Polyrhachis xiphias

Quick Summary

• Difficulty: Hard
• Origin & Habitat: Native to the Australasian and Indomalaya regions: Indonesia (West Irian, Waigeo Island) and Papua New Guinea (West Sepik, Gulf Province). They live in lowland rainforest at 150-500 meters elevation, nesting in rotting wood ^[1].
• Colony Type: Colony structure is not documented. Only two queens have been measured, and males are unknown ^[1]. Likely single-queen (monogyne) colonies, but this is unconfirmed.
• Size & Growth:
  • Queen: 10.33-10.89mm ^[1]
  • Worker: 6.00-6.80mm ^[1]
  • Colony: Unknown, no colony size data available
  • Growth: Unknown, no development timing data exists
  • Development: Unknown, no direct data. Based on related Polyrhachis species, estimate 6-10 weeks at 24-28°C. (Development has not been studied. Keep at stable tropical temperatures and observe.)
• Antkeeping:
  • Temperature: 24-28°C is recommended. As a tropical species, keep temperatures stable and avoid drops below 22°C. A gentle gradient helps the ants self-regulate.
  • Humidity: High humidity is essential. Keep the nest substrate consistently moist but not waterlogged. Aim for 70-85% relative humidity, achievable with a moisture chamber or regular misting.
  • Diapause: No, as a tropical species from near the equator, they do not need hibernation. Maintain consistent conditions year-round.
  • Nesting: Naturally nests in rotting wood ^[1]. Provide cork, wood pieces, or a plaster/Y-tong nest with high moisture. Avoid acrylic nests, they don't retain humidity well. Offer a naturalistic setup with wood-like material.
• Behavior: Calm and non-aggressive, like most Polyrhachis. They are generalist foragers and moderately active. Their defense mechanism is biting and spraying formic acid (common to formicines). Escape risk is moderate due to their 6mm worker size, standard barriers work, but keep the setup sealed. No stinger, so they cannot sting.
• Common Issues: very limited knowledge, no captive care data exists, you will be pioneering, high humidity is critical for survival, especially during founding, wild-caught colonies may carry parasites or diseases, males have never been collected, so nuptial flight timing and mating behavior are unknown, this species is rarely available in the hobby, sourcing might be extremely difficult

Natural History and Distribution

Polyrhachis xiphias is endemic to New Guinea and surrounding Indonesian islands. It was first described from a single queen (holotype) collected by Alfred Russel Wallace on Waigeo Island in 1863 ^[1]. More specimens have since been found in West Irian (Indonesia) and several provinces in Papua New Guinea, including West Sepik and Gulf Province ^[1]. The ants inhabit lowland rainforest at 150-500 meters, nesting in rotting wood pieces. Males have never been collected, which is unusual and suggests either very localized nuptial flights or that reproduction occurs in an atypical manner ^[1].

Identification and Distinguishing Features

This species belongs to the Polyrhachis xiphias species-group within the subgenus Campomyrma. Unlike most Campomyrma, which have a scale-like petiole, P. xiphias has a columnar petiole armed with two horizontal, posteriorly-directed spines ^[1][2]. Workers are identified by their moderately convex eyes that break the head outline in full-face view, blunt humeral angles on the pronotum, and divergent petiolar spines ^[1][2]. Color: black body, bright yellow legs with dark brown joints at the femora and tibiae, and dark brown tarsi. Antennae dark brown at base, lightening toward the tip, with yellow condylae. Queens are similar but larger (10.3-10.9mm) with shorter propodeal spines and a developed mesosoma ^[1].

Housing and Nesting Preferences

Since they nest in rotting wood in the wild [10111

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References