Mycetagroicus triangularis

Mycetagroicus triangularis

Mycetagroicus triangularis is a tiny fungus-farming ant native to the Brazilian Cerrado. Workers measure just 2.72mm and are brown with fine hairs covering their body. Queens are slightly larger at 3.75mm with a ferrugineous brown coloration. This species gets its name from the distinctive triangular teeth on its clypeus (the face area above the jaws). As a member of the Attini tribe, these ants cultivate fungi for food, but unlike the famous leaf-cutter ants, they grow simpler 'lower agriculture' fungi fed on dead plant material rather than fresh leaves. This is one of the rarest ant species in cultivation, with almost no information available on captive care.

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Native to the Brazilian Cerrado savanna regions. Specimens have been collected from Mato Grosso (Gustavo Dutra/Sao Vicente), Distrito Federal (Brasília), and Bahia (Encruzilhada). The Cerrado is a tropical savanna with distinct wet (October-March) and dry seasons. They are documented as nesting subterranean (underground) ^[1].
• Colony Type: Colony structure is unconfirmed. As an Attini ant, they likely form single-queen colonies, but this has not been directly studied. No information exists on whether they are monogyne or polygyne.
• Size & Growth:
  • Queen: 3.75mm ^[1]
  • Worker: 2.72mm ^[1]
  • Colony: Unknown, likely small based on related lower Attini species
  • Growth: Unknown, likely slow to moderate based on related species
  • Development: Unknown, estimates based on related Trachymyrmex species suggest 6-10 weeks at optimal temperature (No direct development data exists for this species. Related lower Attini typically take 6-10 weeks from egg to worker at warm temperatures.)
• Antkeeping:
  • Temperature: Estimated 22-26°C based on Cerrado climate and related species. Provide a gentle thermal gradient if possible.
  • Humidity: Moderate, aim for 50-70% relative humidity. The Cerrado has distinct wet and dry seasons, so allow some drying between mistings.
  • Diapause: Likely a mild dormancy period during the dry season (May-September). However, this is unconfirmed for this specific species.
  • Nesting: Subterranean nesters, they dig underground chambers for their fungal gardens. In captivity, a deep soil-based formicarium or naturalistic setup with several inches of substrate works best. They need darkness and minimal disturbance to their fungus chamber.
• Behavior: Behavior is poorly documented. As a lower Attine, they are likely less aggressive than leaf-cutter ants and more secretive due to their subterranean nesting. Workers are tiny (2.72mm) so escape prevention with fine mesh is essential. They are not known to sting and their sting is likely too weak to penetrate human skin.
• Common Issues: This species is virtually never available in the antkeeping hobby, finding a colony is extremely difficult, No captive husbandry information exists, keepers must be prepared for significant experimentation, The fungus garden can be easily disrupted, avoid disturbing the nest chamber, Small size makes escape likely without fine mesh barriers, Subterranean lifestyle means they need deep substrate, not just shallow setups

Fungal Agriculture

Mycetagroicus triangularis belongs to the Attini tribe, ants that cultivate fungi for food. This species practices 'lower agriculture, ' a more primitive system compared to the leaf-cutter ants (Atta, Acromyrmex). Lower Attines feed their fungal gardens with dead plant material, detritus, and organic fragments rather than fresh leaf pieces. The queen carries a fungal inoculum when she founds the colony, planting it in a chamber where it grows to feed the first workers. In captivity, you would need to provide appropriate fungal substrate, this typically consists of moist organic matter like decaying leaves, wood fragments, or specialized fungal garden substrate. The fungus is the primary food source, workers themselves eat the fungal tissue. This makes Mycetagroicus significantly more difficult to keep than regular ants because you must maintain a healthy fungal culture alongside the colony.

Natural Habitat and Nesting

This species is known from the Brazilian Cerrado, a vast tropical savanna ecosystem. Specimens have been collected from underground nests in Mato Grosso, Distrito Federal (Brasília area), and Bahia at elevations ranging from near sea level to 960m. The only documented biological observation notes 'subterranean nest', meaning they dig chambers underground rather than using pre-existing cavities like many tree-nesting ants. The Cerrado has a pronounced wet season from October to March when dealated queens (already mated, wingless) were collected in November. This suggests nuptial flights occur at the start of the rainy season. In captivity, provide deep substrate (at least 5-10cm) for them to dig their nest chambers. A naturalistic setup with soil or a deep formicarium works better than shallow acrylic nests. ^[1]

Temperature and Seasonal Care

The Brazilian Cerrado experiences warm temperatures year-round, typically 20-30°C. Based on this and related Attini species, aim for 22-26°C in the nest area. A slight thermal gradient allows ants to regulate their own temperature. The dry season (May-September) is cooler and drier, you might consider a mild reduction in temperature and humidity during this period to simulate natural seasonal changes, though this species' exact diapause requirements are unconfirmed. Use a low-wattage heating cable on one side of the nest if room temperature falls below 22°C. Avoid overheating, temperatures above 30°C can kill the fungal garden.

Feeding and Diet

As fungus farmers, these ants have a unique dietary requirement, they grow fungi, not hunt insects like predatory ants. The fungal garden is their primary food source. In captivity, you would need to provide organic material for the fungus to grow on. This typically includes moistened leaf litter, wood fragments, or specialized substrate. Some lower Attine keepers use a mixture of damp soil, decaying leaves, and small amounts of protein sources like crushed insects. The ants will process this material and feed it to their fungus. The fungus, in turn, produces special structures called gongylidia that the ants eat. Do not expect these ants to readily accept sugar water or standard ant feeds, their nutrition comes from the fungal cultivation. This makes them one of the most challenging ant species to keep successfully.

Finding and Acquiring Colonies

Mycetagroicus triangularis is one of the rarest ants in the hobby, it has never been commercially available and likely has never been kept in captivity. The original specimens were collected in the 1950s-1980s during scientific surveys. If you ever encounter this species, it would almost certainly be through a researcher or a rare wild-caught queen. The species was only described in 2001,and very little biological information exists. Expect to work with a researcher if you hope to obtain specimens. This is not a species for beginners, it requires significant expertise in fungus-farming ant care and ideally access to scientific literature or experts who can guide captive cultivation of the fungal symbiont. ^[1]

Frequently Asked Questions

References