Romblonella longinoi

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Borneo, Malaysia (Sabah). Known only from Mamutik Island where it was collected from a dead stem in wet tropical forest at 10 m elevation ^[1].
• Colony Type: Unknown, only a single nest series has ever been collected. Colony structure (single queen vs multiple queens) has not been documented.
• Size & Growth:
  • Queen: Unknown, queen caste has not been described ^[1]
  • Worker: 3.7-4.1 mm ^[1]
  • Colony: Unknown, only known from 18 workers in the type series
  • Growth: Unknown
  • Development: Unconfirmed (No development data exists for this species. Related Crematogastrini ants typically develop in 4-8 weeks at tropical temperatures.)
• Antkeeping:
  • Temperature: Estimated: keep at 24-28°C. This is an educated guess based on its habitat, a lowland wet tropical forest in Borneo where temperatures remain warm year-round ^[1].
  • Humidity: High humidity required, collected from wet tropical forest. Keep nest substrate consistently moist but not waterlogged.
  • Diapause: Unlikely, being a tropical lowland species from near the equator, no winter dormancy period is expected.
  • Nesting: Inferred from collection data: found in a dead stem, suggesting they nest in small cavities in rotting wood. In captivity, a small test tube setup or a natural nest (e.g., plaster or soil-based) with moist substrate works well. The tiny colony size means chambers should be appropriately scaled.
• Behavior: No specific behavioral observations have been documented. As a member of the Crematogastrini tribe, this species likely uses a smearing defense mechanism (modified stinger for applying venom), rather than piercing stings. They are probably not aggressive. Escape risk is high due to their small size (4 mm), use fluon or oil barriers on the outworld.
• Common Issues: extremely limited availability, this species has rarely if ever been kept in captivity, no established care protocols, all recommendations are inferred from habitat and genus, queen and colony structure unknown, founding behavior unconfirmed, wild-caught colonies may have parasites or diseases with no documented treatment, very small colony size means slow growth and high vulnerability to stress

Discovery and Taxonomy

Romblonella longinoi was described in 2016 by David Emmanuel M. General, making it one of the most recently described Romblonella species. The species was named in honor of Dr. John T. Longino, a renowned myrmecologist who collected the only known nest series from Mamutik Island in Sabah, Malaysia on August 29,2010 ^[1]. The type series consists of 18 workers and 2 male alates, remarkably, this represents essentially all specimens of this species ever collected. The holotype worker measures 4.01 mm total length, with paratype workers averaging 3.97 mm ^[1]. The genus Romblonella contains only a handful of species, and R. longinoi stands out for its uniquely broadened head capsule that widens toward the back, a feature not found in any other Romblonella species ^[1].

Identification and Appearance

Workers of Romblonella longinoi have a distinctly bicolored appearance. The body is yellow to orange, contrasting with brown antennal club, legs, and the distal edges of the first gastral segment along with gastral segments 2-5 ^[1]. In full face view, the head is longer than wide with sides that diverge posteriorly, creating that distinctive broadened appearance. The eyes are positioned laterally, slightly behind the midlength of the head. A shallow scrobe (groove) is present, and the frontal carinae (ridge-like structures) extend almost to the posterior margin of the head. The scapes (antenna segments) are short, exceeding the posterior edge of the eye by about twice the width of the distal scape. The propodeal spines are long and stout, and the petiole is massive, larger and taller than the postpetiole ^[1]. These are tiny ants: workers range from 3.67 to 4.14 mm.

Natural History

This species is known only from its type locality on Mamutik Island in Sabah, Malaysia, at approximately 5.97°N latitude and 116.01°E longitude, around 10 meters elevation ^[1]. The only collected specimen came from a dead stem in a wet tropical forest environment. This nesting preference suggests R. longinoi colonizes small cavities in rotting wood, similar to many other small Myrmicinae. The wet tropical forest habitat indicates this species requires high humidity and stable warm temperatures year-round. No behavioral observations have been documented in the scientific literature, and nothing is known about their diet, foraging patterns, or colony structure. The male alates were collected alongside workers, suggesting nuptial flights may occur in late August for this region ^[1].

Housing and Care

Since this species has never been kept in captivity, all care recommendations are educated guesses based on its habitat and what is known about related ants. Provide a small test tube setup or a natural nest (e.g., plaster or soil-based) with chambers scaled to their tiny 4 mm size. Keep the nest substrate consistently moist, this is a wet tropical forest species. Maintain temperatures in the 24-28°C range, matching their lowland Borneo habitat. Use fine mesh or fluon barriers, as these small ants can squeeze through standard gaps. Feed small protein sources like fruit flies, pinhead crickets, or similar tiny prey. Sugar water should be offered, but acceptance is uncertain. Given how rare this species is, only experienced antkeepers should consider keeping it, and wild collection is not recommended due to the extremely few specimens known. ^[1]

Conservation Status

Romblonella longinoi is known from a single nest series collected in 2010, essentially 18 workers and 2 males represent the entire scientific knowledge of this species. This makes it one of the rarest ants in the world from a documentation perspective. Its known range is extremely limited (Mamutik Island in Sabah), and nothing is known about its population size or trends. The species has not been evaluated for IUCN conservation status. For antkeepers, this means R. longinoi is essentially unavailable and would be extremely difficult to acquire. Any captive colonies would likely be from scientific breeding programs rather than wild collection, which should be avoided given the species' extreme rarity. ^[1]

Frequently Asked Questions

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References