Most pill woodlice have a smooth, rounded head. This one has a crest. The front of the head on Armadillidium hauseni rises into a raised, scalloped shield, notched into points along its edge, and the whole animal is finished in a frosted, granular texture that catches the light like sugar on a biscuit. Put one on a piece of cork and it looks less like a garden woodlouse and more like something that ought to be in a museum case. That crest is where the trade name comes from, and it is the reason to buy this species: nothing else in the Armadillidium collection has a face like it. Ours are captive-bred here in the UK.
Names, and the Island It Comes From
The species is Armadillidium hauseni Schmalfuss, 1985, a true pill woodlouse in the family Armadillidiidae, sold in the hobby as the Triceratops isopod. The epithet honours a Hausen; I have not found a record of who. What the science does record is where it lives, and that is the part worth knowing. In the revision of the Greek Armadillidium published in six parts between 2006 and 2012 and summarised in 2013, this species is listed as known only from Paxos, the small Ionian island just south of Corfu. Not Greece in general. One small island.
That is less strange than it sounds. The genus is at its most diverse around the north-eastern Mediterranean, which the same revision calls its radiation centre: it counts 59 valid Armadillidium species from Greece alone, notes comparable numbers in Italy and the former Yugoslavia, and records several of them from a single island each. Paxos gave science two woodlice in 1985 alone, this one and a tiny unpigmented tuberculate species in a genus of its own named after the island. Greek Armadillidium are still few in the trade; the nearest relatives by geography on our shelves are the Corfu Silver and the Pallasii 'Corfu', which take their names from the next island up. The island is where the species was described from, not where our animals come from.
What They Look Like
Start with the head, because everyone does. The frontal shield stands up here as a raised crest with a scalloped edge that reads as three points from the front. That is the Triceratops. It is not a horn in the sense of a spike, more a frilled shield.
Behind it the body is heavily granulated, every plate covered in fine raised beads, which is what gives the frosted look. Colour on our line is pale: a peach to apricot ground, the plate edges a paler cream, the legs and antennae almost white, the eyes the only dark thing on the animal. The very young are paler still, a washed-out yellow, with the granular finish already showing. Adults here run 15 to 20 mm; I have not found a published measurement to check that against, so treat it as our figure.
Like every true Armadillidium they conglobate, rolling up when disturbed; one of the animals on the listing is caught halfway through doing it. Ours were out on the bark in daylight for several of the listing's photographs.
Temperature: A Warm Room Is Enough
The panel on the listing gives 18 to 26°C, and for once an English home sits inside the band without help. The measured average in an English home over the heating season is around 19°C, which is the bottom of the range rather than below it, so a heated room does the job for most of the year. The exception is an unheated room in winter that sits below the 18°C floor; our guide to heating isopods covers the heat cable along the back of the shelf on a thermostat, which is how I do it across the racking. The top of the band matters as well: sustained heat above about 26°C slows breeding in this genus, so a tub on a sunny windowsill in August is the other thing to avoid. Our seasonal care guide has the year laid out.
Humidity: The Drier Pill Woodlouse Rules Apply
The band is 50 to 70%, and the number to hold in your head is the bottom one. This is a Mediterranean island species, and the way to lose it is a sealed, misted tub run like a tropical Cubaris. Set up a gradient instead. One end damp, a patch of sphagnum kept lightly moist, the rest of the surface allowed to dry on top between waterings, and the whole thing ventilated well enough that condensation never forms on the lid. I run two to four large vents on an 11-litre tub and an oscillating fan across the shelf. The reasoning is in our humidity guide, and the practical side of getting air through a box without drying it out is in ventilation and humidity. If mould appears on the food or the wood, that is the enclosure telling you it is too wet; our mould guide says what to do about it.
Substrate, Cover and Calcium
They eat the floor they live on, so the floor has to be food. A base of flake soil and crumbled white-rotted hardwood over organic topsoil, five to eight centimetres deep, gives them that. I keep coco coir out of it: it holds water and feeds nothing, which is the wrong trade for an animal that grazes its substrate. Over that goes a thick layer of hardwood leaf litter, with magnolia leaves as the long-lasting cover and oak or beech to graze, and flat cork bark laid across the gradient so they can choose their moisture. The full mix is in our substrate guide.
Calcium is the one thing I would not let run out. The whole genus carries thick armour and needs a permanent source to moult cleanly, and a heavily granulated animal like this one is no exception. A piece of crushed oyster shell, cuttlebone or limestone sitting in the tub at all times is the whole of it; why that matters more than a dusting on the food is in the calcium guide.
Feeding
Leaf litter and rotting wood are the diet; everything else is a supplement. A little grated vegetable once or twice a week, courgette or carrot, lifted out before it moulds, and a small amount of protein now and then, less than a Porcellio would take, with anything uneaten lifted out before it turns: uneaten protein in a warm tub is how grain mites arrive. I feed a varied diet across the range because variety is what I have seen lift breeding across every species I keep, and our guide to feeding insects to isopods covers the protein side in more detail than a species page can. A culture of springtails in the same tub cleans up what they leave and keeps the damp end from turning.
Breeding: The Genus Pattern
This is a genus of pouch-brooders. Females carry the fertilised eggs in a marsupium under the body and release fully formed young, mancae. Across the genus the pattern is a brood every four to six months and young reaching breeding age at six to ten months, and I have no reason to think this species runs faster than that. The colonies that build are the ones left alone: warm room, dry-side gradient, calcium in, lid on. Start with twenty or more animals if you want a colony rather than a pair of survivors; our piece on how many isopods you need to start a colony explains why the number matters. If nothing has happened after six months, the breeding troubleshooting guide works through the usual causes; with this one, check the humidity first.
Who This Species Suits
The listing rates it medium difficulty and rare, and both are fair. The care is not hard, but it is a drier discipline than a first tub usually teaches, and the animals are scarce enough that a lost colony is not easily replaced. It is not a first isopod. Learn the gradient on a Magic Potion or a Zebra, then come to this. Where it earns its place is in a collection: it sits naturally with the other Mediterranean pill woodlice, the Clown and the Corfu Silver, and it is a textural counterpoint to the bright morphs rather than a competitor with them. Our guide to expanding your isopod collection is written for exactly that stage, and the complete Armadillidium guide puts the species beside the rest of the genus.
Frequently Asked Questions
Why is it called the Triceratops isopod?
For the crest on the head. The frontal shield, which is a low plate on most pill woodlice, is raised and scalloped on this species and shows three points from the front. It is a frill rather than a spike, and the adults carry it.
Where does Armadillidium hauseni come from?
Science knows it from one place: Paxos, a small Ionian island south of Corfu, which is the only locality in the published revision of the Greek species. Our animals are captive-bred in the UK from established stock.
Do Triceratops isopods need heating?
Not in a normally heated room. The band is 18 to 26°C and an English home over the heating season averages around 19°C, which is inside it. A cold unheated room in winter is the exception; there, a heat cable on a thermostat is the fix.
What humidity do they need?
50 to 70% with a gradient, and err dry. One damp corner of sphagnum, the rest allowed to dry between waterings, and enough ventilation that the lid never fogs. A wet, sealed tub is the way to lose them.
What colour are they?
Ours are pale: a peach to apricot ground with cream plate edges, pale legs and dark eyes, with a frosted, granular surface across the whole body. Juveniles are a paler yellow. The colour is soft rather than bright, so the appeal is shape and texture as much as pigment.
How big do they get?
Adults on our shelves run 15 to 20 mm. I have not found a published measurement for the species, so that is our own figure.
Are they good for beginners?
The drier care and the scarcity make them a better second or third Armadillidium than a first. A forgiving species teaches the gradient; this one rewards having learned it.
Every colony leaves us captive-bred, packed in a ventilated deli tub on damp sphagnum inside a double-walled box, sent Monday to Thursday by Royal Mail next day before 1pm with a 20% overcount and our live arrival guarantee. The Armadillidium hauseni listing shows what is in stock, and the tub, vents, leaf litter and calcium are all in our accessories range.
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