Armadillidium nasatum 'Dalmatian' Isopods

Dalmatian Armadillidium nasatum are born without their spots. Mancae leave the pouch plain and the black patterning comes in over the following weeks and moults, 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. The dalmatian mutation works 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 some places the same morph is traded under the name 'Pearl'.

The gene is recessive, and in A. nasatum it is male sex-linked and only weakly expressed on top of that, showing in roughly one male in ten across a culture. 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 nosed pillbug, 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. Behaviour is otherwise ordinary for the genus, quiet under bark by day and out across the litter 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 honestly dry. Temperature wants 15 to 28°C, which is UK room temperature all year with nothing switched on.

Underneath, a nutritious base substrate deep enough for an animal to bury itself out of sight while it moults, 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 prolific, 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 the same dalmatian mutation understood to run in A. vulgare. Our Armadillidium care guide goes further, and the rest of the Armadillidium we keep is worth comparing.

Nothing goes out after a Thursday. Monday to Thursday is the whole posting window, deliberately so: it means no colony of ours is left standing in the network across a weekend. Damp sphagnum goes into a ventilated deli tub, and that tub sits within an outer of double-walled cardboard. The service is Royal Mail tracked next-day, so the box should reach you before 1pm. You will find surplus animals in with the group you paid for, and live arrival is guaranteed on every order.