Stigmatomma caliginosum

Quick Summary

• Difficulty: Hard
• Origin & Habitat: Japan (Kanagawa, Chiba, Ishikawa prefectures) and South Korea (Gyeongsangnam-do). Found in broadleaf forests under stones and in leaf litter at low altitudes. South Korean record at 17m elevation ^[1][4].
• Colony Type: unconfirmed, colony structure has not been studied.
• Size & Growth:
  • Queen: No data available, body size undocumented.
  • Worker: Approximately 2mm ^[1]
  • Colony: Unknown, no colony size data exists.
  • Growth: Unknown
  • Development: Unconfirmed, no development data available for this species. (Development timeline has not been studied.)
• Antkeeping:
  • Temperature: unknown, no specific studies exist. Based on the temperate broadleaf forest habitat, room temperature (20-24°C) is a reasonable starting point. Create a gradient if possible ^[1].
  • Humidity: moderate to high. Keep the nest substrate damp but not waterlogged. In nature they live under stones where moisture is consistent ^[1].
  • Diapause: unknown, no studies on overwintering. Given the temperate distribution, a cold period likely occurs naturally, but it is unconfirmed.
  • Nesting: in nature they nest under stones and in leaf litter ^[1]. In captivity, use a naturalistic setup with moist substrate and small chambers. Test tubes can work with careful humidity control, but escape prevention is critical due to tiny size.
• Behavior: as an Amblyoponinae ant, it has a functional stinger. Workers are only 2mm, so escape prevention is critical. Hunting is likely solitary. Temperament is probably docile due to small size, but detailed behavior is unstudied.
• Common Issues: escape prevention is critical due to tiny 2mm size, workers can squeeze through standard test tube barriers., humidity management is challenging, too dry or too wet can kill the colony., no established care guidelines exist, requiring careful observation and experimentation., cold tolerance is unknown, improper winter temperatures could be fatal., meeting predatory dietary needs with appropriate live prey (springtails, fruit flies) may be difficult.

Identification and Distinguishing Features

Workers are about 2mm long and yellowish-brown, making them conspicuously small and bright. They have 11-segmented antennae (distinguishing them from Stigmatomma silvestrii which has 12), five stout dentiform setae on the anterior clypeal margin, and seven mandibular denticles in a single row. The head is distinctly longer than broad and rectangular ^[1][2][3].

Natural Habitat and Distribution

This species has a limited distribution in East Asia. In Japan it is known from Kanagawa, Chiba, and Ishikawa prefectures on Honshu and Kyushu ^[4][3]. A 2021 discovery in South Korea (Gyeongsangnam-do,17m elevation) extended the known range. The South Korean specimens were collected by litter sifting in broadleaf forest. The species appears to have a patchy distribution and is likely rare based on few records ^[1].

Feeding and Diet

As a member of the predatory subfamily Amblyoponinae, this ant is expected to hunt small arthropods such as springtails, mites, and other tiny invertebrates found in the forest floor. In captivity, offer appropriately sized live prey like springtails and fruit flies. Sugar sources may be accepted but are not a primary food. Acceptance of commercial ant foods is uncertain, experimentation is needed.

Temperature and Care

No specific thermal studies exist. Base temperature on the natural habitat: temperate broadleaf forest with under-stone nesting. A starting range of 20-24°C is likely suitable. Use a heating gradient to allow the colony to self-regulate. Avoid extremes and observe behavior, if workers cluster in warm areas, increase heat slightly, if they avoid heated areas, reduce ^[1].

Nesting and Humidity Requirements

In nature, these ants nest under stones in broadleaf forests where the substrate is consistently moist but not waterlogged ^[1]. In captivity, maintain humidity by keeping the nest substrate damp (moist to the touch but no pooling water). A naturalistic setup with a moist soil/gravel mixture under flat stones or small chambers works well. Test tubes can work but require careful water management. Good ventilation is needed to prevent mold. All chambers should be appropriately scaled for tiny workers.

Behavior and Temperament

As an Amblyoponinae ant, it has a functional stinger, but the tiny size (2mm) means any sting is very mild. Workers likely hunt solitarily rather than using group recruitment. Escape prevention is critical due to their small size, fine mesh or fluon barriers are recommended. Colony structure and social organization remain poorly studied. ^[1]

Frequently Asked Questions

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References