Crematogaster roslihashimi

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Endemic to Peninsula Malaysia (near Kuantan) on the east coast. Found exclusively in Macaranga plants (Macaranga constricta and Macaranga hypoleuca) in tropical forest habitats ^[2].
• Colony Type: Colony structure is unconfirmed. As a Crematogaster species in the borneensis group, it is likely monogyne (single queen) but this has not been directly studied.
• Size & Growth:
  • Queen: 5.8-6.1mm ^[2]
  • Worker: 2.8-2.9mm ^[2]
  • Colony: Unknown, only known from a few collections. Based on related species, likely reaches several hundred workers.
  • Growth: Unknown, no development data exists for this species
  • Development: Unknown, no direct measurements exist. Based on typical Crematogaster patterns in tropical conditions, estimate 4-8 weeks at warm temperatures. (This is a rough estimate based on genus-level data since no species-specific development studies exist.)
• Antkeeping:
  • Temperature: Keep warm, roughly 24-28°C. As a tropical species from Malaysia, they need stable warmth. A heating cable on one side of the nest can create a gradient.
  • Humidity: High humidity is essential, these are plant-ants from tropical forests. Keep nest substrate consistently moist but not waterlogged. Aim for 70-85% humidity.
  • Diapause: No, this is a tropical species that does not experience cold winters. No hibernation period is needed.
  • Nesting: This species naturally lives inside hollow Macaranga plant stems. In captivity, a naturalistic setup with narrow chambers or a Y-tong/plaster nest works well. The key is providing conditions similar to their plant-dwelling lifestyle, humid with small, tight chambers scaled to their tiny size.
• Behavior: Workers are active and forager-focused, typical of Crematogaster. They have a distinctive defensive behavior, when threatened, they raise their heart-shaped gaster and can release a sticky, irritating secretion. They are not particularly aggressive toward keepers but will defend the colony. Escape prevention is important given their small size, use fine mesh and tight-fitting barriers. They likely have a mutualistic relationship with their host plants in the wild, so they may benefit from live plant elements in a naturalistic setup.
• Common Issues: This species is extremely rare in the hobby and virtually no captive breeding success stories exist, be prepared for a steep learning curve., Their obligate association with Macaranga plants means they may have specialized habitat requirements not yet understood., Small size (under 3mm) makes escape prevention critical, they can squeeze through standard test tube barriers., High humidity needs can lead to mold problems if ventilation is inadequate., No established feeding protocols exist, you will need to experiment with what they accept.

Natural History and Distribution

Crematogaster roslihashimi is one of the rarest ant species in the hobby, known only from a tiny region near Kuantan on Malaysia's east coast. This species was formally described in 2016 and was previously known as Crematogaster sp. 9 in earlier research publications. It belongs to the Crematogaster borneensis group, specifically the Crematogaster decamera subgroup, and is obligately associated with Macaranga plants from the section Pachystemon. The ants live inside the hollow stems of these plants in a mutualistic relationship, the ants get shelter while the plants receive protection from herbivores. This specialization to a single plant genus makes this species unique among antkeepers' favorites ^[2][1].

In the wild, they've only been found on two Macaranga species: Macaranga constricta and Macaranga hypoleuca. The distribution covers Peninsula Malaysia, Borneo, and Sumatra, but records are extremely sparse. This is not a species you'll find collecting in the wild easily, it's known from only a handful of scientific collections.

Housing and Nest Preferences

Since this species naturally lives inside plant stems, you'll want to replicate those conditions as closely as possible. A naturalistic setup with live or artificial plant elements works well, the key is providing narrow, humid chambers that mimic the inside of a Macaranga stem. A Y-tong or plaster nest with small chambers can work, but you may need to get creative with adding plant material or creating a more naturalistic environment.

The nest should be kept consistently moist but never waterlogged. These are tropical plant-ants, so they need high humidity, think damp forest interior, not dry room conditions. Use a water reservoir or moisture gradient to maintain humidity levels around 70-85%. Because they're tiny (workers are under 3mm), the chambers and passages in the nest should be appropriately scaled, tight spaces help them feel secure. ^[2]

Feeding and Diet

No specific feeding studies exist for this species, but Crematogaster generally are omnivorous with a preference for protein and sugar. In the wild, plant-ant species like this one likely feed on honeydew from scale insects or aphids that live on their host plants, plus small insects that wander by.

For captivity, offer a mix of sugar sources (honey water, sugar water) and protein sources (small insects like fruit flies, pinhead crickets, mealworms). Start with sugar water constantly available and offer protein prey 2-3 times per week. Remove uneaten prey after 24-48 hours to prevent mold. Since this species is so rarely kept, be prepared to experiment, they may have preferences not yet documented in the hobby. ^[2]

Temperature and Seasonal Care

As a tropical species from Malaysia, Crematogaster roslihashimi needs warm, stable temperatures. Aim for 24-28°C in the nest area, with a slight gradient if possible so the ants can choose their preferred temperature. Room temperature may be sufficient if your home stays in this range, but a heating cable on one side of the nest can help maintain optimal conditions.

No diapause or hibernation is needed, this is a tropical ant that doesn't experience cold winters. Maintain consistent warmth year-round. Sudden temperature drops or cold drafts can stress the colony. Keep them away from air conditioning vents and windows in cooler months. ^[2]

Behavior and Defense

Crematogaster ants have a distinctive defensive behavior that gives them their common name, acrobat ants. When threatened, they raise their heart-shaped gaster over their head, like a scorpion ready to strike. This position allows them to apply their defensive secretion to potential threats. The secretion is sticky and can be irritating to other insects and small predators.

For antkeepers, this means they're capable of defending themselves but generally not aggressive toward humans. They're small enough that their bite or sting isn't painful to us. The main concern is their ability to escape, at under 3mm, they can slip through surprisingly small gaps. Use fine mesh on any outworld connections and check for gaps regularly. ^[2]

Frequently Asked Questions

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References