Armadillidium nasatum 'Dalmatian' Isopods

Dalmatian Armadillidium nasatum are born without their spots. Mancae leave the pouch plain, and a 1969 breeding study found young nasatum begin to colour at about two months, so a tub of juveniles looks very little like the adults in any photograph. Anyone buying young stock should know that in advance. The pattern is on its way, but it is not there on the day the parcel lands.

What arrives is worth understanding, because this morph does not work the way most colour morphs do. Breeders describe the dalmatian mutation as working by subtraction: it suppresses pigment across the body and lets colour survive only in islands, so the animal in front of you is a depigmented one with pigment remaining in spots, not a normally coloured one wearing pale markings over the top. Most carry black spots and patches on a paler ground, while some individuals throw brown instead. Adults finish at 12 to 16mm, and sub-adults will breed before they reach full size. In the United States the same morph is usually traded as 'Pearl', though that name also covers paler, nearly white stock.

No study we know of covers how the pattern is inherited in A. nasatum, so the genetics you will read are breeders' working accounts rather than findings, and they disagree: some treat it as recessive, others as semi-dominant. The practical part is agreed: left to run on its own, a colony drifts back towards ordinary animals, so the line has to be selected and maintained deliberately, generation after generation, by whoever is keeping it. Ours are captive-bred here in the UK.

Armadillidium nasatum Budde-Lund, 1885 is the Nosey Pill-Woodlouse, named for the rectangular protrusion towards the front of the head that separates it from A. vulgare. Listings repeat one thing about it that will not hold up. Nasatum does not close into a complete ball. It partially encloses when disturbed, tucking down without ever sealing shut the way A. vulgare manages. How much of them you will see is something keepers disagree on: some see them roaming the litter in daylight, others find them shy and mostly about after dark.

Conditions

This is not a damp species, whatever the rest of the genus might suggest. The wild animal lives in drier ground than most woodlice and it will not thrive in a saturated enclosure. What is true is that it tolerates a wider humidity band than most Armadillidium, roughly 45 to 80 per cent, which is a different claim and a more useful one. Build a gradient, not a level, with about a third of the floor kept moist and the rest left dry, then let the colony choose. Medium ventilation keeps the dry end dry. Temperature ideally sits at 18 to 24°C, and an English home averages about 19°C over the heating season, so a heated room covers most of the year. If you want young through the winter, add a low-wattage heat mat or heat cable on a thermostat, fixed to the side of the tub and never underneath.

Underneath, 5 to 8cm of nutritious base substrate, enough for a species that shelters under things far more than it digs, then dry hardwood leaf litter in quantity over the top and bark for cover. Leaves are the constant food here, and the layer should never be allowed to vanish. Keep calcium available permanently, cuttlebone or crushed shell worked through the soil, and add the occasional vegetable scrap or pinch of dried protein on top of that. Growth is normal, breeding is dependable, and the species forgives most beginner errors, which makes it a sound first Armadillidium as well as a dependable clean-up crew. The wild-type nasatum is the parent stock, and the Orange and White lines share the same shape and the same husbandry. For pattern that reads a different way on the eye, the Zebra wears dark bands across a pale ground and comes off as stripes where this one comes off as spots, while Magic Potion is a multi-toned line of A. vulgare, a different species. Our Armadillidium care guide goes further, and the rest of the Armadillidium we keep is worth comparing. The Armadillidium nasatum care guide covers the species on its own, the Pearl name included.

We post Monday to Thursday so that no colony of ours sits in the network over a weekend. Damp sphagnum goes into a ventilated deli tub, and that tub sits within an outer of double-walled cardboard. It travels by Royal Mail on the service you chose at checkout, Next Day or Tracked 24. You will find surplus animals in with the group you paid for, and live arrival is guaranteed on every order.