Polyrhachis metella

Polyrhachis metella

Polyrhachis metella is a striking large ant native to New Guinea and the Bismarck Archipelago. Workers measure 9-11mm with a distinctive appearance featuring very long, slender propodeal spines and appendages, a disc-shaped mesonotum, and a deeply notched clypeus. The body is black with medium reddish-brown on the gaster, mandibles, and legs, covered with golden pile that gives it an iridescent sheen. This is a rare species endemic to New Guinea, one of only two Hagiomyrma species not found on the Australian mainland. The genus Polyrhachis is known for their elaborate spines and this species has some of the longest in the subgenus.

Quick Summary

• Difficulty: Unknown, limited data available
• Origin & Habitat: New Guinea and Bismarck Archipelago, tropical rainforest regions. Subterranean nester in soil ^[1][2].
• Colony Type: Colony structure unconfirmed, likely single-queen based on typical Polyrhachis patterns.
• Size & Growth:
  • Queen: ~11.2 mm ^[3], estimated from single measured queen
  • Worker: 9.42-11.14 mm ^[3]
  • Colony: Unknown, likely moderate-sized based on related Polyrhachis species
  • Growth: Unknown, likely moderate
  • Development: Unknown, estimated 6-10 weeks based on typical Polyrhachis development at tropical temperatures (No direct development data available. Related tropical Polyrhachis species typically develop in 6-10 weeks at warm temperatures.)
• Antkeeping:
  • Temperature: Unknown, likely requires warm conditions (24-28°C) based on tropical New Guinea origin. Start in this range and observe colony activity.
  • Humidity: Likely requires high humidity, aim for 70-85% similar to other New Guinea Polyrhachis species. Keep substrate consistently moist but not waterlogged.
  • Diapause: Unlikely, tropical species from consistent climate. No diapause expected.
  • Nesting: Subterranean nester, requires soil or soil-like nesting medium. A naturalistic setup with deep soil chambers or a plaster/acrylic nest with soil chamber works well. Avoid completely dry conditions.
• Behavior: Behavior is poorly documented. Likely similar to other Polyrhachis species, relatively non-aggressive, arboreal to subterranean habits. Escape risk moderate due to large size, standard barriers should suffice. They have pupal cocoons which is unusual for Formicinae.
• Common Issues: limited availability, this is a rarely kept species, no established captive breeding in the hobby, specific humidity and temperature requirements unclear due to limited data, wild-caught colonies may struggle to adapt to captive conditions, growth rate and development timeline unknown makes planning difficult

Appearance and Identification

Polyrhachis metella is one of the larger Polyrhachis species with workers reaching 9-11mm. The most distinctive features are the extremely long, slender propodeal (middle section) spines that point backward, and similarly long spines on the petiole (the narrow waist segment). The mesonotum has an unusual disc-shaped appearance when viewed from above. The clypeus (the plate covering the mouth) has a deep U-shaped notch. The entire body is black with a covering of golden pile that creates an iridescent sheen, particularly visible on the gaster. Legs and antennae are reddish-brown. Queens are similar but larger at around 11mm with the typical sexual features including larger eyes and ocelli. ^[3]

Distribution and Habitat

This species is endemic to New Guinea and the Bismarck Archipelago, making it one of the more restricted Polyrhachis species. It is considered rare in the wild and has been missing from most recent collections. The type specimen was collected from Dory in New Guinea, with additional records from Bachian Island. They are subterranean nesters, building colonies underground in soil rather than in trees or vegetation like some related Polyrhachis species. The tropical climate of New Guinea is warm and humid year-round with high rainfall. ^[3]

Nesting Behavior

Polyrhachis metella is one of the subterranean-nesting species in the genus, unlike many Polyrhachis that nest in vegetation or rotting wood. They construct underground nests which likely consist of chambers connected by tunnels. This species has pupal cocoons, which is actually unusual for the Formicinae subfamily where most species have naked pupae. For captive care, this suggests they need soil or a soil-like medium for proper colony establishment. A naturalistic setup with a deep soil chamber or a plaster nest with soil-filled chambers would be most appropriate. ^[1][2]

Care Requirements

Due to the limited data on this specific species, care recommendations must be based on related Polyrhachis species and the known tropical origin. Keep the nest area warm, likely in the 24-28°C range, with a slight gradient allowing the ants to choose their preferred temperature. Humidity should be kept high, around 70-85%, with consistently moist but not waterlogged substrate. Provide a water source and sugar water or honey as an energy source. Protein should come from small insects or other arthropods. Since they are subterranean nesters, ensure the nesting medium allows for proper tunnel construction and chamber creation.

Colony Structure and Development

The colony structure of P. metella has not been documented in detail. Like most Polyrhachis species, they are likely monogyne (single queen colonies). The development timeline is unknown, but related tropical Polyrhachis species typically produce first workers (nanitics) in 6-10 weeks under warm conditions. The presence of cocoons means the pupal stage is more visible than in many Formicinae species. Colony size in the wild is unknown but likely moderate, possibly reaching dozens to low hundreds of workers based on similar species. ^[3]

Frequently Asked Questions

References