Tetramorium depressum

Quick Summary

• Difficulty: Easy
• Origin & Habitat: Endemic to the Canary Islands (El Hierro, Fuerteventura, Lanzarote). Found from 20 to 1300 m elevation in the Palaearctic region. They prefer rocky, shaded areas under stones, with colonies thriving in cooler, higher areas and struggling in dry coastal zones ^[1][2].
• Colony Type: Likely single-queen colonies (monogyne), inferred from typical *Tetramorium* patterns. Colony size can reach several hundred workers in established nests.
• Size & Growth:
  • Queen: Approximately 5-6 mm, based on typical *Tetramorium* queen sizes (not measured directly for this species).
  • Worker: Approximately 3-4 mm, based on small size noted in lowland populations and typical *Tetramorium* workers ^[1].
  • Colony: Big, populous nests at higher altitudes, likely several hundred workers ^[1].
  • Growth: Moderate
  • Development: Estimated 6-8 weeks at optimal temperature, based on typical *Tetramorium* development (specific data for this species unavailable). (Development time inferred from genus-wide data, exact timing for *T. depressum* is unconfirmed.)
• Antkeeping:
  • Temperature: Keep at 20-26°C, with room temperature (~22°C) ideal. Based on their Canary Islands origin, they tolerate cooler conditions better than heat. Avoid prolonged temperatures above 30°C ^[1].
  • Humidity: Keep the nest substrate on the drier side. Since they naturally nest under stones in well-drained areas, avoid saturation. Provide a dry zone and a slightly moist zone so the ants can choose. Overly wet conditions lead to mold and stress.
  • Diapause: Unconfirmed. Canary Islands have mild winters, so true hibernation may not be required. However, a brief cool period (15-18°C for 4-6 weeks) during winter may benefit colony health, though this is undocumented for this species.
  • Nesting: Natural nesting under stones translates well to captivity. Y-tong (AAC) nests or plaster nests work well. Provide a shallow water reservoir and keep the nest relatively dry. A naturalistic setup with flat stones or slate as the nesting surface mimics their wild habitat.
• Behavior: Generally peaceful and non-aggressive. Workers are active foragers that search for seeds, small insects, and honeydew. Their primary defense is smearing venom using a flattened stinger (Crematogastrini tribe). Escape risk is moderate to high, workers are small (~3-4 mm) and can squeeze through tiny gaps, use tight-fitting lids or fluon barriers.
• Common Issues: coastal wild populations are weak, so maintain stable, cool conditions to avoid stressing your colony., overwatering leads to mold and can kill the colony, keep the nest relatively dry., colony growth is slow at first, be patient during founding, as the queen may take months to raise her first workers., small workers can easily escape, ensure the outworld is escape-proof.

Origin and Natural Habitat

Tetramorium depressum is a Canary Islands endemic, found on El Hierro, Fuerteventura, and Lanzarote ^[2]. The species was originally described by Forel in 1892 as a subspecies of T. semilaeve and was elevated to full species status in 2007 by Espadaler ^[1]. They inhabit elevations from 20 to 1300 m, with the largest and most vigorous colonies found at higher altitudes where conditions are cooler and more humid. These ants nest under stones, which provides protection from the sun and helps maintain stable temperature and humidity in the nest chamber ^[1]. Coastal populations in drier areas tend to be smaller and appear stressed, with fewer workers ^[1]. This preference for elevated, cooler habitats is important to replicate in captivity.

Housing and Nest Setup

These ants do well in Y-tong (AAC) nests or plaster nests that allow for moderate humidity control. A naturalistic setup with flat stones or slate as the nesting surface works well, since they naturally nest under stones in the wild. The nest should have a shallow water reservoir to maintain light moisture without becoming wet. Because they prefer drier conditions than many ants, ensure adequate ventilation to prevent mold. A test tube setup can work for founding colonies, but monitor water levels carefully, too much water can drown the queen and brood. For the outworld, provide a moderate foraging area with access to protein and sugar sources. Use fluon or similar barriers to prevent escapes, as workers are small ^[1].

Feeding and Diet

Like most Tetramorium species, these ants are omnivorous. They readily accept small insects (fruit flies, pinhead crickets, mealworms) as protein sources. They also collect seeds, particularly small grass seeds, which they may store or consume. Sugar sources like honey water or sugar water are typically accepted. In nature, they likely forage for honeydew from aphids and scale insects, so offering a sugar source regularly helps maintain colony health. Feed small amounts 2-3 times per week for growing colonies, removing uneaten prey after 24 hours. Note: This diet information is based on typical Tetramorium feeding habits, as no species-specific dietary studies are available.

Temperature and Seasonal Care

Keep the nest at 20-26°C, with room temperature (~22°C) ideal. Their Canary Islands origin means they prefer moderate warmth but can tolerate cooler conditions, especially given their presence at higher elevations. Avoid temperatures above 30°C, which can stress colonies. During winter, a brief cool period (15-18°C for 4-6 weeks) may benefit colony health, though true hibernation is likely not required given the mild Canary Islands climate. Monitor colony activity, if workers become sluggish, slightly increasing temperature can help. The key is avoiding both extreme heat and excessive moisture ^[1].

Colony Development and Growth

Colony founding is likely claustral, the queen seals herself in a chamber and raises the first workers entirely from her stored fat reserves. This means no feeding is required during the founding stage. First workers (nanitics) are typically smaller than mature workers. Growth rate is moderate, expect roughly 6-8 weeks from egg to first worker at optimal temperature (based on genus data). Established colonies can reach several hundred workers, with the largest nests found at higher altitudes in the wild ^[1]. Be patient during founding, as small colonies are vulnerable to stress. Once the colony reaches a stable size (roughly 20-30 workers), growth typically accelerates, though specific timing is unconfirmed.

Frequently Asked Questions

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References