Apterostigma angustum

Apterostigma angustum

Apterostigma angustum is a small fungus-growing ant from the tribe Attini, found in the mountainous forests of northern South America. These ants live in mid-elevation habitats from 115 meters up to 1221 meters above sea level in Venezuela, Colombia, and French Guiana ^[1][2]. Workers have distinctive triangular frontal lobes, an egg-shaped head profile when viewed from the side, and relatively small compound eyes ^[1]. Unlike the famous leaf-cutter ants, this species belongs to the non-leaf-cutting fungus growers. They cultivate fungal gardens using insect droppings and dead plant material rather than cutting fresh leaves ^[2].

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Mid-elevation tropical forests of Venezuela, Colombia, and French Guiana ^[1][2]
• Colony Type: Unknown, likely single-queen based on typical Attini patterns, but unconfirmed
• Size & Growth:
  • Queen: Unknown ^[2]
  • Worker: Unknown, likely 2-4mm based on typical Apterostigma size ^[2]
  • Colony: Unknown, likely small to moderate based on genus patterns ^[2]
  • Growth: Slow
  • Development: 8-12 weeks (estimated based on Attini tribe patterns) (Fungus-growing ants typically develop slowly. Nanitic workers may emerge slightly faster than normal workers.)
• Antkeeping:
  • Temperature: 20-24°C (estimated from 600-1221m elevation range) ^[1]. Start at 22°C and adjust based on colony activity.
  • Humidity: High humidity required, roughly 70-80%. Keep the nest substrate damp but not waterlogged.
  • Diapause: No, tropical species active year-round ^[1]
  • Nesting: Requires enclosed cavities with space for fungus garden. Naturalistic setups with rotting wood or plaster nests work best ^[2].
• Behavior: Slow-moving, cryptic foragers that process organic debris. Non-aggressive toward humans. Moderate escape risk due to small size.
• Common Issues: fungus garden contamination with mold kills colonies quickly, incorrect substrate (fresh leaves instead of dried matter) causes garden failure, temperatures above 26°C damage the sensitive fungus, low humidity desiccates both the ants and their fungal food source, wild-caught colonies may carry parasitic mites that overwhelm captive setups

Fungus Garden Care

As a member of the Attini tribe, Apterostigma angustum cultivates a fungal garden that serves as the colony's primary food source. Unlike leaf-cutter ants, this species uses insect droppings (frass), dead plant material, and other organic debris to feed their fungus ^[2]. You must provide a suitable substrate such as dried leaves, small twigs, or pre-digested plant matter. The fungus garden requires constant humidity and temperatures around 20-24°C to prevent mold contamination. If the garden dies, the colony starves. Watch for white or gray mold spreading through the garden material, this signals contamination that usually proves fatal.

Nest Design and Setup

In nature, these ants nest in cavities in rotting wood or under stones in humid forests ^[2]. In captivity, use a naturalistic setup with a moist plaster or Y-tong nest section connected to a foraging area. The nest chamber must maintain high humidity (70-80%) and provide space for the fungus garden. Avoid dry nests or those with excessive ventilation, as the fungus requires stable moist conditions. A test tube setup will not work for this species, they need room to establish and expand their fungal garden.

Temperature and Humidity

Collection records show this species lives at elevations from 115m to 1221m in the Colombian Andes and Venezuelan mountains ^[1]. This suggests they prefer cooler tropical conditions than lowland Amazonian species. Keep them at 20-24°C with high humidity around 70-80%. Use a heating cable on one side of the nest to create a gentle gradient, but avoid overheating as this damages the fungus garden. The substrate should feel damp to the touch but not waterlogged. If workers cluster near the heat source, increase temperature slightly, if they avoid it, reduce heat.

Feeding Your Colony

Do not offer fresh leaves or vegetables. Instead provide dried leaves, small pieces of hardwood, insect frass, or partially decayed plant matter that the ants can process for their fungus ^[2]. They may also accept small amounts of sugar water or honeydew for energy, but the fungus garden provides their main nutrition. Remove uneaten perishable food quickly to prevent mold that could contaminate the garden. The ants will chew the plant material into a pulp to feed their fungus, you will see them carrying bits of debris into their nest chambers.

Colony Founding and Growth

Founding behavior is unconfirmed for this species. Most Attini queens seal themselves in (claustral founding) and raise the first workers using stored body reserves while starting a small fungus garden using spores carried from their natal colony. Growth is likely slow, with colonies possibly reaching only a few hundred workers over several years. Development time from egg to worker is unknown but likely ranges from 8-12 weeks based on related fungus-growing ants. Be patient, these are not fast-growing species like Lasius or Formica.

Frequently Asked Questions

References