Polyrhachis injinooi

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Cape York Peninsula, Queensland, Australia, open forest and savannah woodland. Nests are built in the ground with entrances hidden under pieces of wood or stones ^[1].
• Colony Type: Unconfirmed colony structure. No specific data on queen number or social structure.
• Size & Growth:
  • Queen: Unknown, queen size has not been documented
  • Worker: 5.74-7.16 mm ^[1]
  • Colony: Unknown, maximum colony size has not been documented
  • Growth: Unknown, growth rate has not been documented
  • Development: Unknown, based on typical Polyrhachis patterns, expect 6-10 weeks at tropical temperatures (Development may vary with temperature and colony conditions)
• Antkeeping:
  • Temperature: Keep warm, roughly 24-28°C, based on tropical habitat. Use a heating cable to create a gradient if needed.
  • Humidity: Provide moderate humidity with a moist substrate area, allowing some drying. Mist occasionally and offer a water tube.
  • Diapause: Unlikely required for this tropical species. A slight cooling period in winter may be appropriate but is not necessary.
  • Nesting: Ground-nesting species. Use a naturalistic setup with soil substrate or a Y-tong/plaster nest with a soil chamber. Include debris like wood or stones on the surface ^[1].
• Behavior: Moderately active foragers that search the ground for food. Defends by spraying formic acid, not aggressive but may defend the nest if disturbed. Escape risk is moderate due to worker size, standard prevention measures suffice.
• Common Issues: limited availability in the antkeeping hobby due to rarity., no established husbandry guidelines for this species., unknown queen and colony development details., wild-caught colonies may be stressed from collection and transport., requires consistent warmth year-round due to tropical origin.

Natural History and Distribution

Polyrhachis injinooi is endemic to Cape York Peninsula in northern Queensland, Australia, with its range extending south to Cooktown ^[1]. This species inhabits open forest and savannah woodland, building ground nests with entrances hidden under debris like wood or stones ^[1].

Identification and Appearance

Workers measure 5.74-7.16 mm in total length and have a reddish-brown to rusty-red coloration with black markings ^[1]. They can be distinguished from similar species by their larger size, flattened antennal scapes, and sparse pubescence on the gaster ^[1].

Housing and Nest Setup

As ground-nesters, provide a soil-filled container or a Y-tong/plaster nest with a soil chamber. Include small pieces of wood, stones, or leaf litter on the surface to mimic natural nesting behavior ^[1]. Ensure the substrate stays moderately moist but not waterlogged.

Temperature and Seasonal Care

Keep temperatures around 24-28°C, as this species comes from a tropical region. Use a heating cable on one side of the nest to create a gradient. A slight cooling period in winter may simulate seasonal cycles but is not required.

Feeding and Diet

Offer sugar water or honey as a constant energy source. Provide protein such as small insects (e.g., fruit flies, crickets) 2-3 times per week. Remove uneaten prey after 24 hours.

Defense Mechanism

Like other Formicinae, Polyrhachis injinooi lacks a sting and defends itself by spraying formic acid from an acidopore. This is a primary defense mechanism for the subfamily.

Challenges and Considerations

This is a rarely kept species with no established care guidelines. Keepers may need to experiment with conditions. Obtaining colonies can be difficult due to restricted distribution in remote Australia ^[1].

Frequently Asked Questions

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References