Pseudomyrmex goeldii

Pseudomyrmex goeldii

Pseudomyrmex goeldii is a relatively large ant species native to southeastern Brazil, specifically the Atlantic rainforest region around Sorocaba, São Paulo. Workers measure 0.81-0.87mm in head length, making them larger than other members of the goeldii species group ^[1]. They have a distinctive appearance with a smooth, shiny head featuring fine punctulae, uniformly dark brown coloration, and slightly lighter appendages ^[1]. This species is a generalist dead twig inhabitant, nesting in hollow plant stems and dead branches in forest environments ^[1]. Known only from a type series collected over a century ago, P. goeldii remains one of the more obscure species in the Pseudomyrmex genus, with limited documented observations in the wild ^[1][2].

Quick Summary

• Difficulty: Unknown, limited data available
• Origin & Habitat: Southeastern Brazil (Sorocaba, São Paulo) in Atlantic rainforest region ^[1][2]. Generalist dead twig inhabitant in forest environments ^[1].
• Colony Type: Unconfirmed colony structure. Based on typical Pseudomyrmex patterns, likely single-queen colonies, but this has not been documented for this specific species.
• Size & Growth:
  • Queen: Unknown, not described in available literature
  • Worker: 0.81-0.87mm head length,0.65-0.66mm head width ^[1]
  • Colony: Unknown, no colony size data available
  • Growth: Unknown, no development data available
  • Development: Unknown, no direct measurements exist. Based on typical Pseudomyrmex patterns from related species, estimate 6-10 weeks at tropical temperatures, but this is an educated guess. (No specific development data exists for this species. Related Pseudomyrmex species typically develop in 6-8 weeks under warm conditions.)
• Antkeeping:
  • Temperature: Unknown for this specific species. Inferred from Atlantic rainforest habitat: aim for warm conditions around 22-28°C with a gentle gradient. Adjust based on colony activity.
  • Humidity: Unknown for this specific species. Inferred from rainforest origin: moderate to high humidity (60-80%) with some drier areas for escape. Keep substrate moderately moist but not waterlogged.
  • Diapause: Unknown, no seasonal data available. As a tropical Brazilian species, likely year-round active without true hibernation, but may show reduced activity during cooler months.
  • Nesting: Natural nesting: dead twigs and hollow plant stems ^[1]. Captive recommendations: test tube setups or acrylic nests with narrow chambers scaled to their small size. Provide dead twig or stem-like structures for natural feel.
• Behavior: Described as having a timid demeanor in the wild ^[1]. Based on typical Pseudomyrmex behavior, they are likely arboreal and may show moderate aggression when defending their nest. Escape prevention is important due to their small size, use fine mesh barriers. Activity level is likely moderate, with workers foraging individually or in small groups.
• Common Issues: limited availability, this species is rarely available in the antkeeping hobby, no established captive care protocols, keepers will be pioneering husbandry methods, escape risk due to small size requires fine mesh barriers, unknown dietary requirements, may require experimentation, wild-caught colonies may have parasites given limited collection history

Availability and Rarity

Pseudomyrmex goeldii is extremely rare in the antkeeping hobby. This species is known only from the original type series collected over a century ago by Emílio Goeldi in southeastern Brazil ^[1][2]. There have been few, if any, documented collections since that initial series. This means virtually no captive colonies exist in antkeeping collections worldwide. If you encounter this species, it would likely be from a wild-caught queen from the Sorocaba region of Brazil. The extreme rarity makes this a species for advanced keepers interested in pioneering captive breeding of poorly documented species.

Natural History and Habitat

P. goeldii belongs to the goeldii species group within Pseudomyrmex and is native to the Atlantic rainforest region of southeastern Brazil ^[1]. The type locality is Sorocaba, São Paulo, an area that was historically covered in Atlantic forest but has since undergone significant development ^[1]. As a generalist dead twig inhabitant, this species nests in hollow plant stems, dead branches, and similar cavities found in forest environments ^[1]. Unlike some Pseudomyrmex species that are specialized acacia-ants, P. goeldii appears to be a more generalist species occupying various dead wood microhabitats. The Atlantic rainforest is a biodiversity hotspot with high humidity and warm temperatures year-round.

Identification and Morphology

Workers of P. goeldii are relatively large for the genus, with head lengths of 0.81-0.87mm and head widths of 0.65-0.66mm ^[1]. This places them among the larger Pseudomyrmex species. They can be identified by their smooth, shiny head with scattered fine punctulae, relatively short eyes (REL 0.55-0.56), and a weakly angulate juncture between the dorsal and declivitous faces of the propodeum ^[1]. The body is uniformly dark brown with slightly lighter appendages ^[1]. The timid demeanor noted in field observations suggests they are not aggressive defenders compared to some related acacia-ant species.

Housing and Nesting

In nature, P. goeldii nests in dead twigs and hollow plant stems ^[1]. For captive care, a test tube setup works well for founding colonies, while established colonies can be housed in acrylic nests or naturalistic setups that provide narrow chambers and passages scaled to their small size. Include small dead wood or twig-like structures if possible to mimic their natural nesting preferences. Ensure escape prevention is excellent, their small size means they can squeeze through standard gaps. Use fine mesh on any ventilation openings.

Temperature and Humidity

As a species from the Atlantic rainforest of southeastern Brazil, P. goeldii likely prefers warm, humid conditions. Aim for temperatures in the range of 22-28°C, providing a gradient so the ants can choose their preferred zone. Humidity should be moderate to high (60-80%), keeping the nest substrate consistently moist but not waterlogged. Since this species has never been documented in captivity, these recommendations are educated inferences from the genus and habitat, observe your colony and adjust accordingly.

Feeding and Diet

The specific dietary requirements of P. goeldii are unknown. Based on typical Pseudomyrmex behavior, they likely forage for honeydew and small insects. Offer sugar water or honey as a constant energy source, and provide small protein sources like fruit flies, pinhead crickets, or other appropriately sized live prey. Start with modest offerings and observe what the colony accepts. Given their small size, prey items should be very small.

Frequently Asked Questions

References