Pheidole bison

Pheidole bison

Pheidole bison is a Neotropical ant species described by Wilson in 2003,belonging to the tristis group. It gets its name from the distinctive massive humped back of the major workers, reminiscent of a bison. Majors measure around 1.26mm in head width with a dark reddish-brown head and medium reddish-brown body, while minors are smaller at 0.62mm and brownish-yellow in color. The species is only known from its type locality in Bolivia's Noel Kempff Mercado National Park at 700m elevation, where it was collected from a savanna habitat. This is one of the more recently described Pheidole species, and like many Neotropical ants, it remains poorly studied in captivity.

Quick Summary

• Difficulty: Unknown, likely Medium
• Origin & Habitat: Bolivia and Argentina (Neotropical region). Collected from savanna habitat at 700m elevation in Noel Kempff Mercado National Park ^[1].
• Colony Type: Colony structure is unconfirmed. Pheidole species are typically monogyne (single queen) but some can be polygyne. The tristis group species may have variable colony structures.
  • Founding: Claustral
• Size & Growth:
  • Queen: Unknown, not described in original description. Pheidole queens are typically 6-10mm.
  • Worker: Major: 1.26mm HW. Minor: 0.62mm HW.
  • Colony: Unknown, no colony size data available. Pheidole colonies typically reach hundreds to thousands of workers.
  • Growth: Unknown, no development data available. Estimated based on genus patterns.
  • Development: Unknown, estimated 6-10 weeks based on typical Pheidole development at tropical temperatures (No direct development data exists for this species. Estimates based on related Neotropical Pheidole species.)
• Antkeeping:
  • Temperature: Keep at 24-28°C, this matches their tropical savanna origin. A gentle gradient allows workers to self-regulate.
  • Humidity: Moderate humidity around 50-70%. Savanna species can tolerate drier conditions than rainforest ants. Allow substrate to dry partially between waterings.
  • Diapause: Likely minimal or no diapause given their tropical origin. Some seasonal slow-down may occur in cooler months.
  • Nesting: No specific nesting data exists. Based on collection from termite nest and savanna habitat, they likely nest in soil or rotting wood. A standard Pheidole setup with test tubes for founding and a Y-tong or plaster nest for established colonies works well.
• Behavior: Behavior is unstudied in captivity. Pheidole species are generally non-aggressive, with majors primarily serving as defense and seed/cr food processing. They are likely diurnal foragers. Escape risk is moderate, use standard mesh barriers. The major workers have distinctive humped promesonotum which may serve a defensive function.
• Common Issues: limited data makes care recommendations uncertain, this is a rarely kept species, no confirmed diet preferences, likely generalist like other Pheidole, colony structure unconfirmed, assume single queen unless observed otherwise, wild-caught colonies may have parasites or diseases, slow establishment if founding chamber is disturbed

Species Identification and Morphology

Pheidole bison is a distinctive species within the tristis group, named for the bison-like hump on the major workers' promesonotum. The major workers have a dark reddish-brown head covered with longitudinal carinulae (ridges), except for the frontal triangle and central clypeus. Their most striking feature is the massive, single-piece promesonotum that forms a convex dome and drops vertically to the metanotum. Minor workers are much smaller at 0.62mm head width and appear brownish-yellow overall. The minors have foveolate (pitted) and opaque head and mesosoma surfaces, with reduced propodeal spines appearing as small denticles. This species was described from Bolivia in 2003 and remains known only from that region. ^[1]

Natural History and Habitat

Pheidole bison was collected from a termite nest in savanna habitat at 700m elevation in Bolivia's Santa Cruz department. This association with termite nests is interesting and may indicate either a predatory relationship or opportunistic nesting in termite structures. The savanna environment suggests they prefer warmer, relatively drier conditions than rainforest-dwelling Pheidole species. The type locality in Noel Kempff Mercado National Park is in the transition zone between Amazon and Pantanal ecosystems. Like other Neotropical Pheidole, they likely have generalist diets, consuming seeds, insects, and honeydew. ^[1]

Housing and Nesting

Since specific nesting data doesn't exist for this species, housing recommendations are based on typical Pheidole husbandry and the savanna habitat clues. For founding colonies, use a standard test tube setup with a water reservoir and cotton plug. Keep the tube in darkness and avoid disturbing the queen during the claustral founding period. Once the colony reaches 20-30 workers, they can be moved to a formicarium. A Y-tong (acrylic) nest or plaster nest with moderate humidity chambers works well. The nest should have chambers sized appropriately for their minor workers (around 0.6mm) with narrow passages. Include an outworld area for foraging.

Feeding and Diet

Pheidole species are generalist omnivores, and P. bison likely follows this pattern. Feed a mix of protein and carbohydrate sources. Protein options include small insects (fruit flies, pinhead crickets, mealworms), and carbohydrate sources include sugar water, honey, or commercial ant sweets. Pheidole majors often specialize in seed processing, so you might offer small seeds once colonies are established. The association with termite nests in the wild suggests they may prey on termites or other small arthropods. 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 Neotropical species from Bolivia, P. bison prefers warm conditions around 24-28°C. This can be achieved with room temperature in most homes, or a heating cable on one side of the nest to create a gentle gradient. Avoid temperatures below 20°C or above 32°C. Given their tropical origin, a true hibernation or diapause is likely not required. However, they may show reduced activity during cooler winter months if your home temperature drops. Monitor colony behavior, active workers indicate comfortable temperatures, while lethargy or clustering may indicate too-cool conditions.

Frequently Asked Questions

References