Linepithema aztecoides

Linepithema aztecoides

Linepithema aztecoides is a small, distinctive ant species native to South America, found in central and southeastern Brazil and eastern Paraguay. Workers measure just 0.61-0.69mm in head length, with a unique flattened body shape that sets them apart from other Linepithema species ^[1]. Their most striking feature is their behavior of running with their abdomens held high above their heads, giving them the appearance of tiny Azteca ants. They are reddish brown to dark brown in color and have long antennae relative to their head size ^[1]. This species inhabits low, open forests like cerrados and riparian gallery forests, where they forage in humid subtropical conditions ^[2].

What makes L. aztecoides particularly interesting is how rarely it is encountered despite being described in 2007, queen and male castes remain unknown, and no nests have ever been documented ^[2]. They are attracted to protein baits like honey and sardine, suggesting an omnivorous diet. Their flattened body shape is an unusual adaptation that likely helps them navigate through tight spaces in their forest floor habitat. This species remains one of the more mysterious ants in the Linepithema genus, making it a challenging but intriguing species for experienced antkeepers who can obtain a colony.

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Central and southeastern Brazil (Mato Grosso to São Paulo) and eastern Paraguay, in low open forests such as cerrados and riparian gallery forests at elevations around 220m ^[1][2]
• Colony Type: Unknown, queen and male castes have not been documented, no nests have ever been found in the wild ^[2]
• Size & Growth:
  • Queen: Unknown, queen caste has not been described ^[1]
  • Worker: 0.61-0.69mm head length (HL),0.52-0.60mm head width (HW) ^[1]
  • Colony: Unknown, no colony size data available
  • Growth: Unknown, no development data available
  • Development: Unknown, development has not been studied (No data exists on egg-to-worker development time. Related Linepithema species typically develop in 4-8 weeks at warm temperatures, but this is a rough estimate only.)
• Antkeeping:
  • Temperature: Inferred warm conditions (subtropical), aim for 22-26°C based on habitat. Provide a gentle temperature gradient so ants can self-regulate.
  • Humidity: High humidity preferred, these ants come from humid subtropical forest edges. Keep nest substrate consistently moist but not waterlogged. Provide a humidity gradient with a moist area and a slightly drier area.
  • Diapause: Unknown, no data on overwintering requirements. Given their subtropical origin from Brazil/Paraguay, they likely do not require a true hibernation but may slow down during cooler months.
  • Nesting: No documented nesting preferences exist since no wild nests have been found. Based on habitat (forest floor of cerrados and gallery forests), they likely nest in soil or under stones. In captivity, a test tube setup or small acrylic nest with moist substrate would be a reasonable starting point.
• Behavior: These ants are active foragers that recruit to protein baits, they were collected at honey and sardine baits in the wild ^[1]. Their most distinctive behavior is running with their gaster held above their head, which is unusual and may help them navigate through dense vegetation or detect chemical trails more effectively. Workers are small (under 1mm) so escape prevention is critical, they can squeeze through tiny gaps. Temperament is unknown since no live colonies have been studied, but related Linepithema species are generally not aggressive. Their small size and cryptic habits suggest they are non-confrontational foragers.
• Common Issues: no documented queen or colony structure makes captive care extremely speculative, no known nesting preferences, trial and error required to determine what setup they accept, escape prevention is critical due to their tiny size, use fine mesh and tight-fitting lids, extremely rare in the antkeeping hobby, finding a colony may be impossible, no development data means you cannot track whether your colony is growing normally, related to invasive Argentine ant (L. humile), never release in North America

Discovery and Rarity

Linepithema aztecoides was only described in 2007 by Alexander Wild, making it one of the newer additions to the antkeeping world ^[1]. The type series was collected in Paraguay at a honey bait, and another specimen was found in Brazil at a sardine bait, both protein-rich attractants. What makes this species remarkable is that despite targeted collecting efforts, no one has ever documented a nest or found the queen or male castes. This means we know almost nothing about their natural colony structure, how they reproduce, or what their nests look like. The species appears to be genuinely rare in the wild, which adds to the challenge of understanding its biology. For antkeepers, this rarity also means finding a colony of L. aztecoides is extremely difficult, they simply are not available in the hobby trade ^[1].

Unique Physical Characteristics

The most distinctive feature of Linepithema aztecoides is its dorso-ventrally flattened body, the head, mesosoma, and petiole are all compressed vertically ^[1]. This is unusual among Linepithema species and gives them a very different silhouette than their relatives. Their head is chord-shaped (wider at or behind the eyes, narrowed toward the front), and they have relatively large compound eyes with 65-80 ommatidia. The antennae are long, with the scape exceeding head length in some populations (particularly those from Mato Grosso). The propodeum (the section behind the mesosoma) has distinctive spiracles at the posterolateral corners. Workers are medium reddish brown to dark brown, with lighter-colored trochanters and tarsi that can be nearly white ^[1]. The gaster (abdomen) is also flattened and triangular when viewed from behind.

Field Behavior and Foraging

In the field, Linepithema aztecoides shows a behavior that immediately catches the eye of anyone who observes them, they run with their gaster held dramatically above their head ^[2]. This gives them a striking resemblance to ants in the genus Azteca, which is how they got their species name 'aztecoides' (meaning 'Azteca-like'). This unusual posture likely helps them navigate through dense understory vegetation in their forest floor habitat, or perhaps it helps them deploy chemical defenses more effectively. They are confirmed to recruit to baits, with the type series collected at honey and another specimen collected at sardine ^[2]. This suggests they are omnivorous and will accept both sugar and protein sources. Their small size (workers under 1mm) means they likely target tiny prey and liquid carbohydrates in the wild.

Habitat and Distribution

This species is known from a relatively limited range in South America, central and southeastern Brazil (from Mato Grosso to São Paulo) and eastern Paraguay ^[1]. They inhabit low, open forests including cerrados (tropical savanna) and riparian gallery forests (forests along rivers). The type locality was in humid subtropical low forest along the edge of a small cerrado at about 220 meters elevation ^[2]. This habitat type suggests they prefer warm, somewhat humid conditions with moderate ground cover. The variation in body proportions across their range is notable, specimens from Mato Grosso consistently have longer appendages than those from Goiás, São Paulo and Paraguay ^[2]. This geographic variation suggests some local adaptation to different conditions within their range.

Keeping an Undescribed Species

Keeping Linepithema aztecoides presents unique challenges that most antkeepers will never face. Since no one has ever documented a wild colony, we have no information about their queen, colony size, or basic biology. This makes L. aztecoides truly an 'expert only' species, you would essentially be pioneering captive husbandry for a species that exists almost entirely in scientific literature. If you somehow obtain workers, you would need to experiment with nest setups, temperatures, humidity levels, and foods with no guidance whatsoever. The lack of a known queen also means you cannot start a colony from scratch. For these reasons, L. aztecoides is more of a scientific curiosity than a realistic keeping project. Most antkeepers interested in Linepithema species would be better served by keeping the well-documented Argentine ant (L. humile) or other more common species in the genus. ^[1][2]

Frequently Asked Questions

References