Scarlet Isopods (Ardentiella sp.)

Scarlet Isopods are a selectively bred colour morph of the Ardentiella genus, developed from Ardentiella sp. "Tricolor" stock. As the name suggests, these Vietnamese isopods display predominantly red colouration with yellow and black accents—a striking combination that makes them stand out immediately. Like all Ardentiella, they're active, bold, and far more visible than many isopod species, but they're not beginners' isopods. These are challenging animals that reward keepers who take the time to understand their specific requirements.

Species Information

• Scientific name: Ardentiella sp. "Scarlet" (formerly Merulanella sp. "Scarlet")
• Common names: Scarlet Isopod
• Origin: Vietnam (selectively bred morph)
• Adult size: 18–20mm
• Difficulty: Hard
• Rarity: Very rare

Taxonomy Note

You may see this species referred to as either Merulanella or Ardentiella. The genus was reclassified—what was previously known as Merulanella is now Ardentiella. Both names refer to the same group of isopods, so don't be confused if you encounter older sources using Merulanella. The care requirements remain identical regardless of which name is used.

Appearance

Scarlet Isopods are characterised by predominantly red bodies with yellow and black splotching. The exact pattern varies between individuals, but the overall impression is of vivid scarlet colouration that's immediately eye-catching. They're a selectively bred morph isolated from Tricolor stock for their enhanced red pigmentation.

Adults reach 18–20mm—a good size that makes them easily visible and enjoyable to observe. Their bold colouration combined with their active nature means you'll actually see these isopods, unlike many species that spend most of their time hidden.

Behaviour

Ardentiella isopods are notably different from most other genera in their activity levels. Key behavioural traits:

• Active day and night: Unlike most isopods that are strictly nocturnal, Ardentiella are active throughout the day
• Surface dwellers: Not a burrowing species—they congregate in leaf litter and under bark rather than digging into substrate
• Social: Often found in small groups of two or three
• Climbers: Will climb vertically on plastic and glass—enclosures must be escape-proof
• Bold: More willing to be visible than many isopod species

This active, visible nature is one of the main appeals of Ardentiella species. If you want isopods you'll actually see regularly, these deliver in a way that many burrowing species don't.

Enclosure Setup

Container

Ardentiella isopods—especially juveniles and mancae (newly released young)—can climb vertically on smooth plastic surfaces. This means:

• Enclosures must be completely escape-proof
• Tight-fitting lids are essential
• Check for gaps around ventilation holes
• Consider a barrier (petroleum jelly) around the upper rim as extra security

Good ventilation is critical. Ardentiella require high air humidity but are sensitive to stagnant air—the combination of moisture and poor airflow can be fatal. Multiple ventilation holes (at least 3–4) help maintain airflow while retaining humidity.

Substrate

Unlike many tropical isopods, Ardentiella don't burrow extensively. They prefer a layered setup similar to Cubaris species:

• Base layer of moisture-retaining substrate (organic topsoil, sphagnum peat moss)
• Keep substrate moist but not waterlogged—they need high air moisture, not wet soil
• Decaying leaves layered on top
• Forest moss
• Pieces of twigs with lichen
• Cork bark or tree bark on top for hiding

This layered approach creates microhabitats at different moisture levels while providing the varied surfaces Ardentiella like to explore.

Temperature

• Range: 19–26°C
• Optimal: Around 20°C (average UK room temperature works well)
• Important: They prefer it cooler than many tropical isopods
• Caution: Higher temperatures (above 26°C) can cause stress and rapid death

This is a critical point—Ardentiella are not heat-lovers despite their Vietnamese origin. Temperatures in the low-to-mid 20s Celsius are ideal. Keeping them too warm is a common mistake that leads to colony crashes.

Humidity

• Range: 60–75%
• Substrate: Moist but not wet
• Air: High humidity with good airflow
• Maintenance: Spray periodically to maintain levels

The key balance with Ardentiella is maintaining high air humidity while ensuring good ventilation. Stagnant, humid air is dangerous for them. Think "humid but fresh" rather than "humid and still."

Diet

Ardentiella have varied dietary preferences. Offer a rotation of:

Staples:

• Decaying leaves (oak, maple, birch)
• Rotting white wood
• Forest moss
• Lichen (on twigs or bark)

Fresh foods:

• Vegetables: cucumber, courgette, sweet potato, carrots
• Fruits: mango has been noted as particularly successful
• Greens: various leafy vegetables

Supplements:

• Protein 2–3 times weekly: fish flakes, dried gammarus shrimp, high-protein powder foods
• Calcium: cuttlebone, crushed eggshells, oyster shells, limestone

Alternative foods:

• Kinshi (fungus-colonised wood substrate)
• Moultings from other invertebrates or reptiles

Remove uneaten fresh food before it moulds. Ardentiella reportedly don't eat bee pollen, so don't rely on that as a food source.

Breeding

Ardentiella breed at a medium rate—not as prolific as Porcellio or Armadillidium species, but steady once established. Success depends on maintaining correct conditions consistently:

• Stable temperature in the optimal range (19–26°C, ideally around 20°C)
• Correct humidity balance (high air moisture, good ventilation)
• Varied diet with adequate protein and calcium
• Undisturbed colony—avoid excessive handling or enclosure disruption

Breeding is possible once you understand their requirements, but expect a learning curve. These aren't isopods that breed explosively regardless of conditions.

Why They're Challenging

Ardentiella sp. "Scarlet" are rated as hard difficulty for good reasons:

• Temperature sensitivity: Too warm and they decline rapidly
• Ventilation requirements: Need high humidity AND good airflow—a tricky balance
• Climbing ability: Escapes are easy if enclosures aren't properly secured
• Price point: At £90 for 5, mistakes are expensive
• Availability: Very rare—replacement stock isn't always available

They're not impossible, but they require attention to detail that more forgiving species don't demand.

Care Summary

• Temperature: 19–26°C (prefer cooler end, around 20°C)
• Humidity: 60–75% with good ventilation
• Substrate: Moist but not wet, layered setup
• Ventilation: Critical—multiple openings, avoid stagnant air
• Diet: Leaf litter, rotting wood, moss, lichen, vegetables, protein supplements
• Calcium: Essential—cuttlebone, eggshells, oyster shell
• Behaviour: Active day and night, surface-dwelling, climbers
• Breeding: Medium reproduction rate
• Escape risk: High—can climb smooth surfaces

Pricing

• 5 isopods: £90
• 10 isopods: £170
• 20 isopods: £330

Who Are They For?

Scarlet Isopods are best suited for:

• Experienced keepers: Those who've successfully maintained other tropical species (Cubaris, other Ardentiella morphs)
• Collectors seeking colour: The vivid red colouration is exceptional
• Keepers who want visible isopods: Their active, surface-dwelling nature means you'll actually see them
• Those willing to learn: The genus has specific requirements but isn't impossible once understood

They're not suitable for beginners or anyone expecting set-and-forget care. If you haven't kept tropical isopods before, consider gaining experience with easier species first—the investment in Scarlet Isopods is significant, and losing a colony to avoidable mistakes is frustrating.

Related Morphs

Scarlet is one of several morphs within the Ardentiella sp. "Tricolor" lineage. Others include "Blister" and "Pink Lemonade" (a high-yellow morph developed from Scarlet stock). If you enjoy Scarlet Isopods, exploring other Ardentiella varieties offers similar care requirements with different colour expressions.

Ardentiella sp. "Scarlet" reward patient, attentive keepers with some of the most vibrant colouration and active behaviour in the isopod hobby. They're challenging, but the combination of stunning appearance and visible activity makes them worth the effort for those ready to meet their needs.