Patagonomyrmex angustus

Patagonomyrmex angustus

Patagonomyrmex angustus is a small, dark ant native to southern Argentina and Chile. Workers measure 5.4mm in body length with a distinctive dark brownish-black to black coloration, making them easy to distinguish from reddish Pogonomyrmex species like P. vermiculatus and P. bispinosus ^[1]. They have long inferior propodeal spines that are similar in length to their superior spines, and their body surface has a granulate-punctate texture that appears dull rather than shiny ^[2]. This species is part of the Patagonomyrmex angustus complex, which is sister to all other pogonomyrmecines and contains species that are not specialist seed-harvesters unlike most other Pogonomyrmex ^[3][4]. They inhabit cool, humid regions in southern South America dominated by Nothofagus (southern beech) or Austrocedrus (Chilean cedar) forests.

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Southern Argentina (Neuquén, Río Negro, Chubut) and southern to southcentral Chile (Valparaíso to Chiloé). They live in cool, relatively humid climates with short growing seasons, typically in habitats dominated by Nothofagus or Austrocedrus forests, ranging from the Valdivian Temperate Forest to Chilean Matorral ecoregions ^[2].
• Colony Type: Single-queen colonies (monogyne). Colonies typically contain 1-2 reproductive dealate queens. Colony size is small, probably under 300-400 workers ^[2].
  • Colony: Monogyne
• Size & Growth:
  • Queen: 1.10-1.39mm head width ^[2]
  • Worker: 0.81-1.16mm head width,5.4mm body length ^[2][5]
  • Colony: Probably under 300-400 workers ^[2]
  • Growth: Moderate, inferred from small colony size
  • Development: Unknown, no direct development data exists. Based on typical Myrmicinae patterns and cool habitat, estimate 8-12 weeks at optimal temperature. (Development is likely slower than tropical species due to their cool native habitat. Temperature-dependent, cooler temperatures will slow development.)
• Antkeeping:
  • Temperature: Keep at 18-22°C. These ants come from cool southern latitudes and prefer temperatures lower than most tropical ants. Avoid overheating, they are adapted to cool, humid conditions ^[2].
  • Humidity: Moderate to high humidity (60-80%). They inhabit humid forest regions and should be kept in moist but not waterlogged substrate. Provide a gradient with a damp area and a slightly drier area for workers to choose ^[2].
  • Diapause: Yes, they require a winter dormancy period. Native to cool southern latitudes with distinct seasons, they would naturally slow down during the austral winter (roughly May-September in the Southern Hemisphere). Provide a cool period around 10-15°C for 3-4 months ^[2].
  • Nesting: Soil-nesting species. In captivity, use a test tube setup for founding colonies, then transition to a naturalistic or plaster nest with moist substrate. Nests in the wild are variable, from simple entrances without mounds to 10-12cm diameter openings, often under stones or in open areas ^[2].
• Behavior: Workers are diurnal, slow-moving, solitary foragers that are timid and non-aggressive ^[2]. They are granivores (seed eaters) but not specialist seed-harvesters like other Pogonomyrmex species ^[3][4]. They forage individually rather than in groups. Escape risk is moderate, they are small ants but not particularly known for escaping. Use standard barrier methods. They have a stinger but are not aggressive and unlikely to use it against humans.
• Common Issues: colonies are small, slow growth means beginners may lose patience and overfeed or disturb too often, winter dormancy is required, colonies that are kept warm year-round may decline, they prefer cooler temperatures, overheating is a common mistake with this species, wild-caught colonies may have parasites that kill them in captivity, granivorous diet means they need seed-based foods but also accept protein, don't rely on sugar water alone

Housing and Nest Setup

Patagonomyrmex angustus is a soil-nesting species that naturally nests under stones or in open areas with variable entrance sizes ^[2]. For captive care, start with a standard test tube setup for the founding queen. Once the colony reaches 20-30 workers, you can transition to a naturalistic setup with moist soil or a plaster/acrylic nest. Because they come from humid forest habitats, the nest material should retain moisture well. Provide a water tube for drinking and ensure the substrate stays damp but not waterlogged. A small outworld for foraging completes the setup. These ants do not need elaborate escape prevention beyond standard barriers, they are not particularly known for climbing smooth surfaces aggressively.

Feeding and Diet

In the wild, P. angustus are granivores, meaning they eat seeds ^[2]. However, they are not specialist seed-harvesters like other Pogonomyrmex species, they likely have a more varied diet ^[3][4]. In captivity, offer a mix of seeds (millet, grass seeds, cracked sunflower seeds) as a staple, along with protein sources like small insects (fruit flies, small mealworms, crickets). They are timid foragers, so place food in the outworld and give them time to discover it. Sugar water or honey can be offered occasionally but should not be the primary food source. Feed them every 2-3 days, removing uneaten food to prevent mold. Fresh water should always be available.

Temperature and Seasonal Care

This is one of the most important aspects of keeping P. angustus successfully. They come from cool southern latitudes in Argentina and Chile, where temperatures are much cooler than typical room temperature for most antkeepers. Keep the nest area at 18-22°C, avoid temperatures above 25°C. A heating cable on one side of the nest can create a gentle gradient if your room is cooler, but many keepers find that room temperature in temperate climates is actually ideal for this species. They also require an annual dormancy period. During the austral winter (roughly May to September), reduce temperatures to 10-15°C and reduce feeding. This mimics their natural cycle in the cool southern hemisphere and is essential for colony health long-term. If you cannot provide this cooling period, the colony may decline over time. ^[2]

Behavior and Colony Dynamics

P. angustus workers are diurnal and forage individually rather than in groups ^[2]. They are described as slow-moving, timid, and non-aggressive, they will not attack or sting readily. This makes them a peaceful species to observe but also means they are not exciting for keepers who want aggressive foraging displays. Colonies remain relatively small, typically under 300-400 workers ^[2]. This slow growth is normal for the species, do not mistake it for a problem. Queens areclaustral (they seal themselves in to raise the first brood), though this has not been directly documented for this species. The colony will produce alate (winged) reproductives seasonally, sexuals have been collected from October through May in the wild, with mating flights likely occurring during the austral summer (late January through March or later) ^[2].

Frequently Asked Questions

References