Pheidole heyeri

Pheidole heyeri

Pheidole heyeri is a small to medium-sized ant belonging to the tristis group, native to southern Brazil. Major workers have the characteristic big heads that define Pheidole species, with a head width of about 2mm, while minor workers are much smaller at around 0.8mm. Both castes display a reddish-yellow coloration throughout their bodies. This species was originally described as a variety of Pheidole guilelmimuelleri before being elevated to full species status in 2003. It inhabits the subtropical grasslands of São Paulo and Rio Grande do Sul states, where it has been found in both native forest and modified landscapes like eucalyptus plantations.

Quick Summary

• Difficulty: Unknown, biology unstudied
• Origin & Habitat: Southern Brazil (São Paulo and Rio Grande do Sul states), subtropical grasslands ^[1]
• Colony Type: Likely single-queen colonies based on typical Pheidole patterns, but unconfirmed for this species
  • Colony: Monogyne
  • Founding: Claustral
• Size & Growth:
  • Queen: Undescribed in literature, estimated 6-8mm based on genus
  • Worker: Major: 2.02mm HW, Minor: 0.82mm HW
  • Colony: Unknown, typical Pheidole colonies reach hundreds to low thousands
  • Growth: Unknown, estimated moderate based on genus patterns
  • Development: Estimated 6-8 weeks at optimal temperature based on typical Pheidole development (Development time is unstudied for this species, estimates based on related Pheidole species)
• Antkeeping:
  • Temperature: Keep around 22-26°C, southern Brazil experiences subtropical to temperate conditions with seasonal variation. A gentle temperature gradient allows ants to self-regulate.
  • Humidity: Moderate humidity around 50-70%. Southern Brazilian grasslands experience reasonable moisture. Keep nest substrate moderately moist but not waterlogged.
  • Diapause: Likely, southern Brazil has cooler winters. Consider providing a cool period (15-18°C) for several months, but this is unconfirmed for this species.
  • Nesting: Natural nesting habits unstudied. Most Pheidole species nest in soil or under stones. A standard test tube setup works for founding colonies, larger colonies can move to Y-tong or plaster nests as they grow.
• Behavior: Pheidole species are generally non-aggressive but will defend their nests. Major workers (soldiers) use their large heads for seed-crushing and colony defense. They are active foragers that search for seeds and small insects. Escape prevention should be moderate, major workers are about 2mm but minors are very small at under 1mm, so fine mesh barriers are recommended.
• Common Issues: biology is completely unstudied, care recommendations are estimates based on genus patterns, slow growth may frustrate beginners expecting fast development, wild-caught colonies may carry parasites not well-documented for this species, very small minor workers may escape through standard barriers

Appearance and Identification

Pheidole heyeri is a distinctive species within the tristis group. Major workers have large, squared heads with shallow scrobes (grooves) that lack sculpturing. The dorsal surface of the head is mostly smooth with scattered foveae (small pits). The postpetiole (the segment behind the waist) has distinctive horn-like projections. Minor workers have transversely carinulate (ridged) markings on the back of the head and a subangulate (slightly angular) humerus. Both castes are reddish yellow in color, making them relatively easy to identify in the field. The major workers reach about 2mm head width while minors are much smaller at around 0.8mm. ^[1]

Distribution and Habitat

This species is known only from southern Brazil, specifically São Paulo and Rio Grande do Sul states. It belongs to the tristis group which is associated with the southern grasslands of Brazil. Research has recorded specimens in Santa Catarina state, including both the western region (São Miguel do Oeste, Chapecó, Xanxerê) and the plateau region (Lages, Otacílio Costa, Campo Belo do Sul). Interestingly, more specimens have been collected in eucalyptus plantations (19) than in native forest (5), suggesting some tolerance for modified landscapes. The region experiences subtropical to temperate climate with distinct seasons.

Feeding and Diet

While no specific dietary studies exist for Pheidole heyeri, the genus Pheidole is primarily granivorous (seed-eating) with omnivorous tendencies. Major workers have specialized large heads adapted for seed crushing. In captivity, offer a varied diet including: small seeds (millet, sesame, grass seeds), protein sources (small insects like fruit flies, pinhead crickets, mealworms), and carbohydrates (sugar water, honey). Feed protein 2-3 times per week and keep sugar water available constantly. Remove uneaten prey after 24-48 hours to prevent mold.

Temperature and Seasonal Care

As a species from southern Brazil, Pheidole heyeri likely experiences seasonal temperature variation in the wild. The region has subtropical to temperate conditions with cooler winters. Keep the nest area at roughly 22-26°C during the active season. A heating cable on one side of the nest creates a temperature gradient allowing the colony to self-regulate. During winter, consider providing a cool period around 15-18°C for several months, this is typical for subtropical species from this latitude. Monitor colony activity: if workers become sluggish and cluster together, they may be entering a rest period.

Colony Development

The biology of Pheidole heyeri is completely unstudied, so colony development specifics are unknown. Based on typical Pheidole patterns, founding is likely claustral: the queen seals herself in a chamber, lives off stored fat reserves, and raises the first brood alone. First workers (nanitics) will be smaller than normal workers. Expect the first workers to emerge after 6-8 weeks under optimal conditions, though this is an estimate. Colony growth will be gradual, Pheidole colonies typically reach several hundred workers over time. Major workers (soldiers) appear as the colony matures and are used for seed processing and defense.

Housing and Nesting

For founding colonies, a standard test tube setup works well. Fill the tube with water and plug with cotton, providing a humidity chamber. Cover the setup with a dark cloth during founding to reduce stress. Once the colony reaches 20-30 workers, you can transition to a formicarium. Y-tong (acrylic) nests or plaster nests work well for Pheidole species. Ensure the nest has appropriately sized chambers, major workers are about 2mm so standard sizing is fine, but the very small minors (under 1mm) may need attention to prevent escape through tiny gaps.

Frequently Asked Questions

References