Merulanella Isopods (Now Ardentiella): The Updated 2026 Care Guide

If you've been keeping or shopping for Merulanella isopods over the past year, you've probably seen the name Ardentiella appearing alongside or in place of Merulanella. This isn't a trade rebrand — it's the result of a major 2025 scientific reclassification that moved virtually every "Merulanella" species in the hobby into a newly erected genus.

This guide brings the science up to date and gives you accurate information on what these isopods actually are, where they come from, how to care for them, and which morphs are available. If you've read older articles about Merulanella that mention them being "from the Americas" or "1–5 mm long," you've encountered information that's now well out of date — and we'll explain why.

Quick Answer: What Are Merulanella Isopods?

Merulanella isopods (now scientifically reclassified as Ardentiella) are tropical isopods native to Southeast Asia — primarily Vietnam, with related species in Thailand, Laos, Myanmar, and southern China. They belong to the family Armadillidae and are prized in the hobby for their vivid colouration, large adult size (up to 20 mm), and distinctive active behaviour. Popular morphs include Ember Bee, Red Diablo, Phoenix, Scarlet, Tricolour, and Pink Lambo. They are not beginner isopods — they require specific humidity, ventilation, and dietary conditions to thrive.

The 2025 Reclassification: Merulanella → Ardentiella

In March 2025, Benedikt Kästle and Omar Rafael Regalado Fernández published a taxonomic reassessment of the genus Merulanella in the journal Natural History Collections and Museomics. Working with historical type specimens and modern morphological analysis, they concluded that the genus as previously defined was unnaturally broad — spanning three biogeographic realms — and needed to be split.

The headline outcome for keepers:

• Genuine Merulanella is now restricted to three species native to New Caledonia in the South Pacific. None of these are kept in the hobby.
• All "Merulanella" species in the pet trade — Ember Bee, Red Diablo, Phoenix, Scarlet, Tricolour, Yellow Phoenix, Pink Lambo, and the rest — were moved to the newly erected genus Ardentiella.
• A separate new genus, Floresiodillo, was created for two former Merulanella species from Flores, Indonesia.

Practically, this means anything you've ever seen for sale as a Merulanella isopod is now correctly Ardentiella. Both names will continue to circulate in the hobby for some time, but the new taxonomy is now the scientifically accepted one and is being adopted across UK and European breeders.

You'll still see the old name on older articles, social media posts, and some product listings. We use both on our Ardentiella isopods for sale page so people searching with either name can find what they're looking for.

Where Do Merulanella / Ardentiella Isopods Actually Come From?

This is where older guides have repeatedly got it wrong. Ardentiella isopods are not American. They are not found in Central or South America, despite some hobby articles claiming otherwise — that information appears to stem from a long-running confusion in early hobby literature.

The actual range:

• Vietnam — the heartland of most popular morphs. Tricolour, Ember Bee, Phoenix, Red Diablo, and Scarlet are all Vietnamese in origin.
• Thailand, Laos, southern China — additional undescribed Ardentiella species are known from these regions, though most have not yet been formally described or entered the hobby.
• Myanmar — home to Ardentiella bicolorata, the type species of the new genus.

Their natural habitat is humid tropical and subtropical forest floor, where they live among leaf litter, rotting wood, and the underside of bark in conditions of consistent warmth and high humidity. Understanding this is the key to keeping them well — they are not a temperate species, and they will not thrive at UK room temperatures without supplementary heat.

What Family Do They Belong To?

Another correction worth making: Ardentiella (formerly Merulanella) is in the family Armadillidae — the same family as Cubaris and Armadillidium. They are not in Trachelipodidae, which is a separate family containing different terrestrial isopods.

Like other Armadillidae, they can conglobate (roll into a tight ball) when threatened, which is one of the defining features of the family.

Physical Description and Size

Ardentiella isopods are among the largest and most spectacular isopods in the hobby. Adults typically reach 18–20 mm, with some morphs slightly larger. This is significantly bigger than common UK woodlice and noticeably larger than most Cubaris — they are substantial, eye-catching animals.

Their colouration is the main reason they command premium prices:

• Bold colour patterns — bright reds, oranges, yellows, and pinks against jet-black bases
• Iridescent sheen on some morphs that catches the light
• Active surface behaviour — unlike many isopods that hide constantly, Ardentiella are often visible during the day, climbing surfaces and exploring

If you've seen photos and assumed they must be photoshopped or unusually well-lit, you haven't — these animals genuinely look like that in person, which is why they've become some of the most prized species in the international hobby.

Popular Morphs Currently in the UK Trade

Morph (Current Name)	Former Name	Origin	Notable Features
Ardentiella sp. "Ember Bee"	Merulanella sp. "Ember Bee"	Vietnam	Bold orange striping over glossy black
Ardentiella sp. "Red Diablo"	Merulanella sp. "Red Devil"/"Red Diablo"	Vietnam	Deep red with black accents
Ardentiella sp. "Phoenix"	Merulanella sp. "Phoenix"	Vietnam	Pastel/yellow phoenix-like patterning
Ardentiella sp. "Scarlet"	Merulanella sp. "Scarlet"	Vietnam (selectively bred)	Intense red, derived from Tricolour stock
Ardentiella sp. "Tricolor"	Merulanella sp. "Tricolor"	Vietnam	Black, yellow, and red — the foundation morph
Ardentiella sp. "Pink Lambo"	Merulanella sp. "Pink Lambo"	Vietnam	Distinctive pink colouration
Ardentiella sp. "Yellow Phoenix"	Merulanella sp. "Yellow Phoenix"	Vietnam	Bright yellow striping over black

Several of these are detailed in our species-specific guides — see our notes on caring for Tri-Colour Ardentiella, Red Diablo care, and the Pink Lambo care guide.

Care Requirements

Ardentiella are not beginners' isopods. They have specific environmental requirements, can be sensitive to husbandry mistakes, and represent a significant financial investment. If you're new to the hobby, we'd strongly recommend gaining experience with hardier species first — see our beginner's guide to keeping isopods in the UK for sensible starting points.

That said, well-kept captive-bred Ardentiella are far more manageable than their wild-caught reputation suggests. Here's what they actually need.

Enclosure

A 6–10 litre clip-lock plastic container with mesh-covered ventilation in the lid works well for a starter colony of 5–10 animals. Glass terrariums look attractive but require more attention to humidity stability. The enclosure must be escape-proof — Ardentiella are climbers, and small juveniles can squeeze through surprisingly tiny gaps.

Ventilation is more important than for tropical Cubaris. Ardentiella tolerate stagnant humid air poorly, and good airflow significantly reduces mould risk. Mesh vents on the lid (rather than the sides) work best.

Substrate

A multi-layered substrate at 6–8 cm depth:

• Base layer of organic topsoil mixed with coir
• Generous quantity of crumbled white-rotted hardwood (oak, beech, alder)
• Thick top layer of dry leaf litter
• Sphagnum moss patches for humid retreats
• Cork bark hides and small branches for vertical structure

Ardentiella are semi-arboreal — they actively use vertical surfaces — so a setup with multiple climbing options encourages natural behaviour and reduces stress.

Temperature

22–26°C is the target range. UK ambient temperatures are too cold for Ardentiella to thrive year-round, particularly in winter. A heat mat on a thermostat, attached to one side of the enclosure (not underneath, as this dries out the substrate), will hold the right range.

For background on isopod heat management in general, see our isopod temperature range guide.

Humidity

70–85%, with a moisture gradient. The substrate should be reliably damp throughout the lower layers, with a slightly drier surface at one end. A patch of moist sphagnum moss provides a high-humidity refuge that mancae and recently moulted animals will use.

Misting frequency depends on your specific enclosure, but most setups need a light mist on the damp end every 2–3 days. Avoid soaking the enclosure — Ardentiella tolerate humidity well but can suffer in waterlogged substrate.

For deeper detail on managing humidity properly, our complete humidity guide for isopods covers the gradient setup, troubleshooting, and species-specific targets.

Diet

Ardentiella are detritivores with healthy appetites. A good diet includes:

• Base food — leaf litter (oak, beech, magnolia) and white-rotted hardwood, always available
• Vegetables — small amounts of courgette, sweet potato, carrot offered every few days
• Protein — fish flakes, gammarus shrimp, or specialist isopod protein offered twice weekly. Ardentiella are particularly responsive to protein, and well-fed colonies show better colour and more active breeding
• Calcium — cuttlebone, crushed eggshell, or limestone always available. Critical for moulting

Remove uneaten fresh food after 24 hours to prevent mould.

Breeding

Ardentiella reproduce via the same pouch-brooding method as other terrestrial isopods — females carry eggs in a marsupium (brood pouch) on the underside of the body until they hatch into miniature mancae.

Breeding in captivity requires patience. Compared with Porcellio scaber or Trichorhina tomentosa, Ardentiella are slow breeders. A healthy colony should produce regular broods, but you should expect colony growth measured in months rather than weeks. Consistent conditions are far more important than aggressive feeding or warm spikes — fluctuations stress the colony and can suppress reproduction.

If your colony stops breeding, our isopod breeding troubleshooting guide covers the most common causes and fixes.

Captive-Bred vs Wild-Caught

This matters more for Ardentiella than for many other genera. Wild-caught Vietnamese imports have a long-standing reputation for high mortality — animals arriving stressed, dehydrated, and parasite-laden, often failing to establish. Captive-bred (CB) Ardentiella that have been stabilised through several generations are considerably more forgiving and will breed reliably under good husbandry.

If you're investing serious money in this group, buy captive-bred from a reputable breeder. The price difference between WC and CB stock looks significant on paper, but factor in mortality, quarantine, and the time spent acclimating wild-caught animals, and CB is almost always the better long-term value.

For more on this, our article on collecting and sourcing isopods responsibly covers the broader case for captive-bred stock.

Behaviour and What to Expect

Ardentiella are unusually active for isopods. While most species spend the majority of their time hidden, Ardentiella regularly come out onto cork bark, climb the sides of the enclosure, and forage during the day as well as at night. This visible activity is part of what makes them so popular — you actually see what you've paid for.

They're also gregarious. Colonies form clear social groups, particularly around feeding and brooding. Keep them in groups of at least 5–8 animals; solitary specimens do poorly.

Like other Armadillidae, they can conglobate when threatened. Combined with their bright colouration, this makes them genuinely entertaining animals to observe.

Frequently Asked Questions

Why are Merulanella isopods now called Ardentiella?

A 2025 taxonomic paper by Kästle and Regalado Fernández reassessed the genus Merulanella and concluded it had been historically defined too broadly. They restricted Merulanella to three species native to New Caledonia and erected a new genus, Ardentiella, for the species native to Southeast Asia — which includes essentially every "Merulanella" in the pet trade.

Are Merulanella and Ardentiella the same isopods?

For practical purposes in the hobby, yes — what you previously knew as Merulanella is now Ardentiella. The animals haven't changed; only the scientific name has been updated to reflect a more accurate understanding of their evolutionary relationships.

Where are Merulanella / Ardentiella isopods from?

Southeast Asia — primarily Vietnam, with related species in Thailand, Laos, southern China, and Myanmar. They are not native to the Americas, despite some older hobby articles incorrectly stating otherwise.

Are Ardentiella isopods good for beginners?

No. They have specific humidity and temperature requirements, are sensitive to husbandry mistakes, and tend to be expensive — making errors costly. We recommend starting with hardier species like Porcellio scaber or Armadillidium vulgare before investing in Ardentiella.

How big do Ardentiella isopods get?

Adults typically reach 18–20 mm in length, making them among the largest isopods commonly kept in the hobby. This is significantly larger than most Cubaris and many times larger than dwarf species like Trichorhina tomentosa.

What's the price range for Ardentiella isopods in the UK?

Prices vary considerably by morph, group size, and availability. As a rough guide, expect to pay anywhere from £30 to £100+ for a small starter group, with the rarer morphs (Scarlet, Pink Lambo, certain Phoenix variants) commanding the highest prices. Check our current Ardentiella isopods for sale page for live availability.

Can I keep different Ardentiella morphs together?

Technically possible, but strongly discouraged for breeding projects. Different morphs may interbreed and produce offspring that don't reliably express either parent's colour, diluting the lineage. Keep each morph in its own enclosure to maintain colour stability.

Final Thoughts

Ardentiella isopods (which most keepers still know as Merulanella) sit at the premium end of the hobby for good reason. They combine size, vivid colouration, and visible activity in a way that few other isopod groups manage. They reward keepers who take the time to set up their environment properly — and they punish those who don't.

If you're ready to take them on, browse our captive-bred Ardentiella isopods — we maintain UK-bred stock of several morphs, with care notes specific to each. If you're still building experience, the beginner-friendly species in our main collection are a far better place to start.

Either way, knowing the current taxonomy puts you ahead of most of the older guides still floating around online. Welcome to the genus Ardentiella.