Porcellio succinctus 'Black Ribs' Isopods

It is a study in high contrast: a clean white skirt running the edge of the body, and bold black ribs banded across a dark back. Few isopods read as graphically as this one. This is Porcellio succinctus 'Black Ribs', also sold as the Black Rib, a large and rare Spanish Porcellio where the look really is the whole point. A pale white margin frames the dark dorsal surface, and across that back sit the bold black transverse bands, the ribs, that give the animal its name. Long antennae and elongated uropods finish the profile, so there is real presence here beyond the patterning alone.

Young animals are worth the wait as well. Juveniles start out almost entirely white with just a few dark dots, then build their banding gradually through successive moults, so an established group shows the whole range from pale youngsters to high-contrast adults. Like all Porcellio, the Black Ribs cannot conglobate: it is flat-bodied and will not roll into a ball, relying instead on speed and on wedging itself into tight crevices. It is a characterful giant, and it keeps good company. Set it alongside the giant Titan (P. hoffmannseggii), the aspirational P. magnificus, or the equally bold P. nicklesi, and browse the wider Porcellio collection or our guide to the different types of Porcellio to see where it fits.

Care follows from its origins. This is a dry Spanish Porcellio, happiest at warm room temperature of roughly 18 to 25°C, and it wants to be kept on the drier side. Aim for a clear moisture gradient: dampen one end and let the rest dry out, so the colony can choose its comfort zone rather than sitting in a wet box, which it will not tolerate. Pair that with medium to high ventilation, plenty of cross-flow through mesh vents, so the air never turns stagnant and the dry end stays dry.

Give it a deep substrate to suit a large species: a well-draining mix with flake soil worked through, topped with a thick layer of leaf litter and rotting hardwood. Large magnolia leaves hold up well and double as food and cover, and with the rotting wood they make up the bulk of the everyday diet. Leave calcium in permanently, cuttlebone or crushed limestone, because a woodlouse this size needs it for its big moults, and offer a little protein regularly, as Porcellio are protein-hungry and grow and breed better for it. Space and cover matter too: this is a big, sometimes territorial animal, so give it room and plenty of bark and crevices to spread out. A springtail clean-up crew helps keep any damp corner free of mould.

Breeding is a steadier, slower affair than you will find with the weedy tropical species that flood a tub in months. Females carry their young in a marsupium and release them as miniature white juveniles, and a colony builds at an unhurried pace once it settles. Keep the conditions stable, the calcium constant and the protein regular, and patience does the rest: this is a slow build rather than an explosion, which is part of the appeal.

Your Black Ribs are captive-bred and travel well packed. Each order goes into a ventilated tub of damp sphagnum inside a double-walled box, dispatched Monday to Thursday by tracked next-day Royal Mail for delivery by 1pm. Every parcel carries our live-arrival guarantee, and we add a 20% overcount as standard, so you can settle your new colony in with confidence.