Mycetagroicus cerradensis

Mycetagroicus cerradensis

Mycetagroicus cerradensis is a small fungus-growing ant from the Brazilian Cerrado, with workers measuring just 3.4 mm in total length ^[1]. These ants are evolutionary celebrities, they represent the sister lineage to all higher attine ants (like leaf-cutters), yet they practice lower attine agriculture by cultivating a primitive fungus without the specialized nutrient-rich structures called gongylidia ^[2][3]. In the wild, they construct remarkably deep nests, with fungus chambers located up to 3.7 meters beneath the surface, making them one of the deepest-nesting attine species documented ^[2].

Their nests consist of a single entrance surrounded by a small soil mound, leading to vertical tunnels just 3-4 mm wide that descend through multiple soil-filled chambers before reaching the garden chambers far below ^[2]. Colonies are monogynous (single-queen) and reach approximately 600-800 workers ^[2]. Unlike leaf-cutters, these ants forage for minute plant fragments and tiny grass seeds rather than cutting fresh leaves ^[1].

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Brazilian Cerrado savanna (savanna-like formation), specifically in transition zones between cerradão and cerrado sensu stricto, and campo cerrado vegetation ^[2][4]. Native to Minas Gerais, São Paulo, Goiás, and Mato Grosso do Sul states ^[1].
• Colony Type: Monogyne, single-queen colonies with documented populations of 600-800 workers ^[2].
  • Colony: Monogyne
• Size & Growth:
  • Queen: Unknown (not described in available research).
  • Worker: 3.36 mm total length ^[1].
  • Colony: Approximately 600-800 individuals ^[2].
  • Growth: Moderate, fungus-dependent growth limits speed.
  • Development: Likely 6-10 weeks based on typical lower attine fungus-growing ant development patterns, though not directly measured for this species. (Lab colonies can produce additional workers over several months when properly maintained ^[2].)
• Antkeeping:
  • Temperature: Maintain around 22-25°C based on the mean annual temperature of 22°C in their native Cerrado habitat ^[2]. Provide a gentle heat gradient if possible.
  • Humidity: Moderate humidity with well-drained substrate. The Cerrado has distinct wet and dry seasons, keep nest material damp but never waterlogged, similar to red latosol soil conditions ^[2].
  • Diapause: Unknown, unlikely to require true hibernation given subtropical habitat, but may slow during cooler months.
  • Nesting: Requires exceptionally deep nesting space, vertical tunnels descending 1-4 meters with chambers for fungus gardens. Standard formicaria are inadequate, custom deep setups or naturalistic terrariums with deep substrate necessary ^[2].
• Behavior: Non-aggressive between nestmates, workers from different chambers of the same nest show no aggression when combined ^[2]. Foraging behavior involves collecting minute plant fragments and grass seeds rather than active hunting or leaf-cutting ^[1]. Workers are small and fast, requiring excellent escape prevention.
• Common Issues: fungus garden collapse without proper substrate and humidity maintenance., insufficient nest depth, standard shallow formicaria will not accommodate their natural nesting biology., contamination of fungus garden by Trichoderma or other unwanted fungi ^[2]., escape prevention is critical, at only 3.4 mm, workers can squeeze through tiny gaps., obtaining the correct fungal cultivar, they require lower attine Clade 2 fungus, not leaf-cutter fungus ^[2].

Deep Nesting Biology and Captive Housing

Mycetagroicus cerradensis constructs some of the deepest nests known among fungus-growing ants. Excavated nests revealed fungus chambers located at 3.5 to 3.7 meters below the surface, connected to the entrance by vertical tunnels only 3-4 mm in diameter ^[2]. Above the garden chambers, the ants create multiple soil-filled chambers at depths of 1.5 to 2.6 meters, possibly for ventilation or waste storage ^[2].

This presents a unique challenge for captive keeping. Standard horizontal formicaria or shallow plaster nests are completely unsuitable. You will need to provide significant vertical depth, ideally 1 meter or more of substrate, to allow for natural tunneling behavior. A tall terrarium or tube setup with deep, well-structured soil (similar to red latosols found in their habitat) is essential ^[2]. The entrance in nature consists of a single hole surrounded by a small mound of excavated soil pellets, often with a circular crater about 5 cm across ^[2]. In captivity, provide a deep substrate layer with a starter tunnel to encourage downward excavation toward the fungus chamber location.

Fungus Cultivation and Diet

Unlike leaf-cutter ants that cultivate higher attine fungi with specialized nutrient-rich gongylidia, Mycetagroicus cerradensis practices lower attine agriculture. Their fungus gardens display small whitish nodules that are actually swollen hyphae, not true gongylidia, placing their cultivar in Clade 2 of lower attine (G3) fungi ^[2]. This fungus is closely related to those cultivated by Mycetophylax faunulus, Myrmicocrypta cf. buenzlii, and Mycocepurus smithii ^[2].

The garden appears sessile (not in carton structures) and fills the chambers completely, with small rootlets passing through the soil and contacting the garden ^[2]. In captivity, you must provide the correct fungal cultivar, you cannot substitute leaf-cutter fungus. The ants forage for minute plant fragments, very small grass seeds, and other unspecified plant material to feed their fungus ^[1]. Offer dried grass clippings, small seeds, and bits of dried leaves. The fungus garden requires high humidity but good air exchange to prevent contamination by Trichoderma or other parasitic fungi ^[2].

Notably, Escovopsis, the specialized fungal parasite that attacks many attine gardens, was not detected in wild colonies, though other filamentous fungi were present ^[2].

Temperature and Seasonal Care

Native to the Brazilian Cerrado, these ants experience a subtropical climate with a distinct dry winter (May through September) and rainy summer (October through April) ^[2]. The mean annual temperature at study sites is 22°C, with mean annual precipitation of 1650 mm ^[2].

Maintain your colony at approximately 22-25°C year-round. You can create a gentle thermal gradient by placing a heating cable at the top of the nest setup, allowing the ants to thermoregulate by moving deeper into the cooler soil or closer to the surface as needed. Avoid overheating, the deep soil provides natural temperature buffering in the wild. While the region has seasonal rainfall patterns, you should maintain consistent moderate humidity in the nest year-round rather than attempting to simulate dry seasons, as the fungus garden requires constant moisture to survive.

Colony Structure and Development

Colonies are strictly monogyne, containing only a single queen even when multiple garden chambers are present ^[2]. Excavated nests contained approximately 302 workers at the time of collection, with lab-reared fragments growing to 350+ workers, suggesting natural colony sizes of 600-800 individuals ^[2].

The queen was found between the two garden chambers in the excavated nest, suggesting she moves between garden sections or stays in connecting areas ^[2]. When the queen died in February 2009 in laboratory conditions, the colony continued with 350 workers preserved, indicating possible worker longevity but no replacement queen system ^[2]. Males remain undescribed for this species, and nuptial flight timing is unknown ^[2].

Growth rate depends entirely on fungus garden health. Based on patterns from related lower attine species, expect egg-to-worker development of approximately 6-10 weeks at optimal temperatures, though this is not directly documented for M. cerradensis. The first workers (nanitics) will be small and will immediately begin foraging for plant material to expand the garden.

Associated Organisms and Nest Commensals

Nitidulid beetles were found living inside the nest chambers and tunnels of excavated colonies ^[2]. These beetles are common commensals in attine ant nests, often feeding on fungal debris or waste. While their exact relationship with M. cerradensis is not detailed, they do not appear to harm the colony. In captivity, you may notice small beetles or mites in the nest, most are harmless decomposers, but watch for signs of parasitic infestation or fungal contamination that could indicate hygiene issues.

Frequently Asked Questions

References