Its true affinities within the family Armadillidiidae are yet unknown, but two hypotheses have been made:[1][4] Paxodillidium schawalleri is a small-sized species, reaching maximum dimensions of about 6 x 3 mm.

Its tergites are decorated with a number of conspicuously large tubercles: 4 on the posterior part of the head and on each pereion-tergite and 2 on each pleon-tergite and on the telson, along the mid-line.

The species is totally pigmenless, except for the eyes, which are black, or with some slightly pigmented areas on the head and pereion-tergites, the distribution and extent of which varies.

All of the epimera are kind-of flattened and protrude outwards and those of the first pair of pereion-tergites lack a ventral schisma/groove (a character present in Cyphodillidium, but absent in Echinarmadillidium).

The tubercles seem to increase the diameter of the rolled-up animal considerably, and, as such, put it outside of the prey-size spectrum of various predators, like lacertid lizards and geckos.