[3] This genus is distinguished by the position of the ozopores, the shape of the ocelli and the gonopod legs, the presence of accessory claws on the juveniles, and the presence in males of a large fovea, a cavity where sperm are stored.

[1] Familiar species include the black Portuguese millipede (Ommatoiulus moreletii).

It is an invasive species in Australia known for its "plagues", when it emerges in swarms so massive that they stop trains, which crush them in huge numbers and make the rails slippery.

Like some other millipedes, it produces a secretion with an obnoxious odor and tendency to stain floors when the swarms invade houses.

In 2002 it flooded the streets of Dąbrowa Górnicza in Poland, "causing panic among the inhabitants".