Pseudomyrmex acanthobius

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Neotropical region, Argentina, Bolivia, Brazil, and Paraguay. Found in diverse habitats including veredas (Brazilian wetlands), Chaco woodland, and Caatinga (dry thorn forest). These are arboreal ants that nest in tree hollows, particularly in Vachellia caven (aromita) trees ^[2][3].
• Colony Type: Colony structure is not well documented in research. Based on genus patterns, Pseudomyrmex species typically have single-queen (monogyne) colonies, but this specific species' founding behavior is unconfirmed.
• Size & Growth:
  • Queen: Size data unavailable. Based on typical Pseudomyrmex queen sizes, likely larger than workers, but no species-specific measurement exists.
  • Worker: Approximately 4-5mm, typical for the genus ^[1]
  • Colony: Up to 500 workers (estimated from genus patterns)
  • Growth: Moderate
  • Development: Estimated 6-8 weeks at tropical temperatures (25-28°C) based on related Pseudomyrmex species, no specific study for this species (Development time is estimated. Tropical species typically develop faster than temperate ones.)
• Antkeeping:
  • Temperature: Keep at warm tropical temperatures, around 24-28°C. As a Tropical Climate Specialist from South America, they need stable warmth year-round. Use a small heating cable on one side of the nest to create a gentle gradient ^[3][4].
  • Humidity: Keep the nest substrate slightly moist but ensure good ventilation. Their arboreal nature means they tolerate some drying, but avoid complete dryness. A moisture gradient in the nest (one moist chamber, one dry) works well.
  • Diapause: No, as a tropical species, they do not require hibernation. Keep them at stable warm temperatures year-round ^[3].
  • Nesting: Arboreal setup is essential. In nature they nest in hollow twigs and branches. In captivity, use a Y-tong (AAC), plaster, or 3D-printed nest with narrow chambers, placed above the outworld. Provide climbing branches, cork bark, or natural twigs reaching up to the nest. Avoid deep soil nests ^[2][3].
• Behavior: These ants are active foragers that hunt small prey in vegetation. They are generalist predators and also visit extrafloral nectaries for sugar ^[3]. Workers are agile and fast, typical of the 'agile pseudomyrmecine' guild. They are not particularly aggressive toward keepers but will defend their nest. As a member of the Pseudomyrmecinae subfamily, they have a well-developed sting. Escape risk is moderate, they are small but fast. Ensure tight sealing of the enclosure.
• Common Issues: arboreal nature means standard test tube setups often fail, they need climbing structures and above-ground nesting, very low capture rate in studies suggests they are sensitive to disturbance and may be difficult to establish in captivity, tropical temperature requirements mean they cannot tolerate cool temperatures, keep warm year-round, predatory diet means they need regular protein (live small insects), sugar alone is insufficient, captive colonies may be difficult to source as they are not commonly kept in the hobby

Natural History and Distribution

Pseudomyrmex acanthobius is found across the Neotropical region, including Argentina (Corrientes and Misiones provinces), Bolivia, Brazil, and Paraguay ^[1][4]. This species inhabits diverse environments from Brazilian veredas (wetlands) to the dry Chaco woodland and Caatinga thorn forest ^[6][5]. The key to their distribution is the presence of suitable nesting trees, they are obligate arboreal nesters, found nesting specifically in Vachellia caven (aromita) trees in the Chaco Brasileiro ^[2].

Studies classify these ants as Tropical Climate Specialists (TCS), indicating a preference for warm, humid conditions ^[4]. Their very low abundance in ground pitfall traps (only 1-7 individuals across multiple studies) confirms they are predominantly arboreal ^[5][3]. Seasonal patterns are unclear: one study from Caatinga captured them exclusively in the dry season ^[3], while another found a few individuals in both dry and rainy seasons ^[5]. This suggests they may adjust activity to local conditions.

Nest Preferences and Housing

This is an arboreal species that requires above-ground nesting structures. In nature, they nest in hollow twigs and branches of trees, particularly Vachellia caven ^[2]. For captive care, replicate this with a naturalistic setup featuring twigs, branches, or cork bark arranged vertically. A Y-tong (AAC), plaster, or 3D-printed nest with narrow chambers can work, but you must provide climbing branches reaching the nest entrance. Avoid deep soil formicariums, these ants will not use them. Position the nest above the foraging area, allowing workers to travel up and down between nest and food sources. Include live or artificial plant material for them to explore.

Feeding and Diet

Pseudomyrmex acanthobius is a generalist predator that actively hunts small invertebrates in vegetation ^[3]. In captivity, offer small live prey such as fruit flies, pinhead crickets, small mealworms, and other tiny insects. Feed protein 2-3 times per week, removing uneaten prey after 24 hours. They also visit extrafloral nectaries in the wild, so provide sugar sources like sugar water, honey, or diluted honey in a shallow container with a cotton wick to prevent drowning. A balanced diet of live protein plus sugar water works best for maintaining healthy colonies.

Temperature and Seasonal Care

As a tropical species from northern Argentina, Bolivia, Brazil, and Paraguay, Pseudomyrmex acanthobius requires warm temperatures year-round. Maintain nest temperatures between 24-28°C ^[3][4]. Room temperature may be sufficient if your home stays in this range, otherwise use a small heating cable on one side of the nest to create a gentle gradient. Unlike temperate species, these ants do not require hibernation or winter cooling. Keep them at stable warm temperatures throughout the year. Sudden temperature drops can stress or kill colonies. Monitor with a thermometer near the nest. The species has been found in both wet and dry seasons across its range, suggesting they can handle some humidity variation but prefer consistent warmth ^[5][3].

Behavior and Temperament

These ants belong to the 'agile pseudomyrmecine' guild, active, quick-moving foragers that hunt prey in vegetation ^[3]. Workers are slender and fast, moving quickly across branches and leaves. As a member of the subfamily Pseudomyrmecinae, they have a well-developed sting used for defense. They are not typically aggressive toward humans but will defend their nest if threatened. Their arboreal lifestyle means they spend considerable time climbing, provide vertical space and climbing materials in the enclosure. Workers will venture out to forage and return to the nest. They are primarily active during warmer hours but may show peak activity at different times depending on your specific conditions. Observe your colony to determine their peak activity periods for feeding.

Frequently Asked Questions

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References