Porcellio Hoffmannseggii Sevilla Isopods

Porcellio hoffmannseggii 'Sevilla' is a large, fast-moving Iberian woodlouse — one of the standout giants of the European hobby. Until recently it circulated under the trade name Porcellio sp. "Sevilla" and was thought to be its own undescribed species; as of 2024 it's been confirmed as a morphological variant of Porcellio hoffmannseggii, the so-called Titan Isopod. The 'Sevilla' form shows the classic hoffmannseggii body plan — dark grey body with a pale skirt around the margin — but with the active, prolific temperament that's made it one of the more rewarding large Porcellio to keep.

This is part of our wider Porcellio collection, which includes the standard hoffmannseggii, the bright Orange morph and the burrowing Yeti form. The 'Sevilla' sits naturally alongside these as a locality variant of the same species, and it pairs particularly well in a collection with the Porcellio expansus — Spain's other genuine giant.

One honest framing point up front. 'Sevilla' is more forgiving than some of its hoffmannseggii cousins thanks to its high activity levels and strong breeding response, but it's still a Porcellio: it needs proper ventilation, a real dry-to-moist gradient and a bit of space. Comfortable for a keeper with a season or two of experience; not the species to start with if you've never kept isopods before. New keepers should master Porcellio scaber Dalmatian or similar first.

Quick Care Summary

• Scientific Name: Porcellio hoffmannseggii 'Sevilla' (previously distributed as Porcellio sp. "Sevilla")
• Common Name: Titan Isopod (Sevilla form)
• Family: Porcellionidae
• Origin: Southern Iberian Peninsula — Andalusia region of Spain, with the wider species also extending into Morocco and the Balearic Islands
• Adult Size: 25–35 mm (substantial for a Porcellio)
• Lifespan: 2–3 years typical
• Difficulty: Intermediate — comfortable for keepers with prior isopod experience
• Temperature: 18–26 °C — happy at standard UK room temperature
• Humidity: 50–65% with a strong moisture gradient — drier than most isopods
• Ventilation: High — this genus does poorly in stuffy conditions
• Conglobation: No — runs rather than rolls when disturbed
• Appearance: Substantial grey to dark grey body with a pale cream-white skirt running along the margin; smooth, slightly glossy dorsal surface; long uropods on males
• Behaviour: Very active and visible; strong runners; bold surface feeders rather than burrowers
• Breeding: Prolific under good conditions — one of the more reliable large Porcellio for colony growth
• Rarity: Uncommon in the UK hobby

What Makes 'Sevilla' Special

The taxonomic story. 'Sevilla' was traded internationally for years as Porcellio sp. "Sevilla," a presumed undescribed species from southern Spain. In 2024, Dr Julio Cifuentes — an isopodologist with specific expertise in Spanish Porcellio — confirmed that the Sevilla form is actually a morphological variation of Porcellio hoffmannseggii, the Titan Isopod first described by Brandt in 1833. The trade name has stuck because the look and behaviour are distinct enough to be worth distinguishing, but taxonomically this is hoffmannseggii. Genuinely interesting provenance for collectors who care about the science.

The activity. Where some of the large Spanish Porcellio are slow, secretive or reluctant feeders, the 'Sevilla' form is conspicuously busy. They forage openly across the substrate, climb cork bark, and stay visible day and night — making them one of the more rewarding giants to actually observe rather than just own. Most keepers report a noticeably stronger feeding response than the standard hoffmannseggii.

The breeding response. 'Sevilla' breeds prolifically when conditions suit it, with established colonies expanding faster than many of the larger Spanish species. That makes it a sensible choice for a keeper who wants a substantial isopod that will actually produce a self-sustaining colony rather than slowly tick over.

The aesthetic. A clean, understated look — large grey body, neat pale skirt, no fussy patterning. It's a species that earns its place visually through size and presence rather than colour. Sits well alongside more colourful Porcellio in a collection, providing scale and contrast.

The Iberian Porcellio cluster. Spain and the wider Iberian Peninsula are the global hotspot for giant Porcellio diversity, and 'Sevilla' is a properly representative species from that region. Combined with P. expansus, hoffmannseggii Orange and hoffmannseggii Yeti, it builds a focused Iberian-giant collection that's hard to beat in the UK.

About the Name

You'll see this species referenced under several different names — worth a clarification.

• Porcellio sp. "Sevilla": The original trade name, used internationally before the 2024 reclassification. Still in wide circulation across hobby retailers and forum threads.
• Porcellio hoffmannseggii 'Sevilla': The current taxonomically accurate name following Dr Cifuentes's confirmation that this is a variant of hoffmannseggii.
• Hoffmannseggii vs hoffmannseggi: The correct spelling is hoffmannseggii with a double 'i' at the end (Brandt, 1833). The single-'i' form hoffmannseggi is a common misspelling but refers to the same species.
• Titan Isopod: The common name applied to P. hoffmannseggii in general, including all its locality and colour forms.

Setting Up the Enclosure

A 10–15 litre plastic container with a secure clip-lock lid suits a starter colony of 10 individuals; scale up for larger groups. Drill plenty of ventilation holes around the sides as well as in the lid for proper cross-flow — like the rest of the genus, 'Sevilla' will not tolerate a stuffy, stagnant enclosure. Cover ventilation holes with fine mesh to keep escapees in and pest insects out.

Provide multiple hides — cork bark flats, chunks of decaying hardwood, ceramic or stone hides — distributed across the moisture gradient so individuals can pick the conditions that suit them at any given moment. Substantial isopods need substantial cover. Keep the enclosure out of direct sunlight and away from heat sources that cause humidity to swing.

Important husbandry note: Skip the standing water dish. A wet corner and occasional misting on the moist side provides all the water they need, and open water in a low-humidity setup encourages mould and gnat issues without serving any real purpose.

Substrate

Use a free-draining, calcium-rich substrate that supports the dry-to-moist gradient this species needs:

• Organic topsoil (pesticide-free) as the foundation
• Sphagnum moss concentrated in the moist corner only — not mixed throughout
• Composted hardwood leaf litter mixed through the upper layer
• Crushed limestone or oyster shell distributed throughout for calcium
• Rotting hardwood pieces — an important food source and natural cover
• A small amount of fine sand or aquarium gravel mixed in to keep the base end well-draining

We recommend a topsoil-based mix rather than coco coir. Substrate depth around 5–7 cm is enough — 'Sevilla' is a surface forager rather than a deep burrower, so depth matters less than getting the gradient right.

Top layer: a generous covering of hardwood leaf litter — oak, beech, hazel — plus cork bark and pieces of rotten wood. Maintain a clear distinction between the moist end and the dry end so the colony can self-regulate.

Humidity and Temperature

Maintain humidity around 50–65% overall, with one quarter to one third of the enclosure kept consistently damp via lightly misted sphagnum, and the remaining majority allowed to dry out properly between waterings. This is a meaningfully drier setup than most isopod keepers will be used to — get this right and 'Sevilla' thrives; get it wrong and the colony will struggle. The dry zone should genuinely be dry, not just less wet.

Temperature should be 18–26 °C, which matches normal UK room temperature for most of the year. They handle the cooler end without difficulty, and breeding picks up in the warmer half of the range. No supplementary heating is required in most heated UK homes; avoid placement near radiators, windows or other heat sources that cause humidity to swing unpredictably.

Diet

'Sevilla' are bold, opportunistic feeders that take a wide range of foods:

• Hardwood leaf litter (oak, beech, hazel) — the dietary foundation, always available
• Rotting hardwood pieces — important secondary nutrition source
• Vegetables 2–3x weekly: courgette, carrot, sweet potato, squash, cucumber. Replace within 24–48 hours.
• Fruit occasionally in small amounts (apple, melon, banana)
• Protein 1–2x weekly: fish flake, dried shrimp, dried daphnia. The genus has a notable protein requirement — underfed colonies become aggressive and may nip soft-bodied tank mates.
• Calcium (essential — always available): cuttlefish bone, crushed limestone, oyster shell, eggshell.

Feed protein and fresh foods on the drier side of the enclosure to slow spoilage. 'Sevilla' have a stronger feeding response than many of the larger Spanish Porcellio, so don't be alarmed by how quickly food disappears in an established colony.

Breeding

'Sevilla' breed reliably and prolifically in the right conditions — one of the more rewarding large Porcellio on that score. Females carry developing young in a brood pouch (marsupium) and release fully-formed miniature versions of the adults, which join the colony immediately and require no separate care.

For breeding success:

• Stable temperature in the upper half of the range (22–26 °C is ideal for peak breeding)
• Consistent humidity gradient — avoid wet swings or stuffy conditions
• Abundant calcium for breeding females
• Regular protein supplementation to support reproductive output
• Plenty of secure hides, especially flat cork bark for females to gather under
• Larger starter groups (10+) establish noticeably faster than smaller ones and offer better genetic diversity

Like the rest of the genus, hoffmannseggii females are noted for a degree of maternal behaviour — they remain near their young in the immediate post-release period rather than dispersing.

Who Should Buy 'Sevilla' Isopods?

Ideal for:

• Keepers with prior isopod experience looking to step up to a substantial, active species
• Collectors building an Iberian or Spanish Porcellio cluster alongside P. expansus or other hoffmannseggii forms
• Display keepers who want a large, visible isopod that actually shows itself rather than burrowing out of sight
• Keepers running drier setups — many isopods need high humidity; 'Sevilla' is one of the relatively few large species that prefers it on the dry side
• Anyone interested in the taxonomic story of trade names being formally resolved (the 2024 reclassification is a recent and well-documented case)

Not ideal for:

• Complete beginners — start with Porcellio scaber Dalmatian or P. laevis Milk Back first
• Keepers who run their isopod setups consistently damp — 'Sevilla' need a proper dry zone and won't thrive if it's missing
• Tight, low-ventilation enclosures — this genus is notably intolerant of stagnant air
• Mixed setups with very small or soft-bodied tank mates — 'Sevilla' are fast, bold and protein-driven, and may harass smaller species if underfed

Realistic Expectations

They need drier conditions than most isopod care guides assume. The most common reason a hoffmannseggii colony struggles is over-misting and poor ventilation. If your current setups all run damp and stuffy, this isn't the species to slot straight in — set up a dedicated enclosure with a real dry zone and proper airflow.

They're active runners, not rollers. 'Sevilla' can't conglobate into a ball; their defence is speed and a willingness to flatten against substrate. Expect quick, busy animals that scatter when you lift cork bark — it's part of what makes them rewarding to keep, but it's worth knowing if you were expecting an Armadillidium-style roller.

The look is understated, not vivid. Grey body, pale skirt, clean lines. 'Sevilla' isn't trying to compete with the bright morphs — its appeal is size, presence and behaviour rather than colour saturation. If you want bold colour, the Orange hoffmannseggii is the same species with a much louder palette.

The name will keep changing. 'Sevilla' is still widely sold under its old trade name Porcellio sp. "Sevilla," even after the 2024 reclassification. Both names refer to the same animal, and you'll see them used interchangeably across UK and international retailers for some time yet.

It's not the very biggest hoffmannseggii. The species as a whole can push past 35–38 mm in its largest individuals, and the 'Sevilla' form sits in the mid-to-upper part of that range. For absolute maximum size, P. expansus 'La Senia' remains the genuine giant of the European hobby.