Stenamma sardoum

Stenamma sardoum

Stenamma sardoum is a small, cryptic ant species native to Sardinia and possibly Corsica in the western Mediterranean ^[1]. Workers measure 3.3-4.3mm and have a distinctive rusty reddish-brown (ferrugineous) coloration that sets them apart from the similar and more common Stenamma debile, which is darker brown ^[1]. They belong to the westwoodii species group and can be identified by their elongated postpetiole, irregular promesonotal sculpturation, and relatively long scapes (SI usually ≥90) ^[1]. Queens are larger at 4.4-5.0mm and similarly pale in coloration. This species is a Sardinian endemic, making it a rare and unusual choice for antkeepers interested in Mediterranean species.

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Sardinia, Italy (possibly Corsica), found in mountainous areas like the Gennargent mountains at Aritzo ^[2]. They inhabit forested areas with moderate elevation, typical of the westwoodii species group which prefers cool, shaded microhabitats ^[3].
• Colony Type: Unconfirmed colony structure. Based on related Stenamma species, likely single-queen (monogyne) colonies, though this has not been directly documented for this species.
• Size & Growth:
  • Queen: 4.4-5.0mm ^[1]
  • Worker: 3.3-4.3mm ^[1]
  • Colony: Unknown, likely small to moderate based on typical Stenamma colony sizes (dozens to low hundreds of workers)
  • Growth: Moderate, inferred from typical Stenamma development
  • Development: Estimated 8-12 weeks based on related Stenamma species and Mediterranean climate conditions (Development time is unconfirmed for this species. Related westwoodii group species typically take 2-3 months from egg to worker at optimal temperatures.)
• Antkeeping:
  • Temperature: Keep at room temperature, roughly 18-22°C. Mediterranean species but not heat-loving, they prefer cooler conditions typical of their forest floor habitat ^[3]. Avoid temperatures above 25°C.
  • Humidity: Moderate to high humidity preferred. These are forest-floor ants that naturally encounter damp conditions. Keep nest substrate moderately moist but not waterlogged, with some drier areas for workers to regulate their own moisture needs.
  • Diapause: Likely required. As a Mediterranean species from a temperate climate region, colonies probably need a winter rest period of 2-3 months at cooler temperatures (10-15°C). This is typical for European Stenamma species.
  • Nesting: Natural nesting occurs in soil and under stones in forested areas. In captivity, a test tube setup works well for founding colonies. For established colonies, a Y-tong (AAC) or plaster nest with moisture chambers maintains appropriate humidity. Avoid dry, heated nests.
• Behavior: Stenamma sardoum is a cryptic, ground-nesting species that forages primarily on the forest floor. Workers are not aggressive and typically avoid confrontation. They are slow-moving and secretive, spending much of their time in underground chambers. Escape risk is moderate due to their small size, they can squeeze through small gaps, so ensure escape prevention is adequate. They likely forage for small insects and honeydew, similar to other Stenamma species.
• Common Issues: limited availability, being a Sardinian endemic, this species is rarely available in the antkeeping hobby, escape prevention needed due to small worker size, slow colony growth may frustrate beginners expecting rapid development, winter diapause is likely required but specific requirements unconfirmed, no captive breeding data available, wild-caught colonies may struggle in captivity

Housing and Nest Setup

For founding colonies, a standard test tube setup works well. Fill the tube one-third with water, plug with cotton, and place the queen in the tube chamber. Keep the tube in darkness and undisturbed for 4-6 weeks until the first workers (nanitics) emerge. For established colonies with 20+ workers, transfer to a Y-tong (AAC) formicarium or a plaster nest with moisture chambers. These ants prefer tight, enclosed spaces rather than large open areas. The nest should have chambers sized appropriately for their small workers (3-4mm). A small outworld for foraging completes the setup. Because they are small and can escape through tiny gaps, apply fluon or use fine mesh on all openings. ^[1]

Feeding and Diet

Based on typical Stenamma behavior, these ants are generalist predators and scavengers. Offer small live prey such as fruit flies, small crickets, and mealworms. They likely also accept sugar sources, offer a drop of sugar water or honey occasionally and observe acceptance. Feed small amounts every 2-3 days, removing any uneaten prey after 24 hours. Do not overfeed as this leads to mold problems. Fresh water should always be available. Since this species has not been kept in captivity before, acceptance of various foods may need to be experimentally determined.

Temperature and Seasonal Care

Keep the nest at room temperature, ideally 18-22°C. They are not heat-loving ants, excessive heat stress can be harmful. A slight temperature gradient allows workers to choose their preferred zone. During winter, provide a diapause period of 2-3 months at 10-15°C, similar to other European ant species. Place the colony in a cool location (garage, basement, or refrigerator) during this period. Do not feed during diapause but keep the water reservoir in the test tube or nest moist. Resume normal temperatures and feeding in spring when the queen becomes active again. ^[3]

Handling and Colony Maintenance

These ants are docile and easy to handle. Queens are relatively calm during founding compared to some aggressive species. When moving colonies, use gentle techniques, coax workers into a new container rather than shaking them. Monitor for mold in test tube setups and replace the tube if mold becomes excessive. For established colonies, maintain humidity by adding water to the moisture chamber or cotton reservoir regularly. Check that the nest does not dry out, as this can kill brood. These are slow-growing ants, so patience is essential, do not disturb the colony frequently or try to force faster growth.

Differentiating from Similar Species

Stenamma sardoum can be distinguished from the more common Stenamma debile by its distinctly paler, rusty reddish-brown coloration (S. debile is brown) ^[1]. The petiolar and postpetiolar sternites are more concave below the nodes in profile, a subtle but consistent difference when specimens are compared directly ^[1]. From Stenamma westwoodiii, separation is more difficult and relies on differences in the postcranial index (PCI), promesonotal sculpturation, and postpetiole shape ^[1]. When keeping multiple Stenamma species, ensure proper identification to avoid mixing species.

Frequently Asked Questions

References