Basiceros convexiceps

Basiceros convexiceps

Basiceros convexiceps is a small to medium-sized ant native to the Brazilian Atlantic Forest. Workers measure 6.58-6.61mm and queens reach 7.64-7.67mm, making them one of the larger Basiceros species ^[1]. They have a distinctive reddish-ferruginous color with a trapezoidal head and specialized hairs covering their body that adhere to soil particles, giving them excellent camouflage, this cryptobiotic habit is how they got their 'dirt ant' common name ^[2]. This species is part of the manni species-group and represents some of the most generalized morphology in the genus ^[3].

What makes B. convexiceps particularly interesting is its polygynic colony structure, the only documented colony had 60 workers and three wingless queens living together ^[4]. They nest in rotting wood and leaf litter in the Atlantic Forest, and are predatory on small arthropods ^[2]. This is a rare species that is very rarely collected in full colonies, making captive husbandry challenging.

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Brazilian Atlantic Forest biome, from Santa Catarina to Bahia. Found in rotting wood, under bark, and leaf litter ^[4].
• Colony Type: Polygynic, colonies can have multiple queens (documented with 3 wingless gynes in one nest). Small colony size with around 60 workers ^[4].
  • Colony: Polygyne
• Size & Growth:
  • Queen: 7.64-7.67mm ^[1]
  • Worker: 6.58-6.61mm ^[4]
  • Colony: Small, up to approximately 60 workers documented ^[4]
  • Growth: Unknown, likely slow given small colony sizes
  • Development: Unknown, no direct development data available. Based on related Attini tribe patterns, estimate 6-10 weeks at optimal temperature. (Development timeline has not been directly studied. Related tropical Myrmicinae typically take 6-10 weeks.)
• Antkeeping:
  • Temperature: Keep around 22-26°C. Atlantic Forest is warm and humid with moderate temperature fluctuations. A gentle gradient is recommended.
  • Humidity: High humidity preferred, think damp forest floor. Keep substrate consistently moist but not waterlogged. These ants naturally live in rotting wood and leaf litter which retain moisture.
  • Diapause: Unlikely required, as a tropical Atlantic Forest species, they probably do not need a true diapause. However, a slight reduction in temperature during winter months may be beneficial.
  • Nesting: Rotting wood and leaf litter dwellers. In captivity, a naturalistic setup with rotting wood pieces, leaf litter, and moist substrate works well. Y-tong or plaster nests with high humidity can also work.
• Behavior: Cryptobiotic ants that camouflage themselves with soil particles using specialized hairs. Predatory on small arthropods. They are not aggressive and will flee rather than fight. Escape risk is moderate, their medium size means standard barriers work well, but they are agile and may explore for exits.
• Common Issues: very rare in the hobby, finding colonies is extremely difficult, small colony sizes mean colonies are fragile and sensitive to disturbance, predatory diet requires live small prey, cannot survive on sugar alone, cryptobiotic habit means they may be hard to spot in naturalistic setups, wild-caught colonies may have parasites given their rarity

Appearance and Identification

Basiceros convexiceps workers measure 6.58-6.61mm and queens reach 7.64-7.67mm, making them one of the larger species in the genus ^[1]. They have a distinctive reddish-ferruginous (rusty orange) coloration throughout their body ^[4]. The head is trapezoidal (wider at the back) with a continuously convex vertexal margin except for a shallow median groove. Their most distinctive feature is the specialized hairs covering their cuticle that actively adhere to soil particles and debris, providing excellent camouflage, this is why they are called 'dirt ants' ^[2]. The subpetiolar process (a projection on the waist) consists of a single forward-curved projection. Queens are similar in color but larger with three ocelli on the head ^[1].

Natural History and Distribution

This species is restricted to the Brazilian Atlantic Forest biome, with confirmed records from Santa Catarina to Bahia ^[4]. They are endemic to this region and have not been found in Espírito Santo. The Atlantic Forest is a tropical to subtropical biome with high humidity and moderate temperatures year-round. B. convexiceps has been collected from rotting wood (under bark and inside decaying trunks) and from leaf litter samples, indicating they both nest and forage in these microhabitats ^[4]. The documented colony from Jussaral (Rio de Janeiro) was found in a wide, rotted trunk, this is the only complete colony ever recorded. They are predatory on small arthropods ^[2].

Colony Structure

Basiceros convexiceps is one of the few Basiceros species with confirmed polygynic (multi-queen) colonies. The only fully documented colony had 60 workers and three wingless gynes (queens) living together in a rotting trunk ^[4]. This suggests the species naturally forms small colonies with multiple reproductive queens. The presence of wingless gynes (rather than fully winged queens ready for nuptial flights) indicates these were likely ergatoid replacement reproductives, queens born without wings that can take over if the primary queen dies. Colony sizes appear to be naturally small, the maximum documented colony had only about 60 workers. This is typical of the genus, which generally forms small colonies ^[4].

Feeding and Diet

Basiceros convexiceps is predatory on small arthropods ^[2]. In captivity, you should offer small live prey such as springtails, fruit flies, small crickets, and other micro-arthropods. As Attini tribe members (the fungus-growing ant group), they may also accept some plant matter, but their primary diet appears to be predatory. Feed small prey items 2-3 times per week, adjusting based on colony size and consumption. Remove uneaten prey after 24-48 hours to prevent mold. Sugar sources are not a primary food source, these are predators, not sugar-seekers. A small amount of honey or sugar water may be occasionally accepted but should not be relied upon.

Housing and Nesting

In the wild, B. convexiceps nests in rotting wood and leaf litter in the Atlantic Forest ^[4]. For captive care, a naturalistic setup works best, a container with moist substrate (like a mix of soil and rotting wood pieces) with leaf litter on top. The setup should maintain high humidity. You can also use a Y-tong or plaster nest with a water reservoir, but ensure humidity stays high. These ants are cryptobiotic, they camouflage with debris, so providing materials they can stick to themselves (small soil particles, detritus) helps them feel secure. A shallow foraging area with small prey items completes the setup.

Temperature and Humidity

As a tropical Atlantic Forest species, B. convexiceps prefers warm and humid conditions. Aim for temperatures around 22-26°C with some variation allowed. A heating cable on one side of the nest creates a gentle gradient they can choose from. Humidity should be high, the substrate should feel consistently moist but not waterlogged. These ants naturally live in rotting wood and leaf litter which naturally retain moisture. Mist occasionally but rely more on water reservoirs and damp substrate. Good ventilation is essential to prevent mold while maintaining humidity. ^[4][2]

Behavior and Temperament

Basiceros convexiceps is a cryptic, non-aggressive ant. Their primary defense is camouflage, the specialized hairs on their body collect soil particles, making them nearly invisible against the forest floor. When disturbed, they are more likely to flee than to fight. They do not have a painful sting and pose no danger to keepers. Their small colony sizes and cryptic nature mean they are not active foragers in the open, they hunt small arthropods in the leaf litter and rotting wood. Workers are moderately sized at about 6.6mm, so standard escape prevention works well, though they are agile climbers. ^[2][4]

Frequently Asked Questions

References