Tetramorium severini

Tetramorium severini

Tetramorium severini is a striking Malagasy ant species known for its very dark brown to black coloration and remarkably long, curved propodeal spines. Workers measure 0.87-1.08mm in head length, making them a medium-sized Tetramorium species ^[1]. This ant is the sole member of the T. severini species group and is widely distributed across the rainforests and montane rainforests of eastern and northern Madagascar, from Montagne d'Ambre in the north to Andohahela in the southeast, with populations also on islands like Nosy Be ^[1][2]. They nest in leaf litter and the ground, typically at elevations between 25 and 1125 meters ^[2]. The combination of their dark coloration, large body size, and distinctive long spines makes them immediately recognizable among Malagasy Tetramorium species ^[1].

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Native to Madagascar, specifically the rainforests and montane rainforests of eastern and northern Madagascar. Found at altitudes ranging from 25 to 1125 meters ^[2].
• Colony Type: Colony structure is unconfirmed. Based on typical Tetramorium patterns, likely single-queen (monogyne) colonies, though this requires verification for this specific species.
• Size & Growth:
  • Queen: Estimated 6-8mm based on genus-level Tetramorium patterns
  • Worker: 0.87-1.08mm head length (approximately 3-4mm total body length) ^[1]
  • Colony: Unknown for this species, typical Tetramorium colonies reach several hundred to a few thousand workers
  • Growth: Moderate, based on typical Myrmicinae development patterns
  • Development: Estimated 6-10 weeks at optimal temperature based on related Tetramorium species (Development time is not directly documented for this species. Estimates based on genus-level patterns for Myrmicinae ants in tropical rainforest environments.)
• Antkeeping:
  • Temperature: Keep at 22-26°C. As a rainforest species from Madagascar, they prefer warm, stable conditions. A gentle gradient allowing workers to self-regulate is ideal.
  • Humidity: High humidity required, aim for 70-85%. These rainforest ants need consistently moist substrate conditions. Keep the nesting area damp but not waterlogged, with some drier areas available for the ants to self-regulate.
  • Diapause: Unlikely, as a tropical species from Madagascar, they do not require a true diapause. However, slight seasonal slowing may occur during cooler months.
  • Nesting: They naturally nest in leaf litter and soil. In captivity, a naturalistic setup with moist substrate or a Y-tong/plaster nest works well. They prefer tight chambers scaled to their size ^[2].
• Behavior: Generally non-aggressive and manageable in captivity. Workers are moderately active foragers that search through leaf litter and substrate. They are not known for stinging, Myrmicinae ants have stingers but Tetramorium species typically use chemical defenses rather than stinging. Escape prevention should be moderate as they are not particularly small.
• Common Issues: humidity control is critical, they quickly decline in dry conditions, wild-caught colonies may harbor parasites or pathogens from their native habitat, slow colony establishment means beginners may lose patience, tropical species are sensitive to temperature drops below 20°C, limited availability makes this a species for more experienced keepers

Natural History and Distribution

Tetramorium severini is endemic to Madagascar, where it occupies a wide range across the island's eastern and northern rainforest regions. Their distribution spans from Montagne d'Ambre at the northern tip of the island down to Andohahela in the southeast, with additional populations on the northwestern side including Ampasindava and Manongarivo, as well as island populations on Nosy Be ^[1]. They inhabit elevations between 25 and 1125 meters, primarily in rainforest and montane rainforest environments ^[2]. This species is the sole member of the T. severini species group, making it taxonomically distinct from other Malagasy Tetramorium ^[1]. The very dark brown to black coloration and exceptionally long propodeal spines (PSLI 38-43) set them apart from related species in the region ^[1].

Housing and Nest Preferences

In the wild, T. severini nests in leaf litter and the ground, preferring the humid, stable microclimate of the rainforest floor. For captive care, provide a naturalistic setup with moist substrate (a mix of soil and sand works well) or use a Y-tong or plaster nest designed for medium-sized Myrmicinae ^[2]. The nest should have chambers scaled appropriately to their worker size, roughly 3-4mm body length means they need moderately tight spaces but not the ultra-tight chambers required for tiny species. Keep the nesting area consistently humid but ensure some drier areas exist so ants can self-regulate. A water reservoir connected to the nest helps maintain humidity without constant misting.

Temperature and Humidity Requirements

As a rainforest species from tropical Madagascar, T. severini requires warm and humid conditions. Maintain temperatures between 22-26°C, avoiding drops below 20°C which can stress colonies. A heating cable on one side of the nest can create a gentle gradient, but always ensure the ants can move to cooler areas if needed. Humidity should remain high at 70-85%, the substrate should feel consistently damp but never waterlogged. These ants are sensitive to drying out, so monitor moisture levels regularly and rehydrate when the surface begins drying. Good ventilation is essential to prevent mold while maintaining humidity.

Feeding and Diet

Like most Tetramorium species, T. severini is likely omnivorous, accepting both protein sources and carbohydrates. Offer protein-rich foods such as small insects (fruit flies, small crickets, mealworms), and provide sugar sources like honey water or sugar water regularly. In their natural rainforest habitat, they likely forage for small invertebrates and tend aphids for honeydew. Feed protein 2-3 times per week and keep sugar water available at all times. Remove uneaten prey after 24-48 hours to prevent mold.

Colony Development and Growth

Colony development details are not directly documented for this species. Based on typical Tetramorium and Myrmicinae patterns, expect the first workers (nanitics) to emerge approximately 6-10 weeks after founding at optimal temperature. Initial colony growth is slow as the queen raises her first brood alone. Once established, colonies grow moderately but steadily. Maximum colony size is unknown but likely reaches several hundred to a few thousand workers based on related species. Patience is essential, this is not a fast-growing species, and colonies may take months to reach 20-30 workers after founding.

Behavior and Temperament

T. severini workers are moderately active and likely forage through leaf litter and substrate in search of small invertebrates and sweet substances. They are not particularly aggressive and can be handled with care. As Myrmicinae, they possess a stinger but Tetramorium species typically rely on chemical defenses rather than stinging. Escape risk is moderate, they are not tiny ants but can still squeeze through small gaps, so use standard escape prevention. They are a calm species suitable for observation but may be less interactive than some larger ant species.

Frequently Asked Questions

References