Polyrhachis kebunraya

Quick Summary

• Difficulty: Unknown, Insufficient Data
• Origin & Habitat: Java, Indonesia, tropical lowland forest at approximately 290 m elevation in Bogor Botanical Gardens ^[1]
• Colony Type: Unknown, colony structure has never been documented
• Size & Growth:
  • Queen: Undescribed, no queens have been collected ^[2]
  • Worker: 7.21-7.31 mm total length ^[1]
  • Colony: Unknown, only three worker specimens have ever been collected ^[1]
  • Growth: Unknown
  • Development: Unknown, no brood development data exists for this species (Related Polyrhachis species typically develop from egg to worker in 6-10 weeks at tropical temperatures, but this is a genus-level estimate only)
• Antkeeping:
  • Temperature: Likely 24-28°C based on tropical Java origin, no direct data exists
  • Humidity: Likely moderate to high (60-80%) typical of tropical forest ants in Java, no direct data exists
  • Diapause: Unlikely, tropical species from Java probably does not require hibernation, but unconfirmed
  • Nesting: Likely arboreal or in vegetation/rotting wood based on genus patterns, no direct observations exist
• Behavior: Behavior is unstudied. As a Formicinae ant, Polyrhachis kebunraya lacks a functional stinger and defends by biting and spraying formic acid into the wound. Based on related species, it is likely a moderate forager. Escape prevention is important: workers are 7 mm and good climbers, so use a fluon or oil barrier on the outworld rim.
• Common Issues: very limited availability, only three workers ever collected, not present in the hobby, no captive breeding data, all care advice is inferred from genus patterns, tropical requirements may be challenging without heating in temperate climates, no information on founding behavior, queen type, or colony structure, diet and feeding preferences undocumented, recommendations are speculative

Species Overview and Rarity

Polyrhachis kebunraya is one of the most poorly known ants. Only three worker specimens have ever been collected: two in December 1990 by Fuminori Ito and one in September 1999 by Simon Robson, all from Bogor Botanical Gardens on Java ^[1]. No queens, males, or immature stages have been found ^[2]. The species was formally described in 2013 by Rudolf Kohout ^[1]. Because so little is known, almost every aspect of captive care must be inferred from related Polyrhachis species rather than from direct observation.

Natural History and Habitat

The type locality is Bogor Botanical Gardens (Kebun Raya) in West Java, Indonesia, at about 290 m elevation ^[1]. This tropical lowland botanical garden has warm, humid conditions year-round. The closest relative, Polyrhachis dimoculata from Borneo, suggests the aculeata species-group prefers humid tropical forest ^[1]. No specific nesting observations exist for Polyrhachis kebunraya, the specimens were collected without nest records ^[1]. Based on general Polyrhachis ecology, they may nest arboreally or in vegetation, but this is unconfirmed.

Identification and Morphology

Workers measure about 7.3 mm in total length and are entirely black except for the reddish-brown tip of the antenna ^[1]. Key features include distinctly convex eyes that are truncated posteriorly, longitudinal sculpture on the head and mesosoma, and long, sharp pronotal spines with a carina running from base to tip. The petiole has a pair of spines. Compared to its closest relative Polyrhachis dimoculata, this species has more convex eyes, longitudinal striation with fine appressed pubescence on the head and mesosoma, and hairs along the upper edge of the antennal scapes ^[1].

Housing and Nesting (Genus-Level Guidance)

No nesting data exists for Polyrhachis kebunraya. Based on typical Polyrhachis husbandry, they likely prefer arboreal nests in vegetation or rotting wood. Provide a nest made of Y-tong (AAC), plaster, or 3D-printed material with a moist substrate. Since Polyrhachis are good climbers, apply a fluon or oil barrier to the outworld rim to prevent escapes. The outworld should include twigs and vertical surfaces for climbing.

Temperature and Climate Requirements

As a tropical species from lowland Java (about 290 m), Polyrhachis kebunraya almost certainly needs warm conditions. Aim for 24-28°C based on related tropical Polyrhachis species. Java's climate is stable year-round (25-30°C), so avoid large temperature swings. A heating cable on one side of the nest can help if room temperature runs cooler. This species likely does not need a winter diapause, maintain tropical conditions all year.

Feeding and Diet

The diet of Polyrhachis kebunraya has never been documented. Polyrhachis ants are generally omnivorous, feeding on honeydew, nectar, and small insects. For captive care, provide sugar water or honey constantly and offer protein sources like small crickets or fruit flies 2-3 times per week. The 7 mm workers can handle prey items of moderate size. These are genus-level inferences, actual feeding preferences are unknown.

Frequently Asked Questions

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References