portal, AZ.

MORGAN, R.C. (1993): Natural History Notes and Husbandry of the Peruvian Giant Ant Dinoponera longipes* (Hymenoptera: Formicidae). SASI-ITAG Invertebrates in Captivity Conference Proceedings, pp. 140-151.

OVERAL, W.L. (1980): Observations on colony founding and migration of Dinoponera gigantea. Journal Georgia Entomol. Soc. 15(4):466-469.

PAIVA, R.V.S. (1993): Another case of association between ants: Dinoponera and Pheidole. Notes From Underground, A Myrmecological Newsletter, No. 8. (Tobin, J.E, Chavarria, G., and Alpert, G.D., eds.), MCZ Labs., Harvard Univ., Cambridge, MA.

PEETERS, C. (1993): Monogyny and polygyny in ponerine ants with or without queens. In: Queen Number and Sociality in Insects, Keller, L. (ed.), pp. 234-261. Oxford University. Press.

SCHMIDT, J.O. (1990): Hymenopteran Venoms: Striving Toward the Ultimate Defense against Vertebrates. In: Insect Defenses, Adaptive Mechanisms and Strategies of Prey and Predators (Evans, D.L. and Schmidt, J.O., ed's.), pp. 387-419. State Univ. of New York Press, Albany.