Brachymyrmex donisthorpei

Brachymyrmex donisthorpei

Brachymyrmex donisthorpei is a tiny yellowish ant species native to the Neotropical region, found in Brazil, Colombia, Ecuador, and Paraguay ^[1]. Workers are among the smallest in the ant world, measuring only about 2.5-3mm in total length, with a distinct yellowish body color and dense short pubescence covering their entire body ^[1][2]. Their most distinctive feature is their very small eyes, containing only 3-4 ommatidia, positioned below the midline of the head, along with short scapes that barely reach the posterior margin of the head ^[1]. These ants were originally described from Colombia in 1939 and are typically found in montane wet forest leaf litter ^[1]. The biology of this species remains largely unknown, making them an intriguing species for advanced antkeepers who enjoy observing and learning from less-documented ants.

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Neotropical region, specifically found in Brazil, Colombia, Ecuador, and Paraguay. In Colombia, they have been recorded in montane wet forest habitats, specifically in sifted leaf litter ^[1][3].
• Colony Type: Colony structure is unconfirmed. Based on typical Brachymyrmex genus patterns, likely single-queen (monogyne) colonies, though this has not been directly studied for this specific species.
• Size & Growth:
  • Queen: Not documented, estimated 4-5mm based on genus patterns
  • Worker: Workers 2.5-3mm total length (HL 0.32-0.41mm, HW 0.26-0.35mm) ^[1][2]
  • Colony: Unknown, likely small colonies of under 500 workers based on typical Brachymyrmex patterns
  • Growth: Moderate, estimated based on genus
  • Development: Estimated 6-8 weeks at optimal temperature based on related Formicinae species (Development timeline is unconfirmed for this specific species. Temperature around 24-28°C likely optimal given their Neotropical origin.)
• Antkeeping:
  • Temperature: Keep at 24-28°C. These are Neotropical ants from montane wet forests, so they prefer warm, stable temperatures. A heating cable on one side of the nest creates a suitable gradient ^[1].
  • Humidity: High humidity preferred, they come from montane wet forest leaf litter. Keep the nest substrate consistently moist but not waterlogged. The substrate should feel damp to the touch with some slightly drier areas available for the ants to choose.
  • Diapause: Unconfirmed, likely no true diapause given their tropical origin, but may show reduced activity during cooler periods. Monitor colony behavior and reduce feeding if activity decreases.
  • Nesting: These tiny ants naturally nest in leaf litter and rotting wood in humid forest environments. In captivity, they do well in test tubes with a water reservoir, or small acrylic/plaster nests with tight chambers scaled to their tiny size. Their small size means they can squeeze through standard test tube barriers, use fine mesh or cotton plugs that are well-packed.
• Behavior: Temperament is generally peaceful, Brachymyrmex species are not known for being aggressive. Workers are small and likely forage individually or in small groups for honeydew, small insects, and other tiny food sources. Their very small eyes suggest they may rely more on chemical trails than visual cues. Escape prevention is critical, their tiny size means they can squeeze through the smallest gaps. Use excellent escape prevention with fine mesh barriers and tightly sealed lids. They are not known to sting and pose no danger to keepers.
• Common Issues: escape prevention is critical, their tiny size allows them to squeeze through standard barriers, colonies may fail if humidity drops too low, they come from wet forest habitats, slow growth and small colony size may frustrate keepers expecting rapid development, wild-caught colonies may have parasites that are difficult to detect in such small ants, overfeeding can lead to mold problems in small nests, remove uneaten food promptly

Housing and Nest Setup

Brachymyrmex donisthorpei is a tiny ant that requires appropriately scaled housing. Test tubes work well for founding colonies, use a small water reservoir with a well-packed cotton plug to prevent flooding. For established colonies, small acrylic nests or plaster nests with tight chambers work best. The key is ensuring chambers are appropriately sized, too large and the ants may feel insecure, too small and they cannot move freely. Their natural habitat is leaf litter in montane wet forests, so include some damp substrate material. Escape prevention is absolutely critical, these ants are so small they can squeeze through standard cotton plugs and gaps in lid seals. Use fine mesh (at least 0.5mm or smaller) on any ventilation holes and ensure all connections are tight. A layer of fluon on the inner rim of the outworld container provides an additional barrier. ^[1]

Feeding and Diet

Based on typical Brachymyrmex genus behavior, these ants are likely generalist feeders that accept both sugar sources and protein. Offer sugar water or honey water in a small container (like a cotton ball in a vial cap), change it every 2-3 days to prevent mold. For protein, offer tiny insects like fruit flies, small mealworms, or other appropriately sized prey. Since they are so small, prey items should be no larger than they can handle, essentially tiny arthropods. They likely also forage for honeydew in nature, so sugar sources are important. Feed small amounts 2-3 times per week and remove any uneaten food within 24 hours to prevent mold in their small nests.

Temperature and Seasonal Care

As Neotropical ants from montane wet forests, Brachymyrmex donisthorpei prefers warm, humid conditions. Keep the nest area at 24-28°C, which is warm for most ant species. A small heating cable placed on one side of the nest creates a temperature gradient that allows the ants to choose their preferred temperature. Avoid temperature extremes, they are from stable tropical environments and do not tolerate cold well. There is no documented diapause requirement, but you may notice reduced activity during cooler periods in your home. If the colony becomes less active, reduce feeding frequency but maintain humidity. Room temperature in the low-to-mid 20s°C is often suitable if your home stays in that range. ^[1]

Handling and Observation

These ants are extremely small and delicate, making detailed observation challenging but rewarding. Their tiny size means you will need good lighting and potentially magnification to observe them properly. They are not aggressive and do not sting, making them safe to handle. However, their small size makes them easy to accidentally crush, use soft tools like paintbrushes when moving them. Their very small eyes (only 3-4 ommatidia) are an interesting morphological feature, they likely rely heavily on chemical pheromone trails rather than vision for navigation. Watching these tiny ants establish trails and forage can be a meditative experience, though their small size means you may need to set up the outworld carefully to observe them effectively. ^[1][2]

Colony Establishment Tips

Starting a colony of Brachymyrmex donisthorpei can be challenging since their biology is poorly documented. If you obtain a founding queen, provide her with a small, dark test tube setup with a water reservoir. She will likely seal herself in and lay eggs, be patient as development may be slow. The claustral founding process (where the queen seals herself in and lives off stored fat) is expected based on typical Formicinae behavior, though not confirmed for this specific species. Keep the setup undisturbed in a dark location for several weeks. Once workers emerge, gradually introduce them to an outworld with food. Given how little is known about this species, keeping detailed notes on your colony's behavior will contribute to our collective understanding of these fascinating tiny ants.

Frequently Asked Questions

References