Trachelipus ratzeburgii Isopods for Sale

Disturb one and it stops. Where a Porcellio bolts and an Armadillidium shuts itself into a ball, this woodlouse presses down against the bark and holds still, and the German field literature notes the habit specifically. It is a woodland animal that has committed to not being noticed, and it works: the mottled dark grey-brown with pale flecks down the sides is exactly the colour of the wet oak bark it lives under.

Two corrections before anything else, both to our own page.

The handle on this listing spells the species rotzeburgi. It should be ratzeburgii - Trachelipus ratzeburgii, and Brandt put it in Porcellio when he described it in 1833, hence the brackets round his name now. The visible title is right and the URL is wrong, and that is on our list to fix.

The old copy also called the man Johann Theodor Christian Ratzeburg. The forest zoologist of that era was Julius Theodor Christian Ratzeburg. We have cut the sentence instead of correcting the forename, because no source we can find actually states that the epithet honours him - the English common name implies it, and nobody has written it down.

Range and size

Central European and strongly so: Germany and Austria account for the large majority of records, with Italy, France, Czechia, Switzerland, Hungary, Poland and Slovenia behind them. It is not a British species, whatever a stray record suggests, and our native member of this genus is T. rathkii instead.

On size, sources disagree. One gives females at 11.5mm, another 12 to 16mm. Our own older page printed a flat 15mm with nothing behind it. Somewhere around 11 to 16mm is the honest span.

The finer identification points, if you like that sort of thing: eyes of eighteen to twenty-five facets, rust-coloured hind corners to the coxal plates, strong tuberculation across the tergites that weakens towards the edges, and no median stripe down the back. It is almost exclusively a woodland animal, found under wood, bark and litter and only rarely out in the open.

It is worth being plain that this is not a British woodlouse, whatever the odd stray record suggests. The member of this genus that is genuinely resident here is T. rathkii, a different and commoner animal. If you have turned woodlice out of a Midlands log pile, you have not met this one.

Keeping

Cool. 18 to 24°C suits them and they tolerate the lower end better than the upper. This is a genuinely easy species for a UK room, needing no heat and no particular attention through winter.

Humidity graded across the tub, 60 to 75%. Structure is what they actually want: overlapping bark, flat stone, and enough leaf litter to vanish into. Substrate 5cm is ample since they are surface animals, not burrowers. White-rotted hardwood, permanent calcium, protein occasionally.

They will not roll up. The whole genus is built to cling and flatten instead, and if you push one it will grip harder before it will curl.

All of that is shelf practice; the tolerances of this species have never been tested.

Being a cool-running species this one travels well nearly all year, and we only pause in a genuine heatwave. Animals go out Monday through Thursday in an air-holed tub bedded on moist moss, inside a double-skinned box, plus 20% over the number your order shows, guaranteed to land alive.